Abrupt change in Arctic Sea Ice Volume

Sea ice is a key component of the Arctic climate system. Arctic sea ice extent has decreased steadily, as global warming has manifested. The evolution of the pan-Arctic sea ice volume is, however, sparsely represented in studies, and the intricate coupling to other climate system components is still being unravelled. In this study, we look at sea ice volume in the Arctic and show how its response to increasing temperatures has changed in recent years. Using a Bayesian statistical model framework, we detect changepoints in trends in reanalysis data of sea ice volume. We further compare these findings with climate model data and find a similar behaviour in several models. Our results suggest that as global temperature increases, there is a temperature threshold at which the Arctic sea ice volume experiences an abrupt change. The abrupt change primarily originates from loss of sea ice thickness in the Canada Basin. This nonlinear response demonstrates that it does not suffice to merely consider ice extent or area when evaluating potential tipping points in Arctic sea ice, and cements the importance of ice volume in the total Arctic energy budget.