Half of the glaciers in the Alps will have disappeared within 20 years

BarcelonaThe loss of glaciers worldwide is usually calculated in terms of square kilometers or ice volume. But each individual glacier, however small, is unique. "It might be a historical and cultural site, a tourist attraction, or a symbol of regional identity. Its loss might not impact sea levels or water resources, but it can have a very significant local impact," says researcher Lander Van Tricht of the Swiss Federal Institute of Technology (ETH Zurich). Some studies suggest that We have already lost 10% of the world's glaciers due to the climate crisisNow Van Tricht is leading a study, published this Monday in the journal Nature Climate Change, which predicts the number of glaciers that will be lost this century based on various degrees of global warming.

In the best-case scenario, of the more than 200,000 glaciers that exist in the world today, only half (around 100,000) will survive by the end of the century. This assumes we manage to keep global warming below 1.5°C, as called for in the Paris Agreement. However, in the worst-case scenario, if the global temperature rises by 4°C by the end of the century, only 10% of the glaciers will survive. This could happen if the world's governments follow Donald Trump's example and renege on their climate commitments. But right now, the UN's forecast, based on governments' emissions reduction commitments, is [not specified in the original text].The world will warm by 2.7°C by the end of the century.Thus, in this scenario, the study predicts that only 20% of current glaciers will survive; that is, 80% will disappear, leaving only 40,000 glaciers in the world by 2100. One of the regions that will suffer the most is the European Alps, where "more than 50% of the glaciers will disappear in the next two decades." This is because in the Alps, most glaciers are "small and responsive" to environmental changes, as is the case in the Caucasus, the subtropical Andes, and northern Asia, regions where the study makes the same projection. In fact, even in the most optimistic scenario, the study predicts that more than 80% of the Alpine glaciers will disappear by the end of the century (in the most pessimistic scenario, the percentage would be 99%). The most plausible scenario currently, with a 2.7°C increase, would mean "that 110 glaciers will remain in the Alps by the end of the century," but if climate policies are abandoned and global warming reaches 4°C, "only 20 will remain," Van Tricht explained at a press conference.

The peak of extinction, in the middle of the century

The report predicts that glacier extinction will peak around mid-century and then begin to decline, because the smaller glaciers will disappear first, and once only the larger ones remain, the rate of extinction will slow, Van Tricht explained. The precise timing of the peak and the number of glaciers lost depend on each scenario: if we manage to keep global warming below 1.5°C, the peak would be around 2,000 glaciers lost annually by 2041. If temperatures rise to 4°C by 2050, the number would exceed 4,000 glaciers lost annually. "This level is equivalent to losing all the glaciers in the European Alps in just one year and represents a rate three to five times greater than the current rate, in which it is estimated that between 750 and 800 glaciers are lost annually," the study states. A glacier is considered "extinct" when its area has fallen below 10 meters or its volume represents less than 1% of its initial value. "We simulated the evolution of each individual glacier using three global models and determined the point at which each one would be too small to be considered a glacier," the researcher explained. In regions with small glaciers, like those mentioned earlier, the peak of extinction would also arrive sooner. In contrast, areas like Greenland, Antarctica, and the Russian Arctic, where the largest glaciers are located, would reach their peak of extinction later. In fact, in terms of the number of glaciers, the regions that will retain the most by the end of the century will be the Russian Arctic, which would lose 40%; the Canadian Arctic, which would slightly exceed 40% extinction; and Antarctica, which would also lose slightly more than 40%. But these areas contain very large glaciers, so even if they lose fewer individual glaciers than other regions, the total mass of ice lost will still be very considerable.