In its 2007 report, the Intergovernmental Panel on Climate Change (IPCC) identified mountain areas as particularly sensitive to climate change. In this sense, the mountains are veritable “living laboratories”, witnesses, precursors, of climate change that could affect other regions.
The Pyrenees mountain range, set between the Atlantic Ocean and the Mediterranean Sea, is particularly representative of typical mountain climate patterns. Among the southernmost ranges of Europe, the Pyrenees is subject to the radical transformations associated with climate change: melting glaciers, decreased snow cover, the retraction of plant species to higher altitudes, phenological variations in plant life, advance of harvest dates, etc.
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Climate change in the Pyrenees is a reality:
• a rise in temperature of +1.1ºC since 1900 in south-west France and throughout the Pyrenees mountain range (Météo France / ONERC, 2007);
• plant species retracted to higher altitudes at a rate of 3 metres per year in 1971-1993 and more than 64 metres for forest species (INRA, 2008);
• since 1990, harvests are earlier by about 15 days in the Banyuls area of the eastern Pyrenees (Bodega cooperativa / ARPE, 2008);
• 10-15 days less snow cover in 1971-2008 in semi-mountainous regions (Hospitalet, 1400 m) (Météo France, 2008);
• 85% reduction in Pyrenees glacier surface since 1850 (Association Moraine, 2009)
In the event that the average temperature on earth rose a minimum of 2ºC, which is very possible by the end of the century, climate change measures should be aimed at reducing greenhouse gases and adapting to the inevitable changes it would produce.
These 2 actions should be carried out jointly. One obstacle: our society does not know how to prevent and adapt to slow evolutions (IPCC).
From a broader outlook on biodiversity, and beyond climate or environmental changes, rural exodus and the evolution of farming methods in certain areas of the Pyrenees have resulted in the loss of biological, landscape, cultural, and economic diversity. These areas have consequently become even more sensitive to the effects of global change.
The population thus becomes vulnerable, especially because of the following factors:
• an aging population, located on the borders of the mountain range;
• localised developments with pollution peaks;
• residential areas that consume large amounts of energy;
• artificial ground associated with areas of dense population and tourism;
• developments in the foothills and overcrowding on the coast;
• increased traffic in highly urbanised areas;
• in general, changes associated with human activities (deforestation, artificial ground and urbanisation, etc.) make certain areas more vulnerable to natural disasters.
As of today, there is not enough information collected in a consistent manner to first, establish a climate change diagnosis for the entire Pyrenees mountain range and precisely follow trends, and second, consider adaptation strategies that should be put in place. But the key is there, for the Pyrenees, for the future of its ecosystems, and for its populations.
Climate: today and tomorrow
Outlooks on temperature trends show the Pyrenees Mountains to be among the most sensitive regions to climate change. While national temperatures rose 0.9º C in one century, temperatures in the Pyrenees have increased 1.1ºC in the same period (Météo France/ ONERC, 2007).
According to the IPCC (IPCC 2007), the average temperature on earth would increase between 1.4 and 5.8ºC in 1990-2100. According to Spain’s State Meteorological Agency (AEMET, Spain; 2008), temperatures in the Pyrenees will rise between 4.5º and 5º by 2100, especially during the winter months.
By the end of the 21st century, temperatures could rise an average of 2.7ºC (Levrault et al. 2010) , with an increased number of hot days (>20 days) and global radiation (+10W/m²/year), and a reduced number of days of autumn frost (Terray, 2010) .
Climate model predictions are much less certain for precipitation as they are for temperature. According to the IPCC scenario A1B, precipitation is expected to decrease 25 mm/year by the century’s end, with seasonal extremes marked by decreased spring and summer precipitation throughout the region, and especially in southern France (Terray et al. 2010); this decrease could vary between 30% and 40% (among the largest decreases of total annual precipitation). According to regionalisation methods of the Météo-France ARPEGE model, the decrease in precipitation will be more pronounced in south-western France after 2050 (Itier, 2010).
In terms of water planning, anticipated changes will face a dual problem: supply (precipitation, P) and demand for vegetation cover (evapotranspiration, ETo). The total annual increase of ETo is 0.5-0.6 mm per day from now until 2100. This reduction in rainfall combined with increased evapotranspiration will markedly worsen the annual climate water shortage (PETo); this problem shall become more accentuated in 2070-2100 (Levrault et al, 2010) .
A shared profile on the Pyrenees provides a first state of characteristics and key features of the mountain region (social, economic, and environmental) in the face of climate change.
For more information about the main challenges facing the mountain range and impacts observed in the Pyrenees, download the Observatory brochure.
 Brisson N. et Levrault F. (2010) – Livre vert du projet Climator, Changement climatique, agriculture et forêt en France : simulations d’impacts sur les principales espèces, ADEME, 334p.