CHERSKY, Russia — The Russian scientist shuffles across the frozen lake, scuffing aside ankle-deep snow until he finds a cluster of bubbles trapped under the ice. With a cigarette lighter in one hand and a knife in the other, he lances the ice like a blister. Methane whooshes out and bursts into a thin blue flame.
Gas locked inside Siberia’s frozen soil and under its lakes has been seeping out since the end of the last ice age 10,000 years ago. But in the past few decades, as Earth has warmed, the icy ground has begun thawing more rapidly, accelerating the release of methane — a greenhouse gas 23 times more powerful than carbon dioxide — at a perilous rate.
Some scientists think the thawing of permafrost could become the epicenter of climate change. They say 1.5 trillion tons of carbon, locked inside icebound earth since the age of mammoths, is a climate time bomb waiting to explode if released into the atmosphere.
“Here, total carbon storage is like all the rain forests of our planet put together,” says the scientist, Sergey Zimov — “here” being the snow and ice stretching toward Siberia’s horizon, as seen from Zimov’s research facility nearly 220 miles above the Arctic Circle.
Climate change moves back to center stage Monday when governments meet in Cancún, Mexico, to try again to hash out a course of counteractions. But U.N. officials hold out no hope that the two weeks of talks will lead to a legally binding accord governing carbon emissions, seen as the key to averting what might be a dramatic change in climate this century.
Most climate scientists, with a few dissenters, say human activities — the stuff of daily life such as driving cars, producing electricity or raising cattle — is overloading the atmosphere with carbon dioxide, methane and other gases that trap heat, causing a warming effect.
But global warming is amplified in the polar regions. What feels like a modest temperature rise is enough to induce Greenland glaciers to retreat, Arctic sea ice to thin and contract in summer, and permafrost to thaw faster, both on land and under the seabed.
Yet awareness of methane leaks from permafrost is so new that it was not even mentioned in the seminal 2007 report by the Intergovernmental Panel on Climate Change, which warned of rising sea levels inundating coastal cities, dramatic shifts in rainfall disrupting agriculture and drinking water, the spread of diseases and the extinction of species.
Robert Corell, a U.S. climate- change researcher and Arctic specialist, said he and other U.S. scientists are pushing Washington to deploy satellites to gather more information on methane leaks.
The lack of data over a long period casts uncertainty over the extent of the threat. An article in August in the journal Science quoted several experts as saying it’s too early to predict whether Arctic methane will be the tipping point.
Studies indicate that cold- country dynamics on climate change are complex. The Arctic Monitoring and Assessment Program, a scientific body set up by the eight Arctic- rim countries, says overall the Arctic is absorbing more carbon dioxide than it releases.
“Methane is a different story,” said its 2009 report. The Arctic is responsible for up to 9 percent of global methane emissions. Other methane sources include landfills, livestock and fossil-fuel production.
Katey Walter Anthony, of the University of Alaska Fairbanks, has been measuring methane seeps in Arctic lakes, starting around Chersky 10 years ago.
She was stunned to see how much methane was leaking from holes at the bottom of one of the first lakes she visited. “On some days, it looked like the lake was boiling,” she said. Returning each year, she noticed lakes doubling in size as warm water ate into the frozen banks.
More than 50 billion tons could be unleashed from Siberian lakes alone, more than 10 times the amount now in the atmosphere, she said.
Permafrost is defined as ground that has stayed below freezing for more than two consecutive summers. Most of Siberia and the rest of the Arctic, covering one-fifth of Earth’s land surface, have been frozen for millennia.
During the summer, the ground can defrost to a depth of several feet. As Earth warms, the summer thaw bites deeper, awakening ice-age microbes that attack organic matter buried where oxygen cannot reach, producing methane that gurgles up and into the air.
The newly released methane traps more heat, which deepens the next thaw, in a cycle.
