The scientific evidence on the rapid increase in global warming have become in a constant and unstoppable drip. The last, a report prepared by more than 100 experts for two years for the Pyrenean Observatory of Climate Change (OPCC). It breaks down the already visible impacts in a mountain chain of as much relevance as the Pyrenees. The glaciers are in danger of extinction, some migratory birds have advanced their arrival 10 days and other species will continue to climb meters until they have no more space, rainfall is getting smaller, the snow is in retreat and the forests are moving forward.
The Pyrenees, which the OPCC groups in a bioregion, face an increase in temperature of 1.2 degrees Celsius, 30% higher than the world average, of 0.85 degrees, since 1950. The figure replicates the growth trend that scientists have observed in other high mountain areas, more affected by the emission of greenhouse gases than other flat areas.
The observatory intends that the study serves as a basis for making decisions that they advance to some changes that are developed with more acceleration than expected. The rise in temperature, measured between 1949 and 2010, has not occurred in a regular manner, but with ups and downs. Until the eighties there was a downward trend. From that date, the scenario was reversed, and mercury began to mark rising values. The warmest year was 1997 and the coldest year 1972. To this framework is added the decrease in the annual volume of rainfall, 2.5% per decade in the last 50 years, not linear either. The days with frosts have decreased around 0.3 days per decade between 1985 and 2014.
It is more complicated to determine how the snow cover has evolved since 1950, because historical data are missing, the report says. But, from beacons installed on the southern slopes of the Pyrenees, "a significant decrease in the snow cover has been identified". With similar antecedents, the OPCC considers that for the horizon 2030, the annual increase of the maximum temperatures with respect to the period of reference 1961-1990 could be, "in average and for the whole Pyrenean area, between 1ºC and 2,7ºC". , the lack of rainfall could decrease the recharge of aquifers by 20% by the middle of the century and could lead to a reduction in the flow of many springs.
Another of the silent sufferers is the fauna. There are species of birds such as the ptarmigan, adapted to the Arctic-Alpine systems, which are seeing their physiological state and abundance altered. For example, migratory birds have advanced their arrival date, and there have been advances in the first sightings of butterflies. Among the vertebrate groups, amphibians are the most vulnerable. "Considerable population decreases have been observed among Pyrenean triton populations coinciding with the years of extreme climatic events", specify the scholars
Many species respond to climate change by moving to higher areas in search of the weather conditions that are lost in their usual spaces, although there will come a time when they are isolated increasing their vulnerability, they add. "It has been estimated that in recent years European species have moved from an average of 11 meters per decade to higher altitudes," specifies the OPCC. All this, in a scenario where forests rise: in the last 50 years the height of the forest boundary has shifted 35 meters, "a little more than half a meter per year".
Activities such as skiing are also affected, and would translate, in the case of predictions, into a reduction in winter tourism. As proof, the OPCC indicates that the start of the ski season has been delayed between 5 and 55 days in the stations that are lower and between 5 and 30 in the average. Especially dramatic is the situation of the glaciers, the southernmost in Europe. Since 1984, more than half of those counted have disappeared (there are 19), some are just snowfields and those that remain have decreased in mass and surface area. On the other hand, the softer temperatures in autumn and spring could increase visitors in summer.
In this framework, "it is highly probable" that the Pyrenees suffer an increase in extreme weather events. "The most documented evolution in this sense is that of heat waves, but it is very likely that droughts, heavy rains and cold waves also increase their frequency and intensity, but hailstorms will only increase in intensity", the scientists
The OPCC is a cross-border territorial cooperation initiative on climate change of the Pyrenees Working Community (CTP), launched in 2010 under the chairmanship of Midi-Pyrénées. The members of the CTP, and therefore of the OPCC, are the Principality of Andorra and the Governments of Nouvelle-Aquitaine, Aragón, Catalunya, Euskadi, Navarra, and Occitanie.