Marmolada, The fragile system of glaciers

The Marmolada tragedy on Sunday, July 3, brought climate change back to the center of public debate. The anomalous heat of recent months, in fact, played a key role in the collapse of a portion of the Marmolada glacier that, although in retreat, did not show any particular criticality or signs that could have been alarming. Climatologist Roberto Barbiero’s analysis.

By Roberto Barbiero, physicist and climatologist. Coordinator of the Trentino Forum on Climate Change.

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Eleven victims and seven injured hospitalized in various hospitals: this is the dramatic balance of the tragedy that on the hot Sunday of July 3 struck some roped teams of climbers hit by the sudden flow of mud and ice caused by the collapse of a portion of the Marmolada glacier on the Trentino side. It was one of the most serious accidents observed in the Alps and the exact dynamics will be defined only after the necessary technical evaluations, but undoubtedly the anomalous heat played a key role, putting the issue of global warming and climate change firmly back in the spotlight.

Phenomena of detachment of glacier portions are known in the Alps and there are some glaciers, for example in Valle d’Aosta and Switzerland, that are constantly monitored because they are at greater risk of collapse due to their particular size and slope as well as because they are located in exposed areas due to the presence of population centers and infrastructure.

The Marmolada glacier, although in retreat, nevertheless did not show any particular criticality or signs that could have raised alarm, and it is the consensus opinion among experts that this was therefore an event that could not have been foreseen on this scale.

The truly abnormal heat probably resulted in the formation of a huge amount of water that seeped into the crevasses, promoting a lubricating effect and then creating pressure on the bottom of the glacier that resulted in its disconnection from the rock, and when the ice’s ability to resist was then exceeded, the collapse occurred, which unfortunately happened at a time when hikers were busy transiting the glacier.

The situation of the glaciers has been severely tested in recent months after a long period of above-average temperatures and low precipitation. In fact, both winter and spring turned out to be warmer than average, with May among the hottest ever observed, leading up to June that also turned out to be particularly warm and with temperatures in Trentino above the average for the 30-year period 1991-2020 by as much as 2.0°C (“June 2022 Weather Analysis,” by Meteotrentino)

The day of Sunday, July 3, turned out to be the hottest of this long period of temperature anomalies, touching, for example, a temperature of 36.8°C at the Trento Roncafort station in Val d’Adige, while at Sas del Mul (Marmolada) at an altitude of 2606 m, as many as 16.8°C of maximum temperature was measured.

Due to the lack of winter and spring precipitation and the above-average temperatures that marked the two seasons, at the end of the snowfall accumulation season (end of May) the monitored Trentino glaciers (Marmolada, La Mare, and Careser) had rather poor snowfall, already severely affected by melt, a situation generalizable to all Trentino and Alpine glaciers (“Campaign of accumulation measurements on Trentino glaciers, report 2022,” by Meteotrentino).

At least one month in advance, the uncovering of some glacial fronts, such as that of Marmolada Glacier with anomalies ranging from -40% to -50% compared to normal conditions, is noted in late May.

The anomalous warmth in June and early July, therefore, favored the continuous and progressive melting of glaciers. The Marmolada event has highlighted the fragility of the mountains and brought the issue of climate change back into focus since the regression of the Alpine glacier cover is probably the most pronounced sign of the impacts of ongoing warming.

Alpine glaciers have shrunk by an average of half since their most recent peak, which occurred in the Little Ice Age (PEG, mid-1800s). South of the Alps, however, the loss has been greater. For example, the total extent of glaciers in Trentino in 2015 was around 32 km2, corresponding to 28 percent of the approximately 123 km2 estimated in the mid-1800s (“State of the Environment 2020 Report,” APPA on Meteotrentino data).

The rate of reduction is accelerating, and to date, it is estimated that the area of glaciers has shrunk to about a quarter of the last maximum expansion reached. The elevation of the glacier front, on average located in the PEG maximum around 2,550 m elevation, has risen to about 2,800 m, exceeding 3100 m elevation for glaciers facing southeastern Trentino.

This intense retreat process has resulted in the fragmentation of glaciers, which have increased in number, becoming smaller and, therefore, more prone to melting. These impressive ablation processes (loss of snow and ice to water equivalent) manifested in recent decades are also confirmed by measurements of glacier frontal changes and their mass balances. For example, the historical series of mass balances performed for Careser Glacier from 1967 to the present, shows its continuous regression despite some partial slowdowns due to winters with exceptional precipitation (e.g., 2013-2014 season, 2020-2021).

Alpine glacier retreat could reach record levels by the end of the 2022 summer season if the expected scenarios of seasonal forecasts for the July, August and September quarter are confirmed, which could still be characterized by above-average temperatures and below-average precipitation.

The state of glaciers is in any case likely to worsen in the future. The increase in temperatures expected in the coming years and the lower snow supply, especially at mid-low altitudes, unfortunately suggests that glaciers will continue to melt. According to a study by EURAC by 2050, glaciers in the area could retreat above 3,000 m (Climate Report – South Tyrol 2018).

The gradual disappearance of glaciers forces a number of problems that could be exacerbated in the future: the availability of water for different uses, drinking, hydropower, and agriculture; the loss of ecosystems; and landscape change that will impose new ways of accessing the mountains.

There is a need to act quickly first on mitigation policies to reduce the causes of climate change and thus eliminate the production of climate-altering gases from fossil fuel use in particular.

This may slow down the ongoing warming but not eliminate its impacts since there is now so much delay in taking the necessary measures. The impacts of climate change are therefore inevitable and make it imperative to take appropriate adaptation measures to limit the damage to ecosystems and humans.

Delayed action will cost increasingly expensive if Alpine regions do not find appropriate and urgent ways to cooperate to address climate change adaptation with synergistic and  across-the-board measures