Climate change is clearly impacting the state and distribution of permafrost in the polar regions. Gradual thawing through deepening of the seasonally active layer as well as rapid thawing through coastal erosion, thermokarst, and thaw slumping is intensifying. Thawing processes are accelerated by positive feedbacks, and associated landforms are becoming more abundant. The interaction of these processes with the carbon cycle is of global relevance since polar permafrost stores enormous amounts of organic matter. Release of carbon as C02 or CH4 accelerates global climate change. A priority of current permafrost and climate research is to understand and quantify these processes and to integrate them into climate models.