Climate-Change Calculus

Why it's even worse than we feared

by Sharon Begley, Newsweek, July 24, 2009; from the magazine issue dated August 3, 2009.

Among the phrases you really, really do not want to hear from climate scientists are: "that really shocked us," "we had no idea how bad it was," and "reality is well ahead of the climate models." Yet in speaking to researchers who focus on the Arctic, you hear comments like these so regularly they begin to sound like the thumping refrain from Jaws: annoying harbingers of something that you really, really wish would go away.

Let me deconstruct the phrases above. The "shock" came when the International Polar Year, a global consortium studying the Arctic, froze a small vessel into the sea ice off eastern Siberia in September 2006. Norwegian explorer Fridtjof Nansen had done the same thing a century before, and his Fram, carried by the drifting ice, emerged off eastern Greenland 34 months later. IPY scientists thought their Tara would take 24 to 36 months. But it reached Greenland in just 14 months, stark evidence that the sea ice found a more open, ice-free, and thus faster path westward thanks to Arctic melting.

The loss of Arctic sea ice "is well ahead of" what the Intergovernmental Panel on Climate Change forecast, largely because emissions of carbon dioxide have topped what the panel—which foolishly expected nations to care enough about global warming to do something about it—projected. "The models just aren't keeping up" with the reality of CO2 emissions, says the IPY's David Carlson. Although policymakers hoped climate models would prove to be alarmist, the opposite is true, particularly in the Arctic.

The IPCC may also have been too cautious on Greenland, assuming that the melting of its glaciers would contribute little to sea-level rise. Some studies found that Greenland's glacial streams were surging and surface ice was morphing into liquid lakes, but others made a strong case that those surges and melts were aberrations, not long-term trends. It seemed to be a standoff. More reliable data, however, such as satellite measurements of Greenland's mass, show that it is losing about 52 cubic miles per year and that the melting is accelerating. So while the IPCC projected that sea level would rise 16 inches this century, "now a more likely figure is one meter [39 inches] at the least," says Carlson. "Chest high instead of knee high, with half to two thirds of that due to Greenland." Hence the "no idea how bad it was."

The frozen north had another surprise in store. Scientists have long known that permafrost, if it melted, would release carbon, exacerbating global warming, which would melt more permafrost, which would add more to global warming, on and on in a feedback loop. But estimates of how much carbon is locked into Arctic permafrost were, it turns out, woefully off. "It's about three times as much as was thought, about 1.6 trillion metric tons, which has surprised a lot of people," says Edward Schuur of the University of Florida. "It means the potential for positive feedbacks is greatly increased." That 1.6 trillion tons is about twice the amount now in the atmosphere. And Schuur's measurements of how quickly CO2 can come out of permafrost, reported in May, were also a surprise: 1 billion to 2 billion tons per year. Cars and light trucks in the U.S. emit about 300 million tons per year.

In an insightful observation in The Guardian this month, Jim Watson of the University of Sussex wrote that "a new breed of climate sceptic is becoming more common": someone who doubts not the science but the policy response. Given the pathetic (non)action on global warming at the G8 summit, and the fact that the energy/climate bill passed by the House of Representatives is so full of holes and escape hatches that it has barely a prayer of averting dangerous climate change, skepticism that the world will get its act together seems appropriate. For instance, the G8, led by Europe, has vowed to take steps to keep global warming below 2 degrees Celsius by reducing CO2 emissions. We're now at 0.8 degree. But the amount of CO2 in the atmosphere is already enough to raise the mercury 2 degrees. The only reason it hasn't is that the atmosphere is full of crap (dust and aerosols that contribute to asthma, emphysema, and other diseases) that acts as a global coolant. As that pollution is reduced for health reasons, we're going to blast right through 2 degrees, which is enough to exacerbate droughts and storms, wreak havoc on agriculture, and produce a planet warmer than it's been in millions of years. The 2-degree promise is a mirage.

The test of whether the nations of the world care enough to act will come in December, when 192 countries meet in Copenhagen to hammer out a climate treaty. Carlson vows that IPY will finish its Arctic assessment in time for the meeting, and one conclusion is already clear. "A consensus has developed during IPY that the Greenland ice sheet will disappear," he says. Cue the Jaws music.

Begley Is Newsweek’s Science Editor.

Link to this article: http://www.newsweek.com/id/208164