Scientists have made concerted efforts in recent years to understand the relationship between permafrost and climate change, and now they'll have a another tool at their disposal.
A team of researchers that includes University of Alaska Fairbanks professors has developed a model to predict the amount of carbon that will be released to the atmosphere from the thawing permafrost soils.
The new model confirms earlier studies, which predicted persistent and significant carbon emissions, but the scientists reached their conclusions in a new and more direct way, according to a paper describing the research published this week in the journal Philosophical Transactions of the Royal Society A.
Scientists combined existing data -- including global maps of soil carbon levels, laboratory measurements of carbon emission rates from thawing permafrost, and field calculations of how soils in cold regions are responding to warming air temperatures -- to conduct a "meta-analysis" of permafrost observations. Previous analysis of global permafrost carbon emissions relied on Earth system models, which assess a much larger array of ecological information.
"We have tried to construct the simplest possible model of the permafrost carbon feedback," said the study's lead author, Charles Koven, a staff scientist at the Department of Energy's Lawrence Berkeley National Laboratory. "We are using permafrost data instead of global data."
The analysis considered two climate change scenarios. In the first, fossil fuel burning drops dramatically by the year 2050 and the global temperature goes up by 1.8 degrees Celsius (3.24 Fahrenheit) on average. In the second, the use of fossils fuels remains steady and a warming of 3.4 degrees (6.12 Fahrenheit) Celsius occurs. The study accounted for the fact that the Arctic warms faster than the planet as a whole.
Averaging the two scenarios, Koven's team found that for every degree Celsius of global warming, thawing permafrost releases 15 billion tons of carbon into the atmosphere. That number is equivalent to the carbon output of all human activity for a year and a half at today's rates, Koven said.
For decades, scientists have known that the frozen soils found across the Arctic contain enormous deposits of carbon. And for as long as climate change has been in the spotlight, those scientists have theorized that warming air could trigger the emission of greenhouse gases from thawing ground -- which would in turn lead to more warming.
But analyzing the magnitude and rate of carbon emission has been a challenge.
That's why the new study, and the new model it uses, holds promise as a major advance in the attempt to predict -- on a global scale -- how much carbon dioxide and methane will enter the atmosphere as the Arctic warms.