Climate and energy: More than meets the eye!
Amid all the hubbub about climate, warming and energy, we wonder what the scientists who study warming, and the journalists who cover them, think about on their own time? Are they obsessed with exhuming or embalming the moribund "Kyoto-Copenhagen" process, or do they think other vital issues need airing?
Jon Foley: Looking at the land
When considering global warming, don't just worry about cars, power plants and factories, Foley says. "We need to look much more at land use and agriculture as a driver of global environmental change, including global climate change. For example, about one-third of all human-derived greenhouse gasses (including carbon dioxide, methane and nitrous oxide) come from land use and agricultural practices. In fact, agriculture and land use release more greenhouse gasses than all of the worlds transportation, or all of the world's electricity generation, or all the world's industry and manufacturing. And yet we don't really talk about the need to reform land use and agriculture as a way to combat climate change."
Although farming has come under attack for various environmental transgressions, environmentalists usually miss the point regarding global warming, says Foley. "The emissions from agriculture and land use do not come from the usual suspects: 'food miles,' agricultural chemicals, or energy use in farm machinery. While often discussed, this stuff is small potatoes. The vast majority of emissions from agriculture come from tropical deforestation (clearing land almost entirely for new croplands and pastures), methane from rice fields and cattle, and nitrous oxide from over-fertilized fields. Everything else is tiny. Unfortunately, the movement for 'local food' (which can be good in many other ways, of course) does very little to reduce global greenhouse gas emissions. The energy used to transport food around the world is very small compared to the carbon dioxide released from deforestation."
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Robert Charlson: Hazards of haze
Aerosols are a key factor in global warming, says Charlson, who recently reported that the lower atmosphere has warmed only 40 percent of what would be expected from the measured rise in greenhouse gases (see #1 in the bibliography).
Two factors, perhaps in combination, could explain the discrepancy, Charlson and his co-authors concluded: Either a given amount of greenhouse gas produces less warming, or something is counterbalancing their effects.
Charlson thinks aerosols are a key explanation for the discrepancy, but says it's difficult to put numbers on the relative heating and cooling. "Research has been heavily concentrated on greenhouse gases," and although a 1996 report from the National Academy of Sciences called for a "large, coordinated national, international program to address the issue, virtually nothing has changed as a result."
On the bright side, aerosols don't last nearly as long as carbon dioxide. If soot is indeed a major cause of warming, avoiding forest fires and using cleaner woodstoves and engines could rather quickly help brake planetary warming. Further, Charlson says that poor understanding of aerosols prevents accurate predictions of how much warming to expect from future estimations of greenhouse gases.
Lonnie Thompson: Melting glaciers
Mountain glaciers, source of water for large parts of Asia and South America, may be declining even faster than we thought, Thompson says. "We see lots of discussions about the area decreases," showing how their margins are melting and shrinking, but some glaciers he's measured are also thinning at the top, which is "not recorded in aerial photos or satellite images."
Changes in ice area alone can be deceptive, he adds, because "about 50 percent of the loss is due to thinning."
When Thompson's group installed a stake in the top of the glacier capping Mount Kilimanjaro in Africa, they discovered that it lost half a meter per year between 2000 and 2009.
This glacier could disappear about 2018, says Thompson, who notes that travel to "Kili" is Tanzania's largest source of foreign exchange and wonders how many travelers will stay home once the iconic icecap is history.
Tropical glaciers are an irreplaceable source of water in many dry regions, Thompson adds. If the early reports of thinning on top are, forgive us, the tip of the iceberg, he adds, "Water resource issues downstream will arise very much faster than if we were just talking about glaciers retreating up the valley."
In Peru, Thompson says, "80 percent of the population lives in a desert on the dry side of Andes; the country is very much dependent on water from rivers that are sourced in glaciers." And because 76 percent of Peru's electricity comes from dams on rivers, low water during the dry season will have "a very significant impact on the power supply."
Normally, a glacier accumulates snow and ice up high, and flows down to an altitude where the ice melts. Glaciers that cease accumulating ice "are really relics of an earlier climate," Thompson says, and may be doomed in a warming world.
Michael Lemonick: Seeing sea level
Much as global warming is affecting local temperatures differently, the resulting rise in sea level will also vary from place to place. "This has not been talked about," says Lemonick. "Sea level rise will differ; some places will be less than global average, and other places significantly higher."
An extremely complicated set of factors will affect local sea level:
Geologic factors will affect the shoreline and therefore influence the relative height of the sea, Lemonick adds. Removals of oil and gas can "deflate" the land, causing sinking. Tectonic plates can move vertically in either direction. Rivers deliver silt to their deltas, adding weight that can cause a local depression. The kind of marshland destruction seen around New Orleans will reduce barriers to storms.
How much difference do these local factors make? "I have not seen a number, because it's so complicated; it draws in oceanography, atmospheric dynamics, gravity measurements and geology," Lemonick says.
David Tenenbaum: Starved for feedback
I'm startled by the under-coverage of positive feedbacks -- the phenomena that can intensify themselves. About the only well-covered positive feedback occurs in the Arctic: When the ice-cap melts, it leaves open water that is darker than ice and therefore absorbs more sunlight, which causes more warming, and then more melting.
Climate may show negative feedbacks: More carbon dioxide in the air can speed plant growth, locking up more carbon and reducing the greenhouse effect. Yet climate is full of positive feedbacks:
All of these phenomenon have the potential to feed back upon themselves to cause more warming.
Terry Devitt, editor; Steve Furay, project assistant; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive