Global Tidal Impacts of Large-Scale Ice Sheet Collapses

Abstract

Recent studies show that the glaciers draining both the West Antarctic and the Greenland Ice Sheets are experiencing an accelerated ice loss, highlighting the possibility of large-scale ice sheet retreat and sea level rise in the coming centuries and millennia. These sea level changes would vary spatially and could significantly alter global tides as the latter are highly dependent on bathymetry (or water column thickness under ice shelves) and basin shape. This paper investigates how the principal semidiurnal (M2) tidal amplitudes and energy dissipation respond to the nonuniform sea level changes induced by complete ice sheet collapses. The sea level changes are calculated using gravitationally self-consistent sea level theory, and the tides are simulated using an established tidal model. Results from the simulations show global and spatially heterogeneous changes in tidal amplitudes. In addition, pronounced changes in tidal energy dissipation occur in both the open ocean and in shelf-seas, also altering the location of tidal mixing fronts. These changes have the potential to impact ocean mixing, and hence large-scale currents and climate patterns, and the contribution of shelf-sea to the global carbon cycle. The new results highlight the importance of considering changes in the tides in predictions of future climate and reconstructions of past climate phases such as the Last Interglacial.