Among all animals, amphibians are in the worst shape; fully 30 percent are classified as threatened or endangered. Amphibians – including frogs, toads and salamanders — are under attack by a deadly fungus. They are losing habitat to farms and cities, and collected as food or pets. Amphibians are suffering from chemical pollution and the warming climate.

The present is harsh enough, but the future seems worse.

This week, Nature publishes the first global attempt to forecast the impact of three big threats to amphibians by 2080 – a year chosen to be one century after the study’s baseline data.

By comparing areas with plenty of amphibian species with projections of climate change, land use change and the chytridiomycosis fungus, the researchers forecast a grim future for these cold-blooded, four-legged vertebrates. “The bad news is that more than two-thirds of all high-richness regions will probably be affected, to a high intensity, by one of these three threats,” said lead author Christian Hof, who did the work as a Ph.D. student and post-doctoral fellow at the University of Copenhagen.

The geographic study of data on 5,527 amphibian species found little overlap between the cool, moist areas afflicted by fungal serial killer chytridiomycosis, and the places likely to suffer the worst effects of changes in climate and land use.

And the losers win!

In forecasting the future of amphibians, the study coined two technical terms: “losers” — species that are expected to suffer due to disease or changes in climate or land use, and the less numerous “winners,” which are expected to prosper by 2080.

The projection hinged on whether an expected change would make a habitat more or less suitable to the species, says Hof, who’s now at the Biodiversity and Climate Research Center in Frankfurt, Germany. “We ran a number of climate-change models and based on them, calculated a change in climate suitability for each region across the globe.”

Based on these changes in suitability due to climate, land use and disease, Hof adds, “We calculated the number of species that would probably decline due to a decline in habitat suitability. We classify the species as a loser in a particular region, but that does not mean it will decline across its whole range.”

Overall, the researchers found an increasingly dire future for amphibians. For example, 54 percent of frogs are likely to be “climate losers” in the average grid cell of their model. And heavy impacts are projected for about two-thirds of the regions with the highest species richness in frogs and salamanders.

In fact, the future could be even worse, since the study ignored a number of potentially damaging factors, including chemical pollution from cities, factories and agriculture.

Photo: Robert Fletcher, Ohlone Preserve Conservation Bank

Tougher times might await this prowling California tiger salamander, an endangered California native.

Going down!

It’s frustrating but understandable that the study could not predict rates of decline among amphibians. “For many species, we are not sure about the actual distribution, many have tiny ranges and we don’t know where they occur, so we can’t relate historic changes to, say, climate change. We were very careful not to predict extinctions, based on these uncertainties.”

Data are scarce in the study of amphibians, agrees Anna Pidgeon, an assistant professor of forest and wildlife ecology at University of Wisconsin-Madison. “It’s frustrating, amphibians are out at night, often in remote areas, they are small and many are cryptic, so it’s a huge challenge” to understand their populations and ecologies. “We work with the best data we have all the time … and try to make inferences from what we know about close relatives.”

Pidgeon, an expert on habitat needs of vertebrates, says predicting 70 years into the future is always dicey, but that the study’s analysis of multiple threats and global scope are major accomplishments. “They did a lot of things to make sure they were using consensus data, and that makes it a pretty solid approach.”

Although the study looked at overlapping threats, it did not actually look at interactions between those threats, Hof says. “What needs to be done, and we could not do that with our model, is to look at, for example, how climate change would affect susceptibility to the fungus. How would habitat fragmentation affect susceptibility to climate change?”

Although the study does not suggest practical changes that could sustain amphibians in the short run, “The general conclusion is that it’s very important, when thinking about the future for amphibians, to consider different threats together,” says Hof. “Just looking at one threat will not give us the whole picture.”

– David J. Tenenbaum

In a world studded with intractable conflicts, none seems more nettlesome than he one between Israelis and Palestinians. In this and many other conflicts, people are often trained to believe the worst about the other side, who are variously stereotyped as immoral occupiers or immoral terrorists.

These conflicts, as history has shown, are not ideal for peacemaking based on compromise, and yet the conflicts in Northern Ireland and South Africa have come to peaceful resolutions.

But during the conflict, even mentioning the opposing side can backfire, says Eran Halperin, a professor of political psychology at the Interdisciplinary Center in Herzliya Israel. “When you try to tell an Israeli something positive about a Palestinian, or vice versa, the immediate reaction is defensive. In many cases, they are not willing to hear positive information about the other side.”

A sideways approach, however, may be more effective at changing attitudes and creating a willingness to compromise. In a study just published in Science¹, Halperin and co-authors demonstrated that simply reading a few sentences about the successful resolutions of historic conflicts elsewhere made Israelis and Palestinians more amenable to compromise.

“There are positive pieces of information that the parties could absorb, that could lead to a change in positions,” says Halperin, “but people in almost every group involved in a conflict are not willing to hear it. But if you try to go more indirectly … to talk in a general way, you hope they will apply these beliefs to the other group, and this is what our results show.”

Testing tolerance

In a series of experiments, Halperin and colleagues asked Palestinians and Jewish and Arab Israelis to read a few paragraphs in a supposed “reading comprehension” test. Then, as part of a supposedly different study, the same people were asked about their attitudes toward the opposing side.

The tested paragraphs that contained a more positive interpretation of history strongly affected willingness to compromise to resolve conflicts.

Instead of confronting the subjects by stressing that the other side could change its views, Halperin says, the test paragraphs “say that people in other conflicts went through meaningful change in their positions and behavior, and we expect people to understand by themselves that this can happen here.”

The study opens a crack in the despair aroused by prolonged conflicts, says Halperin. “We have now the first indication of what kind of message we should convey to people, to make them more open to the other side. And we already have preliminary data showing that the exact same pattern occurs in other long-term intractable conflicts around the world.”

Still to come, he acknowledges, is “the biggest challenge, using a larger scale intervention to make these changes.” Using the education system and mass media, he proposes a “simple message: Groups change, and behavior that is violent and immoral is a result of a specific situation, leaders and economics. They are not the result of a long-term culture with a fixed character.”

The intervention was focused on hope, Halperin says. “One of the biggest barriers to peace is because people don’t have hope, they don’t believe that the other group can change. If you don’t believe the other side can change its attitude, and as a result its behavior, there is no reason to offer a gesture or compromise, to take a risk in negotiation, and then you can’t make any progress in any intergroup conflict.”

– David J. Tenenbaum

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.

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.

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:

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

Uganda is looking for answers as about 20 students and a teacher were killed June 28 by lightning that struck their school in this highland nation in Eastern Africa. With dozens of children also injured by electricity, Ugandans wonder if the serious string of lightning strikes is related to climate changes, or are just the consequence of an unusually heavy stream of moist air coming from the Atlantic.

We can’t answer, but the tragedy did get us Why Filers to thinking about lightning. Although lightning bolts killed “only” an average of 39 Americans over a recent 10-year stretch, the injuries, which concentrate on the vulnerable nervous system, can be severe and lifelong.

Satellites tell us that 1.2 billion lightning flashes occur in the atmosphere each year — although not all reach Earth.

What is lightning? How does it injure and kill? And what has been learned in the past few years from the millions spent studying nature’s electricity?

2003, NASA Johnson Space Center

A string of lightning flashes are seen from space.

Boom-boom room

Thunder — the cracking or rumbling you often hear — is caused by thermal expansion and contraction. Lightning bolts can get far hotter than the sun’s surface — up to 20,000° Celsius. That heats the air, causing it to expand, and starting a shock wave that moves as sound waves — thunder.

If you’re close to the lightning bolt, you’ll hear a cracking; further away, you’ll hear rumbling because that sound has come from several parts of the bolt, and been reflected from buildings and hills.

And yes, if you start counting “one Mississippi,” when you see the flash, you can estimate the distance to the bolt: Light essentially reaches you instantly, but sound takes about five seconds to travel one mile. Divide the number of seconds by five to find miles, or by three for kilometers.

Silence is — mysterious

One of the many lightning mysteries is this: Sometimes you hear the thunder, and sometimes you don’t. For example, “heat lightning” is an eerie, silent flash that often lights clouds in thunderstorms.

The sound has been gobbled by an audio version of the visual mirages that cause trekkers to see water in stone-dry desert. These visual mirages are caused by heat that bends light waves. You look straight ahead, but you actually see the sky, shimmering like a tempting lake.

Similarly, in a thunderstorm, the sharp boundaries between warm and cool air can channel sound waves away from the observer, as you can see from the nifty applet, below.

Much the same phenomenon was noticed during the Civil War, when artillery was visible in the distance but audible only in some parts of the battlefield.

Go play with lightning.

Nature’s lighting foundry

We think of clouds as billowy places, couches for angels in Renaissance paintings. In thunderclouds, however, air and water – liquid, frozen and in between — may be whizzing up and down at a furious clip — up to 100 miles an hour.

That’s a place where angels fear to tread.

The motion in these cumulonimbus clouds is powered by convection, a force that separates fluids based on density. The dense, cold air falls while the warmer air rises. Smaller water droplets hitchhike up on the updrafts, which can’t support the larger droplets.

Because smaller particles tend to carry positive charges, the movement caused by temperature, humidity and density (which can include snow, ice, and water vapor) segregates electrical charges: The top of a cloud becomes positive and the bottom negative.

Regions of different charge can only exist if surrounded by an insulator — namely air. Insulators, however, eventually fail when they are overwhelmed by electric “pressure.” In a thunderstorm, that “failure” results in lightning.

Hangin’-motor blues

Having trouble envisioning this? Imagine a chain holding a greasy V-8 motor above a ’63 Ford Fairlane in a shade-tree auto mechanic’s backyard. If the engine is too heavy, or the chain too weak, the chain will snap as it is overwhelmed by the gravitational attraction between Earth and engine.

Thunk!

Substitute air’s insulation for the chain, and electrical attraction between positive and negative charges for gravity, and you have a greasy-fingered picture of how air can separate electrical charges during a thunderstorm.

To go further, we need one hunk of physical-science jargon: electrical potential is how fast charge changes with distance, and it’s measured in volts per meter. Electrical potential is the “pressure” that’s “trying” to start an electric current between areas of opposite charge.

(Opposite electrical charges are like young lovers: They will do anything to get together.)

Just as an overweight V-8 can snap a skimpy chain, excess electrical potential can “break” air’s insulation. When that happens, an electrical current — in the form of a lightning bolt — neutralizes the opposing charges.

Flash!

Diagram: Encyclopædia Britannica, Inc.

Lightning leaps between separate negative and positive regions during a storm. Most cloud-to-ground flashes originate in the cloud’s negative regions.

In a cloud-to-ground flash, the huge electrical potential — measured in millions of volts — eventually overcomes air’s electrical resistance, and a “streamer” or “leader” begins reaching, about 50 meters at a time, toward ground. The streamer makes an ionized (conducting) pathway of plasma, allowing current to flow.

Where am I safe?

As the current approaches the ground, its electrical potential can cause a surge of oppositely-charged particles to “reach” up toward it. Because this upward current often springs from tall objects, trees and other tall objects make lousy shelter during a storm.

For a 2001 Why File on lightning, David Rust, who was then director of forecast research and development at the National Severe Storms Laboratory, told us that the safety of a building is determined by the degree of grounding. A steel building that’s securely grounded, he said, will be safer than a wooden one that’s not, even if the steel building is taller. Steel and other conductive metals provide an easy pathway to ground for the lightning, and that translates into safety.

Once the ionized pathway is established, electric currents flow back and forth between ground and cloud so quickly that they appear as flickers rather than separate bolts. (More on lightning safety.)

We’ve heard that a big cloud-to-ground bolt carries one trillion watts of electricity. If that estimate is right, during its fraction-of-a-millisecond life, the flash carries about the same current as the total U.S. generating capability. (Watts measure the flow of electric current at any instant. The more familiar watt-hours measures an hour of flow of a given current; 1 kilowatt hour equals 1,000 watt hours.)

But nobody has figured out how to put this energy to work. Though we have heard one proposal, the currents are insanely high and the strikes are too brief and too unpredictable.

Keeping a close watch on lightning

Our understanding of lightning grows with improvements in technology, and a new instrument on trusty weather balloons has pointed to a surprising source for the electric charge. The process involves a small, spongy relative of hail called graupel, says Don MacGorman a physicist at NOAA’s National Severe Storms Laboratory.

“As graupel accumulates tiny, pristine ice particles, and then falls through liquid water, there can be some charge exchange in collisions where the tiny ice particles rebound,” MacGorman says. In the lab, this interaction seems powerful enough to be main source of electricity – and therefore lightning — in large areas of the storm.

Within a few years, a better understanding of lightning formation could improve predictions, MacGorman says. “We will not be able to say lightning will a hit particular location. Lightning is too random for that, but we are getting to the place where it may be possible to say that a storm will produce a little or lot of lightning, and that would be helpful for storm safety.”

Cloudy picture

The graupel explanation, however, raises a question: If the interaction of water and ice creates the electric charge, why is lightning found in dry sectors of the storm, including the large “anvil” structure that exhausts cold, dry air above the storm? “We have seen lightning initiated almost 100 kilometers from the heavy precipitation area, so something else must be going on in the anvil,” says MacGorman. “This does not accord with how we’d viewed anvils.”

Scientists are also probing cloud flashes, caused by the flow of current between regions of clouds with opposite charges and does not hit the ground. Formerly dissed because they don’t kill people, cloud flashes are getting some respect.

For one thing, they are the most common type of lightning, accounting for perhaps one-quarter of all lightning flashes. Adding cloud-to-ground and cloud-to-cloud lightning gives a better indicator of total storm intensity than ground flashes alone, “which have very little relationship to storm severity,” says MacGorman. “You can have huge ground flashes in a relatively innocuous storm, but total lightning is well related to things that affect severity and strength: the size of the updraft, the amount of ice in the clouds, and so it gives us clues as to how intense the storm is.”

Positively speaking

The biggest recent discovery on lightning, says MacGorman, concerns storms that produce a large amount of positively charged cloud-to-ground lightning rather than the usual negative currents. During a field research program called STEPS, in a lightning-rich region of the high plains, some storms contained negative charges in places that normally would be positive, and vice versa. In these conditions, instead of dropping the normal negative charge to the ground, the lightning bolts were positive.

The unusual phenomenon could arise in clouds containing a high concentration of liquid water, MacGorman says, and that would also raise the odds of large hail. “Hail typically forms because graupel or another seed particle starts collecting liquid water faster than it can freeze, and the water spreads over the surface, then freezes into a solid layer of ice.”

These dense particles are more likely to happen in an area with a lot of liquid water, and therefore, these positive lightning strikes could be a harbinger of large, destructive, hail.

The view from on high

For the next stage in lightning observations, scientists will go to GOES-R, a series of geostationary satellites scheduled for launch in 2015. These high-orbital spyglasses will carry an optical gadget that should “see” upwards of 90 percent of total lightning activity. “The viewing area will cover pretty much all of the continental United States, and parts of Africa and South America, and eventually, half of the Pacific Ocean,” says MacGorman. “This will allow us to detect thunderstorms over the oceans, which we have not had good way to see in the past.”

That should help airplanes dodge storms, but also aid weather prediction, MacGorman says, since thunderstorms can trigger other thunderstorms. They also add water vapor to the lower atmosphere, which also feeds storms.

Nothing light about lightning

Lightning gathers myths. Whether it’s Zeus throwing thunderbolts from the ancient Greek sky, or the moronic misconception that victims become untouchables because they retain an electric charge, these bolts spark the imagination.

But lightning can change your life, as Steven Marshburn, Sr., of Jacksonville, N.C., told us in 2001. Marshburn was struck in 1969 while working in a bank. Although the sky was blue and no storm was in sight, a bolt entered through a wire from the drive-up window.

Afterwards, Marshburn “suffered from severe headaches, chronic daily pain, grand mal [epileptic] seizures, dizziness, problems with my eyes going blurry. Many health problems persist. I have had 20 lightning-related surgeries…”

In 1989, in response to his brush with death, he formed Lightning Strike & Electric Shock Survivors International to investigate the medical aspects of lightning and to support victims and families. In 2001, he told us that members had talked 13 fellow survivors out of suicide.

A shock to the nervous system

Lightning usually kills by attacking the heart, which runs on electrical impulses. While high-voltage electrical injuries often cause severe burns, they are rare with lightning, likely because the bolts — lasting only 0.1 to 1 millisecond –- are too brief to cause severe burns.

Although burns may result if clothing ignites or sweat boils and steam is trapped under clothing, wet, sweaty clothing may actually conduct a heavy current outside the body and reduce the damage.

Raphael Lee, a professor of surgery and medicine at the University of Chicago, and an expert on the effects of lightning strike, told us that most of the initial current in a lightning strike does not pass through the body. However, two electromagnetic phenomena can produce a strong voltage drop across the body:

Strong electric fields are a problem for nerves and muscles, Lee says, because they “have been structured through evolution to be very sensitive to tiny electric fields.” That, combined with their physical length, which spans a large electrical gradient, “makes them very sensitive to lightning.”

Nerve cells can be a meter long, and by extending into different parts of an electric field, they are exposed to high voltages, Lee says. One focus of concern is the cell membrane which can die if strong voltages poke holes in it. Voltage can also wreak havoc in the pores in the membrane, which regulate the cell’s physiology by controlling how ions enter and leave the cell. Normally, for example, the potassium concentration is 1,000 times higher inside a cell, and damage to the pores can result in malfunction or cell death.

Lightning = thunder in the brain?

Although electricity is the natural focus of lightning damage, Lee suspects that an acoustic pulse, or shock wave, plays a major role, and perhaps a dominant one. A lightning bolt is surrounded by hot, ionized gas that arises in nanoseconds or microseconds and whose temperature may exceed 10,000 ° C. “When you heat something in a small area in such a short period, there are going to be shock waves,” he says.

The power of this acoustic wave is obvious when lightning hits and splits a tree, Lee adds. But inside the brain, the shock can trigger traumatic injuries similar to those caused by a roadside bomb or artillery shell.

Neurological injury: no passing matter

Lightning injury can be severe, long-lasting, and hard to treat, and it “may affect any or all parts of the nervous system,” according to Mary Ann Cooper, an emerita professor of emergency medicine at the University of Illinois-Chicago.

In a 2009 study of survivors of lightning and other electric shocks, 78 percent of the survivors had at least one psychiatric diagnosis; many of the troubles related to learning, memory and executive function.

In 2001, Cooper told The Why Files that confusion, caused by slowed information processing, is a hallmark of lightning injury. Symptoms include “difficulty in short-term memory, coding new information and accessing old information, multitasking, distractibility, irritability and personality change.”

Damage to the frontal lobe, the site of much higher thinking, is common, according to Cooper. “Many suffer personality changes because of frontal lobe damage and become quite irritable and easy to anger. The person who ‘wakes up’ after the injury often does not have the ability to express what is wrong with them…and cannot carry on a conversation, work at their previous job, or do the same activities that they used to handle. As a result, many self-isolate, withdrawing from church, friends, family and other activities.”

Cooper said some cell types continue suffering for weeks after the injury, and that nerve cells seem to “spend a long period trying to heal themselves, until finally the cell body is exhausted” and the cell dies. That process accounts for a delayed disability syndrome among survivors.

Help at hand?

Long-term neurological consequences are a major research area, Lee says, because they also occur in traumatic brain injury. “People are trying to sort out what is the best treatment, and understand why some people are more susceptible to delayed neurological problems. The body is very complicated and … the weight of evidence suggests there are genetic predispositions to complications after a blast causes traumatic injury to the brain, and lightning injury may be no different. Many people recover, but some don’t. What is different about the people who don’t?”

– David J. Tenenbaum

Humans and cats go way back. The relationship sprouted around 2000 BC in Egypt, where humans first domesticated felines. Today, more than 90 million cats in the United States alone enjoy the companionship of humans, while another estimated 90 million are stray or feral.

As in most relationships, there are still secrets between humans and their feline friends. But a recent study published in the Journal of Wildlife Management shed light on one secret that may have been nagging cat owners: what do outdoor cats, otherwise known as “free-roaming,” do all day?

Since there are several cat enthusiasts at The Why Files, we, too, wondered about the answer to that question. And the answer belies a few thorny predicaments peculiar to the cat-human relationship.

A day in the life of a free-roaming cat

Decked with radio collars that tracked their every move, 42 free-roaming cats (18 of them pets, 24 of them owner-less) were the stars of the two-year University of Illinois study. The researchers’ goals were to compare what owned versus un-owned cats did all day, where and how far they wandered, and how likely they were to survive in the often risky outdoors.

Certainly, to no cat owner’s surprise, the felines spent much of their time lounging or sleeping, just like their strictly-indoor counterparts. However, the amount of time pet cats versus owner-less cats spent snoozing differed significantly. Pet cats lazed about for 80 percent of their days, while un-owned cats loafed for “only” 62 percent of the time.

“That alone is very interesting. It could be associated with their requirements. It’s possible that the cats without owners have to spend more time looking for resources to take care of themselves,” speculated Nohra Mateus-Pinilla, study co-author and wildlife veterinary epidemiologist at the Illinois Natural History Survey.

Another important finding, according to Mateus-Pinilla, were the differences in the cats’ ranges. While, not surprisingly, un-owned cats roamed further afield than owned cats, Mateus-Pinilla and her co-authors were surprised by how far the stray cats strayed and by the diversity of habitats they skulked in, as compared to pet cats. While most of the pet cats stuck close to home, the most itinerant stray cat wandered around a 547-hectare (1,351-acre) area.

From original map by Jeff Horn

Despite range differences, un-owned and owned cats’ territories can overlap. The red outline shows the largest range tracked for an un-owned cat in the study, and the yellow dot indicates one pet cat’s range.

“Because of the large home range sizes in the evidence of both cats without ownership and cats that are owned, their home ranges are overlapping. And because of the mortality evidence, these animals could be facing a certain amount of risks that we are unable to measure,” said Mateus-Pinilla.

Indeed, the risks of being a free-range cat are much higher than those of indoor cats, and if the cat has no owner, its fate is almost always bleak. In their study, six stray cats died, while only one owned cat died.

Mateus-Pinilla said their study raises many new questions. To The Why Files, however, it seems that living in the company of humans has its advantages for cats. But keeping this relationship indoors may have advantages for wildlife and people too—-implications that drive the otherwise curious research on free-roaming cats.

Too many kitties on the range

While the indoor-outdoor debate lives on in the cat owner community, and regardless of whether or not cats enjoy the out-of-doors, their secret lives outside entail some dirty secrets that are alarming scientists and laypeople alike.

The sheer number of free-range cats, owned or not, has become a conservation and health concern, some scientists say. Like any species, too many can spell trouble.

Cats, by nature, are superb predators. A cat stalking a bird or squirrel is simply doing what cats do. However, their prowess as hunters, combined with their overpopulation, has wildlife biologists and enthusiasts biting their nails over the potential endangerment or extinction of some prey species.

“There are a growing number of landscapes in which free-ranging cats are not only the most abundant mid-sized mammalian predator, but they can outnumber all of the native mammalian mid-sized predators combined. So they really do become the dominant mid-sized predator in many landscapes,” said Stanley Temple, an emeritus professor of forest and wildlife ecology at the University of Wisconsin-Madison, who was among the first to study the ecological impacts of free-roaming cats.

Because of their impacts on both native predators and prey, conservation scientists consider free-roaming cats invasive species. While not the greatest threat to wildlife, they add to the increasingly complex web of existing threats.

Species most at risk of death-by-kitty are birds that spend a lot of time on the ground, small mammals and reptiles, according to Temple. In fact, cats are second to habitat destruction as the cause of bird extinction. Thirty-three bird species have met their fate to the paws of cats since the 1600s.

The world’s ever-shrinking “islands” of wildlife habitat are hotspots of conservation concern over free-roaming cat populations, since the native species in these areas are the hardest hit by invading cats. For example, birds that live in America’s dwindling grasslands or on the increasingly crowded seashore are finding themselves in a precarious situation.

Open and fragmented landscapes, which also include forest outskirts and farmland, are the territories of choice for cats. And, except in subtropical locales, they tend to stick close to humans. Even if un-owned, most cats are still dependent on people for either food or shelter, or both.

“They are remarkably resourceful at taking advantages of the opportunities that we present,” said Temple, who clarified that free-roaming cats are only truly “feral” if they are completely independent of humans.

Their dependency on humans highlights another dilemma: free-range cats can easily spread diseases and parasites that can jump from cat to cat, cat to wildlife, and even cat to human. The list of contagions includes feline leukemia, feline immunodeficiency virus, worms, rabies and toxoplasmosis, a parasite-caused disease that can damage the developing brains of unborn human babies, if their mothers are infected.

Free-roaming cats’ close proximity to both humans and other animals thus creates a potentially strong reservoir for these diseases. While vaccinating both owned and un-owned cats can help reduce the spread of disease, vaccines are not 100 percent effective and the logistics of vaccinating every single cat may be impossible, especially since many vaccinations are annual.

Photo: Rodrigo Basaure

These street cats certainly benefit from a human handout, but do humans benefit from the cats’ potential disease threat?

It’s complicated

Indeed, solutions to these predicaments aren’t easy. While the science may seem to imply that rounding up every cat on the range may be the best solution, the ubiquity of free-roaming cats and the emotions wrapped up in some people’s relationship with felines complicate the matter.

Studies suggest that many free-range cats are people’s beloved pets that are allowed outside, said Temple. But, while keeping every pet cat indoors would significantly and immediately cut the number of free-range cats, not every cat owner agrees that indoor life is best for kitty.

To further complicate things, one of the often promoted “humane” methods of attempting to reduce un-owned cat populations — trap, treat, neuter, release — repeatedly fails. Not only are there always the cats that get away, but releasing the cats back into the “wild” still does not eliminate the risks to wildlife.

Temple believes that for a cat-control method to work, three criteria must be met: the strategy must actually control cat numbers over large areas, it can’t harm any other part of the ecosystem, and it is socially acceptable. The last criteria can be the trickiest to meet and often creates tension between humans.

Photo: Flickr

Is this outdoor kitty taunting his indoor pal? But who has the better life?

“The divide over how to deal with cat overpopulation, in one way, can be simplified as the group of people who are really concerned about ecological impacts of cats versus those that are really concerned about the welfare of individual animals,” said Temple, based on his years of experience conducting public outreach on the issue. He clarified that he likes cats and is actually the owner of a 21-year-old feline.

Temple believes solutions that meet both factions on common ground do exist. Keeping pet cats inside and trapping, treating, neutering and confining un-owned, free-roaming cats are two strategies that meet his criteria. Though, for some people, it will take some convincing.

Mateus-Pinilla was careful to emphasize that their study did not seek to evaluate management options. They were focused on adding to the science and remaining neutral in the debate about solutions to the issue of free-roaming cats.

– Jenny Seifert

For controlling agricultural insects, bats are worth at least $3 billion a year to U.S. agriculture, according to a 2011 study from Boston University. “People often ask why we should care about bats,” said study co-author Paul Cryan, a research scientist with the U.S. Geological Survey in Fort Collins, Colo. “This analysis suggests that bats are saving us big bucks by gobbling up insects that eat or damage our crops. It is obviously beneficial that insectivorous bats are patrolling the skies at night above our fields and forests—these bats deserve help.”

As conservation officials scramble to respond to white nose, they are enacting quarantines to prevent people – cavers, bat-lovers and scientists alike – from transporting the fungus between caves. Last year, for example, the National Wildlife Refuge System halted public access to all caves and mines on its refuges, and set protocols to prevent scientists from spreading the infection.

In May, 2011, the Fish and Wildlife Service rolled out a national plan for confronting and controlling white nose syndrome.

But bats can do plenty of transportation on their own. Even non-migratory bats may fly 200 miles between their hibernation site and their summer range, says David Blehert, a microbiologist at the U.S. Geological Survey National Wildlife Health Center in Madison, Wis., and a leader of white nose studies. “They can move large distances, across state lines, so there is potential for significant disease spread based on bat-to-bat interactions.”

What is the white nose syndrome situation now? Why is it so deadly? What bright ideas are afoot to preserve insect-eating bats, and what is the likely end game?

Why deadly?

In the short time since white nose syndrome appeared in 2006, scientists have pinpointed a fungus called G. destructans as the killer. But how does G. destructans do its work? One clue comes from the fact that it only kills during hibernation, when bats live in mines and caves at a rather chilly 7°C. “The fungus only grows in the cold, and when insectivorous bats hibernate in a temperate region, they drop their core body temperature to the ambient level,” says Blehert.

(The fungus is not likely to attack fruit-eating bats, says Blehert, because they do not have long periods of “torpor,” the slow-metabolism hibernation state that is conducive to the white-nose fungus.)

A low body temperature allows the bats to survive winter without eating, but it could also curtail the immune system, Blehert says. “Studies of bat immunology are in their infancy, but based on what is known about the physiology of other hibernating mammals, especially the 13-lined ground squirrel it’s likely that the immune system becomes suppressed, and that leaves them particularly vulnerable” to the fungus.

How does the fungus kill? It apparently does not enter systemic circulation, as internal organs are not damaged. All mammals awaken from hibernation occasionally, but Craig Willis of the University of Manitoba has speculated that infected bats have more waking hours, causing them to run out of energy during a period when they neither eat nor drink.

Blehert and his colleagues favor a second explanation: dehydration. Despite the “white nose” name, Blehert says, the most significant infection occurs on the wings. “The wings of a bat have eight times as much skin as the trunk; it’s a massive, very delicate and exposed membrane” with a single layer of epidermis surrounding a thin layer of connective tissue and some muscles and glands. “The fungus selectively invades the wing skin, and destroys everything in its path,” Blehert says.

Beyond their role in flight, bat wings are also needed to regulate temperature, fluids and electrolytes. “The wings may be the Achilles heel that exposes them to such significant infection,” Blehert says.

Indeed, an emerging disease that is devastating amphibians, the chytrid fungus, also affects the skin, and is thought to kill by causing an electrolyte imbalance. “The amphibian’s skin is very important for the balance of water and electrolytes, which has been the basis for our hypothesis about why white nose syndrome is so deadly. There was a paper¹ in 2009 that demonstrated that a superficial chytrid infection causes an ion imbalance in frogs, causing a disruption of the potassium gradient that causes the heart to stop. A superficial fungal infection causes a cardiac arrest! This is a very different concept than getting athlete’s foot and having an itchy foot.”

Stopping the wave of death

As dead bats pile up in caves, what can be done to stop the spread of G. destructans? The first step, trying to slow dispersal, is already under way in affected states, with restrictions on cave entry, and new protocols for disinfecting equipment and people who have a legitimate reason to visit hibernation spots.

The fungus does respond to common anti-fungal agents, according to a 2011 study, which found, unexpectedly, that the meds worked at the low cave temperatures that the fungus prefers. “The challenge is, how could you use pharmaceuticals to manage a disease in free-ranging wildlife?” says Blehert. “They don’t go to the doctor, and they inhabit environments that are likely contaminated with fungus. Say you could treat bats and cure them of the infection. If you can’t remediate their hibernation sites, they will become reinfected when they re-enter the cave.”

The authors of the anti-fungal study did raise the possibility of using meds to decontaminate caves, but this process is not being done, Blehert says. “Going into a cave with a general fungicide would be like dropping a nuclear bomb on a city. Caves are full of bacteria, fungi, invertebrates and vertebrates that may only exist in that unique ecosystem, and getting rid of such an important group of organisms [fungi] could risk significant unintended consequences.”

Willis has proposed using little heaters, since bats seem to fare better in warmer regions of caves, perhaps because that sustains immune function. Small heaters are being tested as bat refuges in some New York State caves, says Lisa Warnecke, a post-doctoral fellow at Manitoba.

Lessons from Europe

G. destructans is an “emerging exotic disease,” and to investigate such diseases, scientists always want to know how the pathogen interacts with hosts in its land of origin, which seems to be Europe:

In 2009, the fungus was found in a greater mouse-eared bat in France²;

ENLARGE

Photo: Gabrielle Graeter, NCWRC

Is this bat unhappy about the tufts of fungus on its muzzle — or the researcher’s big hands?

During the winter of 2009-2010, infected bats were found in 76 of 98 sites in the Czech Republic; and

A 2010 study³ in Europe found a white nose pathogen in 21 of 23 suspected bats that was “100% identical” to the U.S. pathogen.

Although the fungus been found in at least five bat species in Europe, die-offs have not been seen there, suggesting that something is different about how the pathogen, host and environment interact. Pathogens and hosts co-evolve through time in a complex dance:

The pathogen may become milder, improving its own survival (and that of its host);

hosts may evolve immune resistance; and

hosts can change their behavior to reduce exposure to the disease.

In the lab in Manitoba, Willis and Warnecke are studying how long little brown bats are awake during hibernation, whether the fungus is a necessary and sufficient cause of death, and if the North American or European strains of fungus have different effects on the bats. “If both isolates show the same severity for North American bats, that may mean that bats in Europe have co-evolved with the fungus and are resistant to it,” says Warnecke. “On the other hand, if the European isolate does not cause trouble for North American bats, then the fungus in North America is a mutant that has gotten really aggressive.”

Other factors could explain the lack of disease in Europe, says Blehert. “European bats are larger, which may provide them with more of a buffer against a physical insult like a fungal infection.” The little brown bat, the preeminent victim of white nose, weighs about 6 grams – about the weight of two pennies, Blehert says.

European bats also tend to hibernate in small groups. “They don’t have those 100,000-plus hibernacula like we see in the United States. With fewer animals, the disease transmission dynamic is likely to be reduced, with less amplification of the fungus, and lower rates of bat-to-bat transmission.”

In the long run, Blehert says, American bats may evolve some resistance. “In general, the population decline in caves and mines comes to about 78 percent, but the bats have not disappeared. We would expect something that gets into population to cause high mortality and a steep drop-off in population. Then, with fewer animals around, disease transmission could moderate.”

Although the regional extinction of the brown bat has been predicted to occur 16 years from now, “our bats may ultimately develop population dynamics more like Europe, with fewer animals and moderated disease transmission and progression,” Blehert says.

Evolution, in other words, could select for animals that, for behavioral or immune reasons, are less susceptible to white-nose.

But letting the situation play out without trying to help the bats, Blehert says, amounts to a high-stakes gamble with one of the wonders of the night sky.

On March 11, a catastrophic earthquake — one of the four largest in the past century — struck in the ocean east of Japan, sending a colossal tsunami against the shore. By March 21, the toll of dead and missing, mainly from the tsunami, was estimated at 22,000.

As Japan confronted what Emperor Akihito called the worst crisis since World War II, we began to hear that the six-reactor complex at the Fukushima Daiichi plant, located directly in the tsunami’s path, had lost electrical power. The emergency generators also failed, apparently due to water damage to them or their fuel supply.

As we focus on the nuclear disaster at Fukushima, we emphasize that as of now, the tsunami itself is the far larger human tragedy. But like the tsunami itself, the nuclear disaster may portend further problems in other places, and is likely to affect a trend toward greater use of nuclear power around the world.

Not cool

Immediately, the arrow of trouble aimed at the most ominous type of nuclear accident: loss of cooling. Fission — splitting of radioactive elements that powers nuclear reactors — can stop when reactor operators flip a switch to insert control rods to absorb neutrons. This stops the chain reaction — the divison of uranium atoms that releases neutrons that split other atoms and generate heat — which is the whole point of building nuclear reactors to boil water and drive turbines.

But once the fission reactions cease, decay heat continues to be released from the unstable atoms that remain after fission, and it is this heat that must be removed by a cooling system after shutdown.

Past accidents have shown that decay heat can build up in seconds; and significant damage to the fuel and potentially reactor equipment can occur within minutes. The danger of such a “meltdown” is a major reason why nuclear designers and engineers focus so much effort on cooling the reactor core.

In the beginning, there was Three Mile Island

Japan, target of the only two atomic bombs used in war, is hardly the first nation to confront a “loss of coolant” emergency at a reactor. That happened on March 28, 1979, in the United States, where Pennsylvania’s Three Mile Island (TMI) reactor #2 began a partial melt-down.

Much later, the Nuclear Regulatory Commission concluded that the accident “was caused by a combination of personnel error, design deficiencies, and component failures.” As hundreds of alarms buzzed in the control room, operators, lacking a direct measurement of the water level inside the reactor, made a bad situation worse, the reactor went at least partly dry, and a large percentage of the fuel melted.

It’s safe to say the public reaction verged on panic as a bubble of explosive hydrogen built up inside the plant and evacuations were ordered.

The slow, dangerous removal of fuel revealed massive heating and damage inside the reactor. According to the book, “TMI 25 Years Later”¹: “A large portion of the core melted and flowed into the lower vessel. Most of the core experienced temperatures of at least 1727° C, with certain parts reaching 2527°C.”

At these temperatures, the essential containment vessel can weaken and fail.

TMI, the above book concluded, neared a complete a meltdown. “No one can say for sure, but some experts say that had the accident continued for another 20 to 45 minutes, the [reactor] vessel would have heated up and the metal would have lost its strength, leading to a rupture,” preventing further cooling and allowing superheated fuel to melt through the reactor vessel and enter – and likely exit — the reactor building.

From there, it’s impossible to speculate how widely the radiation would have spread, the authors wrote, but this is what is called the China Syndrome — a runaway load of reactor fuel melting its way down into the earth. Oddly, “China Syndrome” – the movie — was released 12 days before the TMI meltdown.

TMI #2 has since undergone a major cleanup. Intact and damaged fuel has been moved to storage at Idaho National Engineering Laboratory. Reactor #1 is operating normally, and final removal of the destroyed #2 awaits the decommissioning of its companion.

According to the Nuclear Regulatory Commission: “Estimates are that the average dose to about 2 million people in the area was only about 1 millirem. To put this into context, exposure from a chest X-ray is about 6 millirem.”

Nevertheless, the alarm over TMI sent the U.S. nuclear industry into a tailspin.

 

The meltdown of TMI was the death knell for growth in American nuclear industry — the spate of plants licensed during the 1980s had all been planned or under construction by 1979. Rollover to see a comparison of present dependence on nuclear energy.

Graph 1: U.S. Nuclear Regulatory Commission. Graph 2: International Atomic Energy Association

Chernobyl – the unmitigated disaster

The Lord Voldemort of nuclear accidents started on April 26, 1986, when Chernobyl reactor #4 exploded, burned and melted down in a spectacular fire that spewed an estimated 50 tons of radioactive fuel over a swath of Eastern Europe. Unlike TMI (and the imperiled Japanese reactors) Chernobyl had no vessel to contain its fuel, and a giant fire – consuming the estimated 800 tons of graphite used to slow neutrons in the reactor — burned for more than a week as brave crews tried to damp it with sand, boron and lead.

Chernobyl was located in a part of the Soviet Union that is now in Ukraine.

The meltdown produced some of the worst radiation injuries in history, and hundreds of thousands were force-evacuated from an “exclusion zone” — roughly 30 kilometers in radius — around the smoking, radioactive hulk of #4.

Within months, the cooling reactor was hastily wrapped in a giant concrete “sarcophagus” (stone coffin) to contain further radiation. But the sarcophagus is leaking, says Leon West, a professor of mechanical engineering at the University of Arkansas, who has 40 years of experience in nuclear physics, radiation protection and nuclear engineering. “Chernobyl is still open and is still a threat to the local environment.”
“Construction has already begun on the New Safe Confinement,” says photographer Michael Foster Rothbart, who lived 12 miles from the exclusion zone between 2007 and 2009, “and although it keeps falling behind schedule, target finish date is 2013.”

Japan: Facing Three Mile Island or Chernobyl?

By March 21, 10 days after the tsunami, the owners of the Fukushima power plant reported that it had reconnected electric power to all six reactors. The disaster seems headed toward resolution, says Jeff Geuther, who manages a research reactor at Kansas State University. “My understanding is that the fuel [in the three recently operating reactors and the three spent-fuel pools at other reactors] is all under water. The radiation dose has been falling at the plant, an indication that water level has increased in the spent fuel pools.”

Although it’s not clear how much fuel has melted, Geuther says, “It’s fairly clear that the cladding [a thin sheathing on the fuel rods], at a minimum, had some damage. Iodine and cesium have been detected offsite; these are fission products that would be typically be trapped inside the cladding.”

By March 23, the utility reported that the lights were on in the control room of reactor #3, but work had not yet begun on monitoring equipment and reactor cooling pumps in the three reactors that were operating before the quake. By March 24, smoke was rising from several reactors, three plant employees were being treated for radiation exposure, and the zone of concern about radiation in drinking water had been expanded. The local populace remains under evacuation.

Near-term progress in stabilizing the Fukushima plant will be measured by

A near miss?

Two positive factors helped what looks like a near-miss at Fukushima. First, those reactors (unlike Chernobyl) had thick steel containment vessels, which, despite some reports of damage, seemed to hold up reasonably well.

Second, also unlike Chernobyl, Fukushima used water, not combustible graphite, to slow neutrons.

On the other hand, Fukushima faced systemic difficulties due to the precipitating natural disasters: After the epochal earthquake-towering tsunami sequence shut the reactors down, the electric grid died, killing the emergency cooling pumps.

Then the emergency diesel generators failed, and without cooling, the reactors quickly overheated. But with roads out and the nation tending to survivors and victims of the tsunami, the nuclear emergency festered for days, through a series of explosions, fires, bursts of radiation, and evacuations of plant workers.

At one point, just 50 workers were on hand to deal with multiple emergencies at several reactors and pools of spent fuel. The desperation was on display when helicopters tried to dump buckets of water into the fuel pools and fire trucks sprayed cooling water through explosion-blasted walls.

How many broken reactors?

Despite early fears that Fukushima was mimicking Chernobyl, it seems rather to be headed toward the less malignant TMI precedent, says West. “A big leak [like Fukushima] is not like the open-air nuclear bonfire of Chernobyl that spewed radioactive materials into the upper atmosphere. The extent of the release of radiation and the continuing difficulties with cooling of reactors and spent fuel has clearly put the Daiichi site at the TMI stage.”

As radioactive particles cross the Pacific on the jet streams, “California, Oregon, and Washington should start reporting measurable traces of radioactive materials in air samples,” says West, “but for the United States, this should be more like a Chinese test of a nuclear weapon and of no health consequence.”

Radiation has already been detected on milk and green vegetables near the reactor, and now in drinking water in Tokyo. “The Japanese will need to monitor and control agriculture products to minimize the risk to public health,” says West. “This will be similar to efforts in the United States during the 1950′s, when the U.S. was detonating nuclear weapons in Nevada,” and farmers were prohibited from selling milk for four days afterwards.

Japanese meltdowns, American reverbs

As Japan evacuated neighbors from the Fukushima plant, the U.S. Nuclear Regulatory Commission (NRC) advised American citizens in Japan to move at least 50 miles away. That’s much further than specified American evacuation plans, notes Vicki Bier, a professor of industrial engineering at the University of Wisconsin-Madison. “If the NRC is concerned up to 50 miles in Japan, that certainly calls into question emergency planning here, which is limited to 10 miles.”

On March 16, California Senators Barbara Boxer and Dianne Feinstein asked the NRC to review safety at two California plants located near earthquake faults. “Roughly 424,000 live within 50 miles of the Diablo Canyon and 7.4 million live within 50 miles of San Onofre Nuclear Generating Station,” the senators wrote.

And on Mar. 22, the Nuclear Regulatory Commission agreed to accelerate a safety review at Indian Point, a pair of reactors 30 miles from Manhattan.

Japan: How prepared, in reality?

How did such severe nuclear troubles arise in Japan, where “tsunami” was coined, and which is the world’s leader in earthquake engineering and disaster preparedness?

For starters, the tsunami was much bigger than expected. But we’ve also learned from the Associated Press (on March 24) that Japanese preparations focused on natural disasters.

Was the nuclear emergency made worse because six reactors were at one location? As we saw, radiation vented from one reactor caused the flight of workers trying to tame other reactors. But multiple siting had “always been considered to be a really good idea,” says West. “You have a collection of focused professionals with lots of resources [for example, to fight fires], so if one reactor has difficulties, you could take those excess resources and focus on that situation. … This is the first situation, where [multiple sitings] appears to need to be reexamined.”

Early reports point to a critical design failure at Fukushima, says Bier, an expert on risk assessment at nuclear plants. “They were designing for earthquake and tsunami, but not for this level of damage; you’ve got to give engineers some criteria; they can’t design for anything. They could have designed for what did happen, but they apparently decided it was too unlikely.”

Design: Where are the goalposts?

A specific weakness concerned the emergency diesel generators needed to run the pumps, which apparently were swamped by the tsunami, says Bier. “There is a lot we won’t know for months, but there is reasonable speculation about things that could be done differently at modest cost. You can’t prepare for every eventuality, but probably it would have been possible to get better protection for the diesels in a bunker or on higher ground.”

The systematic disruption and near chaos interfered with tasks like avoiding melt-downs in the pools holding spent fuel, which lack the containment usually found on reactors. As Fukushima proved, accidents can be made worse as effects are compounded: the real-life scenario included a combination of a Japan-record earthquake, massive tsunami damage, regional blackouts and radiation releases.

“The surrounding area was so damaged by earthquake and tsunami that it impeded the emergency response,” says Bier. “We have seen stories about people within the evacuation zone who could not evacuate because the roads are impassable or buildings have collapsed, and they were not sending in rescue teams because the radiation was too high. Certainly it was not anticipated that the damage would be this severe, or the radiation would be too severe to evacuate.”

 

Photo: Japan Red Cross Society

Thousands of Japanese have been evacuated from around the Fukushima Daiichi reactors; masks retard the spread of disease in close quarters. Few experts expect the need for a permanent exclusion zone, like the one in Chernobyl, around Fukushima.

Fukushima: End game

Will the six reactors at Fukushima Daiichi be dismantled, like TMI #2, or wind up inside a Chernobyl-style concrete coffin?

The three reactors that got emergency cooling with sea water are likely finished due to corrosion, not to mention possible explosion damage. “Salt water is a killer,” says Robert Rosner, professor of astronomy, astrophysics and physics at the University of Chicago. Rosner expects these reactors to be taken apart and trucked to long-term storage.

Although the age of the reactors – about 40 years – militates against spending large sums on refurbishment and updating, Japan now faces an electricity shortage, so Rosner expects one or two of the plants to return to service, at least for a while.

West, however, suggests that at least one reactor may wind up encased in concrete. “If I were an engineering manager, I would be looking at the possibility of stabilizing it to deal with all the issues” and then build an outer containment to isolate the reactor but allow service visits.

Credibility at stake

Assessing the long-term impact of Fukushima requires us to look at the technology’s unique place in the popular eye. Whether the nuclear industry likes it or not, nuclear carries plenty of emotional baggage. Nuclear physics produced the mushroom clouds over Hiroshima and Nagasaki long before it was used to make electricity. And because ionizing radiation is invisible, it’s a case where what you don’t know can hurt you.

Nuclear energy also arouses fear because power-plant neighbors cannot control it, says Nathan Hultman, an assistant professor of public policy at the University of Maryland. “A lot of research has looked at why people view risks differently, and both dread and the degree of control in nuclear are nerves that are touched very strongly. We feel safer driving cars than in an airplane, even though statistically, airplanes are much safer, because we feel in control in a car.”

 

Photos: TMI, Cherobyl:Wanrouter.

While TMI today shows the scars of its accident (reactor #2 on left melted down in 1979), Chernobyl’s gravesite (rollover) evokes a much bleaker history and deeper wounds. The thrown-together concrete enclosure may need to be replaced – a hazardous, expensive task.

The Japanese nuclear industry also faces credibility problems, Hultman notes.

“Small nuclear accidents were covered up,” says Hultman. “Often the initial reaction was ‘Everything is just fine, the situation is normal,’ then it came out there was a deeper problem. Now we are in a situation where very bad things are happening, and people are not sure what to believe.”

Hultman adds that these issues are a likely fixture in the coming debate over nuclear power. “Nuclear is not the only way to boil water to generate electricity,” he says, and the discussion of energy sources must be broader than that. “Rather than say, ‘We must have nuclear,’ we need to talk about alternatives as well.”

The Fukushima debacle could further polarize a nuclear debate that was altered by both TMI and Chernobyl, says Hultman. “There is almost a religious division. People who believe it’s good think it will be the answer to all our problems, and people who don’t like it, really really don’t like it.”

An omen for the future?

The Fukushima disaster carries striking ironies. Japan was the only country at the receiving end of atomic bombs, and studies of survivors at Hiroshima and Nagasaki have been the basis for understanding the health effects of low-level radiation.

Historically, the Fukushima disaster occurred as nuclear was gaining so much traction as a low-carbon solution to global warming that some prominent environmentalists had begun to talk nuclear. “This is going to have a big effect on the rebound toward nuclear,” says West, who adds, “We just can’t burn our forests — and coal is an old forest — forever,” due to global warming.

Even technological disasters that loom large in the short run may eventually be seen as lessons, West says. “The crash of a major aircraft … does not mean that air travel should end, it means we need to tighten up our design.”

Rosner, however, suggests that nuclear, with its potential for widespread, long-term contamination, needs to live by different rules. “When you are engineering something where the consequences, if something goes wrong, are devastating, even though the probability is very small, you need to engineer to avoid the devastation. We’ve known how to do that for 50 years, but it was always just a bit too expensive on the front end, so the decision was made: The probability is so low, we are not going to worry about it.”

Japan, a world leader in earthquake engineering, has been paralyzed by a series of giant waves that followed one of the most violent earthquakes in a century.

Although the magnitude 9.0 quake on Mar. 11, 2011, apparently did not collapse high-rise buildings, the ensuing tsunamis flattened vast areas along the northeast coast. The death toll is swelling steadily as bodies wash in on the surf, and citizens and Japan’s Self Defense Forces scour a landscape turned upside down by inconceivably powerful waves.

The news recalls the estimated 250,000 people who perished, mainly on the Indonesian island of Sumatra, in the 2004 “Christmas tsunami” that followed a huge, offshore quake. (Both Japan and Indonesia are volcanic lands in the Ring of Fire, which partly surrounds the Pacific Ocean in a giant series of subduction zones and volcanoes.)

Shortly after Japan stopped shaking at 2:46 pm local time on Friday, March 11, we began hearing about troubles at a series of nuclear plants. After the reactors automatically shut down during the quake, emergency systems for removing heat still being generated in the reactors were routinely switched on.

But because the electric grid was down and the standby generators were damaged — perhaps by seawater — the emergency cooling failed. By Tuesday, March 15, three reactors had exploded, a fourth was burning, radioactive material was airborne, reactor workers were being evacuated, electricity was growing short in Tokyo, and the crucial containment vessels were under severe threat if not already breached.

With the first nuclear meltdowns since Chernobyl, in 1986, under way, global stock markets were crashing.

What causes tsunamis?

As Japan licks its wounds, The Why Files wants to know what causes tsunamis. How do they travel across the ocean? How they have impacted coastal people through history? Can we reduce our vulnerability to nature at its most cataclysmic?

Graphic: Anthony Liekens

Movement of the sea floor translates into waves at the surface.

Tsunamis — once slangily called tidal waves — are extremely powerful waves caused by large undersea disturbances. (“Tsunami” derives from Japanese for “harbor wave,” reflecting the fact that harbors can concentrate their energy. True tidal waves are the slow oscillations that drive ocean tides in response to solar and lunar gravity.)

Although landslides and volcanoes cause some tsunamis, probably 95 percent result from underwater earthquakes that contain a strong vertical motion. Such quakes often occur where one of Earth’s tectonic plates dives, or “subducts,” beneath another.

Like the Sunda trench near Sumatra, the subduction zone in the Japan trench is notorious for large earthquakes, says Timothy Masterlark, an associate professor of geological science at the University of Alabama. Although the timing is always uncertain, he says, “The history was known, big earthquakes were known, and even though the people and government went to great lengths to prepare, at some level … there is simply nothing they can do.”

Lessons from Sumatra

Masterlark, who has studied the giant, 2004 earthquake and tsunami in Sumatra, says the magnitude 9.0 earthquake in Japan likely broke a fault stretching at a shallow angle from the sea floor roughly 150 kilometers beneath Japan, along a trench several hundred kilometers in length.

We asked Masterlark how, if the slip was mainly horizontal, the rocks had enough vertical movement to cause a tsunami. “In Sumatra, we found a shallow slip created some vertical movement because the rock at the surface was softer, so the fault became more vertical, which changed the slip from mostly horizontal to mostly vertical.”

To imagine how vertical movement of the seafloor causes a tsunami, imagine making waves by throwing a stone in a pond. Even though earthquakes disturb the bottom of the water, the analogy works: just as a larger stone, thrown faster, makes a larger wave, the size of the tsunami depends on extent and speed of the ocean-floor movement.

The tsunami is usually most intense close to the earthquake: as waves spread from the epicenter in a typical arc-shaped pattern, their energy also spreads out.

Spread out, but still powerful

One factor that distinguishes tsunamis from more familiar waves is their extreme wavelength. On the open ocean, the peaks of waves may be 300 kilometers apart, and they may travel at 500 to 600 miles per hour. Even though they can keep pace with a jetliner, you wouldn’t see a tsunami from the cockpit of a jet. A killer tsunami may be only 2 feet tall in mid-ocean — far too small to be noticed from an airplane or even a ship, yet it can carry huge amounts of energy across the Pacific.

All that kinetic energy can hide in waves we can barely see because long-wavelength waves are extremely deep, and the massive amount of water moving beneath the surface contains enormous energy.

In deep water, boats can ride the worst tsunamis without noticing them; but when they reach shallow water and “run aground,” these waves become dangerous.

Like all waves, tsunamis slow when the lower part of the wave encounters the upward-sloping ocean floor. But while the front of the wave slows, the wave behind is still moving faster, causing a giant pile-up at the front, and the kinetic energy that was spread through the ocean depth concentrates in a towering wave at the surface.

Wild waves

It is these surface waves — which can be 10 meters high or taller as they cross the beach — that cause the utter destruction of tsunamis. Like all waves, tsunamis have both a rising and a falling motion, says Masterlark. “Depending on where you are with respect to the earthquake, you may first see a wall of water, or the opposite, the sea retreating.” In 2005, during a research cruise to Sumatra, “We were told that the tourists had heard that the ocean was retreating, and saw this as a great holiday, ‘Let’s walk on the seashore,” and this wall of water came in and killed them. This was a great warning, when they saw the water retreat, they should have headed away from the shore.”

Tsunamis have other quirks. They can be spaced as much as one hour apart, so subsequent waves can kill those who return to help victims of earlier waves.

In 1998, Harry Yeh, a civil engineering professor now at the University of Oregon, told us that tsunamis can have decidedly unconventional behavior. In one case, he said, a tsunami destroyed houses in a cove without damaging a house on an unprotected headland: “It’s the exact opposite of what a storm wave would do.”

A warning

Modified from original image by NASA

Location of foreshocks, aftershocks and the March 11 Japan earthquake (M 9.0). Circle size represents quake magnitude. Dotted lines = foreshocks; solid lines = aftershocks

The Pacific Tsunami Warning Center, established in Hawaii in the wake of the deadly 1946 tsunami, is a nexus in the global warning network. Since almost all tsunamis originate in earthquakes, the warning centers rely on data from seismographs, many of them located on the unstable ring of fire.

Tsunami warnings are now triggered automatically, says Masterlark, based on measurements of earth movement. “Seismographs are excellent because in seconds they can tell that a quake of some magnitude, big enough to trigger a tsunami, has occurred. This information can automatically trigger a warning in seconds.”

In tsunamis, seconds saved can translate into lives saved.

Researchers are working to use global positioning system (GPS) data to refine size estimates, Masterlark adds, to give “a more refined view of the potential risk, but this takes a little longer and is still in a research mode.”

Further confirmation of the size of the wave may come from special purpose ocean buoys, if they are in the right place, Masterlark says. “But they only work once the tsunami has already arrived, so they can only confirm or help refine the warning.”

Tricks of the tsunami trade

In terms of generating tsunamis, not all underwater earthquakes are created equal, says Andrew Newman, assistant professor of earth and atmospheric sciences at Georgia Tech. “A few times a decade, we have what we call ‘tsunami earthquakes’ that create a tsunami that’s much larger than would be expected for the magnitude of the earthquake,” largely due to a shallow rupture. “Usually a magnitude 7.8 earthquake would create a tsunami that might rise only 20 centimeters to 1 meter [when it reaches land], but one in Sumatra last year created a 17-meter tsunami.”

These large tsunamis come from a smaller break in the ocean floor, and so contain relatively little energy and do not travel well across the ocean, Newman says. But they also offer less warning because local people do not feel the massive shaking associated with a major tsunami.

Newman and colleagues have developed software to detect the peculiar signature of the tsunami earthquake, and are now running it on a research basis. “We get an earthquake or tsunami warning within four or five minutes, our algorithm starts processing, and a few minutes after that, the system sends email to the Pacific Tsunami Warning Center and the U.S.G.S. [Geological Survey],” Newman says.

Although the Japanese had little time between the earthquake and the tsunami, Newman says the national warning system did work. “In some ways, you have to look at real success in Japan. They have developed a substantial tsunami warning system, and it worked in as quickly as three minutes. People did evacuate, for the large part. Much of the video you see is from helicopters, or people watching from two or three stories up in buildings. There is only so much you can do with these events; this is a massive force.”

But the rising casualty counts highlights the deadly role of proximity to the quake, says Masterlark. “The very sad part is that because the quake was so close to the coast, they had very little warning; the time between the earthquake and the tsunami was minutes.”

More distant regions had adequate warning, Masterlark adds. “We had several hours before the wave reached Hawaii, and so were prepared. But Japan, unfortunately, even if you knew it was coming, you had only minutes, and that’s not enough time for many people to get to higher ground.”

Photo: Sarah Ruth

Basic tsunami safety

Public education and quick personal action remain the only ways to reduce the tsunami death toll:

1. Be on guard for strong earthquakes, which can spark a tsunami. If you feel one near the water, run inland.

2. Heed the warnings, and stay tuned to emergency radio stations.

3. Never go down to the beach to watch for tsunamis — they move much faster than you can run. People die doing this.

4. Most structures in the danger zone provide no protection. However, the upper stories of tall, reinforced concrete hotels can provide refuge if you have no time to move inland or to higher ground.

5. A tsunami is a series of waves. Don’t go near the water until you hear the all-clear from emergency authorities.

Following fatal footsteps?

Seismologists are loathe to predict earthquakes, but in the past decade or two, they have recognized that earthquakes occur in series along major faults in Turkey and Sumatra, as big quakes place extra stress on the adjacent fault. In Sumatra, a violent series of quakes began in 2004 with a magnitude 9.1, a magnitude 8.7 in 2005, a magnitude 7.6 in 2009, and a magnitude 7.7 in 2010.

The large quake in 2005 did not cause a major tsunami, but its timing, just three months after the Dec. 26 monster, suggests a compelling reason to focus intensively on the earthquake zone in the Japan trench, says Masterlark. “I am not trying to be alarmist, but I’m trying to look at where earthquakes have occurred along nearby faults to identify faults at risk. We’ll bring in numerical modeling and try to predict this as fast as possible. Time is of the essence, as we saw in Sumatra.”

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.

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.

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.”

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?

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.”

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.”

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.

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.

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…

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.

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.”

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.

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.

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:

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.

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.

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.

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: 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.”

Click here to view the embedded video.

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.

“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.”

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.

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.

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

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.”