Permafrost is not necessarily frozen, because salts in the sediment pore space depress the freezing point below 0 C. Saline permafrost is primarily found in marine deposits beneath shallow shelf seas and inland from present Arctic coasts. On land, saline permafrost formed due to post-glacial rebound exceeding sea level rise, which exposes subsea sediment to the atmosphere. Frozen saline permafrost has a lower freezing point than permafrost containing fresh porewater, making it even more susceptible to thawing as the Arctic heats up. Further, warming saline permafrost creates cryopegs (i.e. unfrozen saline permafrost pockets/layers), where greenhouse gases can accumulate and migrate through permafrost. To evaluate the large-scale impact of saline permafrost in the Arctic, I aim to research how post-glacial isostasy and climate influence its development.
