A new study in which a researcher from the University of Fribourg took part has just made a startling announcement. Between 2000 and 2023, Earth’s glaciers (excepting the polar ice caps) have lost around 5% of their volume. Regional differences are stark with losses of up to 39% in Central Europe, as opposed to 2% in Greenland and Antarctica. And one fact stands out, the process shows a very clear acceleration from 2012 to 2023 with respect to the period of 2000 to 2011 (+36%).

Glaciers offer a particularly striking illustration of human-driven climate change. The accelerating rate of their melting also poses a danger to society since it increases natural risks and threatens fresh water resources. By monitoring this change as closely as possible, we can better assess the risks and take those measures that are clearly needed.

Monitoring glacier mass, however, is complicated for two fundamental reasons. First, because of their number and accessibility, less that 1% of the world’s approximately 200,000 glaciers have been measured onsite. Secondly, scientists around the world have used different ways of calculating their measurements. They have collected data then that are hard to compare. To course-correct these drawbacks, the scientific community has launched GlaMBIE (Glacier Mass Balance Intercomparison Exercise). “It’s a collective effort that aims to homogenize the results of years of observation at the local level,” explained Enrico Mattea, a researcher in the University of Fribourg’s Department of Geosciences. “We took the strengths and weaknesses of each of the methods and did the necessary adjustments to make the data comparable. This project will enable us to provide a more reliable assessment of the loss of glacier mass at the global level.”

Widespread melting on a massive scale
The now standardized way of calculating generally confirms the results of the latest reports by the Intergovernmental Panel on Climate Change (IPCC). The Panel’s main conclusions are as follows.

Between 2000 and 2023, glaciers worldwide lost about 6,542 gigatons of ice, contributing to an 18 mm rise in sea level. Most remarkably, the loss rate of glacier mass jumped 36% between the periods 2000-2011 and 2012-2023. “It comes as no surprise that the last five years have seen a significant acceleration of the melting, with a record 548 gigatons of mass loss in 2023,” Mattea pointed out.

Important regional variations
This loss of mass affects all regions studied by the scientists but varies significantly from one region to another.

The regions most affected are Alaska (-22%), the Canadian Arctic (-20%), Greenland’s peripheral glaciers (-13%) and the Southern Andes (-10%). The regions that have a small glacial area (≤15,000 km²) suffered the greatest relative losses, in particular Central Europe (-39%), the Caucasus (-35%) and New Zealand (-29%).

Meanwhile, the regions with a large glacial area (>15,000 km²) lost between 2% and 12% of their ice.

“Overall, our calculations show that mass loss is up to twice as large on glaciers than on the ice sheets of Greenland and the Antarctic,” Mattea stressed.

Special cases
Scientists note nonetheless that mass loss decreased in Iceland and Scandinavia, a phenomenon they attribute to “regional cooling and an increase in winter precipitation.” Mattea sounded a note of caution, however, “That said, we have also noted an acceleration of mass loss in regions where the glaciers were still advancing a few years ago, a phenomenon called ‘the Karakoram-Kunlun anomaly,’ moreover. So this glaciological quirk seems destined to disappear.” The University of Fribourg scientist was able to observe the loss with his own eyes, having made the trip there several times, “This exceptional melting over the last five years was particularly striking to me because we have noticed the almost total disappearance of snow cover on the glaciers. We are witnessing a real change ushering in a new age, a historic acceleration of the retreat of the Earth’s glaciers.”

Perspectives
Given the inertia of glaciers, which only react to climate changes after a certain delay, scientists expect the loss of glacier mass to continue in the coming decades. “It will only be in the second half of the century that we will see the effects of emission reductions, if society indeed manages to reduce them,” Enrico Mattea concluded.

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The GlaMBIE project has made use of the work of 35 separate research teams that has been going on since the early 2000s. That work involves 19 regions around the world and the resulting data, collected according to several methods of observation (onsite glaciological measurements, satellite imagery, etc.). The authors of the study combined a total of 233 estimates of changes in glacier mass to create a time series running from 2000 to 2023. Their results will serve as a baseline for future impact studies and modeling. Enrico Mattea provided part of the estimates of glacier mass changes, mainly for those in Iceland, using optical imagery data gathered by the French SPOT 5 satellite.

The study titled Community estimate of global glacier mass changes from 2000 to 2023 is published in the journal Nature. https://doi.org/10.1038/s41586-024-08545-z