The Signature of Ozone Depletion in Recent Antarctic Precipitation Change: A Study With the Community Earth System Model.

Although precipitation is a primary control on Antarctic ice sheet (AIS) mass balance, long‐term historical AIS precipitation trends and their underlying external climate drivers remain inconclusive. In this study, we use a novel pair of climate model ensembles to identify a simulated spatial signature of ozone depletion‐forced AIS precipitation change. Distinct areas of little change or precipitation decrease, arising from interaction between ozone depletion‐forced atmospheric circulation changes and ice sheet topography, are outweighed by large‐scale precipitation increases. This signature bears notable similarities to a new ice core‐based reconstruction of AIS accumulation change and yields a significant increase in annual integrated precipitation (38 ± 10 Gt/year over the 1986–2005 period or 51 ± 11 Gt/year over the 1991–2005 period). Remarkably, this simulated ozone depletion‐forced precipitation change is of a similar absolute magnitude to recent observed AIS mass loss trends and as a consequence, it may play a role in dampening recent AIS sea level rise contributions. Plain Language Summary: Stratospheric ozone depletion, also known as the ozone hole, has started in the 1970s and, despite a slow recovery, thanks to the Montréal protocol, will continue well into the 21st century. Previous studies have shown that ozone depletion not only enhances ultraviolet radiation at the surface but also affects weather patterns and sea ice on the Southern Ocean, north of the Antarctic ice sheet. However, a key question still remains: What is the impact of ozone depletion on Antarctic climate, and particularly precipitation? This is important, because the changes in Antarctic precipitation regulates the ice sheet's contribution to sea level rise. In this work, we compare two series of climate model simulations, one with a ozone hole prescribed and one without, to suggest that the ozone hole leads to a substantial increase in Antarctic precipitation. This increase is driven by a shift in weather patterns that bring snowfall onto the ice sheet. The total estimated increase of precipitation on the Antarctic ice sheet is of the same order of magnitude than its current mass loss, suggesting that Antarctic mass loss during the period 1992–2005 would have been roughly twice as much without the ozone hole. Key Points: The net effect of stratospheric ozone depletion is to increase Antarctic ice sheet‐integrated precipitation, mitigating sea level riseDriven by changes in large‐scale atmospheric dynamics, the ozone‐forced change in Antarctic precipitation varies strongly regionallyThe signature of ozone depletion on Antarctic precipitation shows similarity with observed accumulation trends [ABSTRACT FROM AUTHOR]