Subsurface warming in the Antarctica’s Weddell Sea can be avoided by reaching the 2∘C warming target

Abstract

Recently, seasonal pulses of modified Warm Deep Water have been observed near the Filchner Ice Shelf front in the Weddell Sea, Antarctica. Here, we investigate the temperature evolution of subsurface waters in the Filchner Trough under four future scenarios of carbon dioxide emissions using the climate model AWI-CM. Our model simulates these warm intrusions, suggests more frequent pulses in a warmer climate, and supports the potential for a regime shift from cold to warm Filchner Trough in two high-emission scenarios. The regime shift is governed in particular by decreasing local sea ice formation and a shoaling thermocline. Cavity circulation is not critical in triggering the change. Consequences would include increased ice shelf basal melting, reduced buttressing of fast-flowing ice streams, loss of grounded ice and an acceleration of global sea level rise. According to our simulations, the regime shift can be avoided and the Filchner Trough warming can be restricted to 0.5 ∘C by reaching the 2 ∘C climate goal.