WASHINGTON – Global warming gases trapped in the soil are bubbling out of the thawing permafrost in amounts far higher than previously thought and may trigger what researchers warn is a climate time bomb.
Methane – a greenhouse gas 23 times more powerful than carbon dioxide – is being released from the permafrost at a rate five times faster than thought, according to a study being published today in the journal Nature.
The findings are based on new, more accurate measuring techniques.
“The effects can be huge,” said lead author Katey Walter of the University of Alaska at Fairbanks. “It's coming out a lot, and there's a lot more to come out.”
Scientists worry about a global-warming vicious cycle that was not part of their already gloomy climate forecast: Warming already under way thaws permafrost, soil that has been continuously frozen for thousands of years.
Thawed permafrost releases methane and carbon dioxide. Those gases reach the atmosphere and help trap heat on Earth in the greenhouse effect. The trapped heat thaws more permafrost and so on.
“The higher the temperature gets, the more permafrost we melt, the more tendency it is to become a more vicious cycle,” said Chris Field, director of global ecology at the Carnegie Institution of Washington, who was not part of the study. “That's the thing that is scary about this whole thing. There are lots of mechanisms that tend to be self-perpetuating and relatively few that tend to shut it off.”
Most of the methane-releasing permafrost is in Siberia.
Scientists aren't quite sure whether methane or carbon dioxide is worse. Methane is far more powerful in trapping heat, but only lasts about a decade before it dissipates into carbon dioxide and other chemicals. Carbon dioxide traps heat for about a century.
