Unprecedented loss of surface and cave ice in SE Europe related to record summer rains in 2019

Abstract. Glaciers worldwide are shrinking at an accelerated rate as the climate changes in response to anthropogenic influence. While increasing air temperature is the main factor behind glacier mass loss, changing atmospheric circulation patterns and the distribution of precipitation also plays a role, though these are not as well understood. Furthermore, while the mass balance of surface glaciers (from large polar ice sheets to small alpine glaciers) is relatively well documented and continuously monitored, little to nothing is known about the response of cave glaciers (perennial ice accumulations in rock-hosted caves) to atmospheric warming. In this context, we present the response of cave and surface glaciers in SE Europe to synoptic conditions in summer 2019. Our investigation shows that extreme precipitation events occurring between May and July 2019 led to catastrophic loss of ice at levels unprecedented during the last century. As climate models predict that such extreme precipitation events are set to increase in frequency and intensity, the presence of cave glaciers in SE Europe and the paleoclimatic information they host may be lost in the near future. Moreover, the same projected continuous warming and increase in precipitation extremes could pose an additional threat to the Alpine glaciers in southern Europe, resulting in faster than predicted melting.