Impacts of peat and vegetation on permafrost degradation under climate warming

Simulations of maximum annual thaw at a continuous and a discontinuous permafrost site in Canada were performed using Community Land Model version 3 (CLM3) and randomized historical climate records from these sites, superimposed with United Nations Intergovernmental Panel on Climate Change (IPCC), Report on Emission Scenarios (SRES) A2 scenario of climate change. A positive trend in permafrost degradation was simulated for the 2000 to 2100 period in response to climate warming. Surface cover condition and soil properties play a dominant role in affecting ground thaw. In particular, a thin peat layer or surface organic cover can significantly buffer the permafrost against severe degradation. The occurrence of vegetation and extensive presence of a peat and organic layer in the circumpolar areas will modulate the regional impact of climate warming on permafrost thaw.