Figure 2.6.1: Spatial distribution of annual runoff trends a) Annual mean flow, and b) Summer low flow A B
Source: Stahl et al. 2012
substantial losses in glacier mass (27 per cent) and area (18 per cent) during the last 50 years (Farinotti et al. 2015). Future warming will further reduce the extent and area of pan- European glaciers, which in turn will result in major changes in the timing and magnitude of the runoff regime.
Water scarcity – when the exploitation of water resources is approaching or has exceeded sustainable limits – can be defined by the water exploitation index (WEI+), characterized by the withdrawals-to-water availability ratio. If more than 20 per cent of the renewable freshwater resources are used for agricultural, industrial and domestic purposes (WEI+ > 20 per cent), a water resource is under stress, while WEI+ > 40 per cent indicates severe stress and clearly unsustainable resource use (Raskin et al. 1997). In the southern EU-28, Turkey and southern Central Asia, high water demands related to agriculture and human populations are exacerbated by the limited natural availability of water, along with climate variability. Climate change is expected to intensify problems of water scarcity
and irrigation shortfall in the Mediterranean region (Jiménez Cisneros et al. 2014).
Cracks in river bottom in a water basin in Spain. Climate change
will lead to an increased frequency of droughts Credit: Shutterstock/Geir Stene-Larsen