Posted: 10 Apr 2017 09:40 AM PDT
Nearly 4 million square kilometers of frozen soil — an area larger than India — could be lost for every additional degree of global warming experienced, warn scientists. Global warming will thaw about 20% more permafrost than previously thought, they add – potentially releasing significant amounts of greenhouse gases into the Earth’s atmosphere. But these investigators also suggest that the huge permafrost losses could be averted if ambitious global climate targets are met.
…Permafrost is frozen soil that has been at a temperature of below 0ºC for at least two years. Large quantities of carbon are stored in organic matter trapped in the icy permafrost soils. When permafrost thaws the organic matter starts to decompose, releasing greenhouse gases such as carbon dioxide and methane which increase global temperatures.
It is estimated that there is more carbon contained in the frozen permafrost than is currently in the atmosphere. Thawing permafrost has potentially damaging consequences, not just for greenhouse gas emissions, but also the stability of buildings located in high-latitude cities.
Roughly 35 million people live in the permafrost zone, with three cities built on continuous permafrost along with many smaller communities. A widespread thaw could cause the ground to become unstable, putting roads and buildings at risk of collapse. Recent studies have shown that the Arctic is warming at around twice the rate as the rest of the world, with permafrost already starting to thaw across large areas.
The study suggests that permafrost is more susceptible to global warming that previously thought, as stabilising the climate at 2ºC above pre-industrial levels would lead to thawing of more than 40% of today’s permafrost areas.
..Co-author Dr Eleanor Burke, from the Met Office Hadley Centre, said: “The advantage of our approach is that permafrost loss can be estimated for any policy-relevant global warming scenario. “The ability to more accurately assess permafrost loss can hopefully feed into a greater understanding of the impact of global warming and potentially inform global warming policy.”
S. E. Chadburn, E. J. Burke, P. M. Cox, P. Friedlingstein, G. Hugelius, S. Westermann. An observation-based constraint on permafrost loss as a function of global warming. Nature Climate Change, 2017; DOI: 10.1038/nclimate3262