Future Antarctic ice loss under climate overshoot trajectories

Earth’s climate is fast approaching a warming of 1.5°C above pre-industrial levels. While the global mean temperature change may be limited on the long term following an overshoot (or peak-and-decline) climate trajectory, the regional climate impacts in Antarctica that might result are highly uncertain: Given the complex interplay of several amplifying and dampening feedbacks in the Antarctic ice-sheet system and associated tipping dynamics, a rich set of changes – ranging from (fully) reversible to potentially irreversible to irreversible – are possible. 

Here, we quantify the response of the Antarctic Ice Sheet and associated uncertainties across multi-centennial to millennial timescales to a wide range of projected climate overshoot trajectories using the Parallel Ice Sheet Model (PISM). 

Overall, our results suggest that the impacts of overshooting 1.5°C on the Antarctic Ice Sheet worsen with increasing magnitude and duration, and are strongly dependent on the landing climate. Even temporary overshoots can have long-lasting, if not irreversible impacts, stressing the need for limiting global warming to ensure the stability of the Antarctic Ice Sheet across timescales.