A bad climate for endangered species?

Posted on 14 February 2013

Warming worries: Wolverine may get endangered status

On Feb. 1, 2013, the U.S. Fish and Wildlife Service proposed adding the wolverine — a tough, reclusive carnivore that lives in the snow in the Rocky Mountains — to the endangered species list. About 300 of these weasel relatives survive amid the heavy snows and severe climate of the high mountains, but global warming is melting their habitat.

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Photo: Andrew Gainer

Wolverine at an outdoor museum in Skansen, Sweden. Wolverines in the western United States are growing scarce, likely due to a warming climate that is decimating the snowy habitat they require.

The International Union for Conservation of Nature (IUCN) lists 10,820 animal species worldwide. The group’s “Red List” does not distinguish endangered from threatened species.

And now comes the accelerating threat of global warming, a planet-size problem that is sure to make matters worse for rare species in many places and cases. Polar bears and corals have already entered the list of species in danger due to the global changes wrought by greenhouse gases, and more species are doubtless coming, due to changes in precipitation, temperature, disease, ocean acidity, and the timing of flowering, fruiting, migration and the very seasons on our planet.

The Wolverine — no relative of the wolf — is perfectly adapted to the snow, with paws serving as natural snowshoes and dens deep below the snow that are warmed by the lack of wind and insulation from the snowpack. The animals “use snow as a natural refrigerator, caching their food in natural ice boxes,” to sustain them as they bear and nurse their young, says Jonathan Pauli, an assistant professor of wildlife ecology at the University of Wisconsin-Madison. “They are losing this natural refrigerator, which is really problematic because it affects this nutritional pinch point in early spring.”

The wolverine and other snow-dependent mammals are on a collision course with a warming climate, says Pauli. “The winter climate in particular in the Northern hemisphere is changing dramatically. In the last 100 years, we’ve seen an increase of three-quarters of a degree Celsius, and what’s especially relevant is the shortening of the duration and depth of the snow cover. The snow season is being compressed,” he says.

Graph showing average global temperature rising since ~1910; rising above 1901-2000 average in 1970.

The signature of global warming can be traced to about 1980. All of the top 10 warmest years, including 2012, occurred after 1997.

National Climatic Data Center

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Courtesy Jim Woodford

The American marten is a carnivore that spends a lot of time under the snow. Efforts to reintroduce the marten in Wisconsin have faltered, possibly due to a changing climate.

The American Marten is another winter specialist that hunts mice under the snow, but some populations are in trouble. “They are a winter-adapted carnivore,” says Pauli. “They are light and their feet, like the wolverine, are a natural snowshoe” that saves energy. Sinking into deep snow is tiresome and “can put you on the nutritional redline. It’s not just exhausting, it can be deadly.”

The American marten was extirpated from Wisconsin in the 1920s, and reintroduced in the 1950s and again in the 1970s, but they are not prospering, and one possible explanation is the truncated snow season, Pauli says.

Turning turtles

It’s tough to pinpoint the role of a changing climate on endangered species. After all, as pioneering ecologist Barry Commoner said, the first law of ecology is that everything is connected to everything else; nothing exists in isolation. “I don’t know how much hard data there is on a lot of species relative to climate change,” says Scott McRobert, professor of biology at Saint Joseph’s University in Philadelphia. “Although it is probably causing dramatic effects to a large number, it’s hard to isolate climate change from other factors.”

That calculus is evident in the leatherback marine turtles which “have declined exponentially since we started studying them in 1989,” due to hunting of turtles, gathering of eggs, and fishing gear that snared turtles as “by-catch,” says James Spotila, professor of environmental science at Drexel University.

Changing climate is fueling more of the periodic warmings in the central Pacific called el Niño, Spotila says. “When the Pacific warms, there is less [nutrient-rich] upwelling, so the turtles have a harder time getting food,” which impairs growth and reproduction, he says. “Our studies and mathematical model show they will be gravely affected by a changing climate, and it’s starting now.”

Leatherback sea turtles: from eggs to hatchlings

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Photo credits: 1) Daniel Arndt, 2) rustinpc, 3) rustinpc, 4) Crazy Creatures, 5) David Knight, 6) jimmyweee, 7) Ken Clifton, 8) Ken Clifton.

Leatherbacks and other marine turtles face a second difficulty related to warming: The sex of hatchlings is determined by temperature while the egg develops; when it’s hotter, more females develop. The result is that most turtles developed from eggs laid in January and February are female, says Spotila.

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Biodiversity Heritage Library

Hemignathus procerus, or Kauai akialoa, is endemic to the island of Kaua’i, Hawai’i. The endangered honeycreeper eats insects and sucks honey from tube-shaped flowers. Over two centuries, Hawaiian honeycreepers have suffered many assaults and extinctions. According to a 2011 study, avian malaria is spreading as global warming expands the habitat of its mosquito vector.¹ Looking at data on more than 3,000 bird species from seven decades, the authors linked a two- to three-fold increase in bird malaria to about 1°C temperature rise.

On Colombia’s Caribbean coast, 92 percent of leatherbacks are born female in some years, and the temperature anticipated for 2050 will make virtually all of them female. Indeed, a 2012 study.² warns that “complete feminization could occur, as soon as the next decade.”

Without males, a population crash is inevitable.

Heat by itself is also a problem, says Spotila: “As the season progresses, the hatchlings become weaker and more heat stressed. In April [on Costa Rica's Pacific Coast], there is very low hatchling success due to heat stress.”

Climate change is “a giant bummer,” Spotila says. “We spent 23 years setting up Las Baulas National Marine Park, protecting the beach, and getting a handle on fishing. … The overwhelming effect of global warming is going to make life even more difficult. We are going to see species after species getting these problems.”

Walking that long Amazonian road

In the vast tropical forests that survive in Amazonia, climate change will scourge many habitats, according to a new study.³ Kenneth Feeley, assistant professor of biology at Florida International University, asked how far residents of large ecological situations — biomes — would have to move to find suitable habitat by 2050. “The classic way has been to look at the effect of deforestation or fragmentation as almost one field of conservation biology, and a separate field of climate change ecology,” Feeley told us. “There hasn’t been that much study of both simultaneously.”

Feeley combined these threats. “We looked at the conditions you find in a spot in the Amazon, and asked where would you have go to find the same temperature and precipitation” in 2050, he explains.

And he then blocked off areas that would require traversing large, deforested areas. Already, he notes, many Amazonian animals “are really hesitant to cross a break, a trail, a road or a river,” so requiring animals to avoid deforested areas “shows the true distance that a species has to move.” Large-scale deforestation “creates environmental traps for species, because there is no way to reach the future climate area without crossing a deforested area,” Feeley says.

In many cases, he says, animals would have to travel “off the map.”

Minimum distance to suitable habitat in Amazonia, 2050

Left: Map of Amazon for 2050. most organisms will have to migrate at least 200 kilometers to find suitable habitat.

Map at left shows how far species would have to move to find today’s climate after expected changes in temperature and precipitation. Map at right adds in effects of deforestation. Because most organisms cannot cross farm fields, they will have to travel much further to find livable habitat. Organisms now living in the black zones will be homeless.

Both maps used with permission; Feeley and Rehm. Amazon’s vulnerability to climate change heightened by deforestation and man-made dispersal barriers. Global Change Biology. Blackwell Publishing Ltd.

We commented that his maps were profoundly depressing, and Feeley cheerlessly reframed them as best-case scenarios. Organisms, he noted, are inter-dependent: If bird A is needed to pollenate flower B, “that just compounds the difficulties, because both have to arrive simultaneously. And they might depend on a third species. If they do not all arrive simultaneously, it might be impossible for each species to be there.

“The forecast for Amazon biodiversity is really grim,” says Feeley. “Our only hope is that we are wrong.”

What to do?

Scientists are starting to test some tentative fixes for the biodiversity ravages blamed on a changing climate. Many proposals favor preserving more habitat, while choosing more selectively. “We can envisage ways to manage land cover that would mitigate or reinforce the changes we expect,” says Pauli. For example, “Different land-cover types can have a strong effect on ambient conditions in winter; areas with forest cover can have much more moderate temperature than open areas.”

Here are some other ideas we culled from a survey of the changing landscape of hot-world biodiversity preservation:

✻ Mapping migration

The new maps of Amazonia could help in designing migration corridors so species can move as climate changes, says Feeley. “If we know this area will be lost to agriculture, can we plan to place corridors in the most effective places? A lot of the focus in conservation has been on preserving parks, assuming static conditions. Now we are talking more about the need to protect areas to allow species to respond to climate change,” he says.

✻ Change the habitat

Since temperature controls the sex ratio in leatherbacks, Spotila and others are testing whether fresh-water sprinklers and sunshades can cool the beach in Costa Rica to stabilize the male-female ratio and improve hatching success. “We are doing the experiment now, trying to determine which of those options will work,” he says.

Aided by the Climate Adaptation Fund, the Grand Canyon Trust is reintroducing beavers into 87 stream segments in Southern Utah. Rollover to see the change one year later: the new beaver pond has already drowned invasive plants while creating habitat for native plants and animals. Check the video.

First: July 2011, photo by Natalie Jamerson, Whitman College; second: September 2012, photo by Allison Bolgiano, Whitman College

✻ Put wildlife to work!

Beaver dams naturally store water, replenishing aquifers and restoring wetlands for wildlife, while reducing floods and the effects of drought. Now, after centuries of trapping, beavers are returning (via foot or truck) to various landscapes, including the arid Southwest, faced with drought and highly erosive floods in the changing climate.

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Photo by Peter Shanks

The beautiful blue-tongued lizard, under threat from habitat disturbance and a changing climate, could be moved to better habitat around its native range in southern Australia.

✻ Trucking to a better home?

Moving animals to habitat that remains hospitable in the new climate may be a last resort for animals like the endangered blue-tongued lizard, whose native grasslands in South Australia have been transformed by farmers and now climate change. Some scientists have proposed building artificial burrows for the lizards, and even moving them to new locations where the future’s climate should be more benign. “Although we recognize the importance of conservation efforts to improve the quality, connectivity and permeability of the species’ current habitats, the rapidity of climate change will continue to exceed the ability of some species to adapt or disperse to more climatically favorable regions,” wrote the authors of a 2012 relocation study.⁴

✻ More shelter from the storm

Captive breeding has been used to sustain whooping cranes and other animals threatened with extermination in the wild, and McRoberts keeps several endangered turtles from Asia or South America in “assurance colonies” in his lab. “At least we can keep some of them alive in the hope that there might be places where they could live in the wild,” he says. As McRoberts recognizes, captive breeding could deflect time and energy from habitat conservation. “Even as someone who does it, I am not saying it’s an optimal way of saving species, but I don’t see it detracting from survival in the wild,” he says. “It’s best to approach any conservation issue from as many different points of view as you can.”

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Geoclemys hamiltonii, AKA black pond turtle or black spotted turtle, in the McRoberts lab. These threatened turtles eat snails and fish in rivers and ponds with abundant aquatic vegetation in India, Pakistan and Bangladesh.

Courtesy Scott McRoberts, Saint Joseph’s University

Endangered Species Act to the rescue?

Our story started with the potential listing of the wolverine under the Endangered Species Act, a pioneering law premised on the avoidance of extinction. But a 2012 study⁵ of ESA plans for endangered species in the American West found that “few [climate] adaptation projects have made it to the implementation phase,” due to budget constraints and lack of specific direction from the government agencies involved.

Newer habitat conservation plans should pay more attention to climate, says study author Paola Bernazzani, of the Ohio consulting group ICF International. “There are some good plans coming out in the future, but since we looked retrospectively, there was not anything that did a good job,” she says.

The inability to pinpoint the details of future climate and habitat should not excuse the failure to plan for changes, Bernazzani says. “We admittedly don’t know everything we would like to know to plan for 30 or 50 years, but … the Endangered Species Act was written to anticipate flexibility by calling for adaptive management.”

In a forthcoming plan, Bernazzani says, her company is using computer modeling to explore how fish will move through hydroelectric dams: “We are able to alter the scenarios to fit different climate-change assumptions, and we’ll test them. It’s like a fire drill — you know before implementation what are some potential outcomes.”

Habitat plans may also require establishing preserves to buffer against climate change, Bernazzani says, but the reality is that “we are talking about species that are already rare, and adding one other pressure on top, and I am not sure all the conservation planning in the world is going to solve that.”

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Photo: Samuel Chow

Coral “bleaching” was one of the first recognized biological damages of global warming: When water warms, the coral animals expel the symbiotic partners that feed them, and the coral turns white. Unable to eat, the coral can die if temperatures stay too warm. Bleaching has started in the center of this coral in Indonesia, but coral remains alive around the edges.

The bottom line

Back in the 1980s, climate change was tomorrow’s trouble. Not any more. “There is no question that climate change poses an unprecedented challenge to biodiversity,” says Pauli, the mammologist at the University of Wisconsin-Madison. “It’s one of the biggest conservation crises we are facing.”

To a specialist in winter ecology such as Pauli, the truncation of the snow season “is challenging and frustrating, but it does provide an opportunity to understand the winter system; it’s an experiment that unfolds in real time.”

The reality is that the disruptions due to climate change are seamlessly connected to everything else, says McRoberts. “It’s always very difficult to say a species is encountering difficulty from one direction, and every endangered species is also encountering other problems, habitat destruction being the primary one,” he says.

McRobert agrees that it can be daunting for people who have worked for decades to preserve biodiversity to gird themselves to combat a threat with a global reach. “There are so many issues that you can be overwhelmed easily,” he says. “If you are worried about habitat for endangered species, you should keep working on that” instead of worrying specifically about climate change. “It’s hard to address everything at once.”

David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Climate change increases the risk of malaria in birds, Laszlo Garamszegi, Global Change Biology (2011) 17, 1751–1759, doi: 10.1111/j.1365-2486.2010.02346.x ↩
A potential tool to mitigate the impacts of climate change to the Caribbean leatherback sea turtle, Juan Panito-Martinez et al, Global Change Biology (2012) 18, 401–411, doi: 10.1111/j.1365-2486.2011.02532.x ↩
Amazon’s vulnerability to climate change heightened by deforestation and man-made dispersal barriers, Kenneth J. Feeley et al, Global Change Biology (2012) 18, 3606–3614, doi: 10.1111/gcb.12012 ↩
Managed relocation as an adaptation strategy for mitigating climate change threats to the persistence of an endangered lizard, Damien Fordham et al, Global Change Biology (2012) 18, 2743–2755, doi: 10.1111/j.1365-2486.2012.02742.x ↩
Climate change and western public lands … K.M. Archie et al, Ecology and Society, 17:(4) 20, 2012 ↩
Slideshow:Great extinctions and great species recoveries featured at the Natural History Museum in London ↩
USGS Scientists answer questions about climate change in the mountains ↩
Who fades first? Pikas: the climate change sentinel species ↩
Worried about trout? See how they fare under climate change preditictions ↩
Hungry for more leatherback facts? ↩

Tracking frozen methane

Posted on 25 October 2012

Melting methane: New thermometer for ancient ocean?

A staggering amount of natural gas is trapped under the edge of the continental shelf, frozen in a substance called methane hydrate. When this solid material warms, it breaks down and releases methane, a powerful greenhouse gas.

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From original diagram by United States Geological Survey

Methane stabilizes in hydrate where pressure is high and temperature is low, often under the seafloor. Oceanic methane hydrates could hold 500 to 2,500 billion tons of carbon — up to half as much as the estimated 5,000 billion tons held in other fossil fuel reserves.

The ongoing warming of the ocean could release this methane into the atmosphere, starting a nightmare feedback: warming releases methane, which begets more warming, which releases more methane.

But the hydrates are trapped under remote ocean bottoms. They are so difficult to study that basic data is scanty, even on “simple” matters like temperature. A study published this week, however, shows that methane hydrates themselves can tell us about ocean temperatures long ago.

Because Earth gets warmer with depth, methane hydrates can only exist in a sliver of the seafloor where the pressure is high and temperature is low. Below that, the rocks are so warm that methane can only exist as a gas.

It is this relation among temperature, pressure and the physical state of the methane that was used as a retrospective thermometer in the new Nature study.

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May 2010, CSSF/NEPTUNE Canada

Methane bubbles up from seafloor off the coast of British Columbia, as scientists monitored changes in hydrate distribution, depth, structure, properties and venting, due to earthquakes, slope failures and plate motions.

To begin, Benjamin Phrampus and his thesis adviser, Matthew Hornbach, an associate professor of earth sciences at Southern Methodist University, used seismic data — the reflections of sound waves that reveal Earth’s inner structure. Sound waves change speed at the bottom of the hydrate layer, where rocks holding solid gas hydrate transition into warmer, deeper rocks that contain gaseous methane.

Going down

As the warm Gulf Stream passes over the site, Phrampus says, its heat slowly penetrates downward through sediment, rocks and methane hydrate, eventually reaching the bottom of the hydrate layer. But when the scientists used today’s water temperature to calculate where that lower boundary should be, it was not at that depth.

The reason, Hornbach and Phrampus concluded, was warming water, likely due to a change in the location of the Gulf Stream. “The essence of our argument is that the water we are seeing today is warmer than what we would expect, based on the stability regime we see on the continental margin,” Phrampus told us.

The calculated warming came to about 8°C, and started very roughly 1,000 years ago. The warming signal is likely to continue for another 4,000 years, Phrampus says. Over that 50-century period, 2.5 billion tons of methane could be released from hydrates in the 10,000 square kilometers of a Carolina tract.

Although that is equivalent to about 23 percent of the carbon released in one year through fossil fuel combustion, methane hydrates in other places are probably adding to the global release of methane.

Methane molecule diagram centered in pentagonal water molecule cage.

Credit: National Energy Technology Laboratory

Methane molecules in methane hydrate, AKA methane clathrate, are trapped in a cage made of water molecules.

Contemplating collapse

The Carolina Ridge was the site of a massive landslide — roughly 14,000 to 30,000 years ago — and a future collapse could feed on itself as hydrate breaks down, destabilizing the seabed and releasing more methane from hydrate (and perhaps from methane gas stored below the hydrate zone). As Phamprus and Hornbach note, “If continuing hydrate destabilization triggers slope failure at this site, the amount of methane released could be an order of magnitude greater.”

Methane hydrates are one of the big unknowns in geoscience, and they are inherently difficult to study, according to Arne Biastoch, who has studied the interplay between ocean conditions and Arctic hydrates at the GEOMAR Helmholtz Centre for Ocean Research, in Kiel, Germany. “The temporal evolution of the temperatures in the deep ocean remains highly uncertain; most studies, therefore, work with vague estimates, which naturally result in highly uncertain figures for the affected gas hydrate.”

Biastoch says better numbers are needed to evaluate the importance of stored methane in affecting the atmosphere and ocean. “Especially in the light of increasing temperatures under global warming, solid estimations are needed to study potential threats arising by out-gassing (enhancing climate warming), slope instability (triggering tsunamis) and ocean acidification (affecting the oceanic biosphere).”

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Credit: CSSF/NEPTUNE Canada

The study of gas hydrates requires rugged research rigs. This machine is sampling 865 meters below the ocean’s surface, a depth greater than the height of nine Statues of Liberty.

A need-to-know basis

Although some of the released methane will be eaten by ocean bacteria and never reach the atmosphere, that could feed a different problem: acidification of the ocean. Why? Because the critters that eat the methane-eating bacteria will decay, releasing carbon dioxide dissolves in water, making the ocean more acidic and weakening the shells of clams and other crustaceans.

However, the biggest fear is that massive releases of methane could trigger a warming episode like the Paleocene–Eocene thermal maximum. About 55 million years ago, the global temperature rose 6°C after thousands of billions of tons of carbon entered the atmosphere.

Although the Carolina Rise alone would only add 0.2 percent of the carbon needed to rerun that epoch, “This only represents a fraction of the global estimated inventory of gas hydrates,” Biastoch notes. And it’s hardly the only source of carbon dioxide entering the atmosphere …

– David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Recent changes to the Gulf Stream causing widespread gas hydrate destabilization, Benjamin J. Phrampus & Matthew J. Hornbach, Nature 25 October 2012. ↩
What else is down in the deep sea? ↩
Gas hydrate climate crisis? Probably not. ↩
The potential of methan hydrates for energy ↩
Gas hydrates 101 ↩

West Nile virus running wild

Posted on 30 August 2012

West Nile virus: Return of a killer

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Photo: Pete DeVries

Culex pipiens, the Northern house mosquito, is the primary vector of West Nile in the Midwestern United States.

For years, it’s been absent from the headlines. By now in 2012, 1,118 Americans have been diagnosed with West Nile, and 41 have died. On Aug. 22, Houston, Texas, announced it would start airborne insecticide sprays to kill mosquitoes and reduce infections.

And public health authorities are warning about the disturbing “neuroinvasive” infections — which can cause stupors, disorientation, even permanent paralysis.

So let’s put on some long pants and shirts, slather with mosquito repellent, and stay inside at dusk and dawn, when infectious mosquitoes are most active.
And then let’s ask, what accounts for the recent rise in cases and deaths from West Nile? What is the long term picture of this emerging infectious disease?

The first human cases of West Nile were identified in Israel in the 1950s; the disease has since spread throughout the Middle East, North Africa and Europe. West Nile reached the United States in 1999 with an outbreak in New York.

U.S. cases of West Nile virus

Data from: Centers for Disease Control and Prevention

U.S. cases of West Nile have declined since a peak in 2002-3. That uptick in fatalities and neuroinvasive cases will continue, as West Nile is usually worst in late summer and early fall. Not shown: total diagnosed cases reached 9,862 in 2003.

A variable virus

West Nile causes no symptoms in 80 percent of people. Another 20 percent of infected people have general viral symptoms like fever, headache, body aches, nausea, and perhaps swollen lymph glands or a skin rash. About one person in 150 develops the neuroinvasive variety, which can include high fever, headache, stupor, coma, convulsions, muscle weakness, vision loss, numbness and paralysis. An estimated 3 million Americans have been infected. Most did not notice the disease, but likely gained at least some immunity after recovery. Source: CDC.

This year’s upturn was not entirely shocking, says Tony Goldberg, professor of pathobiological sciences and epidemiology at the University of Wisconsin-Madison School of Veterinary Medicine. “I was surprised at how extraordinarily high the numbers are, but my colleagues and I did predict this would be a high year for West Nile. We had a perfect storm of weather events that made us think it might be a good transmission year. There was a mild winter so more of the overwintering mosquitoes survived, then wetter conditions in the early spring [which fostered mosquito reproduction] followed by hot and dry spring and summer.”

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Courtesy Tony Goldberg, University of Wisconsin-Madison

The only good skeeter is a dead skeeter. These corpses were collected during studies of West Nile transmission in Chicago suburbs.

Culex pipiens — the northern house mosquito — is the primary vector in the Midwest, says Goldberg, who has studied West Nile near Chicago for 10 years with National Science Foundation funds. “It breeds in standing water containing fermented organic material, exactly what we see in abandoned swimming pools, unclean gutters, bird baths and storm sewers — where water accumulates in wet weather in early spring. Then, when it’s hot and dry, the water sits there, and the eggs develop.”

Ironically, the droughted spring and summer helped C pipiens, since stormwater could not wash their larvae from the storm sewers, Goldberg says.

Blame the robin

Goldberg and colleagues have just shown that the American robin is the “super-spreader” of West Nile in the Chicago suburbs. “Gabe Hamer [now at Texas A & M University] led our effort to figure out what the mosquitoes in Chicago were feeding on,” says Goldberg. “He trapped a lot of mosquitoes, picked out the ones carrying blood, and did DNA sequencing to figure out what they were eating.”

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Photo: Wanderdrossel

Around Chicago, the American robin is the major source of West Nile virus in mosquitoes, which tend (ecch!) to bite around the eye.

The result, he says, was a long list of mammals, birds, and a few amphibians, “but we were able to calculate that the robin contributes more to the transmission of West Nile than any other species.” (Goldberg is quick to stress that he opposes any vendetta against an archetype of the front yard.)

There are still questions about mosquito vectors for West Nile. To transmit the virus, a mosquito must parasitize birds, not mount an immune attack on the virus, and then bite a person, and these characteristics can vary from place to place. “We are doing a lot of work on which mosquito feeds on people in Madison,” says Susan Paskewitz, a professor of entomology at University of Wisconsin-Madison, who monitors mosquitoes for health departments. “It’s hard to get C pipiens attracted to humans here; there may be subtle population differences in behavior in Madison versus Chicago, and we want to understand why.”

Courtesy Tony Goldberg

This innocent-looking storm drain in the western suburbs of Chicago hides a breeding-ground nightmare for West Nile vectors. Rollover: Notice the soggy, decaying organic crud? That’s home sweet home to C pipiens mosquitoes!

Turning up the heat on infection

Like drought, heat plays a direct role in mosquito transmission, says Edward Walker, a professor of microbiology and entomology at Michigan State University. Newly hatched mosquitoes must be infected by drinking blood from an infected animal and so cannot harbor West Nile.

Even then, the bug cannot immediately spread the infection. “The virus has to incubate in the mosquito’s body and spread from the stomach to the salivary glands,” says Walker. “A mosquito spits on you before biting, and its saliva carries the virus.”

The incubation period depends on environmental temperatures, Walker adds. As insects are cold blooded, the movement into the salivary glands happens more quickly in hot weather, which helps explain why West Nile infection rates peak in late summer, and why the record heat of the last year may be propelling infection rates. (In land in the Northern Hemisphere, July 2012 was the warmest July on record, 1.19°C above average.)

One persistent virus

To slither back to the slimy subject of mosquito spit: Kristen Bernard, an associate professor of pathobiological sciences at the University of Wisconsin-Madison, has found a higher level of West Nile virus among mice that were infected by Nile mosquitoes, compared to infection through injection. She suspects that the saliva carries a chemical that hobbles the host immune system.

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Credit: Pete DeVries

Culex pipiens, the Northern house mosquito, is a key vector of West Nile in parts of the United States.

Considering the high number of neuroinvasive West Nile cases this year, we were disturbed to hear that West Nile isn’t always “cleared” by the body as once thought. Bernard found West Nile in mice up to six months after the symptoms ended — although the virus did eventually disappear.

Bernard did find immune cells that target West Nile in these mice, but they were dormant. The immune system must be tightly controlled to prevent auto-immune disease, she notes, and “I think for some reason the immune cells are being kept in check a little too much.”

In people, West Nile can persist and cause disease in the kidney, and has been detected six years after infection in the urine of people who think they have recovered, says Bernard. “There is a lot of data showing long term consequences years later, with cognitive problems, memory loss, weakness, malaise. People just don’t feel right.”

It’s unclear if these problems result from the initial damage, or from continued viral activity, Bernard says. “There is a good chance that there could be some persistence in the human central nervous system, but we don’t have evidence.”

Texas blues

Why are Texas and nearby states the epicenter of infection this year? An epidemic of infectious disease is often most intense at first, when it confronts an immune system that has never mounted a defense against it.

That surge-and-decline pattern surfaced when West Nile reached New York in 1999, and was repeated as it marched across the country. But Texas “is such a weird anomaly” because it had already seen West Nile, says Hamer, a clinical assistant professor of entomology at Texas A&M. “After West Nile has been here so long, to have such a big epidemic is just strange.”

West Nile by county, August 21, 2012

Credit: CDC

A cluster of reports from Texas, Louisiana and Mississippi are the epicenter of the 2012 West Nile epidemic. A county is shaded if it has any reports of West Nile.

Why the difference?

✘ Mosquito control practices: larva-killing chemicals are used less commonly in the South than in the Midwest and East.

✘ The immune situation in birds: With few people infected in Texas in 2011, it’s unlikely that many birds were exposed that year, either. If few birds now have antibodies against West Nile, they would be more susceptible to the virus.

✘ The weather in Texas: “Last summer, Texas was extremely hot and dry, it broke a lot of records,” Hamer says. After a mild winter, spring 2012 brought “a ton of rain, and now it’s a typically hot and dry summer. This combination of conditions that has never occurred in the last 10 years was conducive to West Nile.”

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Courtesy Susan Paskewitz and Karli Reifschneider

Introducing fish and small animals called copepods could biologically control the mosquitoes that carry the West Nile virus. Here, University of Wisconsin-Madison students check Madison sewers for copepods and mosquito larvae.

Praying for spraying

Vaccines can defeat many viruses, and one already protects horses from West Nile. However, “vaccinating the human population is not considered the most effective way to control West Nile,” says Goldberg. “The vast majority of infections are asymptomatic. There are cost issues and side effects, and the people who are most susceptible to West Nile tend to be elderly or immuno-compromised, and might not respond well to the vaccine.”

Instead, Goldberg favors a traditional tactic against mosquito-borne illness: Vector control; killing carrier mosquitoes. “An ounce of prevention is worth a pound of cure,” he says. “If we could get rid of breeding habitat, that would solve the West Nile problem. Everybody knows where the mosquito likes to breed, C. pipiens breeds in standing water with organic material. They can breed in very small puddles, gutters and abandoned swimming pools.”

Here, public health meets economics: the moribund housing market has converted thousands of homes — together with their swimming pools — into mosquito factories. “The foreclosure crisis has led to a disease emergence problem,” Goldberg says.

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Photo: 2005, Pelham Bay Park, Bronx, New York, Kyrion

New York City responded to a West Nile epidemic by killing mosquitoes that transmit the virus by spraying insecticide from trucks.

The classic anti-mosquito tactic is to drain wet spots, and spread larvacide to kill mosquito larvae on marshes and other wet places that can’t be drained. But faced with West Nile, authorities are spraying adult mosquitoes, especially in Texas, site of roughly half of U.S. West Nile infections.

The logic of killing adults emerges from the biology of vector and virus, says Walker. “Spraying adults with insecticide is a highly rational approach, as it kills the older mosquitoes on the wing, and the older ones are more likely to have the virus infection.”

A spray program in Dallas, during a 1966 outbreak of St. Louis encephalitis, cut the infection rate from one mosquito in 167 to one in 28,000, says Walker.

A 2002 study in Michigan found that the risk of West Nile was 10 times higher outside a five-county mosquito-control area. But in general, it’s difficult to prove that mosquito controls reduce the West Nile rate, Walker says. “Epidemiologically there is some evidence that spraying reduces human infections,” but a careful study would be forced to test many people for West Nile for several years.

“Passive case detection,” asking public health authorities to report illness, is unlikely to prove that spraying works, he says, just as it is unlikely to show that bed nets prevent malaria. Lengthy studies that actively monitor blood samples do prove the benefit of bed nets, however.

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Photo: Wikipedia

Macrocyclops albidus, a copepod, is a ferocious consumer of mosquito larvae.

The big picture

July 2012: warmest month in U.S. history

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Credit: National Climatic Data Center, NOAA

The average temperature for the contiguous United States during July was 77.6°F, 3.3°F above the 20th-century average.

If you’re old enough to remember the days before AIDS, you may be wondering about the steady, deadly parade of new diseases. Viruses are a particularly rich category, and it’s not just West Nile: the list of emerging infectious diseases includes SARS, Ebola, and new strains of influenza and hepatitis.

What accounts for the dramatic increase in new pathogens? Goldberg, who is associate director for research at the Global Health Institute at UW-Madison, says better surveillance and diagnostics make it easier to identify new diseases, “but the majority view is that certain imbalances are the cause. A higher human population is encountering more wildlife, urbanization has created higher density, allowing more transmission, globalization has allowed opportunities for pathogens to escape.”

All these factors, propelled by climate change, are hastening the evolution and emergence of pathogens from the ends of the Earth.

The recurrent outbreak of West Nile shows that viral diseases “are very unpredictable,” says Goldberg. “They can change due to the virus mutating or a change in ecological conditions. We can get new outbreaks of an old disease as soon as we let our guard down.”

With few drugs available to treat West Nile, Goldberg says scientists are gaining the ability to predict the intensity of the epidemic in advance. “In Chicago, we can already predict the size of the epidemic, using early-season data on weather, mosquito population and robin breeding. But extrapolating to new places is very difficult. We really need a universal predictive model of West Nile outbreaks.”

Such a model, he adds, must account for the abnormal weather that is becoming normal with a changing climate. “Everyone has a strong sense that the unusual weather patterns we have seen are responsible for the high transmission rates.”

– David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Mosquito repelling plants ↩
Mosquito repelling phone app ↩
History of West Nile Virus ↩
Mosquitoes and disease ↩
Zimmer on WNV ↩
Preventing bird-borne diseases ↩
Immune system overview ↩

Himalayan glaciers

Posted on 23 August 2012

The melting of Himalaya’s glaciers: fact or fiction?

What’s going on with the largest swath of glaciers outside Greenland and Antarctica? We all know that an Intergovernmental Panel on Climate Change report from 2007 erroneously stated that Himalayan glaciers would disappear by 2035. But the ice fields in these giant mountains are indescribably inaccessible: remote, steep and often enmeshed in politics.

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Mount Everest (left), shown with neighboring Nuptse, is the top of the top of the world. Snow on the Himalayas is the source for numerous glaciers. We endorse measuring Himalayan glaciers from space, but only if it doesn’t hinder opportunities to visit places like this!

Records of glaciers, weather and river flow in the region are imperfect — if they even exist.

Now comes a report that Himalayan glaciers, which cover about 60,000 square kilometers, are “changing at the same rate as the global average,” says Andreas Kääb, a professor of geosciences at the University of Oslo (Norway).

According to Kääb’s new paper in Nature, these glaciers thinned by about 21 centimeters per year between 2003 and 2008, feeding 13 billion extra tons of meltwater each year into rivers that water such nations as China, India and Vietnam.

Despite their importance, these glaciers are difficult to study, Kääb says. “These are the highest mountains in the world, the range is 2,000 to 3,000 kilometers long, and some areas are extremely hard to reach. The major glacier in Bhutan requires a two-week walk from the capital.”

Eye from the sky

Kääb and colleagues used data from space to study Himalayan ice, which presented its own complications. The ICESat satellite, which operated from 2003 to 2009, was built to measure the height of glaciers by timing the reflection of a laser beam. Although the satellite was accurate to within a few centimeters, it was designed for horizontal ice in the Antarctic and Greenland.

Glacial change, Himalayan edition

In the mountains, the 70-meter circle bathed by ICESat’s laser could contain any number of elevations. However, in tests in Svalbard, a mountainous island north of Norway, Kääb figured out how to adapt ICESat readings to steep terrain.

Kääb says ground truthing — the comparison of satellite data to conditions on the ground — continued in the Himalayas, where ICESat measured stable ground and found no movement. “This gives us some confidence that this is a true signal.”

Because ICESat only started operating in 2003, the researchers got baseline data from a Space Shuttle mission that measured the height of ice with radar in 2000.

An average bunch of glaciers

The Nature results showed an overall thinning in the Himalayas that matched the global average. Curiously, the thinning was equally fast in glaciers covered by rocky debris, which supposedly insulates the ice.

“It was puzzling at first,” says Kääb. “It’s true that the debris cover insulates the ice and protects against solar radiation, but that’s only valid for intact debris.” However, the many meltwater pools on Himalayan glaciers accelerate the melting through a positive feedback that can become “a runaway process.”

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009 photo by Kimberley Casey

Ngozumpa Glacier, in the Everest region of Nepal. The peaks are Kangtega (6,779 meters above sea level) and Thamserku. The many melt lakes on this debris-covered glacier counter-balance the insulating effect of rocks, helping explain why the glacier wasted away as fast as bare glaciers in the new study.

The thinning also showed regional variation, with a bit of thickening seen in Karakoram mountain glaciers in the northwestern Himalayas. These glaciers may be getting more snow due to increased water vapor in the atmosphere, a side effect of global warming.

The larger picture in the Himalayas, however, “is very similar to the global average,” says Kääb. “This means that most of these Himalayan glaciers are not the exceptions that they were believed to be for a long time.”

River of worries

More than a billion people live in watersheds fed by the glaciers in the Himalayas and Tibet, which source giant rivers like the Ganges, Brahmaputra, Yangtze and Mekong. According to the Kaab’s calculations, glacier melt supplied, on average, 2 to 4 percent of the extra water flow as these rivers enter the lowlands. “This means that, on average, a 2 to 4 percent surplus is in these rivers right now.”

In general, glaciers store water in winter and release it in summer, says Kaab. “One can imagine shrinking glaciers as a water storage container that slowly empties over the years, even if the seasonal water level in the river goes up an down.”

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Credit: nborun

Bathing in Ganges River, Haridwar, India, as the Ganges enters the North Indian plains. Notice the shrines on the opposite bank? Haridwar is one of the holiest sites of Hinduism. The river originates in a glacier 253 kilometers upstream.

The decline of the Himalayan glaciers does not prove climate change, Kääb says. “What we did was measure glacier thickness over five or six years; no more, no less. Climate is defined as weather over 30 years, so our study did not talk about climate-induced change.”

Further, five or six years is “not a long time,” Kääb says. “It could be that they were very good or very bad years for the glaciers, but there are almost no sufficient meteorological measurements on the ground.”

As scientists debate the condition of the Himalayan glaciers (a estimate from earlier this year put the annual mass loss at a much lower 5 billion tons), a measurement that aligns with numbers from other parts of the world at least passes the sniff test.

“What is clear is that the results are consistent with glacier decline seen elsewhere, and with the ongoing warming of the climate,” Kääb says.

— David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Contrasting patterns of early twenty-first-century glacier mass change in the Himalayas, Andreas Kääb, et al, Nature, 23 August 2012. ↩
Feast your eyes on Himalayan peaks! ↩
Documenting the demise of glaciers ↩
Why understanding glacier melt and growth is important ↩
Tibetan reporting on Himalayan glacial melting ↩

Denial of science, science of denial

Posted on 3 May 2012

Roots of (scientific) denial

Science is the best way to dig out the truth of the natural world, but that doesn’t prevent many people from denying truths that are inconvenient or contrary to their preconceptions or faith.

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U.S. 30, east of Blair, Neb. June, 2011, Iowa DOT

The stunning floods, tornadoes, droughts and heat waves in 2011 caused more Americans to accept global warming — even if climate whizzes are chary of attributing individual weather events to the warming trend.

In the last month, denial of global warming has subsided in the wake of a string of floods, droughts and heat waves, culminating in the “summer in March,” 2012. Although Americans’ attitudes toward warming ebb and flow, on April 17, a Yale University poll reported that 69 percent think global warming is affecting the weather in the United States.

In the same month, however, a Discovery Channel series called “Frozen Planet” attracted ire when scientists noted that it documented massive melting at the poles, but ignored the “why?” question. Scientists have said for decades that polar warming would be an early sign of global warming.

In the recent past, this phenomenon of “denialism” has also appeared in doubts about issues that have long been settled in the scientific community, such as whether:

17th century hand-colored engraving of scientist with compass

HIV causes AIDS;

plants and animals evolve through natural selection;

vaccines prevent disease or cause autism;

refrigerant chemicals destroy the protective ozone layer; and even

whether smoking causes lung disease.

An April conference at the University of Wisconsin-Madison delved into the origin and development of denialism. Is a refusal to face facts growing more common? Are there better ways to explain how the world works?

Denial in the brain

Scientists, by training, are professional skeptics, but if after decades of debate 97 percent of them accept the link between greenhouse gases and global warming, why are so many unconvinced? “The theory is that if we tell people what we know, they will change,” says Arthur Lupia, a professor of political science at the University of Michigan, but that ignores how people really listen and make decisions.

Speaking to a high-level gathering of science journalists in Madison, Lupia said the problem does not reside with the audience. “The problem is us. Our expectations aren’t consistent with how humans react to information, what they will listen to, or what they will remember. People don’t pay attention, or they don’t remember what we said or what we intend them to remember.”

To change an opinion, you must first attract and then hold the audience’s attention, but attention wanders all the time. No matter how important you think your message is, Lupia says, “Biology does not change its rules … about when people will think about things that challenge them. … If I am saying something abstract, that does not connect to your core aspirations,” you may be more interested in counting tiles on the ceiling.

Can you hear me now?

To communicate with a general audience, Lupia says, “You have to make it close, concrete, immediate. I understand the joy of telling the whole story about climate, but there are some audiences that can’t handle it; in their reality, it’s not the most immediate thing. They might be more receptive if you make the conversation about pollution, energy security or energy costs.”

Information is filtered by attention and ideology, Lupia concludes. “Learning is always an away game. All the real action occurs in the audience’s heads,” he says.

Reasoning: Logical or “motivated”?

Ideally, science adheres to logical reasoning: the conclusion must be true if the premises are true.

Logical reasoning

Premise 1: “All dogs like to roll in dead fish.”

Premise 2: “Bert is a dog.”

Conclusion: “Bert likes to roll in dead fish.”

But psychologists say it’s common to see “motivated reasoning,” the tendency to fit new information into existing attitudes.

Motivated reasoning

New information: The climate is warming.

Existing attitude: People are not changing the climate.

Conclusion: The change must be due to natural variation.

Making a judgment or decision can often involve a “fundamental tension between believing what you want and believing what you have to believe based on the information in front of you,” says Peter Ditto, professor of psychology and social behavior at the University of California-Irvine.

“There is overwhelming evidence” that hopes, fears and social connections affect our judgments, Ditto adds, “but it’s not just that we believe whatever we want. I want to be taller, but I don’t believe that because the data won’t let me.”

Since processing information and making judgments have major emotional components, the standards for evidence are skewed in favor of reinforcing our preconceptions. We are more skeptical about ideas that are new, or that conflict with our thoughts and opinions, Ditto contends.

Over the course of evolution, bad events — but not beneficial ones — forced our ancestors to focus on whether to fight or flee. “People are the same way about information,” says Ditto.

The social element in motivated reasoning surfaced in a 1950s experiment, when six people convinced a seventh, the only real subject, that two lines were equally long. One line was clearly shorter than the other, Ditto says, “But six of them are confederates, and a substantial number of [subjects] go with the obviously wrong answer. That’s the power of having other people who believe as you do. It’s much easier to believe something that does not comport with reality if a whole bunch of others” hold the same erroneous belief.

History of denialism

Although denial of global warming and the erroneous link between vaccines and autism both originated in the 1990s, the organized rejection of evolution dates to the 1920s, when some American Christian fundamentalists promoted creationism — a Biblical explanation for the diversity of life on Earth.

In a 2009 survey, 87 percent of scientists, but only 32 percent of all Americans, agreed that organisms have evolved over time through natural processes. Thirty-one percent of Americans thought humans and other living things “have existed in the present form since the beginning of time.”

31 percent of Americans think creatures have existed forever in their present form; 22 percent think evolution was guided by a supreme being.

Scientists and other Americans certainly have a different understanding of how organisms change through time!

Scientist data and general public data from Pew Research Center for the People & the Press surveys, May-June 2009. For question wording, see survey toplines. Numbers may not sum to 100 due to rounding. Reprinted from Pew Research Center’s Forum on Religion & Public Life.

Much of the attention to the issue comes from battles over teaching of evolution or creationism in public schools, but there is “a lot of misunderstanding,” about the anti-evolution movement in the United States, says Ronald Numbers, a professor of the history of science at the University of Wisconsin-Madison, and longtime student of the movement.

Although creationism is commonly considered a backlash against science, “Virtually nobody in the movement [in the 1920s] thought of themselves as anti-scientific,” Numbers says. “They were denying the scientific status of evolution.”

Is denial of science a result of organized campaigns, or is it just easier to ignore unpleasant facts?

The dictionary defines science as “organized, certain knowledge about nature, and they said, ‘Nothing is certain about evolution, nobody has seen it.’”

During the 1970s, primarily in response to court decisions, creationism morphed into “creation science” or “scientific creationism,” Numbers says. “The anti-evolutionists realized that evolution had a great deal of scientific support … so their approach was that they, too, were scientific.”

Unlike most anti-evolutionists in the 1920s, the new creationists used a literal interpretation of the Bible to date creation to less than 10,000 years ago. But this created a problem, Numbers says, since according to the Bible, on the sixth day, “God created the animals and Adam named them all.”

No way Adam could rattle off the more than 1 million names of the modern species so quickly, but Numbers notes that the Bible refers to “kinds,” not “species.” If those “kinds” — created in Eden and saved on Noah’s ark — were equivalent to taxonomic families, they could have evolved into the profusion modern species.

“So creationists can accept evolution within the family, and all the evidence for speciation is welcome, because in only about 4,300 years since the flood, they have to have evolution of all the species,” says Numbers. “It’s evolution in fast-forward,” but only among closely related species.”

Even if “kind” equals family, anti-evolutionists exempt humans from this reasoning, allowing them to reject human descent from apes — our fellow hominids.

“It’s strange, I know,” says Numbers. “They are anti-evolution, but most of the evidence evolutionists use against them, they are happy to embrace! One thing that has not been true for 50 years, but lingers in the popular mind, is that creationists deny all forms of evolution.”

The manual of denialism?

Evolutionary biologists regard evolution through natural selection as the organizing principle of biology. Yet for 30 or 40 years, surveys have shown a substantial fraction of Americans, even a majority, who do not “believe in” evolution, Sean Carroll, vice-president for science education at the Howard Hughes Medical Institute, told the denial conference.

Carroll, who like many biologists is aghast at the effort to squeeze evolution into a biblical straitjacket, says, “The denial of evolution was my introduction to denialism.”

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Card certifies bearer of being a 'Polio Pioneer'

American Museum of National History

In 1954, children got a “Polio Pioneer” card, and a piece of candy after getting a jab of polio vaccine.

Typically, biologists have approached the evolution debate by amassing evidence, but “it’s never been about the data,” maintains Carroll, who is also a professor of genetics at the University of Wisconsin-Madison. “And if it’s not about the data, what are we talking about?”

An earlier example of denialism occurred in the 1950s, after Jonas Salk developed the polio vaccine, a breakthrough that halted a dreaded, paralyzing disease.

Many chiropractors, Carroll found, opposed vaccines since they negated the central premise of chiropractic — that all disease results from misalignment of the vertebrae. “It shocked me. They actively opposed, disputed the efficacy of the polio vaccine. The opposed the March of Dimes, and federal and state efforts to get everybody vaccinated.”

Five hallmarks of denialism

The opposition continued — even after the polio epidemic tapered off as a result of the mass vaccination that started in 1955, says Carroll. And he identifies the tactics used then as a “playbook” of science denial that is echoed in more recent struggles over evolution, vaccines and global warming:

1. Doubt the science:

• “CDC statistics make clear that polio was disappearing anyway.”
• “There is no real evidence that evolution is occurring; evolution is not science at all.”

2. Question the motivation:

• “The vaccine manufacturers are just interested in profits.”
• “Climate scientists are only interested in more grant money.”

3. Exaggerate normal scientific disputes:

• Cite gadflies as authorities even though they are a tiny minority.
• Insist on “balanced coverage” even when almost all of the experts are on one side of the issue.

4. Exaggerate the potential harm:

• “We cannot control global warming without destroying our economy.”
• “Darwin’s talk about the struggle for existence lead to the Nazi Holocaust and World War II.”

5. Appeal to personal freedom:

• “Students should be able to opt out of classes on evolution.”
• “We support each individual’s right to freedom of choice” on vaccines (American Chiropractic Association, 1998).

We just don’t agree!

Add it up, and the theme is this: The science must not be allowed to endanger a key philosophy, Carroll says.

But the cost of denialism is high, Carroll maintains. “It’s difficult, as an evolutionary biologist, to realize that half the county is deaf to anything you have to say, especially if the story you have to tell is about a magnificent achievement, understanding the complex relationship of living things on the planet, the deep history of our species.”

To reach young people, Howard Hughes has begun producing and giving away a series of videos on evolution called The making of the fittest.

Go to links for videos

Title of 'The Making of the Fittest' video, with close-up of head of a frozen fish

Howard Hughes Medical Institute

To bring science to the masses, Hughes has produced videos on evolution; this one describes how cold-water fish evolved “anti-freeze” genes.

The idea is to engage in storytelling — to help people understand and remember facts by putting them into a narrative framework, Carroll says. As a professor, he’s seen the power of a story. “When I got lost, off-topic, and students see me years later, they say they still remember some of those stories, and I know they don’t remember any of the genetics. Stories count.”

Time (dis)honored tactics

Naomi Oreskes, a professor of history and science studies at the University of California at San Diego, has written about the “merchants of doubt.”

The message, she says, is simple: The facts are not all in. We need to hold judgment until the scientists agree.

This kind of corrosive doubt — in the face of scientific certainty — is “very depressing” if you “believe that knowledge is power,” Oreskes says. “Knowledge is not powerful enough — an ideology is more powerful still. It’s about ideas, not facts.”

During the last half-century, she says, “Political powers are willing to attack rational truths, and those who deliver them.”

There is also money at stake in many of the issues, especially in the case of climate change, which threatens the fossil-fuel industry.

Left: Exhaust coming out of a car's tail pipes. Right: Burning cigarette sitting on concrete.

Car exhaust from eutrophication&hypoxia; smoky butt from Raul Lieberwirth

What do these have in common? Many companies in the oil and tobacco industries have sown seeds of doubt about the long-term effects of their products.

The model for such campaigns, Oreskes said, came from the tobacco industry in the 1960s. Facing growing evidence linking their profitable product to lung cancer, the industry settled on a strategy of promoting “Questions, manifested in a memorable maxim: “Doubt is our product.”

And for decades, doubt helped big tobacco deride and deny a tidal wave of evidence that cigarettes cause lung and heart disease.

Table of opinions about global warming evidence and severity from 2006 to 2011.

December, 2011, Pew Research Center for the People & the Press.

After the crazy weather of the past year, pollsters have seen a bump in the number of Americans seeing “solid evidence” for global warming.

The same strategy, Oreskes says, was adapted to undermine “nuclear winter” (the discovery that huge clouds of ash and dust released during nuclear war could freeze and starve the planet), the dangers of the insecticide DDT, acid rain caused by power-plant pollution, the ozone hole, and global warming.

The tactics were to “challenge the evidence, claim the science is not settled, cherry-pick the data, to demand balance from journalists and threaten to sue if they don’t,” says Oreskes.

Changing the climate change story

The basic physics of global warming have been known for 100 years, Oreskes said. Scientists started exploring the subject with early computerized climate models in the 1980s.

In 1992, Oreskes said, the first President George Bush, “Called for concrete action to protect the planet. We had political leadership that committed us to doing something, yet we never did take the concrete steps that Bush called for. It’s a story about political challenges, selling uncertainty, about science in the age of denial.”

No question: hopes, fears and social connections shape our judgments.

The doubters, funded by the oil industry, included some prominent Cold-War physicists who had been advocates for Ronald Reagan’s anti-missile defense system. “They said the science was unsettled, that it would be premature to act,” says Oreskes, who was intrigued to find that one of those physicists, Frederick Seitz, had been a consultant to the R.J. Reynolds tobacco company.

In 1998, Seitz organized a petition against the Kyoto Protocol, the first international agreement to control greenhouse gases.

Seitz and his fellow doubters, Oreskes says, “Found a new enemy: environmental extremism. You see anxiety about environmentalists as socialists, using climate change as a lever to effect social or economic change.”

What began with a handful of people with roots in the Cold War has since spread to “a range of free-market think tanks, including the Cato Institute and the American Enterprise Institute,” Oreskes says.

The arguments against the settled scientific debate over warming, she adds, “are not just different interpretation of the data; that’s a normal part of scientific life. This is not about normal scientific claims. These are the scientific equivalent of saying Belgium invaded Germany during World War I.”

Why deny? Because it works, Oreskes implies. Almost 25 years after the scorching summer of 1988 brought global warming into the public sphere, the United States has yet to get serious about controlling greenhouse gases.

“We ignore the facts of nature at our peril,” says Oreskes. “Ignoring them is not going to make them go away.”

— David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Recap. of the Science Writing in the Age of Denial conference ↩
What is Motivated Reasoning? How Does It Work? Dan Kahan Answers ↩
Basic concepts of logical reasoning ↩
Extreme weather and climate events ↩
AIDS denialism ↩
Retracted autism study an ‘elaborate fraud,’ British journal finds ↩
Resources for understanding evolution ↩
Scientists Quantify Global Warming’s Threat to Public Health ↩
Chiropractors v. Vaccination ↩
Merchants of Doubt, by Naomi Oreskes and Erik M. Conway ↩

Hot: Living through the next fifty years on Earth

Posted on 28 March 2012

Hot: Living through the next fifty years
on Earth

Mark Hertsgaard • 339 pp. Houghton Mifflin Harcourt, 2012.

You’d think — okay, I’d think — that there’s little new to write on the subject of global warming. To anybody who can read a scientific study, the human role in burning things that make carbon dioxide is clear enough.

Likewise, the trajectory of rising temperatures and sea levels is clear and accelerating.

But Mark Hertsgaard, a veteran environmental reporter who lives in California, pivots the focus from slowing greenhouse-gas pollution to the need to adapt and respond to changes wrought by the steady accumulation in heat-trapping gases.

We have just endured the warmest decade in history, and the Intergovernmental Panel on Climate Change says temperatures could rise 5° C by 2100. If that happens, “The Earth would be hotter than at any time in the past 50 million years,” Hertsgaard writes.

Although a few insurance companies, stung by colossal payouts for floods and hurricanes, have responded, most businesses have failed to come to grips with the ongoing warming. “True sustainability is not just about being nice to people and nature,” as one business leader told the author. “It’s about dealing with environmental threats that can put you out of business.”

Sea level is a rising concern in the near future, and Hertsgaard contrasts New Orleans, flooded and ruined by Hurricane Katrina in 2005, with the Netherlands, which is largely below sea level.

The record of injustice, corruption and incompetence in New Orleans augurs poorly for the difficult task of restraining the sea, while the Dutch have resolved to survive as a nation and are building massive sea defenses based on communitarian principles. If some land cannot be saved, those who must sacrifice for the common good are compensated without being allowed to block measures needed for national survival.

The time for discussion is past, Hertsgaard says, and given the momentum in the climate system, he argues that we must prepare now for inevitable warming and flooding.

That action should not just benefit rich people in the rich countries that have created the lion’s share of global warming pollutants, Hertsgaard says. He visits poor, low-lying Bangladesh, threatened by typhoons and floods and observes that a father in Bangladesh loves his daughter just as much as a father in California.

David J. Tenenbaum

Shaking it up: Maverick scientist dies

Posted on 22 March 2012

F. Sherwood Roland, 1927-2012

On March 10, atmospheric chemist “Sherry” Rowland of the University of California-Irvine died in the company of his son and his wife of almost 60 years. Rowland became prominent in the 1970s after warning that common chemicals would destroy ozone 10 kilometers above Earth, exposing life to a shower of harmful radiation.

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Photo: Steve Zylius/University Communications/University of California-Irvine

University of California atmospheric chemist F. Sherwood Rowland, who shared the Nobel Prize for studies on ozone destruction due to refrigerant chemicals, died March 10 at age 84.

While exploring how chlorofluorocarbons (CFCs) degrade after being released into the atmosphere, Rowland and graduate student Mario Molina realized the CFCs would float to the upper atmosphere, be cleaved by sunlight, and release chlorine that would destroy ozone through a chain reaction.

(Ozone contain three oxygen atoms; most oxygen molecules contain two oxygens.)

By intercepting cancer-causing UV radiation, ozone in the stratosphere allows life to exist on Earth. Significant damage to this ozone would cause an epidemic of human and animal cancer, and likely damage plants as well.

This alarming prospect was not popular in industries that relied on CFCs, but it sparked a long and largely successful effort to restrict and then ban production of the chemicals.

And although Rowland never retreated from his findings, his calm, charismatic personality helped his cause. Ralph Cicerone, now the president of the National Academy of Sciences, recalls collaborating with Rowland on CFCs. “We talked on the phone nearly every day. I considered Sherry to be my best friend, and over time I learned that many people considered him to be their best friend, too. In the midst of the debates over CFCs, he never exaggerated the dangers, always cited the science, and treated other people with dignity and respect.”

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Photo: University Communications/University of California-Irvine

Sherry Rowland and Mario Molina at work at the University of California-Irvine.

What must a scientist do?

According to the University of California-Irvine’s press service, Rowland knew his results mattered far beyond the lab: “Mario and I realized this was not just a scientific question, but a potentially grave environmental problem involving substantial depletion of the stratospheric ozone layer. Entire biological systems, including humans, would be at danger from ultraviolet rays.”

At the time, scientists were studying the health implications of ozone-bearing smog in the lower atmosphere, but few people knew or cared about “good” ozone in the stratosphere.

The sudden notoriety of CFCs had a certain irony: The chemicals were invented in the 1920s at General Motors, maker of Frigidaire brand refrigerators, as a stable, non-toxic alternative to the ammonia and explosive propane used in air-conditioning and refrigeration.

CFCs later were used to expand plastic foam, clean electronic parts, and propel paint and deodorant in the mushrooming aerosol-spray business.

Antarctic ozone hole, 2011

Video: NASA

Chlorine and bromine in the upper atmosphere cause rapid ozone destruction in the super-chilled polar winter. Although the ozone “hole” (blue) is declining with the phase-out of CFCs, it still recurs.

They publish lest we perish!

CFCs cooled refrigerators and air conditioners (including, we guess, in 1959 Cadillacs), made foam spongy, and propelled products from aerosol cans. Since the Montreal Protocol, CFCs have been replaced by several alternatives, including hydrofluorocarbons. HFCs are less harmful to ozone than CFCs.Click any image to enlarge.

Refrigerator: litlnemo; Car: Rex Gray; Foam: hoodsie; Aerosol: Pam Morris

Rowland’s 1974 study¹ ignited a long squabble over CFC production. Aerosol Age, the spray-can industry’s trade journal, implied that Rowland was a member of the Soviet KGB who wanted to destroy capitalism!

CFCs remained a back-burner issue, however, until the British Antarctic Survey discovered an alarming absence of ozone in 1985. The “Antarctic ozone hole” gave the theoretical worry sudden significance, and as the industry gradually found substitutes for CFCs, the ozone hole stopped expanding.

Today, as we watch the faltering response to global warming, it’s comforting to recall that the ozone threat prompted prompt collective action: The Montreal Protocol, a treaty to restrict CFC production, became effective in 1989 and has since been tightened after further alarm over ozone destruction, and 196 nations — essentially all of them — have signed the original Protocol. Production of ozone-depleting substances has fallen by more than 95 percent.

“CFCs were extremely useful compounds and their use was pervasive,” says Rudy Baum, editor in chief of C&EN (Chemical and Engineering News). “Although manufacturers maintained that there would be dire consequences if the use of CFCs were restricted or banned, it became clear pretty quickly that alternatives could be found in most cases.”

And yet ozone is still a problem, as shown by a 40 percent drop in Arctic ozone in the winter of 2010-2011. Continuing destruction is blamed on the stability of CFCs and the fact that the replacements, while less damaging, still destroy ozone. “Ozone can be thought of as a patient in remission, but it’s too early to declare recovery,” said Susan Solomon of the University of Colorado.

Not bounded by the lab walls

Nonetheless, the Montreal protocols are considered an epochal case of planetary preventive medicine, and Rowland, Molina and Paul Crutzen, who also worked on CFCs, were awarded the 1995 Nobel Prize for Chemistry.

But for 10 or 15 years, Rowland had played the role of maverick — speaking outside the laboratory about the importance of what he had found inside it. It’s not a comfortable role for many scientists; many find it safer to stay in the lab and let others figure out what to do with their results.

Jonathan Fink, vice-president of research at Portland State University, says “The culture of science is pretty deep in terms of how we are trained. Most science grad students are taught to focus on being the best at something, rather than thinking about the application of what they do to society.”

All along, Rowland explained the science and gently reminded us of our stake in an intact ozone layer. He continued to study atmospheric chemistry, mentor younger scientists, and show by example how scientists could speak responsibly about what their results mean for the rest of us.

Somehow, Rowland managed to fight his battles without making enemies, at least outside the industries that had inadvertently begun calamitous destruction of ozone.

Why do scientists like Rowland speak out? “Because they’re scientists and scientists are addicted to facts and what facts tell them,” says Baum. “I knew Sherry Rowland pretty well — I was the West Coast correspondent for C&EN from 1991 to 2004 … he was a gracious, dignified, reserved individual, certainly not a rabble-rouser. But he knew that his science was solid and that it told him that humans were doing something that would have catastrophic consequences if they didn’t stop. So he spoke out. Simple as that.”

Newspaper coverage of global warming

Maxwell Boykoff, 2012, University of Colorado ²

A new disaster unfolds

Even before the Montreal Protocol was signed, climate scientists were starting to warn that carbon dioxide in the atmosphere would enhance the greenhouse effect and trigger global warming. In testimony to the U.S. Senate in the torrid summer of 1988, NASA climatologist James Hansen linked rising temperatures to rising levels of greenhouse gases from fossil fuels.

On Oct, 10, 2010, climatologist Jim Hansen speaks at a demonstration for clean energy outside the White House. Rollover to see Hansen being arrested at a White House protest against mountaintop-removal coal mining on Sept. 27, 2010.

First photo: 350.org/”RadScienceGeek”. Rollover: Rich Clement/Rainforest Action Network

The debate over global warming and climate change had begun, and going public put Hansen in much the same position as Rowland had occupied 15 years before. Via email, Hansen credited Rowland and atmospheric scientist Don Hunten as “role models… . They showed that it was possible to do first-rate science and also uphold our responsibility to make clear the implications of our research for society.”

Rowland redux?

Until then, Hansen had been a well-regarded but faintly visible NASA expert in planetary atmospheres. He had studied Venus, where an atmosphere choked with carbon dioxide produces a “runaway greenhouse effect” that raises the surface temperature to 460° C.

After making news in 1988, Hansen retreated from the public discussion of warming, but in the early 2000s, as temperatures continued to rise, he began to speak up again. In 2005, after the Bush White House tried to muzzle him, he went public with a vengeance.

Why? Journalist Mark Hertsgaard, who has written extensively about global warming and repeatedly interviewed Hansen, says he “thinks like a scientist, believes if you find the information, and present it properly, the truth should carry the day. I think he came out of hibernation in 2005 only because he felt he had to. He looked around and saw that the information alone was not carrying the day.”

Hansen’s regular emails combine climate facts with political opinions for a broad audience. For example, a recent commentary argued that “Scientists attempt to communicate, but are flummoxed by the ability of the profiteers to manipulate democracies. The scientific method (objective analysis of all facts) is pitted against the talk-show method (selective citation of anecdotal bits supporting a predetermined position).”

On Aug. 29, 2011, Hansen was arrested at the White House with hundreds of others protesting the Keystone XL tar-sand oil pipeline. Tapping such a vast reservoir of carbon, Hansen believes, will bring us that much closer to a “tipping point” on greenhouse warming. “Now we’ve got the spectacle of one of the world’s foremost climate scientists getting arrested and urging others to get arrested,” says Hertsgaard. “This is way beyond speaking out.”

Hertsgaard, a native of Minnesota, says it’s “very hard for [Iowa native] Jim Hansen the person to speak out.” In the Midwest, Hertsgaard says, “it is just not seemly to draw attention to yourself or bring up a topic that is likely to discomfort others. … but it’s not corny to talk without irony about the importance of doing the right thing.”

The glacially slow acceptance of continental drift

ENLARGE

1 November 1930, Photo copyright Alfred-Wegener Institute for Polar and Marine Research

The last photo of Alfred Wegener (left, taken on Wegener’s 50th birthday), and Rasmus Villumsen (age 23), at the start of a rescue mission in Greenland. Both men died during the rescue.

Until German scientist Alfred Wegener traveled the world in the early 1900s, geologists thought the continents were static. But Wegener found evidence for what he called “continental drift”:

• Maps: The outlines of the Americas showed “remarkable conformity” with Africa and Europe, says Fred Ziegler, a professor emeritus of geophysics at the University of Chicago. “It jumps out at you.”

• Evidence for ancient glaciers in hot places like India and Australia. These deposits indicated that this land had once been much closer to the poles.

• Fossils: For millions of years, ancient life in Africa and South America looked oddly similar — until those continents separated.

ENLARGE

Graphic: USGS

Fossils found on continents now separated by thousands of miles of ocean showed that the continents, once joined, were separated through continental drift.

In 1912, Wegener proposed a theory of continental drift, but could not explain a mechanism for that movement. The theory “was not very well accepted, particularly in this country,” says Ziegler. “The American Association of Petroleum Geologists voted on the theory of continental drift and voted it out of existence.”

In the 1950s, new studies began to vindicate Wegener:

• Convection: Scientists realized that a giant, heat-driven circulation in Earth’s mantle could slowly move the continents.

• Magnetism: When molten rock cools, magnetic particles orient to Earth’s changing magnetic field. These tiny magnets became calendars of continental formation and movement.

By the late 1960s, continental drift, renamed “plate tectonics,” had produced a new and integrated picture of the planet that explains earthquakes, tsunamis and volcanoes.

Ziegler ran a mapping project at Chicago that “picked up where Wegener left off, making maps for various periods of geological time. Wegener was a hero to us,” he says.

The scientific culture

A fully indoctrinated scientist is chary of talking much beyond the lab, Hertsgaard says. “Many scientists very much frown on taking the public agitator role, and that’s another tribute to Hansen’s courage. He was prepared not only to take brickbats from the Exxon-Mobil front groups, but to endure the judgment of his own peers, who said ‘That’s not what scientists do.’ He remembers that he’s not just a scientist, he’s a human being too.”

Despite the successful example of the Montreal Protocol, the global warming problem is vastly harder to solve, says Baum of C&E News. “The scale of fossil fuel use is several orders of magnitude larger …. Humans consume between 80 million and 90 million barrels of petroleum every day, and that represents only about a third of the fossil fuel that is consumed.”

Gross revenue for world’s largest companies

ENLARGE

Data from Wikipedia

Data show a single year gross revenue for 2010 or 2011 (reporting periods vary from country to country). Notice the preponderance of oil and gas companies?

Finally, while the specter of cancer caused by increased UV radiation is unsettling, “people actually like the warmer conditions, at least for now,” Baum wrote. “We didn’t have a winter in Washington, D.C., this year … and people loved it.”

So will the environmental victory over CFCs that started with Rowland and Molina be mirrored by serious action over global warming? Maybe not, says Spencer Weart, a long-time chronicler of warming. Comparing the ozone battle to the fight over global warming “is like comparing a single battle to a world war. Ozone depletion (once the ozone hole was detected) was clearly an urgent problem, with a straightforward solution. But with global warming, it’s hard for people to worry much about something that seems remote in space and time — isn’t it just a problem for polar bears and our grandchildren?”

Slowing warming “will require wholesale changes in our entire world economy,” Weart says. “And that must begin with government regulation of the fossil fuels industry, the largest concentration of economic power the world has ever seen. The pushback has been fierce, beginning with industries that suspected their profits would be restricted, and extending to people who fear governmental threats to their freedom.”

Rowland was once libeled as a Soviet spy, but “Scientists who have put themselves into politics like Jim Hansen … have been subject to ad hominem attacks: crude vilification and direct threats far beyond anything that Rowland experienced.”

Hansen and his colleagues, says Weart, “have persisted nevertheless. For the logic of their scientific understanding forbids them from keeping silent about the dangers they foresee.”

– David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Stratospheric sink for chlorofluorocarbon methanes: Chlorine atom catalyzed destruction of ozone, Mario Molina & F.S. Rowland, Nature, 249:810 ↩
Maxwell Boykoff, 2012, ’2000-2011 USA Newspaper Coverage of Climate Change or Global Warming’, University of Colorado at Boulder, Center for Science and Technology Policy Research ↩
NOVA remembers Sherwood Roland ↩
Biography of Mario Malina ↩
Nobel Prize in Chemistry: 1995 ↩
Chemistry explained: Freons ↩
When refrigerators warm the planet ↩
Health effects of overexposure to the sun ↩
James Hansen TED Talk: Why I must speak out about climate change ↩
The NY Times: Global warming and climate change ↩
The Amoeba People present “The Posthumous Triumph of Alfred Wegener” ↩
Synposis of plate tectonics ↩
History of plate tectonics ↩

A Climate of Extremes

Posted on 6 March 2012

Synopsis

Higher temperatures are only part of the climate-change forecast. Are current extreme weather events a sign that warming is already here? What do climate models forecast for weather around the globe? Why is it so hard to predict the climate?

Flat desert landscape with nine dead cattle in foreground and five live cattle walking in line behind them

Find the article:

A Climate of Extremes?

Discussion Questions

How might climate change affect future weather, according to climate scientists?
How could this type of weather affect people?
What are some recent weather extremes (including drought, fire, floods and storms) that are causing concern about the warming climate?
What factors make it difficult to predict weather patterns due to climate change?
One way to test climate models is to use past data to model present weather. How much do climate-change predictions rely on models, and how much on data?

Lesson Plans/Activities

In the news! Have students research the media coverage of extreme weather and climate change (e.g. have them focus on one event or do a general search, to see what they can find). Conduct an in-class discussion or have students write an essay about how extreme weather and climate change are portrayed. Who do the journalists interview? What are some possible reader reactions to these articles?
Uncertain science. Conduct an in-class discussion or have students write an essay answering, what are the standards for accepting or rejecting scientific evidence? Can we really predict the future? How can we know scientists are right? How should scientists and the public deal with uncertainty?
What’s YOUR Impact? Have students research/study the “Environmental Footprint” concept. What is it all about? How is consumption related to greenhouse gases and global warming? Then, have students use the Environmental Footprint Calculator to assess their personal environmental impact. Ask students to imagine living somewhere else — like a big city, a small rural town or a different country — and recalculate their footprint. How does environmental impact differ in these various places? Discuss why.

<a href="http://thewhyfiles.polldaddy.com/s/heating-home-planet-quiz">View Survey</a>

Ocean fish in hot water

Posted on 19 January 2012

A different sort of fish sandwich

The seas’ most sought-after fish are swimming between a rock and a hard place: the fisherman’s net and an encroaching mass of suffocating water.

ENLARGE

Courtesy Guy Harvey, NOAA

The movements of Atlantic blue marlin, such as this one being tagged here, provided researchers with part of the data that lead to their discovery of this predicament.

A recent study has uncovered a new dose of bad news for ocean fish and the fishing industry. Areas of the deep ocean with little dissolved oxygen, called dead zones, are expanding and, thus, shrinking many fishes’ watery homes.

One driving force behind the predicament is none other than that pesky climate problem.

“Climate change is actually working in tandem with overexploitation of the animals to push these populations into a real dangerous place in terms of population collapse,” said Eric Prince, a fisheries biologist with the National Oceanic and Atmospheric Administration’s Southeast Fisheries Science Center and co-author of the study.

For example, Prince and his colleagues calculated that the Atlantic blue marlin, an economically valuable fish that was a focus of their study, has lost about 15 percent of its habitat from expanding dead zones since 1960. Dwindling habitat threatens not only the lives of fishes, but also the sustainability of the already ailing fishing industry.

Breathing room

Like their above-water brethren, fish need oxygen, which is dissolved in the water. Big, predatory fish, such as the blue marlin, need more dissolved oxygen than most, because they require lots of energy to grow and survive. Without sufficient oxygen, they’ll suffocate.

The level of oxygen in the water thus partly delineates fish habitat boundaries. Dead zones often draw these borders.

Diagram of cross-section of ocean and shoreline showing ocean warming, less dissolved oxygen, and widening dead zone

As climate change causes open ocean dead zones to balloon, fish habitat deflates.

Diagram modified from one originally published in Deep Sea Research Part I: Oceanographic Research Papers, Vol 57, Issue 4, Lothar Stramma, Sunke Schmidtko, Lisa A. Levin, & Gregory C. Johnson. Ocean oxygen minima expansions and their biological impacts, 587-595, Copyright Elsevier (2010).

Technically known as oxygen minimum zones, dead zones are actually a natural occurrence. Found at depths of between 200 and 1000 meters, they are caused partly by seawater circulation and partly by the decomposition of organic matter, namely deceased sea critters that sink from surface waters.

As aerobic bacteria nosh on the organic matter, they use up the oxygen in the water. Eventually, hypoxia happens—the water becomes so depleted of oxygen that many creatures can’t survive.

Since deep-sea dead zones are insulated from the ocean’s surface, where the water borrows oxygen from the atmosphere, they can only reload with oxygen if currents make a long-distance delivery, according to Sunke Schmidtko, an oceanographer at the University of East Anglia, the other co-author of the study.

Deep-sea dead zones are different from their coastal cousins like the one in the Gulf of Mexico. Coastal dead zones form due to a buildup of agricultural fertilizer that rivers, such as the Mississippi, collect and then flush out to sea, causing abnormal blooms of plant life.

ENLARGE

Base map from Uwe Dedering

This map shows where the Atlantic’s dead zone has set a shallow floor for the blue marlin’s habitat.

De-fizzing the ocean

The importance of teamwork

While science is often a team sport, rarely are teams as diverse as that of this study. By merging oceanographers’ data on dissolved oxygen with a biologist’s observations of marlins’ growing aversion to deeper water, the study’s authors were able to get a more complete picture of the ocean.

“Collaborative research makes the most out of available data,” said Schmidtko.

Prince hopes the collaboration will help bring more attention to the problem. “When you combine stuff together, you reach a much wider audience than just publishing in your own specialty,” he said.

But climate change is turning what Mother Nature does normally into a big problem. As the air is getting hotter, so is the water, and warmer water can hold less oxygen than colder water.

This is similar to what happens to a soft drink on a hot day. After sitting in the heat and sun, the fizz fizzles, and you are left with a flat, carbon dioxide-depleted beverage.

Also, warmer surface waters are less likely to sink to the ocean’s lower layers, because warm water is lighter than the colder water below, Schmidtko explained. In other words, as the oxygen-rich surface layers heat up, they could have a harder time delivering oxygen to the deeper ocean.

Schmidtko clarified that oceanographers are still trying to determine how exactly climate change is affecting the ocean, but with their knowledge of how water works, these represent their current speculations.

The rock below

With less oxygen to go around, oxygen minimum zones are swelling and intruding on many fishes’ living zones.

For example, marlins often dive deep to feed, sometimes as far down as 800 meters. However, in the eastern Atlantic’s growing dead zone, which is already one of the largest in the world, Prince found that marlins can’t dive as deep as their west-side counterparts.

“They need to go where the food is and where they can breathe,” he said.

Marlin, Flawka; Tuna, Virginia Beach Fishing Report

Recreational fishermen covet the glamorous marlin, because it is a tough catch. Commercial fishermen drool over yellow fin tuna (rollover), another fish featured in this study, because so many people like to eat them.

With less breathing room below, the floor of their habitat rises, and they are pinned to the surface layers. With nowhere to go but up, marlins become squished into tighter, testier quarters with other predatory fish and their prey. They also find it harder to dodge a waiting fishing hook or net.

“Concentrating them makes it much easier for overexploitation by [humans],” said Prince.

The increasing concentration of animals at the top could also lead to a boost in the amount of sinking organic matter, which would further worsen the oxygen shortage below.

Softening the hard place above

As a prized catch, Atlantic blue marlins are already victims of overharvesting. In fact, their populations have dropped 60-64 percent over the past three fish generations (14-18 years).

But the growing dead zones can actually fool scientists and fishermen into thinking fish populations are doing just fine, since more fish are squeezed into a smaller area. Thus, to ensure the dead zone-fishing vise does not become their demise, Prince said scientists must more carefully monitor fish populations, as well as the expansion of the dead zones.

While fish stock assessments are starting to incorporate this information, Prince warned the pace needs to quicken.

And if the Earth is to continue warming, as most scientists predict, Schmidtko added that humans should chill out on fishing.

After all, we will never be capable of “ventilating the ocean,” he said.

– Jenny Seifert

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Expansion of oxygen minimum zones may reduce available habitat for tropical pelagic fishes; Lothar Stramma, Eric D. Prince, Sunke Schmidtko et al.; Nature Climate Change, 04 December 2011. ↩
The Atlantic Blue Marlin, as described by National Geographic ↩
Global climate change and the oceans. ↩
The carbon cycle and the oxygen minima zone. ↩
Expansion of dead zones may reduce available habitat for tropical pelagic fishes. ↩
Coastal dead zones and the fishing industry in the Gulf. ↩
What about the animals who live in the dead zone? ↩
Zooplankton thrive in the dead zone…for now. ↩

Do abundant snowstorms suggest global warming is not occurring?

Posted on 16 January 2012

Do abundant snowstorms suggest global warming is not occurring?

ENLARGE

Graphic: Rutgers University Global Snow Lab

This graphs shows the area of land covered by snow over the past few decades in North America.

No. These storms are individual weather events, which cannot be used to support or refute climate trends. Which also means that the warm weather in Vancouver is not evidence that global warming is occurring. Weather relates to events that will happen over the next few days; climate describes what happens over decades. To make such claims about these storms and climate would be similar to saying “Looks like car accidents rates for WI are going down this year.” after returning from an incident free car ride on a Sunday afternoon. Accident trends are not about individual experiences, and climate and climate trends are not about individual weather events.

It is reasonable to ask, will we see more or less of winter storms in the coming decades with a warmer climate? There is some evidence that a warmer climate will result in more frequent large snowstorms. While the average global temperature 25 years from now will be warmer than current conditions, we will still have winters and summers. A warmer atmosphere means that there will be more water vapor in the atmosphere which could lead to greater snowfall amounts from individual storms during winter. In addition, a warmer world leads to a warmer ocean. So, as winter storms move along the eastern seaboard there could be more evaporation from the warm water. This provides more water for precipitation and more fuel to strengthen the storm.

Steven A. Ackerman and Jonathan Martin are professors in the Department of Atmospheric and Oceanic Sciences at UW-Madison, are guests on the Larry Meiller‘s WHA-AM radio show the last Monday of each month at 11:45 a.m.

Texas is dry and hot. Global warming?

Posted on 27 October 2011

Seven viewpoints

Introduction

Katharine Hayhoe

Richard Alley

John Nielsen-Gammon

John Williams

Michael Notaro

Kent McGregor

Kevin Trenberth

Drought and searing heat in Texas: Is this the face of global warming?

A huge dust cloud rolls over city rooftops, blocking the camera for a few seconds

Courtesy Eric Bruning, Texas Tech University Atmospheric Science

The cold front that blew through Lubbock, Texas on Oct. 17 raised a dust storm not seen since the 1930s Dust Bowl. The dust storm, seen in this movie, is called a “haboob,” an event more common to Saudi Arabia than Texas.

On Oct. 17, a cold front blowing through Lubbock, Tex. raised a red dust cloud that recalled the awesome Dust Bowl of the 1930s, an epoch of drought, enormous dust storms, poverty and social upheaval that depopulated the Great Plains.

The 2011 dust storm served as an exclamation point on a cruel Texan summer, with drought, wildfires, and temperature records that would not quit. On Oct. 19, the Lower Colorado River Authority, source of much water in the Southwest, warned customers that the drought was likely to force another 20 percent cut in water supplies.

In Austin, “Every major Texas heat record was broken,” reported KXAN news of Austin, including:

Hottest summer ever

Hottest month ever

Hottest July

Hottest August

Most 100-degree days

Most consecutive 100-degree days

Most 90-degree days

Most consecutive 90-degree days

Hottest average monthly high

Highest average monthly low

On Oct. 18, Texas Lt. Gov. David Dewhurst instructed the state legislature to study drought-related problems like helping homeowners protect against fire, and ensuring that utilities would get enough water to cool their generators.

As far as we could tell, the multi-pronged assignment did not mention something that many observers think contributes to heat waves, fires and droughts: climate change.

Many recent “natural” disasters have raised the same question: Is the no-sense-denying-it-any-longer human-caused planetary warming intensifying devastating hurricanes, giant rainfalls and snowfalls, or the deadly heat waves in Europe (2003) or Russia (2010)?

Despite political skepticism in the United States, the scientific study of changing climates has grown exponentially for 20 years. In 2009, almost 14,000 research reports focused on climate change, and 20 scientific journals are devoted to the issue.

UPDATED NOV. 18: Today, the New York Times reported that a United Nations panel has concluded that “At least some of the weather extremes being seen around the world are consequences of human-induced climate change and can be expected to worsen in coming decades. It is likely that greenhouse gas emissions related to human activity have already led to more record-high temperatures and fewer record lows, as well as to greater coastal flooding and possibly to more extremes of precipitation, the report said.”

Enough introductory blather. Let’s ask some experts: Is the hot, dry weather in Texas a reflection of global warming? Or is it just proof that the essence of weather is its natural variability? The Why Files talked to seven climate scientists. Peruse their viewpoints in the box above.

Pages: 1 2 3 4 5 6 7 8

Tundra fire: Bad news on warming

Posted on 28 July 2011

Arctic burn

1st image is aerial of brown tundra wilderness, three small lakes, huge plumes of white smoke. 2nd image is barren tundra landscape with dark brown soil, scattered short green plants, rainbow hue in background

The Anaktuvuk River fire scorched 1,000 square kilometers of Alaskan tundra in 2007. A year later (rollover), vegetation that survived and re-sprouted is returning to the charred earth.

1st photo: U.S. Bureau of Land Management, Alaska Fire Service. 2nd photo (mouse over): Jason Stuckey, Toolik Field Station

Burning of the Alaskan tundra can release massive amounts of carbon dioxide, the major greenhouse gas, according to a study published in Nature this week. The Arctic is warming faster than the rest of the planet, causing scientists to wonder what will happen to the carbon that plants have stored in Arctic soils and plant matter, both living and dead.

The new study looked at the aftermath of the Anaktuvuk River wildfire, which burned more than 1,000 square kilometers of tundra on Alaska’s North Slope in 2007. Anaktuvuk burned for almost three months, and by itself, accounted for two-thirds of the total area burned in Alaskan tundra since 1950.

The immediate cause was lightning, but weather played a major role. Between July and September, 2007, the North Slope had the hottest weather in a 129-year record. When the fire was really roaring, daily highs were 5°C to 10°C above average. The Slope also received less than 20 percent of the average rainfall that summer, leaving the tundra abnormally arid.

ENLARGE

Map: Aiyizo

Tundra covers large areas of the northern coasts.

In 2008, Michelle Mack, an associate professor of biology at the University of Florida and her colleagues visited the area and took samples from 1-square-meter quadrants both inside and outside the fire zone. Mack was in the field in Alaska, alas, and did not answer our emails, but her group calculated that the fire oxidized more than 2 million tons of carbon, which entered the atmosphere as carbon dioxide.

Accounting for carbon

The movement of carbon through soils, ecosystems, waters and the atmosphere is critical to the issue of global warming. Releasing carbon to the atmosphere as carbon dioxide speeds warming; and storing carbon compounds can slow or potentially reverse warming.

The moist acidic tundra under study covers as much as one-third of a billion square kilometers of the global Arctic – making it a major “sink” for carbon dioxide. The 2 million-ton release of carbon was equal to at least 50 percent of the amount of carbon stored annually in the Alaskan tundra, meaning this one fire almost cancelled the anti-warming benefit of photosynthesis in the region.

ENLARGE

ACIA, Key finding #2

A warming climate could change carbon cycling in the Arctic. Although boreal forest will absorb more carbon dioxide and methane from the atmosphere, increased forest fires and insect damage could release more carbon to the atmosphere.

Chilling news about a burning issue

The link between global warming and fire also appeared in a new analysis of Yellowstone National Park. “Large, severe fires are normal for this ecosystem,” said Monica Turner, a Yellowstone expert and professor of ecology at the University of Wisconsin-Madison. Historically, the entire Yellowstone landscape has burned every 100 to 300 years, but Turner and company calculated that current trends toward hotter, drier summers, mean fires could consume the entire area every 30 years by 2050.

Wildfires are also becoming more common in the normally fire-resistant tundra of Alaska, and for reasons related to permafrost, reflectivity and feedback, the consequences could be dire:

PERMAFROST: The Anaktuvuk fire burned off much of the insulating layer above the ever-frozen permafrost layer – an essential part of many Arctic ecosystems whose melting is causing major ecological change and destabilizing roads and buildings.

ENLARGE

Image: John A. Kelley, USDA Natural Resources Conservation Service

The soil profile to the right shows the interior of this stunning Alaskan landscape. Notice that permafrost (the white layer) is protected by an insulating layer of plants and soil.

REFLECTIVITY: Fires may increase the “albedo,” or reflectivity, of the surface, which would reduce the absorption of solar energy.

Wildfires in the tundra suggest that warming will produce fires that lead to yet more warming.

FEEDBACK: It’s incontestable that the globe, and especially the Arctic, are warming due to the accumulation of greenhouse gases, and that warming is linked to an increase in fires. If warming begets fires, and fires beget carbon dioxide, and carbon dioxide begets warming, we have a dangerous feedback cycle.

And feedback moves us from the additive realm to the multiplicative one. In the Arctic, feedback also plays a central role related to the release of methane, which has even more warming potential than carbon dioxide. Many warming Arctic habitats have started releasing larger amounts of methane, which could warm the planet, feed back, and stimulate the release of yet more methane.

This feedback, like the one that may be affecting burning tundra, paints a darker picture of what could happen if we ignore the atmosphere and blithely assume that the future will be just like the present.

– David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Carbon loss from an unprecedented Arctic tundra wildfire; Michelle C. Mack et al, Nature, 28 July 2011. ↩
Fire Behavior, Weather, and Burn Severity of the 2007 Anaktuvuk River Tundra Fire, North Slope, Alaska, Benjamin Jones et al, Arctic, Antarctic, and Alpine Research, 41(3):309-316. 2009. ↩
Losing the tundra. ↩
An arctic with fire. ↩
AK fires triggering runaway climate change? ↩
AK fires’ vicious cycle. ↩
Tundra fires, climate and birds. ↩
AK wildland fire info. ↩
AK fire ecology. ↩
NOAA’s arctic theme page. ↩
Arctic climate impact assessment. ↩
Climate change feedbacks. ↩
Permafrost laboratory. ↩
Permafrost. ↩
Permafrost carbon cycle. ↩
Tundra. ↩

Trash: Does burning beat burying?

Posted on 10 March 2011

Who’s right?

Europe burns heaps of garbage, getting lots of electricity and some heat. The United States does not.

tall fence and graffitied cement overpass in foreground, tall smoking chimney in background

Photos, Detroit: j to the jeremy, Vienna: Wikimedia Commons

Detroit’s incinerator, the largest in the world, was briefly shut down last October. Roll over to see an incinerator in Vienna.

Proponents say incineration shrinks the waste and produces heat and electricity while reducing the need for landfills and the diesel-drinking trucks tasked with taking trash to often-distant burial grounds.

These folks acknowledge that incinerators were rather dirty 25 years ago, but note that current air emissions are below Environmental Protection Agency standards. In a modern garbage incinerator, a complex set of filters removes heavy metals and other pollutants; high-temperature operation reduces the output of ultra-toxic dioxins.

On the other side, opponents say incinerators create global warming gases, still release toxins, divert money and attention from recycling, and tend to excuse extreme extravagance on the grounds that we can always turn our trash into energy.

Not in my backyard, they say. Not in anybody’s backyard, they add.

What a difference an ocean makes! Tiny Denmark, population 5.5 million, has 27 waste-to-energy incinerators, almost one third as many as in the United States, population 309 million. In 2009, the European union had at least 429 plants in operation.

Many European incinerators are located in cities, where their steam can be used to heat nearby buildings, not just to produce electricity. This so-called co-generation is a great way to extract more power from combustion – if the incinerator can be placed near the demand – in a city, in other words.

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Courtesy Covanta

A Covanta incinerator, the Hennepin Energy Recovery Center in Minneapolis, feeds steam to Target Field (left), home of the Minnesota Twins, for heating in spring and fall. The incinerator also supplies steam to a downtown district heating system.

Meanwhile, the biggest incinerator news on this side of the pond was the closure last fall of the world’s largest trash-burner, in Detroit. Covanta, which operated the plant and was a minority owner, cited “economic factors” for closing an incinerator that had attracted protests for years. The Detroit incinerator is now running again, under different management, says Brad van Guilder, an incinerator opponent at the Ecology Center, a non-profit environmental organization in Ann Arbor, Mich., but it still requires subsidies to earn a profit, and it’s operating at far below capacity.

Covanta, the leading incinerator operator in the United States, runs 40 of the 87 operating municipal waste incinerators in the United States. It’s expanding an incinerator in Hawaii, and is working on proposals for Ontario and Vancouver, says James Regan, spokesperson for Covanta. Given the widespread skepticism about burning garbage in the United States, he says the company is much more active overseas. The United Kingdom and Ireland, for example, are facing a European Union Landfill Directive to stop burying organic waste by 2020 or start paying 48 Euros per ton for disposal.

Germany diverts the most trash from landfills through burning and recycling, Bulgaria the least

From original graph by Confederation of European Waste-to-Energy Plants

In Europe, there’s quite a contrast between West and East, and North and South. Europe’s Landfill Directive has sparked a wave of incinerator construction in several nations.

So which is it: Is incineration, as proponents call it, waste-to-energy, or is it a waste of energy, a needless expense, and a source of toxic pollution?

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Photo: Langelle/GJEP

These protesters temporarily won their fight to close Detroit’s garbage incinerator, which released as much carbon dioxide as 100,000 passenger cars. Detroit began trucking trash to landfills, but the incinerator is now back in business.

Dumping on the open range

People have long burned garbage in the back yard, but in the United States, the big push for industrial-scale burning dates to the so-called garbage crisis of the 1980s, when incinerators were promoted as a safety valve for America’s overflowing landfills. “Communities were looking for a solution to manage their waste, and it’s more or less the same story today,” says Regan. “The municipal dumps were closing up, and finding a place to put waste was the main driver.”

A few incinerators were built, at great expense, but the specter of trash-derived smoke, laden with heavy metals and toxic dioxins, frequently added up to a public-relations disaster. Since 1980, when less than 10 percent of municipal solid waste was recycled, recycling had risen by 2009 to almost 34 percent of waste. That eased pressure on landfills, which were receiving about 89 percent of our garbage in 1980, and just 54 percent of in 2009. A rise of regional landfills, taking trash from hundreds of miles away, further helped reduce the incentive to incinerate.

The widespread objection to having a smoking, hulking garbage burner in the neighborhood is often mocked as “not-in-my-backyard” syndrome, but the term “NIMBY” is usually used by people who, by virtue of wealth and political power, are unlikely to enjoy such installations in their own backyards.

In Europe, severe land shortages during the 1970s started a switch toward incineration, says Anders Damgaard, a post-doctoral fellow at North Carolina State University. “I’m from Denmark, and 96 percent of our residential waste is not landfilled. We started incineration in the 1970s, not to generate energy, but because we ran out of space and could not build more landfills.”

The big centers of waste to-energy in Europe, Damgaard says, “are countries with the least space, Austria, Denmark, Switzerland. Over the last 30 years, they have been improving the technology for waste-to-energy and brought down the level of air pollution, which was a major concern. That made it more applicable to countries with more space, where they wanted to find a more sustainable solution than putting waste in the ground,” where it can pollute groundwater and release methane, a powerful greenhouse gas.

Total MSW recycling starts at 5.6 million tons and 6.4 percent in 1960, goes to 82 million tons and 33.8 percent in 2009

Graph: U.S. EPA

Waste recycling grew rather steadily in the U.S. between 1960 and 2009, whether measured in tons or percentage.

Toxins and dioxins

Regulators in the United States and Europe are both reporting big drops in air pollution from burning garbage, says Joseph DeCarolis, an assistant professor of water resources and environmental engineering at North Carolina State University. “According to EPA [Environmental Protection Agency] data on waste-to-energy facilities in the U.S., depending on the pollutant, the levels are significantly below their standard.” Most levels, he says, are less than half the EPA limit.

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Photo: Ecomaine

A garbage burner, like a coal plant, needs sophisticated pollution controls as it converts solid fuel to energy. Although incineration reduces the volume of waste, the ash will always need burial.

Those pollution controls are expensive, and cost is a major hindrance to building new incinerators in the United States, where landfill space is relatively cheap.

In Europe, greens get along rather well with incinerators, says Damgaard, although he does note a switch in opposition from pollution worries to the greenhouse-warming impact of incineration (which we’ll discuss later).

That change, he says, is evidence that pollution controls are working. “I think they don’t use air pollution as the main problem because it’s under control now. In Europe, especially in the countries that burn waste, there is really no movement against waste-to-energy. The green organizations see it as viable, they know the alternative is burning more fossil fuel, which is just as polluting if not more so. If you go back to the 1980s, pollution was a huge issue, but in the last 10 years, incinerators have become so much cleaner.”

Landfill is 54.3 percent , waste-to-energy is 11.9 percent, recycled and composted is 33.8 percent.

From original graph by U.S. EPA

Competition for recycling

Do incinerators, by establishing an alternative destination for trash, undermine recycling efforts? Yes, says van Guilder, who notes that for financial reasons, incinerator builders often require a “put or pay” contract that obliges a municipality to pay a penalty if it fails to supply a minimum cargo of waste.

When the embattled Detroit incinerator was built, the city agreed to essentially ban curbside recycling, van Guilder says. “Once the materials are set at the curb, they belong to the Detroit Department of Public Works, which is obligated to deliver all refuse to the incinerator. If a private citizen wanted to pay someone to pick up recyclables, they could be fined.”

Instead of building more incinerators, some opponents in the United States advocate a “zero waste” solution — a ramped version of reduce, reuse recycle — that would leave very little waste — but not zero — to be buried in landfills.

“To truly get to zero waste, we have a big gap,” admits van Guilder, “but if that’s the policy goal, that will give you the vision to move further to reduce, reuse, recycle. The next stage is a policy for extended producer responsibility, for take back, like we’re seeing for electronic waste, and we’ve had for lead-acid batteries, and for bottle [return] bills. These are sporadic examples that need to be more comprehensive.”

But is zero waste a real goal, or an inspiring slogan? “A lot of people are talking about a zero-waste society, but that’s a very philosophical standpoint,” counters Damgaard. “We will always have waste; those who think we can recycle 100 percent, that’s utopian.”

Wasting Less in the West

In exploring how to reduce the need for garbage disposal, Americans can look to cities on the “Left Coast.” San Francisco, for example, intends to be “zero waste” by 2020. The city’s mandatory recycling and composting ordinance requires residents and businesses to separate recyclables and compostables (food and yard waste) from trash. In this “co-mingled” system, all recyclables, from paper to metal, are collected in one container, then separated at a recycling facility. The city also requires recycling of construction and demolition debris. And it has banned restaurants from using Styrofoam take-out containers and large grocers and chain pharmacies from supplying plastic bags to customers.

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Photo: Frank Farm

Signs at a University of California-San Francisco cafeteria tell diners what belongs in which trash can, heeding the city’s requirement to separate compost and recyclables from garbage.

“Reduce, reuse and recycle are the most important things we need to do,” says Regan of Covanta, the incinerator firm. “We would never be caught saying that is not what you should do. Waste to energy is not a silver bullet. People say we compete with recycling, but on average the communities where we have incinerators recycle more. Marion County, Oregon, has almost a 70 percent recycling rate, and we process the residual waste.”

Instead of competing with recycling, Regan argues that the alternative to incinerators is landfills. “We think we are better than landfills, that’s our competition.” Each year, he adds, Covanta recycles more than 400,000 tons of iron, steel and aluminum that otherwise would be buried in landfills.

Recycling and incineration can compete with each other, says Matt McCullogh, an outside advisor to Covanta who works for Canada’s Pembina Institute, which advocates and consults about sustainable energy. “It’s up to the community to ensure they have a solid recycling system in place, so only what cannot be recycled goes to waste-to-energy, and the result is a win-win where there is enough energy content so the facility can be economic.”
Indeed, the European nations with the highest rates of incineration, Denmark, Germany, Sweden, Austria and the Netherlands, recycle 27 percent to 54 percent of their waste.

Is “waste” energy renewable energy?

How might increased incineration affect global warming due to greenhouse gases? Incinerators are often called “waste-to-energy” plants and they are also sometimes considered sources of renewable energy, but the energy equation is extremely complex. Some of the energy in waste organic materials, including paper, is renewable, but other energy comes from plastics that originate in fossil fuel.

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Photo: Herr Olsen

Furnace of the waste-to-energy plant in Solingen, Germany.

Although that energy is not renewable, it is wasted when plastic is buried in a landfill. “If we don’t burn the plastics, we have to create that same energy directly from fossil fuels,” says Damgaard. “As long as the energy system relies on fossil fuel, this just switches between different types of fuel.”

Could incineration excuse ever greater use of plastic? That seems to be the hope of Rusty Wheat, sustainability manager at the French petrochemical giant Total. “We’ll promote anything that increases waste-to-energy,” Wheat told the American Association for the Advancement of Science in February. “We can’t recycle a lot of plastic because it’s contaminated, and cleaning it would cost more environmentally than putting it in a landfill.” The most reasonable approach now, Wheat said, “is to take bulk municipal solid waste straight to the incinerator.”

A recent bill called Waxman-Markey would give renewable energy status and tax breaks for the organic stuff that’s burned in waste-to-energy plants, Wheat said. “That excluded our plastics, and we weren’t too happy about that, and we have been lobbying to get plastics back into Waxman-Markey. Plastic is what provides all the BTU [heat] content, so waste-to-energy plants should want to burn it. We need the renewable energy status for the tax breaks.”

Waste-to-energy, or energy-to-waste?

Turn the argument on its head, and you get a different result. If your goal is to save energy, the best tactic is to reuse or recycle plastic, not burn it, says van Guilder. (To which skeptics at Why Files must observe that many plastic cannot reasonably be reused or recycled, leaving a real-world choice of burning or burying.)

Incinerators release energy through combustion, and landfills create it when bacteria produce methane. This natural gas is a great fuel, but methane is also 21 times more effective than carbon dioxide in trapping greenhouse gases. Although many landfills have labyrinthine pipes to collect methane, 60 to 85 percent of the gas escapes into the air, and a recent study¹ found that counting this escape, landfills produce 1.6 to 5.7 times more greenhouse-warming as waste-to-energy to make the same amount of electricity.

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Photo: ARH346

Are waste-to-energy facilities a more constructive solution to America’s garbage habit?

The bottom line is the bottom line

Thousands of words ago, we promised to explain why Europe is so happy with its incinerators, and the United States is so fearful of them. But here’s the deal: Europe might not even have incinerators if it had enough room to build giant sacrifice zones — landfills. “Unlike Europe, many parts of the United States are not space-constrained,” says DeCarolis. “If it were, there would be a more serious move here toward waste-to-energy.”

To be efficient, incinerators must be located near the people who generate the waste, DeCarolis says. “You don’t want to put incinerators in the middle of nowhere, because the cost of bringing all the waste is too high [and there will be no market for the steam generated]. But when you are close to a population, you run into NIMBYism. People are afraid to have these large plants near them.”

Garbage is not going away, DeCarolis adds. “If we don’t incinerate, we’ve got to do something else. We can recycle and reuse, but at some point, we’re going to end up with residual waste that will need to be landfilled.”

And landfills cause their own environmental threats – methane, groundwater pollution, and removing land from productive use, DeCarolis adds. If we don’t incinerate, he adds, “we will not get away from having an environmental impact.”

– David J. Tenenbaum

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Denmark waste-to-energy. ↩
Europe leads the way. ↩
Energy Recovery Council. ↩
Incinerator as eye candy. ↩
Burn or bury? ↩
EPA: U.S. waste management. ↩
Expansion of “renewable energy” meaning. ↩
WTE technology report. ↩
Heating Target Field. ↩
Closing Detroit’s incinerator. ↩
Detroit: incinerator vs. recycling. ↩
Waste-to-energy directory. ↩
1 Is It Better To Burn or Bury Waste for Clean Electricity Generation? P. Ozge Kaplan et al, Environ. Sci. Technol. 2009, 43, 1711-1717. ↩

I robot. Aye science!

Posted on 27 January 2011

Autonomous! Outstanding!

As deadly American drones work the skies over Afghanistan and Pakistan, we got to wondering how similar remote-control approaches are contributing to science. In science, as in war, leaving the staff behind can slash costs and allow sustained exploration of no-go zones.

Part of the story is propulsion: New science vehicles can travel long distances through the ocean and atmosphere with minimum energy. Brains-on-board also matter: Computers enable these super-sensors to make decisions and work long stretches with little or no back-seat driving.

The result is a lot of science per gallon.

Although the vehicles we’ll look at have scientific purposes, they get major financial and technical support from the Department of Defense, proving that military and peaceful pursuits are inextricably linked in extreme environments.

Header says: 'Sentry on Duty'

If you dig the deep ocean, WHOI — the Woods Hole Oceanographic Institution on Cape Cod — is a good place to be. The renowned saltwater scientific outfit has a new, deep-water explorer that works without a lifeline.

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Photo: Erich Horgan, WHOI

First you grin, then you dive! To deepen our understanding of the ocean, the autonomous underwater vehicle Sentry is happy to explore the top 2.7 miles of the ocean. That slippery shape allows easy horizontal and vertical movement.

Meet Sentry, which can take photos and make chemical and geophysical measurements down to 4,500 meters depth, and has worked two high-profile environmental issues: global warming through methane release, and BP’s Deepwater disaster.

Sentry has been used to look for “cold seeps,” regions of the seafloor that release large amounts of methane, says Chris German, WHOI’s chief scientist for deep submergence. “Cold seeps are like the overlooked younger sisters of hydrothermal vents,” the “black smokers” that release superheated fluids and anchor unique ecosystems at the sea floor, usually in mid-ocean.

Cold seeps are located closer to the continents, and “are not as spectacular thermally or geologically, but they do have some of the same chemistry,” says German, “and a lot of the same kinds of animals, even the exact same species.” Cold seeps may explain the distribution of deep-sea organisms around the ocean, he adds. “We want to understand … whether animals are using these locations as stepping stones.”

Most cold seeps were found by accident, but German thought Sentry could detect subtle chemical clues, and last October, he got to test that idea at an underwater landslide off the coast of Norway. The landslide had released pressure on a material called methane hydrate, and a large amount of methane was bubbling from the seafloor mud, creating a “mud volcano.”

Video: Jack Cook, WHOI

Flying without a pilot, Sentry makes detailed maps and digital snapshots of seafloor features including mid-ocean ridges, hydrothermal vents and cold seeps.

Methane is a much more powerful greenhouse gas than carbon dioxide, and given the staggering amount of methane held in methane hydrates, such releases could create a nightmare feedback: warming releases methane, which traps more heat, causing more warming that releases more methane.

Getting engulfed

By prowling around the known cold seep near Norway, German confirmed the detection hypothesis.

Then, the day after Sentry returned to Woods Hole, a real-world opportunity appeared for the new technique.

Biologist Charles Fisher at Penn State was about to embark on a mission into the aftermath of BP’s blowout in the Gulf of Mexico, and he wanted help locating a coral patch to compare to another he’d already located 1,200 meters deep, 11 kilometers southwest of the blowout.

That coral was coated with a brown goop that looked suspiciously like crude oil. Could Sentry locate, for long-term comparison purposes, a similar coral outside the oil plume?

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Photo: Lophelia II 2010, NOAA OER and BOEMRE

This deepwater coral is downstream of the destroyed BP well in the Gulf of Mexico. In December, Sentry helped find similar coral that was not damaged by the BP spill. The brown goop covering this coral is likely crude oil, and the attached sea star is bleached white, another likely sign of oil damage.

Fisher was part of a National Science Foundation-sponsored “rapid response” cruise to the Gulf, but German was still unpacking. “We’d have two weeks to turn around and get going, and I went to our guys Monday morning and asked, ‘Can you do this?’”

The maintenance crew figured out who would miss what weekend, and they agreed to do it, German says.

Cold seeps and deepwater coral in the Gulf of Mexico are linked, German explains, because the coral live on bare rock, which is often carbonate, and carbonate rock forms at cold seeps when methane is oxidized into carbon dioxide. “So beneath every healthy deep coral, is an active or historic cold seep.”

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Photo: Woods Hole Oceanographic Institution

To assess damage after BP’s blowout in the Gulf of Mexico, Sentry helped scientists locate a site for long-term monitoring of deepwater coral like these.

Suddenly, a theoretically interesting search technique became relevant to the biggest American oil spill in a century.

“Flying” with a map

Based on oil-industry data about the sea bottom, Sentry visited one location southeast of the Macondo well and found no coral. But at the second location, German says, “We hit pay dirt. We flew backward and forward, and found an active cold seep and evidence for tube worms, mussels and coral.”

Ocean-floor research seldom moves so fast, German says, and within hours, he was one of three people to visit the spot in Alvin. “In 36 hours, we went from nothing other than a hunch, to having a topographic map and photos,” German says. “We dove to the sea floor, and there was no mysterious driving around in the dark. Within 15 minutes, we drove to the site because we had a perfect map of where to go.”

In fact, German was holding a fresh, glossy photo of the target, taken less than two days previously.

Sub-terra cognita? Not!

And so is the ocean bottom, as people often say, still less familiar than the far side of the moon? German insists that it still is, despite years of research and an increasingly capable flotilla of deep-sea ships. “In December, in the Gulf, I could see at least 10 to 20 oil rigs… but I’m pretty sure, driving across that seafloor a couple of hours offshore from the United States, that nobody ever laid eyes on it before.”

A recent survey of marine biodiversity shows a chain of ignorance stretching across the Pacific, located near regions of extremely high biodiversity near the Philippines and Australia, German says. “In many of those locations, they’re 300 miles square, there have been fewer than 50 biological measurements in the history of the ocean. This is a chain across the South Pacific ocean, the single biggest contiguous ecosystem on the planet, and it has not been studied.”

And that’s the rule, not the exception, German says. “Close to one-half of the planet is at least 3,000 meters deep, and it’s much further away [and deeper] than the Gulf. From satellite altimetry we have an idea where the bumps are on the seabed, but we don’t know what’s going on; we have a vanishingly small idea.”

header='Gliding beneath the seas'

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Image: Applied Physics Laboratory, University of Washington

Engineers Avery Snyder and Adam Huxtable ready a Seaglider for a 51-day icy swim between Canada and Greenland, in Davis Strait.

Deep water may be the sexiest place in oceanography, but long-term studies are also difficult and expensive in shallow waters, especially if they are remote, icy, stormy, or all three. Propellers, the standard way of moving through water, require a lot of energy and quickly drain batteries on artificial fish.

Gliding — think of soaring like a hawk as opposed to flapping like a sparrow — is a much more conservative approach.

And gliding is the MO of Seaglider, a project built by the University of Washington with money from the Office of Naval Research and the National Science Foundation. Using battery power, the glider alters its buoyancy, causing it to rise or fall through the water. By altering its center of gravity and adjusting its fins, the metal fish moves horizontally with minimal amounts of electric current.

How minimal? In 2009, a Seaglider traveled a record 3,050 miles through the North Pacific during a 9-month journey, without the caress of a human hand or an electric transfusion.

Costing “only” about $100,000 apiece, about 60 gliders are working around the globe, says Craig Lee, a principal oceanographer at UW’s Applied Physics Laboratory, recording basics like temperature, salinity, dissolved oxygen and optical characteristics of its surroundings.

Video: National Science Foundation/U. of Washington

Craig Lee, a principal oceanographer with the Seaglider project, explains how an artificial fish worked solo under the ice in Davis Strait.

In 2008, south of Iceland, gliders and floats studied carbon uptake by phytoplankton — floating plants that bloom in spring and play a major role in the global carbon cycle. The goal was to follow “parcels” of water during the entire bloom — which ends after some weeks when plankton are eaten or sink in the water. Both processes can remove carbon dioxide from the atmosphere for long-term storage, and therefore have implications for global warming.

“We were trying to learn what drives the carbon flow,” says Lee. “Nobody had done this before: the Seagliders and the buoys had the persistence, the ability to be there for the entire duration of the bloom. You would have to schedule a ship one year ahead, and … if you got there on time, it would be too expensive to keep the ship out there for the whole bloom.”

If ice is nice, under ice is nicer!

In 2009, a Seaglider spent 51 days in Davis Strait, the frigid water separating Greenland and Baffin Island, traveling more than 450 miles under the ice. The Strait is a chief source of melt-water from the frozen Arctic Ocean.

Climatologists worry that a rush of cold, fresh water through the Strait could alter the warm Gulf Stream and freeze Northern Europe.

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Image: Applied Physics Laboratory, U. of Washington

Davis Strait already has strings of scientific instruments, but Seaglider can cover more of the same waters, enlarging the stock of data in a location that influences the critical Gulf Stream.

Getting measurements from Davis Strait is expensive and dangerous, especially considering how much of it is under ice. But the Seaglider did just fine, says Lee. “This was very exciting, that ability to stay out there for a long time, and the ability to get to places that otherwise would be difficult. In winter in the North Atlantic, nobody wants to be there…”

The fish navigated under the ice using five anchored sonar beacons that created an undersea version of GPS, Lee says. Ten times, using its software, the glider found holes in the ice, poked its nose through them, and phoned home via satellite telephone. “It tries to sense ice by looking at the temperature of the water,” says Lee. “It emits a ping and tries determine whether ice is overhead, and it has a climate map that tells it, for a given position at a given time, is ice likely to be overhead? Using all that information, it decides whether to surface.”

During those famous North Atlantic storms, “It just keeps working, it does just fine, continues to navigate, continues to report. We’ve been in 40-foot seas, with 60- to 80-knot winds, and everybody’s happy, although it takes a little longer to get a phone call through.”

The glider carries a quarter for the phone call, but no Dramamine…

header reads: Jet-fueled hawkeye

A fruit of the military’s desire to see everything from a safe vantage, Global Hawk is a secretive, high-flying, pilot-free jet that can fly at 60,000 feet for 30 hours, non-stop.

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Photo: NASA Photo/Jim Ross

Global Hawk is a high-tech surveillance plane temporarily drafted as a high-tech, hands-off environmental observatory that can fly 12 miles high for 30 hours. The propeller plane studies Hawk’s wake.

For its occasional forays into peaceful work, Global Hawk carries a large cargo of scientific instruments that can monitor light, pollution, ozone, water vapor, weather, clouds, incoming and outgoing radiation, even particles smaller than 1 millionth of a meter across.

The Hawk, which flew scientific missions from NASA’s Dryden Flight Research Center in California in April, 2010, can also be used for earth observation, such as tracking algal blooms in the ocean, vegetation on land, and various resource issues.

Hawk has tracked pollution from Asia above the North Pacific as it moves toward North America and looked at large-scale atmospheric circulation, which influences weather and the distribution of radiation-blocking high-altitude ozone.

We could not get through to a source at the National Oceanic and Atmospheric Administration, which plays a role in Hawk’s science, but we grabbed a press release issued after Hawk’s first environmental flight.

According to Paul Newman, an atmospheric scientist from NASA, “The Global Hawk is a revolutionary aircraft for science because of its enormous range and endurance. No other science platform provides this much range and time to sample rapidly evolving atmospheric phenomena. This mission is our first opportunity to demonstrate the unique capabilities of this plane, while gathering atmospheric data in a region that is poorly sampled.”

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Photo: August 28, 2010, NASA/NOAA

Make you a bit giddy? Global Hawk eyes tropical storm Frank near Baja California. Global Hawk operates above most airplanes, but below satellites, filling a gap in atmospheric data that could help weather forecasting and studies of pollution, global warming and ozone depletion.

Rise and shine, repeat

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Photo: Scripps Institution of Oceanography / UCSD

Kyle Grindley, a Scripps engineer, helped design the SOLO-TREC, an underwater vehicle that can operate all by itself. Ten cylinders surrounding the central core hold a wax that melts as temperature increases; the resulting expansion drives an electric generator to power all Solo systems.

In their quest for data on the deep, scientists have gotten a trickle of info from sensors attached to deep-diving marine mammals. In November, 2009, the Scripps Institution of Oceanography launched SOLO TREC (Sounding Oceanographic Lagrangrian Observer Thermal RECharging vehicles; glad you asked?), a bobber that can sink 500 meters into the ocean, then return to the surface to report via satellite to scientists who may prefer sipping lattes at a Java Joint to crowding the rail on a topsy-turvy research ship.

Let’s call this Solo, and let’s agree that it’s a strange vessel. Solo can adjust its buoyancy, but lacks propellers and cannot drive laterally, so its location is at the mercy of the currents.

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Solo records basic ocean conditions, but the real accomplishment is proving that its power system needs no recharging and could, theoretically, operate more or less forever – or at least until it breaks or barnacles or plants foul the fish up and slow it down.

Looking like a giant fishing float, Solo rises and sinks in the ocean through a novel electric generator driven by changes in ocean temperature.

Photo: Scripps Institution of Oceanography, UCSD

Solo had already completed 300 dives by March, 2010, and although it sounds like a perpetual motion machine, it actually sucks its energy from the ocean as it rises toward the surface:

The ocean warms and melts a waxy material in 10 exterior tubes;

Pressure rises, forcing liquid wax through a hydraulic motor that generates electricity that is stored in batteries;

The current activates instruments and the buoyancy control system, which causes Solo to sink and then rise again, and the cycle continues.

According to Yi Chao of the Jet Propulsion Lab, a Solo principal investigator, “This technology to harvest energy from the ocean will have huge implications for how we can measure and monitor the ocean and its influence on climate.”

Funded by NASA and the U.S. Navy, Solo’s technology is also obviously useful for monitoring animals and the movement of ships and submarines.

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Global Hawk mission page. ↩
YouTube: Glimpse at Global Hawk. ↩
Sentry’s expedition in the Gulf. ↩
Video: how Sentry works. ↩
Seaglider and climate change research. ↩
Seaglider specs. ↩
Warm and cold water patches power underwater probe. ↩
Tracking SOLO-TREC. ↩
Autonomous robots invade retail warehouses. ↩
Autonomous robots blog. ↩
Discovery news: autonomous robots. ↩
Dying coral at Gulf oil spill site. ↩

A climate of extremes?

Posted on 13 January 2011

Meet your warming climate

Skeptical about global warming? 2010 has just tied 2005, making these the two hottest years on record. And nine of the 10 warmest years on record have occurred since 2001.

Residential city street blanketed in couple feet of snow, car in foreground completely covered in snow

Photo: williumbillium

Was New York’s epic blizzard last month related to climate change?

But temperature is only part of the story. After a year that saw epic floods in Pakistan and California, massive floods have swamped Brisbane, Australia, population 2 million. Russia was toasted by a record heat wave last summer. Europe and, of course, New York were smothered by giant snowstorms.

And we just read that 2010 had the heaviest precipitation on records that date to 1880.

So we have to ask: Is this normal weather, or is this climate change in action?

And as greenhouse gases continue to accumulate in the atmosphere, what will happen the day after tomorrow?

There is good theoretical reason to think that an accelerating greenhouse effect will affect weather: Add greenhouse gases like carbon dioxide and methane to the atmosphere, and they trap more heat. In hotter conditions, more water evaporates from the ocean, which eventually falls as precipitation. Heat is energy, and more energy in the ocean and atmosphere provides more power to drive intense storms.

If, as virtually all climatologists expect, global average temperatures will rise, what will happen to extremes like these:

• Daily record temperatures

• Precipitation

• Drought

• Hurricanes and other storms

These questions are devilishly difficult to answer. It’s a big planet, and assessing conditions during the past few decades, and making projections for the future, is a gnarly task. Climate models are better at getting the big picture than making regional forecasts for future weather. Data records are incomplete, especially as we delve further in the past.

Graph shows large CO2 increase starting at 1950 and corresponding increase in annual global temp

Graph: Progress Report of the Interagency Climate Change Adaptation Task Force: Recommended Actions in Support of a National Climate Change Adaptation Strategy, October 5, 2010

If you doubt that warming temperatures have anything to do with carbon dioxide, the primary greenhouse gas, here’s something to think about. Horizontal divider shows average temperatures, 1901-2000.

Nevertheless, let’s ask our question about both recent weather data and future forecasts.

Record temperatures

As the climate warms, one easy prediction is that record warm days will become more common, and record colds will be less common. When Gerald Meehl, a senior scientist at the National Center for Atmospheric Research, compared the number of record daily highs to the number of record daily lows in the U.S., he found they were roughly equal in the 1950s.
Today, he says, “for every two record highs, there is only one record low. If there was no warming going on, the ratio would be one to one, so we are shifting the odds toward having a better chance for setting a record high versus a record low.”

Meehl says Australian data show the same thing.

Even though the climate has warmed by only about 0.6° C, he says, “This shows that even with a very small change in average temperature, about 1° Fahrenheit, we can get a pretty noticeable change in the extremes.”

http://whyfiles.org/wp-content/uploads/2011/01/GISTEMP_2009update_Dates.mp4

Animation: NASA

Click to see changes in average temperatures around the globe since 1885.

At some point, we may look fondly upon today’s two-to-one ratio, as climate models suggest the ratio will reach 20 to 1 by year 2050 and 50 to 1 in 2100. Yet even then, when the U.S. average temperature may have risen by several degrees C, “We still get some daily record low temperatures,” Meehl says. “We still get extremely cold weather, although it will happen much less frequently.”

Today, he notes, “When there’s a cold snap, people ask, ‘What happened to global warming?’ But even with warming, it will still get cold, but not extremely cold, and not as often.”

Precipitous rise in precipitation?

Rain and snow are two ways that the atmosphere feeds life on the planet. A hotter atmosphere has the ability to hold more moisture because more water evaporates from the ocean, and warmer air can also store more moisture.

Already, says Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research, the water-vapor contained in an imaginary cylinder stretching from Earth to space has been rising 1.3 percent per decade since the 1970s.

And so warming means more potential for precipitation.

Change in very heavy precipitation over U.S.

Map: Progress Report of the Interagency Climate Change Adaptation Task Force: Recommended Actions in Support of a National Climate Change Adaptation Strategy, October 5, 2010.

The amount of precipitation falling in the heaviest 1 percent of all daily events has increased during the last half-century, especially in New England and the Midwest.

“When we review change in the hydrological cycle,” Trenberth says, “not just tropical cyclones [hurricanes and typhoons] but extra-tropical cyclones and individual thunderstorms, the evidence from around the world is that when it rains, it rains harder, when it snows, it snows harder. This is consistent with the understanding we have, the theory.”

That is also happening in the United States, where days with intense rain and snow have been increasing, says Meehl. “When it rains, it pours, we see this in observations, and models show an increase in the future.” For example, a summary published in 2007¹ found that, “Over the last century there was a 50% increase in the frequency of days with precipitation over 101.6 mm (four inches) in the upper Midwestern U.S.”

However, land use plays a role in some observed precipitation changes, says James O’Brien, emeritus professor of meteorology and oceanography at Florida State University. “We studied heavy rainfall over 62 years in Orlando, Fla., and did a simple thing: We divided the time into two periods of 32 years each, and looked at the probability of one or more two-inch rainfalls.”

Extreme floods: Any relation to global warming?

Queensland, Australia, December 30, 2010

Photo: Australian Red Cross
Sindh province, Pakistan, after the monsoon, Oct. 22, 2010.

Photo: U.S. Marine Corps
Laguna Bay, 60 kilometers south of Manila, the Philippines. In September, 2009, Typhoon Ketsana dropped a month’s worth of rain in six hours.

Photo: International Rice Research Institute
June 13, 2008, Lake Delton, Wisconsin, after rains broke a dam.

Photo: Carol Mitchell
Bangladesh after Tropical Cyclone Sidr killed more than 3,000. The U.S. Departments of Defense and State aided the recovery.

Photo: Nov. 27, 2007, Christopher Lange/U.S. Navy

In the recent period, during almost all non-summer months, Orlando had a big increase in heavy rain, but Gainesville, 40 miles away, did not. “The cause in Orlando is absolutely clear,” says O’Brien. “It’s Disney World. It’s all the roads, the concrete, which act as a heat sink. In winter, a cold fronts hits a bubble of heat caused by this heat island, and it kicks up a storm and you get more rain.”

Heavy rain = heavy drought?

Even if total precipitation does not change, there are consequences to the newer “when-it-rains-it-pours” precip pattern. Heavy rain runs off rather than percolating into the soil, so instead of feeding plants, it can cause soil erosion and floods. If, as some models suggest, extreme precipitation increases in springtime, when the ground is still frozen, “that has a significantly different impact than extreme rainfall during summer,” says Daniel Vimont, an assistant professor at the Center for Climatic Research at the University of Wisconsin-Madison, because the rain cannot enter the soil and must run off.

Heavy rain can also contribute to drought by drying the atmosphere, Meehl says. “We have to take into account the number of days between precipitation events. On a map of North America, almost everywhere intensity shows an increase to date, and a projected increase, but we also see dry days increasing, like in the southern tier of states and especially the Southwest. When it rains, it rains really hard, but there are more days between rainfalls. On average, you are getting less total precipitation, but the risk for floods has increased because of this intensity increase. Over long periods, we are seeing drier conditions, because the number of days between events is also increased.”

Facing a wave of drought

A trend toward drought is already under way, according to a 2004 study by Aiguo Dai of the National Center for Atmospheric Research, which found that the percentage of Earth’s land area stricken by serious drought had more than doubled between the 1970s and the early 2000s.

The future seems no more benign. Last October, Dai published a review, based on 22 computer climate models, that projected a major expansion of drought over the next 30 years. The affected area includes the breadbasket regions of North and South America, most of Africa and Australia, and parts of China and neighboring countries.

A climate of drought?

Maps: University Corporation for Atmospheric Research

These maps show projections for drought in future decades, based on expected greenhouse gas releases. Positive numbers on the Palmer Drought Severity Index show unusually wet conditions for each region, and negative numbers show unusually dry conditions. Readings of -4 and below represent extreme drought.

According to the study, the western two-thirds of the United States will be significantly drier in the 2030s, after which matters will only get worse.

In general, the only places that will see more precipitation are in the extreme north — Northern Russia, Scandinavia, Canada and Alaska.

So reindeer need raincoats…

But seriously, “We are facing the possibility of widespread drought in the coming decades, but this has yet to be fully recognized by both the public and the climate change research community,” Dai says. “If the projections in this study come even close to being realized, the consequences for society worldwide will be enormous.”

Cyclones, typhoons and hurricanes

In terms of extreme weather, nothing beats the tropical storms variously called typhoons, tropical cyclones or hurricanes — for their winds, high seas and astonishing rainfalls. So hurricanes are the natural focus of study on the past and future effects of global warming.

In 2005, Hurricane Katrina played the starring role in a series of powerful hurricanes that pounded the Gulf of Mexico and Caribbean, and we reported that hurricanes were packing more power in a warmed planet.

Then came a counter-rebellion: scientists began questioning whether hurricanes were really more powerful, and noted that they were not getting more common (although everybody agrees that increasing population and development along the coasts both contribute to greater storm damage).

The chief hindrances to finding real trends in the tropical cyclones are their long-term, natural variation in strength and frequency, and the wobbly nature of data on older cyclones. In the North Atlantic, home of the best hurricane data, the quality of the data jumped when airplanes began flying into hurricanes in 1944, and again when satellite tracking began around 1970. Data on older Pacific and Indian Ocean storms are even more questionable.

To explore how global warming will affect tropical cyclones, the World Meteorological Organization set up a team under the leadership of Thomas Knutson, of the Geophysical Fluid Dynamics Laboratory. Knutson’s group projected that hurricanes, globally, will become 6 percent to 34 percent less common by 2100, despite the warming trends².

The counterintuitive reduction may be due to wind. These storms need a warm ocean to provide energy, “but you also need an atmosphere that cooperates,” explains Charles Conrad, an associate professor of geography at the University of North Carolina and director of the Southeast Regional Climate Center. Wind shear, a change in wind velocity with altitude, can blow a developing storm apart. “Some global climate models suggest that more wind shear over the tropical and sub-tropical Atlantic may inhibit cyclones, so when you put that together with higher sea-surface temperatures, this suggests that when a system can develop, it will be stronger.”

A question of intensity

Given the rickety data on older storms, Knutson’s group concluded that “it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes.” According to team member Christopher Landsea, science and operations officer at the National Hurricane Center, “Every single paper in the peer reviewed literature, looking at the theoretical side of hurricanes and global warming, or the climate model simulations, says the same thing. The changes today are very, very tiny, maybe 1 percent stronger, due to manmade global warming.”

But another member of the team begs to disagree. “I think the evidence is fairly unequivocal that there has been an increase in intensity,” says Kerry Emanuel, professor of tropical meteorology and climate at Massachusetts Institute of Technology. To gauge intensity, Emanuel used wind speed, measured at six-hour intervals, to calculate a “power dissipation index,” fancy lingo for the amount of energy that enters the hurricane.

Fluctuating lines show dramatic increase in sea surface temp increase and hurricane power starting in 1990s

Graph: Weather and Climate Extremes in a Changing Climate³

Heat energy from the ocean powers hurricanes, and storm intensity closely follows changes in sea surface temperature in the North Atlantic. “Power dissipation” is a measure of the storm’s total power, based on a cube of maximum wind speed.

The index, he says, shows that recent hurricane intensity is “beautifully correlated with ocean temperature in the tropics,” and those warm seas, in turn, result from accelerating greenhouse warming. Changing levels of greenhouse gases and reflective aerosols in the atmosphere “are the cleanest explanation for what happened with hurricanes,” Emanuel says. “I think there is a strong [human-caused] signal in Atlantic hurricanes over the last 40 years.”

Tower of power

And what of the future? The Knutson team projected that average maximum winds would increase 2 percent to 11 percent by 2100, so “a substantial increase in the frequency of the most intense storms is more likely than not globally, although this may not occur in all tropical regions.”

Although the group wrote that intense tropical cyclones, “deserve particular attention, as these storms historically have accounted for an estimated 85 percent of U.S. hurricane damage,” Landsea said, “That’s a very small increase, a long ways in the future,” and it could be offset by a decreasing frequency of storms.

In the world of climate, it’s usually possible to find another voice, and last year, a modeling study⁴ projected that the number of category 4 and 5 storms will almost double by 2100. (Category 5 includes the strongest hurricanes.)

We asked James Kossin, a scientist with the National Oceanic and Atmospheric Administration, who has studied hurricanes since 1987, about those results, and he told us, “There is a lot of uncertainty in our understanding of how tropical cyclones respond to their environment and to changes in their environment.”

Linking changes in hurricanes to human-caused climate changes is “very challenging,” said Kossin. “I have medium confidence that climate change could lead to the strongest storms getting stronger” globally.

Emanuel, however, says the creators of these models “freely admit they will not model intense hurricanes, they don’t have the resolution. What does a 2 percent to 11 percent increase mean if the models are constitutionally incapable of having hurricanes? And this is what the models are telling us, but what does nature say? It tells us that hurricanes intensity is changing much more rapidly.”

Emanuel reminds us that storm destruction equates to at least the cube of wind speed, and therefore, a small increase in maximum wind can mask a much larger increase in intensity and damage.

From here, gentle reader, the arguments devolve from murky to truly obscure. We promise to report back in a few years, but we’re happy to note that this dispute, however contentious, is being fought in print by civil scientists who can cooperatively ponder on our climatic future.

Easy questions can be tough to answer

The complicated connection between extreme weather and global change reflects some fundamental problems:

• Climate models can disagree.

• Climate models are best suited to global, not local, predictions. Small storms can easily “slip through the cracks” in models.

• Data can be surprisingly scarce. For example, hurricanes that did not reach land are likely missing from century-old data.

We’d love to know if warming is affecting wind, but the records do not support such a comparison, says Dan Vimont. In a study on climate change in Wisconsin, for example, “We started to look at wind, but there is not as much observational data. There are 200-odd temperature-precipitation gauges around Wisconsin reporting daily, but … it’s difficult to find a continuous record from a gauge that is monitored well.”

The reality is that as much as we’d like to attribute particular events like the floods in Pakistan and Australia to climate change, we may never know. “For any given event, it’s really hard to gauge how much climate change has contributed,” says Claudia Tebaldi, a climate statistician with the non-profit Climate Central. “Even for heat waves, where it’s obvious that as climate warms you would expect more intense heat waves, [you have to acknowledge that] a given heat wave may have happened anyway without climate change.”

Terry Devitt, editor; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive; Emily Eggleston, project assistant

Bibliography

Weather and Climate Extremes in a Changing Climate, Kenneth Kunkel et al, chapter 2, U.S. Climate Change Science Program, 2007. ↩
Tropical cyclones and climate change, Thomas R. Knutson et al, Nature Geoscience, published online: 21 FEBRUARY 2010 | doi: 10.1038/ngeo779 ↩
Weather and Climate Extremes in a Changing Climate, Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands, chapter 2, Observed Changes in Weather and Climate Extremes, Kenneth Kunkel, editor, U.S. Climate Change Science Program, p. 56 ↩
Modeled Impact of Anthropogenic Warming on the Frequency of Intense Atlantic Hurricanes, Morris A. Bender, et al, Science, 22 Jan. 2010. ↩
Changes in precipitation with climate change, Kevin Trenberth, Climate Research, in press, 2011. ↩
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Hurricanes and climate change. ↩
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