Glacial Isostatic Adjustment speeds past and future Arctic subsea permafrost thaw
Roger Creel, Frederieke Miesner,Stiig Wilkenskjeld, Jacqueline Austermann, Pier Paul Overduin
ABSTRACT: Subsea permafrost forms when sea-level rise submerges terrestrial permafrost in the Arctic. Although year-round sea ice has until recently hindered measurement of subsea permafrost distribution, best estimates indicate that over 2.5 million km2 of permafrost exists under the Arctic continental shelf, with some areas of the Laptev and Kara seas underlain by permafrost that is more than 700 meters thick. Understanding subsea permafrost is important because it stores organic carbon and methane, which, if thawed, may reach the atmosphere as greenhouse gasses. Sea-level variations control subsea permafrost distribution. Yet to date, no subsea permafrost model has included local sea level that differs from the global mean due to glacial isostatic adjustment (GIA). Here we present the first model of pan-Arctic subsea permafrost over the last 400,000 years to incorporate GIA. This model allows us to estimate present-day subsea permafrost extent and explore the effect that relative sea level has on permafrost evolution. Additionally, we extend the subsea permafrost simulation 1000 years into the future for the emissions scenarios outlined in the International Panel on Climate Change’s sixth assessment report. Our future projections enable us to map the vulnerability of Arctic subsea permafrost to climate warming.