Imminent loss of climate space for permafrost peatlands in Europe and Western Siberia

Human-induced climate warming by 2100 is expected to thaw large expanses of northern permafrost peatlands. However, the spatio-temporal dynamics of permafrost peatland thaw remain uncertain due to complex permafrost–climate interactions, the insulating properties of peat soils and variation in model projections of future climate. Here we show that permafrost peatlands in Europe and Western Siberia will soon surpass a climatic tipping point under scenarios of moderate-to-high warming (Shared Socioeconomic Pathway (SSP) 2-4.5, SSP3-7.0 and SSP5-8.5). The total peatland area affected under these scenarios contains 37.0–39.5 Gt carbon (equivalent to twice the amount of carbon stored in European forests). Our bioclimatic models indicate that all of Fennoscandia will become climatically unsuitable for peatland permafrost by 2040. Strong action to reduce emissions (SSP1-2.6) by the 2090s could retain suitable climates for permafrost peatlands storing 13.9 Gt carbon in northernmost Western Siberia, indicating that socio-economic policies will determine the rate and extent of permafrost peatland thaw. Permafrost peatlands are thawing, yet the timing and spatial dynamics of thaw are not well constrained. Under moderate and high warming scenarios, permafrost peatlands in Europe and Western Siberia will cross a tipping point where the climate becomes unsuitable, putting their carbon stores at risk.