Even Between 1.0°C and 2°C, Every Half Degree Matters for the Alps

The Cryosphere, June 15

This study used the new climate models prepared for IPCC AR6 to compare Alps glacier ice loss at 1°C, 1.5°C and 2°C of warming above pre-industrial, and found stark differences with each half a degree increase. By 2100, at 2°C glaciers in the European Alps are projected to lose more than 80% of their 2020 volume, versus about 44% were we to maintain today’s 1°C, and 68% loss at 1.5°C. Looking at long-term glacier evolution, emissions scenarios that subsequently hold global temperatures below 2°C allow some glacier recovery, with gains ranging from about 8-28% of their 2020 volumes. Of significance also for water resources and rivers fed by the Alpine glaciers, annual run-off by 2100 will decrease by 25% at 1.0°C and 35% at 2.0°C; but more significantly, will shift from a current peak in August (when need for water may be greatest, especially in a warming climate), to June; with August run-off decreasing by 55% at 2.0°C. This effect arises because warming is greater than the global mean at higher altitudes, as well as higher latitudes; so that 2°C of warming globally results in over 2.5°C in the European Alpine region.

As the authors note in conclusion, “For glacierised catchments and the areas downstream, these changes in water availability can be expected to have important consequences, ranging from the functioning of ecosystems to the generation of hydroelectricity.” ICCI Note: It is hoped this approach, using AR6-based modeling and projections out to 2300, may be used to project similar changes in other important mid-latitude glacier and snow regions for water resource needs such as the Himalayas; potentially by COP-26.

https://tc.copernicus.org/articles/15/2593/2021/