GLACIERS UNDER EXTINCTION
In September 2020, I was in Trentino Alto Adige, near the Austrian border, to participate in a course on the dynamics of Alpine glaciers. In order for us to observe a glacier live and better understand its dynamics, which until then had only been explained in the classroom, the professors took us on an excursion to the Bella Vista glacier.
What we found was far from the ideal of an Alpine glacier stretching white between the mountains. What remained of the glacier was partially covered by a layer of dark dust and was surrounded by lunar terrain completely devoid of snow. The memory that stuck in my mind the most, however, was the sound of water flowing under the glacier like a river in flood. Once we arrived at the hut of the same name, the manager sadly told us that for decades now he had been slowly witnessing the disappearance of the glacier, of which memories remain only in photographs.
The Bella Vista Glacier tells the story of many other mountain glaciers that are retreating due to the global increase in temperatures. A paper published in 2021 in the journal Nature showed, through the study of satellite images, that glaciers, excluding those in Greenland and Antarctica, lost a total mass of 267 gigatonnes in the period 2000-2019, equal to the mass of 181,000 Cheops pyramids.
Their melting contributed to a global sea level rise of 1.4 cm, which corresponds to about 21% of the total observed rise.
Due to different environmental, geographical and climatic conditions, not all glaciers lost mass at the same rate. The North American glaciers (USA, Canada and Alaska) have thinned greatly in recent years, contributing to half of the global glacier loss due to a sharp reduction in precipitation, while the mass reduction seems to be less marked for Scandinavian and Icelandic glaciers. The famous ‘Karakoram anomaly’. so dear to climate scientists, on the other hand, is now history.
But what future awaits glaciers? A study published in January in the authoritative journal Science showed that even if the global temperature increase were limited to 1.5°C in accordance with the Paris Agreement, half of the world’s glaciers, some 140,000, would still disappear by 2100. Although these glaciers are relatively small in size (less than 1 km2), their disappearance would cause major changes in the hydrological regime on a local scale, negatively impacting communities. Scientists have pointed out that glaciers in North America, Europe and New Zealand will lose at least 60 per cent of their mass even if the temperature increase is limited to 1.5°C compared to pre-industrial times. Moreover, this melting will contribute to a global sea level rise of 11.5 cm.
These results emphasise the great sensitivity of glaciers to rising atmospheric temperatures and sound a global alarm. The gradual disappearance of glaciers will cause serious problems for mountain communities that rely on them as a summer water supply and as custodians of local biodiversity. According to the recently released UNESCO report ‘World Heritage Glaciers, Sentinels of climate change’, it is estimated that two-thirds of glaciers can be saved if global temperatures do not exceed the global increase of 1.5°C.
There is still hope for glaciers and the communities that depend on them, but a global effort is needed to preserve these unique environments before it may be too late.
Article by Ilaria Crotti, Italian Climate Network Volunteer