Thawing permafrost, especially in the Northern Hemisphere, could send huge amounts of heat-trapping gases into the atmosphere by the end of this century, according to a U.N. Environment Program report released Tuesday at international climate talks in Doha, Qatar.
The report’s authors say air temperatures in the world’s arctic and alpine regions are expected to increase at roughly twice the global rate. These regional greenhouse gas emissions could ultimately account for up to 39 percent of total planet-wide emissions, says lead author Kevin Schaefer, from the University of Colorado’s Snow and Ice Data Center.
“The release of carbon dioxide and methane from warming permafrost is irreversible. Once the organic matter thaws and decays away, there is no way to put it back into the permafrost,” he added.
Warming can radically alter ecosystems and cause costly damage or even destroy buildings, roads, pipelines, railways and power lines. The report recommends a special commission to study permafrost emissions, the creation of a national permafrost monitoring network and the development of a plan for adaptation for nations at greatest risk.
Delegates in Doha are meeting to craft a new international climate agreement after the 1997 Kyoto treaty expires next month. As they seek to establish new targets for emission reductions to combat global warming, the new U.N. report urges them to factor in the rapidly melting permafrost.
Most of the current permafrost formed during or since the last ice age and extends to depths of more than 700 meters in parts of northern Siberia and Canada. Permafrost consists of an active layer of up to two meters in thickness, which thaws each summer and refreezes each winter, and the permanently frozen soil beneath.
Should the active layer increase in thickness due to warming, huge quantities of organic matter stored in the frozen soil would begin to thaw and decay, releasing large amounts of CO₂ and methane into the atmosphere.
Once this process begins, it will operate in a feedback loop known as the permafrost carbon feedback, which has the effect of increasing surface temperatures and thus accelerating the further warming of permafrost – a process that would be irreversible on human timescales.