Warming Feedback From Permafrost

Soils can be a critical modulator of global climate because they store large quantities of carbon that can be released into the atmosphere as greenhouse gasses. Land use decisions affecting soil carbon storage can either exacerbate or mitigate climate change. Most of the global soil carbon is located in high latitude permafrost and in peatlands, which are distributed globally. Soil carbon stored in tropical peatlands is particularly vulnerable to land use change, while permafrost carbon, which is not not directly affected by land use, is vulnerable as a result of a changing climate. Permafrost regions contain approximately 1500 petagrams of soil carbon, which is almost twice the amount of carbon that is currently in the atmosphere and three times more carbon than is stored in the world’s forest biomass. The increase in atmospheric greenhouse gases, caused by fossil fuel emissions and land use changes, is placing this large pool of carbon at risk of being thawed, decomposed, and transferred to the atmosphere as carbon dioxide and methane, further exacerbating climate change. The Arctic has been a carbon sink for tens of thousands of years, but the Arctic is warming twice as fast as the global average, and as a result, many areas of the Arctic are now sources of carbon to the atmosphere. Under the current rate of greenhouse gas emissions (“business as usual”), thawing permafrost is expected to release 130-160 petagrams of carbon by 2100, a rate that is on par with current US emissions. The emissions of carbon from thawing permafrost are currently not accounted for in Intergovernmental Panel on Climate Change global climate models that are informing international policy decisions. Global climate policy will need to address these unaccounted for emissions and maintain key Arctic systems in order to reduce the impacts of global climate change and to meet the goal of the Paris Climate Agreement, which is to keep the global temperature increase to below 2C.