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Box 3.1 Glaciers and snow cover are shrinking in the Alps since the 19th century

Sources: (Petita et al., 2017; Elmi et al., 2018; FOEN, 2020a, 2020b, 2020d, 2020c)

 

The Alpine region, which covers approximately 190 700 km2, extends over eight European countries (Austria, France, Germany, Italy, Liechtenstein, Monaco, Slovenia and Switzerland) and it is inhabited by more than 14 million people. The average temperature in the area has risen by almost 2 oC since the 19th century, which is twice as fast as the average rate of temperature rise in the northern hemisphere. Furthermore, future climate change projections show that the average temperature will increase further by 1-2o C in most parts of the region by 2050, which may result in significant impacts.

The extent of the glacier surface in the Alps now is less than 50 %  of what it was in the mid-19th century, and it is projected to decrease further to 30 % or even 10 %, if the temperature increases by another 1 oC and 3 oC respectively (Figure 3.3, left). Furthermore, the Swiss scientists and authorities have observed that the cumulative mass of eight Alpine glaciers shows a decreasing trend which has been accelerated in recent decades (Figure 3.3, right). This is related to the increase of the temperature, which causes larger and earlier melting within the year. And it is also related to the change of the precipitation patterns, which results in an increase of the share of the precipitation falling as rain rather than snow. In the last 50 years, the snowpack in Switzerland has shown decreasing trends across all elevation zones from below 1000 m to over 2500 m.

Figure 3.3              Remaining glacier surface in the Alps (left); annual cumulative glacier mass balance in Switzerland (right)

Source: :(Petita et al., 2017)                                                                   Source: (FOEN, 2020b)

 

The flow patterns of the rivers are impacted in various ways. For example, higher rainfall in winters causes higher winter discharges, increasing the risk of floods. Furthermore, the lower extent and mass of glaciers and snow decreases the storage of equivalent water, which could melt and recharge rivers, especially during the spring months. Higher temperatures are also causing higher evapotranspiration. Thus, summer discharges tend to become lower on average. As drought events are also occurring more frequently, especially in southern and south-eastern Alps, it is expected that climate change will cause further decrease in the observed low river discharges annually. River flow observations in the Swiss part of the Rhône (Porte-du-Scex) since the start of the 20th century show an amplification of seasonal patterns with increased discharges in winter and decreased discharges in summer.

 

The Alpine landscape constitutes a very diverse ecosystem, where 30 000 animal species and 13 000 plant species can be found. As the climate becomes warmer, those species that flourish in colder conditions need to migrate. Therefore, shrinking glaciers and snow cover limit the extent of the suitable habitats for traditional alpine species. It is projected that 30-50 % of the alpine plant species will lose over 80 % of their suitable habitats, resulting in chain effects upon the animal species also.

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