Bifurcations in Ice Sheet Behavior and the Implications for Projections of Future Sea Level Rise

Sea level has been rising globally since at least the early 20^th century. This rise can be explained almost entirely by the expansion of warming seawater and melting of land-based glaciers and ice sheets. More recently, the contribution of melting from the Greenland and Antarctic ice sheets to global sea level rise has increased dramatically. This increase in the rate of ice sheet melt, and corresponding acceleration in the rate of global sea level rise has largely been explained by two factors: (1) increased surface melt on the Greenland Ice Sheet, and (2) increased ice flow speeds and discharge to the ocean (through melting and ice fracture) from both ice sheets. In this talk, I will review explanations for these dramatic changes, using canonical bifurcation theories in ice sheet dynamics. I will then review more recent work adapting ideas from piecewise bifurcation theory and statistical physics to further understand enigmatic aspects of past ice sheet changes and projections of future changes. I will conclude by explaining how these ideas from physics are being used to developing better numerical models of ice sheet evolution, and improve the accuracy of future sea level projections. Such projections are already used by coastal communities as critical tools in planning for future sea level rise in order to avoid trillions of dollars in potential losses from coastal flooding globally.