Researchers predicted a gradual release of greenhouse gases from permafrost soils in Arctic and sub-Arctic regions, which could give humans more time to adapt to the environmental changes.
Permafrost soil is believed to contain about twice as much carbon as what currently exists in the Earth's atmosphere, the University of Alaska Fairbanks. As this soil thaws, it releases carbon dioxide and methane into the atmosphere, further accelerating global warming.
"Twenty years ago there was very little research about the possible rate of permafrost carbon release," said co-author A. David McGuire, U.S. Geological Survey senior scientist and climate modeling expert with the Institute of Arctic Biology at the University of Alaska Fairbanks. "In 2011, we assembled an international team of scientists into the Permafrost Carbon Network to synthesize existing research and answer the questions of how much permafrost carbon is out there, how vulnerable to decomposition it is once it's thawed, and what are the forms in which it's released into the atmosphere."
Permafrost is estimated to have heated up by about 11 degrees Fahrenheit over the past three decades, and is now averaging at over 28 degrees. In the past, researchers believed this thawing would release greenhouse gases into the atmosphere like a "big bomb," and make a significant and sudden impact on global warming.
"The data from our team's syntheses don't support the permafrost carbon bomb view," McGuire said. "What our syntheses do show is that permafrost carbon is likely to be released in a gradual and prolonged manner, and that the rate of release through 2100 is likely to be of the same order as the current rate of tropical deforestation in terms of its effects on the carbon cycle."
The researchers believe this type of work is extremely important in helping scientists set their priorities for climate modeling. In the future, the team plans to continue improving the system in hopes of gaining more insight into the fate of permafrost.
"If society's goal is to try to keep the rise in global temperatures under two degrees C and we haven't taken permafrost carbon release into account in terms of mitigation efforts, then we might underestimate that amount of mitigation effort required to reach that goal," McGuire said.
The findings were published in a recent edition of the journal Nature.