The Fate of Alpine Glaciers

In the previous post, Climate Change Case Study: Austria, we examined recent trends in snow measures and potential impacts of future warming on skiing in the eastern Alps.  Declines in snow and snowcover are evident in the recent past and expected to continue in the next few decades in low- and mid-elevation areas.  High-elevation resorts in Tyrol, where resorts more commonly extend above 2000 meters, are the most "climate resilient" but will still feel the effects of climate change.  Ski area viability declines with ongoing greenhouse gas emissions and future warming.  One estimate suggest that with 2°C of warming relative to 1961–1990, only 64% of Austrian ski areas will be snow reliable.  With 4°C of warming, this number drops to 16%.  

In this post we look at the fate of glaciers in the Alps.  Glaciers are large masses of land-based, perennial ice, and they exist at upper-elevations throughout the Alps.  The map below shows the Alpine glacier coverage circa 2010.  Small glaciers are found from the far western to far eastern Alps, with the greatest concentration of large (5–100 square km) glaciers in the highest Alpine terrain from roughly Mt. Blanc to Zermatt (between about 6.75°E and 8°E).

Source: Huss (2012)

Large glaciers exist elsewhere in the Alps, however, including the Swiss Jungfrau (southeast of Bern), where the Aletsch Glacier glacier, the largest and longest in the Alps is found, the Ötztal and Stubai Alps of Austria's Tyrol, the Ortler and Rhaetian Alps of Italy southwest of Bolzano, and the Hohe Tauern in eastern Austria (between 12°E and 13°E).  

Monte Rosa and the Gorner Glacier above Zermatt

Glaciers in the Alps have been losing mass and retreating in recent decades.  This reflects what is happening across the globe.  The graph below shows the cumulative mass change in mass balance for reference (i.e., well-monitored over decades) glaciers (in cumulative meters of water equivalent) illustrating the downward trend.  Central Europe (blue) includes trends from Austrian (6), Swiss (5), French (3), Italian (2), and Spanish (1, Pyrenees) glaciers. 

It is not unusual for people to argue that these trends in the Alps are due to emergence from the Little Ice Age However, since 1990, a majority of the glacier loss, which is accelerating, is due to human-caused climate change. 

A sad reality for Alpine glaciers is that if we could stop global warming right now, they would probably still lose a substantial amount of volume.  Zekollari et al. (2019), estimated that if the 1988–2017 climate predominated through the 21st century, almost 40% of the glacier mass in the Alps would be lost.  They referred to this as committed loss.  

Source: Zekollari et al. (2019), with annotations added.

This is because the Alpine glaciers are currently out of equilibrium with the rapid warming that has occurred in recent decades.  Given time, even in a stationary climate, they will continue to retreat and shrink.  Not surprisingly, mass losses increase with emissions and warming.  In moderate and high emissions scenarios in which global temperatures increase by 2–4°C, more than 70% of the glacier mass of the Alps is gone.  In the csae of the latter, the only glacier remnants remaining in the Alps are in the high terrain from Mt. Blanc to Zermatt and the Swiss Jungfrau.

Source: Zekollari et al. (2019), with annotations added.

Last week, the Austrian Alpine Club released it's annual glacier survey and report.  They have been surveying glaciers in Austria for over 100 years, but this one got a lot of coverage because they warned that Austria will be largely ice free in 45 years.  In other words, perennial ice will largely be gone.  This is generally consistent with my scientific understanding, although I hope that perhaps some high-altitude glacier remnants may survive in the Austrian Alps if we can get our act together.