Arctic and boreal region carbon (C) emissions remains one of the most important C cycle feedbacks to climate, with implications for global society. Permafrost region soils contain 1440-1600 billion tons of C; release of just a fraction of this pool as carbon dioxide and methane can accelerate climate change. Permafrost degradation can change ecosystem C storage by enhancing microbial activity and ecosystem respiration, but can also stimulate plant growth and increase C stored in vegetation and surface soil. This session invites papers that examine factors causing losses and gains in permafrost C that contribute to current observations and future projections of changing permafrost C through time. Papers may address any aspect of this topic from microbial communities to the global scale, using a range of field or laboratory measurements or modeling to detect and forecast permafrost thaw and the influence on the C cycle and future climate.

• C - Cryosphere