Nature Climate Change, 23 October 2023
A state-of-the-art model suggests that a widespread increase in West Antarctic ice shelf melting, including in regions crucial for maintaining the stability of the bordering ice sheet, is now locked in to occur through at least 2100. This is because water temperatures in the Amundsen Sea off West Antarctica could be up to 2°C warmer than pre-industrial by 2100, even if global mean temperature is limited to 1.5°C of warming. With widespread loss of ice shelves from warmer waters now to some degree inevitable, the opportunity to preserve the West Antarctic Ice Sheet in its present-day state has probably passed. If it were to collapse completely, this ice sheet would raise sea levels by 5 meters. The authors stress that policymakers must therefore prepare to adapt to several meters of sea-level rise over the coming centuries. However, the study stresses that if warming is held at 1.5°C, rates of ice shelf melting start to slow by 2100, suggesting that further losses beyond 2100 may still be preventable; or at least slowed by strict adherence to the lower Paris 1.5°C goal. Reducing sea-level rise after 2100, or even slowing it down, could save many coastal cities and prevent trillions of dollars of damage to coastlines worldwide.