Arctic permafrost stores massive amounts of organic carbon in its frozen soils and deeper deposits.
Arctic permafrost stores massive amounts of organic carbon in its frozen soils and deeper deposits. However, as the Arctic warms particularly rapidly, these deposits are thawing out. As a result, more and more greenhouse gases will be released into the atmosphere. There has been little research on where and how quickly permafrost thaws, as well as on the processes that cause the rapid thaw. PeTCaT (Rapid Permafrost Thaw Carbon Trajectories) is an international project that, above all, aims to increase our knowledge of these rapid thaw processes. Under the leadership of the Alfred Wegener Institute, researchers from Germany, the USA, Canada, the Netherlands, and Sweden plan to build a new dataset that will allow them to make projections about the possible developments and impacts of greenhouse gases from thawing permafrost. The project is funded by the non-profit organisation Schmidt Sciences.
“How quickly permafrost thaws depends on which region of the Arctic we are in and which processes are causing the thaw,” explains project leader Prof. Guido Grosse, Head of Permafrost Research Section at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). Although the active layer naturally thaws each summer, in a warming Arctic this seasonal thaw deepens over time, resulting in the permafrost gradually thawing from above by a few additional centimetres each year. This process is driven for example by continuously rising air temperatures, increased snow depths, or changes in vegetation that raise soil temperatures. However, we also see sudden thaw processes that can quickly cause several metres of permafrost to disappear per decade, or even per year – for example, when thawing coastlines suddenly break off, thermokarst lakes grow and deepen, or thaw slumps uncover icy subsoil. These rapid processes can release large amounts of previously permafrost-stored organic matter, which microorganisms can then convert into CO₂ and methane. “These abrupt processes are precisely where research is currently lacking and they are so far not considered in any climate model”, as Guido Grosse explains. “It is crucial to record these widespread rapid thaw processes and the effects they have so that we can understand their impact on the carbon cycle – particularly over the short time periods relevant for climate policy – in most cases years or a few decades at most.”
Read More: Alfred Wegener Institute
Retrogressive thaw slump (Photo Credit: Guido Grosse)
