We are looking at a future without glaciers, since as many as two out of three could disappear by 2100 due to climate change: this is the worst-case scenario predicted by the study led by the Carnegie Mellon University (Pittsburgh, USA) and published in the journal Science.
Research indicates that the most threatened glaciers are the smallest, those with an extension of less than 1 square kilometer, that are found in Central Europe, including the Alps, in Western Canada and inthe United States.
The new prediction model is based on an unprecedented amount of data about all the glaciers of Earth, more than 215,000, and on the different scenarios of global temperature rise. Even in the most optimistic scenario, in which the temperature increase will not exceed 1.5 degrees Celsius above pre-industrial levels, half of the glaciers will still be lost.
Glacier melting rates, note the researchers led by Dr. David Rounce, have increased steadily in recent decades, and among other things these processes will profoundly affect sea level rise and freshwater availability for billions of people. The capability to predict glacier mass loss as accurately as possible is therefore critical to understand how the environment will change and to guide future global climate adaptation and mitigation efforts.
To improve existing predictions, usually limited to small geographical areas, the researchers processed with supercomputers an unprecedented amount of data covering all the glaciers of the globe, except those of Greenland and Antarctica. The results show that glaciers will lose between 26% and 41% of their mass by the end of the century, depending on a temperature increase of between 1.5 and 4 degrees Celsius. This means that, in the best case about 50% of the glaciers will disappear, and up to 80% in the worst-case scenario. Based on current climate policy commitments, which forecast a global temperature increase of 2.7 degrees Celsius, we will likely see almost all ice disappear from entire regions. This, in turn, will result in a much greater contribution to rising seas than expected, with major impacts on water supply, tourism and local culture.
The authors of the study stress how glaciers' response to climate change takes a long time and even an immediate reduction in emissions will not remove previously emitted greenhouse gases, nor can it instantly halt all ongoing processes that contribute to climate change. This means that even a complete halt in emissions would still take between 30 and 100 years to be reflected in glacier mass loss rates, but “Although it is too late to avoid losing many glaciers, any effort to limit global mean temperature rise will have a direct effect on reducing how many glaciers will be lost.”
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