Economic impacts of carbon dioxide and methane released from thawing permafrost

The Arctic is warming roughly twice as fast as the global average(1). If greenhouse gas emissions continue to increase at current rates, this warming will lead to the widespread thawing of permafrost and the release of hundreds of billions of tonnes of CO2 and billions of tonnes of CH4 into the atmosphere(2). So far there have been no estimates of the possible extra economic impacts from permafrost emissions of CO2 and CH4. Here we use the default PAGE09 integrated assessment model(3) to show the range of possible global economic impacts if this CO2 and CH4 is released into the atmosphere on top of the anthropogenic emissions from Intergovernmental Panel on Climate Change scenario A1B (ref. 4) and three other scenarios. Under the A1B scenario, CO2 and CH4 released from permafrost increases the mean net present value of the impacts of climate change by US$43 trillion, or about 13% (5-95% range: US$3-166 trillion), proportional to the increase in total emissions due to thawing permafrost. The extra impacts of the permafrost CO2 and CH4 are sufficiently high to justify urgent action to minimize the scale of the release.