Arctic Ecosystems and their Services Under Changing Climate: Predictive-Modeling Assessment

There is increasing evidence that permafrost and vegetation have already responded to pronounced warming of the Arctic in the past few decades. In this study we used mathematical models to assess changes of permafrost and Arctic vegetation in the first half of the twenty-first century. We tested the regional performance of the CMIP5 Earth system models and eliminated outliers that have large errors in replicating temperature and precipitation trends in the Arctic over the historical time period. The remaining “best” models were combined into an optimal ensemble and used as climatic forcing in permafrost and vegetation modeling. Probabilistic metrics, such as the number of climate trajectories leading to different levels of impacts on permafrost and vegetation, have been used to evaluate the uncertainties associated with the climate projections. Results under all trajectories predict deeper seasonal thawing of the uppermost soil layer above permafrost, a northward shift of biome ranges, expansion of the boreal forest, and reduction of the tundra area. Such changes will have implications for land use, market and nonmarket economies, infrastructure in the urban and industrially developed regions of the Russian Arctic, indigenous peoples following traditional lifestyles, and wildlife.