Global warming: much less snow in the mountains - IMPORTANT: To stop your posts to be hidden by the flag trollers, just post on https://busy.org/

mybestnews (2)in #global • 6 years ago

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Global warming: much less snow in the mountains

Snow gun operating in a ski resort Christophe Magdelaine

The snow cover of the mountain massifs is very sensitive to climatic variations. With global warming underway, research in recent decades has projected a massive reduction in the amount of natural snow expected over the mountain ranges in the 21st century. A new study conducted by the National Center for Meteorological Research (CNRM, Météo-France / CNRS associated with the University of Toulouse and Grenoble Alpes University concerning the Center for Snow Studies) and the ETNA team of the Irstea in Grenoble used the most recent climate projections and advanced statistical methods for adjusting these projections in mountain areas.

Snow cover plays an important role for mountain ecosystems and human communities (water resources, natural hazards , tourism, etc.). However, the mountain snowpack reacts in multiple ways to the effects of climate change . Small variations in temperature are enough to significantly disturb the distribution of precipitation between rain and snow during the winter, especially in the middle mountains. Higher temperatures are generally associated with an early melting of the snowpack.

The nivometeorological observatory of the Porte pass (1325 m, Chartreuse massif) has made it possible to measure the extent of this phenomenon since the beginning of the 1960s, and is thus one of the witnesses of the National Observatory on the Effects of Global Warming. Climate Change ( ONERC ).
Thus, at Porte pass, the average snow depth in winter for the period 1990-2017 is on average 39 cm lower than for the period 1960-1990, a decrease of about 40% . The air temperature in winter has increased by almost one degree over the same period.

Several studies carried out in France as in other countries since the 1990s have shown that climate change underway and projected in the 21st century was accompanied by a significant reduction in average snow cover , especially at medium altitude. These projections are regularly updated according to progress in climate modeling and mountain snow.

The research published on April 10 in the scientific journal The Cryosphere builds on the latest generation global climate projections (CMIP5) that have fed a set of regional climate models under the EUROCORDEX program. The large mass of data generated for these simulations makes it possible to estimate more robustly than previously the snow trends in the 21st century and their uncertainties for the Chartreuse massif at 1500m altitude, taken as an example in this study. .

The results confirm the downward trend in snow cover for all greenhouse gas concentration scenarios in the 21st century, with a distinction between the scenarios from the middle of the 21st century. The projections also indicate a maintenance of the interannual variability of the snow conditions. However, snow-covered winters will be more and more rare and winters with little snow become more and more frequent .

For the first time, the study also focused on quantifying the links between global warming and local effects (for example, for a mountain range). It shows that local variations in snow cover are proportional to the increase in temperature since pre-industrial times.

For a warming of 1.5 ° C since that time, the decrease in average snow depth over the 1986-2005 reference period is 24% ± 12% and the duration of the snow season is reduced by 23%. ± 8 days.
For a warming of 2 ° C, the reductions in thickness and season duration reach respectively 32% ± 10% and 34 ± 6 days.

For these indicators, compared to a common reference period, 1 ° C of global warming results in a reduction of the average snow depth of 25% and decreases the snow season by almost a month .

The method is being applied to other French mountain ranges (Alps and Pyrenees), and can be extended to other areas of application, such as the future evolution of the risk of avalanches, that of alpine glaciers, ecosystems and, by taking into account snow management methods, winter sports resorts.

Source: Source: https://www.notre-planete.info/
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