WASHINGTON - Massive amounts of greenhouse gases trapped below thawing permafrost will likely seep into the air over the next several decades, accelerating and amplifying global warming, scientists warn.
Those heat-trapping gases under the frozen Arctic ground may be a bigger factor in global warming than the cutting down of forests and a scenario for which climate scientists had not completely accounted, according to a group of permafrost specialists. The gases will not contribute as much as pollution from power plants, cars, trucks, and planes, though.
The scientists predict that over the next three decades a total of about 45 billion metric tons of carbon from methane and carbon dioxide will seep into the atmosphere when permafrost thaws during summers. That is about the same amount of heat-trapping gas the world spews during five years of burning coal, gas, and other fossil fuels
The picture is even more alarming for the end of the century. The scientists calculate that about than 300 billion metric tons of carbon will belch from the thawing Earth from now until 2100.
Adding in that gas means that warming would happen “20 to 30 percent faster than from fossil fuel emissions alone,’’ said Edward Schuur of the University of Florida. “You are significantly speeding things up by releasing this carbon.’’
Usually the first few inches of permafrost thaw in the summer, but scientists are now looking at up to 10 feet of soft unfrozen ground because of warmer temperatures, he said. The gases come from decaying plants that have been stuck below frozen ground for millennia.
Schuur and 40 other scientists in the Permafrost Carbon Research Network met this summer and jointly wrote up their findings, which were published yesterday in the journal Nature.
“The survey provides an important warning that global climate warming is likely to be worse than expected,’’ said Jay Zwally, a NASA polar scientist who was not part of the study. “Arctic permafrost has been like a wild card.’’
When the Nobel Prize-winning panel of climate scientists issued its last full report in 2007, it did not factor in trapped methane and carbon dioxide from beneath the permafrost.
Diplomats are meeting this week in South Africa to find ways of curbing human-made climate change.
Schuur and others said increasing amounts of greenhouse gas are seeping out of permafrost each year. Some is methane, which is 25 times stronger than carbon dioxide in trapping heat.
The World Meteorological Organization this week said the worst of the warming in 2011 was in the northern areas - where there is permafrost - and especially Russia.
Since 1970, the Arctic has warmed at a rate twice as fast as the rest of the globe.