Although summer 2021 was extremely hot in the South East Alps with a value that ranks ninth among the hottest summers of the last 170 years, the huge snow accumulation of last winter allows few glacial remnants to end the 2021 summer ablation period with a surplus of residual snow. The rest of the Alps faced another bad year for the glaciers, keep shrinking everywhere. Few exceptions at special locations like small glaciers fed by avalanches, as well as high altitude accumulation basins are in a decent shape.
GLACIOLOGICAL SURVEYS 2021 IN THE ALPS
The first snowfalls of the season have already whitened the highest peaks of the Alps and winter is approaching. It is therefore time to have a look at some of the first reports of the glaciological year 2020-2021. The end-of-the-year surveys on alpine glaciers have in fact ended in the last recent weeks.
Most of the reports from the four corners of the Alps are negative. Nevertheless, there are few exceptions enclosed in a small alpine area, the Julian Alps. Here, a lot of residual snow from the last winter is still in place and did not melt. But summer 2021 was the ninth warmest summer on record over 170 years.
Above, temperature anomaly in summer 2021 (June, July and August) from Climate Change Service Copernicus
The image below shows the trend of summer temperatures (June-August) from 1851 to 2021 at the Mount Canin weather station (2203 m asl) in the southeastern Alps. In summer 2021, the average temperature was 9.4°C. This means the anomaly was + 2.1°C with respect to the normal climatology of 1961-1990.
When looking at the 1981-2000 climatology, the anomaly equals to + 1.1°C. If we look instead at the more recent 1991-2020 climatology the anomaly reduces to + 0.5°C. On the other hand, summer 2021 was 0.1°C cooler than the average of the last 10 years’ summers 2010-2020.
It is worth noticing how the 2021 summer temperature would have been exceptionally hot before the 1990s. Looking at the long-term trend, the mean summer temperature already raised by about 2.5°C from the 1980s to the present day. In fact, the Alps are recognized as a climatic hot spot. This means if the climate warms up or cools down, the Alps do it at a double rate.
September is probably the most important month for glaciologists of the Earth’s northern hemisphere. In a few weeks, they have to collect data of the closing hydrological year performing glacier mass balance measurements. In the video below, a team of glaciologists in the Julian Alps working on residual snow/ice patches.
In the image below, you can see an ice patch of the eastern Alps, the East Ice Patch of Canin (left in the photo). The picture dates back to September 28, 2021. In the center of the image and on the right, other residual ice patches appear completely covered by residual snow from the previous winter.
In particular, glaciologists reported how a thin snow tongue was still linking the two sectors at the end of summer 2021. The connection of all sectors had not occurred since summer 2014. In the image below (right), for comparison, we insert an image of the same place on October 28, 2014.
Although the angle and the point of view are not the same (pictures are taken from the helicopter), the 2014-2021 differences in the residual snowpack on the ground as well as the snow tongue linking the two sectors are evident.
The image below from a different point of view gives evidence of the residual snow accumulation at the end of the ablation season in 2014, 2019, and 2021. It is quite impressive the increase of snow above the ice body from 2019 to 2021, as well as differences between 2014 and 2021.
Glaciologists annually investigate Glacier’s health through iterated surface mass balance measurements. Mass balance of a glacier is the difference between the snow accumulated in the previous winter and the ice and snow melted through the ablation season.
If summer melting overcomes what was gained from the previous winter, this means the glacier mass balance is negative and the glacier recedes. On the contrary, when the mass of snow accumulated on glaciers exceeds the mass of ice and snow lost during the summer the glacier is therefore in a “healthy” state.
In this case, mass balance is positive and the glacier expands in size and volume advancing. Glaciers losing and gaining the same amount of ice and snow are though in equilibrium, still “healthy”, and will neither recede nor advance. Such mass differences are generally given in meters of water equivalent (w.e.).
Therefore, although the summer snowmelt was very high due to exceptionally high summer temperatures as we saw above, the huge snow accumulation that occurred in winter 2020-2021 allows a positive mass balance over such small ice bodies.
In the image below, we show data of daily snow depth on the ground measured in the Julian Alps at the Livinal Lunc (1837 m asl) station in Canin-Kanin and at Kredarica (2514 m asl), Mount Triglav (2864 m asl) in Slovenia. Both weather stations are located in the Julian Alps. We also respectively report the measurements and the date of the maximum thicknesses reached during the winter of 2020-2021.
This apparently disconcerting result in a global warming era has actually already been explained recently. Small ice bodies in the Julian Alps remained stable in the last 15 years instead of rapidly disappearing, as they should be, due to their smaller size. This happened although summer temperature continued to rise here.
According to a recent study, few ice patches rather grew in size with a long-term positive mass balance.
In particular, the residual ice body of the eastern Canin glacier gained 3.53 m of thickness in the period 2006-2018 (see figure below). Converting this value with the density of the mixture of frozen material made by snow, firn, and ice (791 kg per cubic meters), accounts for 2.79 m of water equivalent.
IT IS INDEED WARMER
Is it indeed much warmer lately and compared to the past, today more snow and ice melt. Applying a degree-day model for this alpine sector, glaciologists found how the potential melting increased about 29 mm w.e. per year. From roughly 4119 mm w.e. in the late 1970s, in the late 2010s was equal to 5279 mm w.e. per year.
You can clearly see this in the figure below where, on the right, we plotted the length in days of the ablation period. From the late 1970s up to now the melting period increased by roughly two weeks. Recent positive mass balance cannot thus be attributed to favorable temperature.
Instead, the recent increase in winter precipitation and few seasonal winter extremes brought much higher than average snowfalls over residual ice bodies of the Julian Alps. From 2006 to 2018 this excess in precipitation led to ice bodies stability and overall a positive mass balance. New bare ice outcropped over the surface of several ice patches.
This proves a long-term trend of ice accretion in this small, but peculiar alpine area between Italy and Slovenia. Such results have been recently published in a scientific paper and attributed to higher sea surface temperature in the Mediterranean, modification of Rossby Waves, and influence of Quasi-Resonant Amplification.
THE 2021 GLACIOLOGICAL SEASON IN THE ALPS
Anyway, what is stated above is indeed an exception in the Alps. The Cryosphere is declining at an accelerated rate almost everywhere. Today glaciers lose annually just about 31% more ice and snow than they did 15 years ago.
The European Alps represent one of the world’s areas with the largest glacier loss. This is mainly due to longer and warmer summers, which trigger increased melting. Between 1850 and 1975, glaciers in the European Alps lost about half of their volume. Another 25% of the remaining amount melted between 1975 and 2000 and 10-15% more in the first 5 years of the century.
The longest alpine valley glacier is the Great Aletsch glacier. This glacier is around 80 square kilometers in size, up to 800 meters thick, and over 20 kilometers long. It contains over a fifth of the total ice volume in the Swiss Alps. After slowly retreating since 1870, it lost 32% of its mass and retreated by about 8.5 kilometers in the last 30 years.
GLACIERS IN SWITZERLAND
According to the Cryospheric Commission of the Swiss Academy of Sciences, the volume of Swiss glaciers decreased by almost one percent in 2021, although the snow was abundant in winter and spring was cooler than normal.
The snowfalls were particularly heavier than usual in May. On the Claridenfirn mountain at 2,890 meters, where the longest uninterrupted records of glacier mass balance worldwide exists, seven meters of snow fell.
This represents the greater snow accumulation in one winter season since observations began in 1914.
Indeed the conditions were right in 2021 to give the glaciers a well-deserved breather. In fact, the losses were smaller than in recent years. Anyway, no gains were recorded for any of the monitored glaciers even with such a huge amount of winter snow.
Melting was above all significant during the months of June and September. In the image above, the global and European temperature anomaly in September. More, despite considerable precipitation in summer, there was hardly any fresh snow in the Alps.
While considerable snow reserves were detected on large glaciers above about 3,200 meters in fall, lower-lying ice bodies were completely depleted again without any sign of reversal. Even though 2021 shows the lowest ice loss since 2013, there is no turnaround in sight for glacial reduction.
In Switzerland, roughly 400 million tons of ice were lost over the last 12 months. This accounts for almost one percent of the remaining glacier volume.
The image above shows Konkordiaplatz on the Great Aletsch Glacier on 2 October 2021. Here the melting was indeed impressive during the last summer. Not only did all the winter snowmelt, but an ice layer of 2-3 meters was lost too.
Nevertheless, as in the case of the Julian Alps in Italy and Slovenia, also Swiss glaciologist Matthias Huss says there may be a few exceptions at special locations like small glaciers with a lot of avalanche snow.
Glaciers in the northern Valais (southwest Switzerland) came closest to equilibrium, he also said. Glaciers in southern Valais, in Ticino, and in the east, however, suffered almost the same losses as the average of the last ten years.
GLACIERS IN AUSTRIA
The Austrian Central Institute for Meteorology and Geodynamics (ZAMG) ranks summer 2021 in the HISTALP report as the tenth warmest summer in the mountains of Austria. Summer started with a rather cool spring and quite good snow conditions, and the glaciers were hidden from the sun under the snow cover for a relatively long time.
On the eastern main ridge of the Alps, more winter snow was able to resist over the summer than in recent years. Therefore, less ice generally melted than in recent years. Nevertheless, large glaciers as Silvretta and the Hohe Dachstein lost almost the entire winter snow cover, says Andrea Fischer and Hans Wiesenegger Leiter in their Gletschertagebuch (glacier diary)
Above, the Stubacher Sonnblickkees with Filleckboden glacier on 21 August 2021
On the Hallstatt Glacier, the snowfall in May still ensured abundant snow thickness, but the white cover melted rapidly in June. Kay Helfricht and Klaus Reingruber observed the evacuation of almost the entire glacier until mid-August, and only very small snow reserves remained.
Snowfall at the end of August and in September indeed reduced the ablation but was unable to form a significant snow cover by the end of the hydrological year. Therefore, the year 2021 results as one of the most negative since measurements began in 2006 for these glaciers. In Austria, the year 2021 will be included in the long-term series of measurements as another year with a widespread loss of mass.
Above, The dark surface of Jamtalferner in the Silvretta, still exposed to the rain on October 4th without any snow, represents a landscape that we have to get used to seeing in the Alps.
GLACIERS IN ITALY
Historically, the Italian glaciological committee investigates glaciers’ health in the Italian side of the Alps. If on the central and eastern alpine chain winter precipitation were definitely abundant compared to the long-term climatology, the western Alps experienced a dry winter.
The widespread sensation of a “subdued” Summer, was indeed not real. Such false belief is due only to a few cloudy and cool weeks between the end of June and the beginning of August. The summer 2021 heat instead, although not extreme but still marked and prolonged, completely melted the modest snowfall of winter 2020-21.
On September 13th, according to the Italian Meteorological Society, the entire surface of the Chardonney glacier was completely free of snow, blackened by debris, and with still very active melting.
The image above refers to the Chardonnay glacier, monitored by the Italian Meteorological Society in the western Alps. Moreover, during the summer only a modest snowfall (probably less than 5 cm) whitened the glacier in the late afternoon of 8 July 2021 (with Tmin 0.3 ° C), for the rest, the melting never stopped.
The losses, transformed into water equivalent correspond to an overall mass balance of -1.33 meters. This result is worse than that of the previous hydrological year (2019-20, -0.78 m), and on the average of the unfavorable thirty years of observations.
In terms of volume, this is a net loss of approximately 680,000 cubic meters of water in one year, the equivalent of approximately 270 Olympic swimming pools.
The image above refers to the complete record of the annual mass balance of the Chardonnay glacier, monitored by the Italian Meteorological Society in the western Alps. Only in the 2000-01 season, thanks to a very snowy winter and a cool summer, a slightly positive balance was observed (+0.16 m).
Also in the Dolomites results are similar. Despite a year among the snowiest of the last thirty years, the Marmolada glacier continues its unstoppable retreat. Measurements carried out in September on 9 frontal signals, recorded an average retreat of over 6 meters compared to the last year, says Mauro Varotto, head of the surveys for the Italian Glaciological Committee.
Similar words are used by the Lombardy Glaciological Service. The 2021 ablation season confirmed the irreversible trend observed in the last 30 years. The good accumulation season 2020-21 helped only glaciers at the highest altitudes, where the snow was preserved locally above 3,300 meters. As in Switzerland, only at special locations like small glaciers or glacierets fed by avalanches, winter snow was still present at the end of the summer.
See here a time lapse evolution of the Fellaria glacier from summer 2019 to summer 2021.
The video above from the international project B-ICE and Heritage shows the reduction of the iconic Fellaria glacier in the Central Alps over the last three summers 2019-2021.
Two-thirds of the ice in the glaciers of the Alps will melt by the end of the century as climate change forces temperatures to rise. Half of the ice in the mountain chain (4,000 glaciers) will be gone by 2050 due to global warming. And this will happen even if global warming will stop today, just because the glaciers are far from their equilibrium with the present climate.
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