Permafrost distribution in the Northern Hemisphere under scenarios of climatic change

The proportion of the Earthʹs land area underlain by permafrost, currently about 25%, is expected to contract substantially in response to climatic warming. Maps of permafrost distribution in the northern hemisphere were generated using three general circulation models and an empirical paleoreconstruction, all scaled to a 2°C global warming, in conjunction with a permafrost model that has successfully replicated the arrangement of contemporary permafrost zones in several high-latitude regions. The simulations indicate a 25–44% reduction in the total area occupied by equilibrium permafrost. Conditions specified by the climate models result in a poleward (north-northeast) displacement of all permafrost zones. The continuous permafrost zone was most severely impacted in the simulations, with reductions in its areal extent ranging from 29% to 67%. The permafrost model was also used to hindcast the distribution of permafrost in Russia during the Holocene climatic optimum and Eemian interglacial. Agreement of modeled results with mappings based on independent criteria confirm the motelʹs effectiveness.