Perspective: Sweltering Heatwaves Paint Grim Outlook for Many Glaciers Globally

News Briefing, 25 August 2023

Soaring temperatures have visibly impacted many mountain glaciers across the planet in past months, as recent heatwaves shrink snowpack, deplete water resources and create unstable ground at risk of sudden collapse. Last week, Swiss weather service scientists reported that they had to climb to a record altitude of almost 5,300 meters to reach the zero degree “freezing point” – the height at which temperature gauges read 0°C. Typically, the freezing point remains within these surrounding mountains; now, it is nearly 500 meters above the highest peak. These freezing point measurements are the highest in the last 70 years in the Swiss Alps, and prevents snow and ice from forming on the mountain slopes below, exposing glaciers to intense heat. Experts predict that the heat will drive similarly staggering ice losses as last year, when 6% of all glacier ice in the Swiss Alps melted in a single summer. By way of comparison, up until now, years with 2% ice loss were considered “extreme;” some scientists have even bid farewell to the hardest-hit glaciers, where there is too little ice remaining to monitor anymore. Just a year ago, temperatures of up to 10°C on the summit of Italy’s Marmolada Glacier in the Dolomites triggered a meltwater-driven collapse of part of the glacier. The detachment released 64,000 tones of water, ice and rock debris that tragically killed 11 people on a nearby hiking trail; such mountain hazards will only increase with continued warming.

The impact of heatwaves on mountain glaciers has not been confined to Europe. Earlier in August, a winter heatwave drove temperatures to above 37°C in the Chilean Andes – unprecedented for the middle of winter. The impact of these record high temperatures on both snowpack and mountain glaciers in this region will be felt later this year during the southern hemisphere’s spring and summer, when lower stockpiles of snowpack will decrease vital water supplies for downstream communities. The cascading impacts of such warm temperatures at high altitudes pose a grave risk to those who depend on stable mountain environments.

Source: Various press reports; compiled in the Italian Alps by Dr. James Kirkham, Ambition on Melting Ice (AMI) Chief Science Advisor and Coordinator, ICCI