Climate change, impacts and vulnerability in Europe ... - MemoFin.fr

Climate impacts on environmental systemsperiod and three future time periods based on thehydrological model LISFLOOD and an ensemble of12 climate models. Blue rivers indicate an increasein flood level and red rivers a decrease. While theensemble mean presented in Map 3.8 provides thebest assessment of all model simulations together,individual simulations can show importantdifferences from the ensemble mean for individualcatchments, partly due to significant decadal-scaleinternal variability in the simulated climate (Feyenet al., 2011). A decrease in 1-in-a-century floods isprojected in large parts of north-eastern Europe dueto a reduction in snow accumulation and hence meltassociatedfloods under milder winter temperatures(Dankers and Feyen, 2009). This projection isconsistent with other studies on snow-dominatedregions, including parts of Finland (Veijalainen et al.,2010), the Alps and Carpathian Mountains (EEA,2009b). Flash floods and pluvial floods, which aretriggered by local intense precipitation events, arelikely to become more frequent throughout Europe(Christensen and Christensen, 2002; Kundzewiczet al., 2006).3.3.4 River flow droughtRelevanceLack of water has severe consequences for Europe'scitizens and most economic sectors, includingagriculture, energy production and industry. Anintense drought throughout the Iberian Peninsuladuring 2004–2005, for example, led to a 40 %decline in cereal production (García-Herrera et al.,2007), whilst low rainfall in 2006 led to a 30 %fall in agricultural production in Lithuania, withan estimated loss of EUR 200 million (EuropeanCommission, 2007). In Slovenia, direct lossesattributable to drought in 2003 are estimated to bearound EUR 100 million (Sušnik and Kurnik, 2005).Furthermore, lack of water detrimentally impactsfreshwater ecosystems including vegetation, fish,invertebrates and riparian bird life (EEA, 2009a).Diminished flow also strongly impacts water qualityby reducing the ability of a river to dilute pollutants.Electricity production has already been significantlyreduced in various locations in Europe during verywarm summers due to limitations of cooling watersupply from rivers. Dry periods can also seriouslyimpact the production of hydropower (Lehner et al.,2005), for example in the case of Catalunia where the2003–2007 drought caused a hydropower reductionof over 40 % (Generalitat de Catalunya, 2010).Past trendsOver the past 40 years, Europe has been affected bya number of major droughts, most notably in 1976,1989, 1991, and more recently (see Map 3.9), theprolonged drought over large parts of the continentassociated with the 2003 summer heat wave andthe 2005 drought in the Iberian Peninsula (see alsoeffects on Energy production in Section 4.5).However, there is no evidence that river flowdroughts have become more severe or frequent overEurope in general in recent decades (Hisdal et al.,2001; Stahl et al., 2008), nor is there conclusive proofof a general increase in summer dryness (based onthe Palmer Drought Severity Index) in Europe overthe past 50 years due to reduced summer moistureavailability (van der Schrier et al., 2006). Severalstations in Europe have shown trends towards lesssevere low stream flows over the 20th century butthis is primarily attributed to an increasing numberof reservoirs becoming operational during thisperiod (Svensson et al., 2005).Whilst public water supplies often have priorityover other uses during droughts, restrictionson use can arise, together with a significant costassociated with emergency water supplies. In2008, Cyprus suffered its fourth consecutive yearof low rainfall and the drought situation reacheda critical level in the summer months. To ease thecrisis, water was shipped in from Greece usingKey messages: 3.3.4 River flow drought• Europe has been affected by several major droughts in recent decades, such as the catastrophicdrought associated with the 2003 summer heat wave in central parts of the continent and the 2005drought in the Iberian Peninsula.• Severity and frequency of droughts appear to have increased in parts of Europe, in particular insouthern Europe.• Regions most prone to an increase in drought hazard are southern and south-eastern Europe, butminimum river flows are also projected to decrease significantly in many other parts of the continent,especially in summer.120 Climate change, impacts and vulnerability in Europe 2012