Vulnerabilities - Germany
The summer of 2003
The hot and dry years in the 1990s, and particularly the year 2003 have shown that Germany can be hit by low water and drought, in spite of lying in the temperate climate zone. In Germany this exceptionally long dry and hot phase has led amongst other things to increased risk of forest fires, losses in the agricultural sector, restrictions on inland waterway traffic and on the operating times of thermal, hydroelectric and nuclear power plants.The reinsurance company Munich Re estimates the costs of the heat wave of 2003 in Germany at more than 1.2 billion € (18). Others report an agro-economical impact of this drought event for Germany of 1.5 billion EUR, and 15 billion EUR for all of Europe (25). However, the supply of drinking water was not threatened during 2003 (19,21).
The summer of 2015
Almost 75% of the area of Germany was under at least moderate drought in July 2015. During August 2015, the total area under drought decreased, but the areas of extreme and exceptional drought conditions increased to 22% and 5%, respectively (26).
The degree to which a region is hit by changes in runoff depends strongly on the size of the change and on the initial situation. Especially regions that presently have an unfavourable water balance and low runoff, such as e.g. the central regions of Eastern Germany, can be strongly impacted by climate change. In these regions, the shift of precipitation from summer to winter leads to further decreases in summer runoff, when the situation has already been difficult in arid years, and causes further water shortages. Even if the results vary between climate models, there is considerable evidence that climate change will increase the risk of arid periods and droughts (17).
Low river runoff
If one merely considers the impacts of climate change on runoff (decrease in seepage water quantities, seasonal shift of precipitation, increased evapotranspiration), there is a slight reduction in annual runoff in the north and northeast, and a slight increase in the south. The differences in summer runoff are greater (21).
Flood and drought conditions in five large river basins in Germany (covering 90 % of the German territory) were estimated from a large number of (regional climate) model projections (based on several models and the A1B emission scenario of moderate climate change) (24). The results for 2061–2100 (compared with 1961–2000) show that many German rivers may experience more frequent occurrences of current 50-year droughts with a moderate agreement by 60–70 % of projections. The results show very large differences between the projected changes for different model projections, however. The uncertainty of the extreme event projections is too large to identify the robust change signals for most German rivers. Robust changing signals agreed by more than 80 % of projections include more frequent extreme droughts in the Rhine basin in 2061–2100. The current 50-year droughts may occur more often with a frequency of <25 years along the Rhine River and its tributary Moselle over the last 40 years of this century. The major trigger of the significantly drier conditions in the Rhine is the significant decrease in summer precipitation (about 13 %) (24).
During the summer there will be much less water available than at present. Between 1990 and 2080 the runoff in summer, depending on the climate model used and the emission scenario considered, will show a decrease of up to 43 percent (22). Rivers with a markedly Alpine runoff regime will also be affected by other components, such as accelerated melting of glaciers or permafrost soils and changes in the stability and thickness of snow cover (21).
Consequences of droughts
More-frequent low-water periods during summer dry periods will affect cooling-water availability and ecological health. Extreme wind and precipitation events could increase, thereby increasing erosion risks and the possibility that pollutant concentrations, waste fertilisers and waste pesticides, from various areas, can find their way into ground and surface waters (20).
Increasing water and bottom temperatures of aquatic systems in summer will, among other effects, reduce lower oxygen concentrations in water bodies. Since Germany's drinking-water supplies are obtained largely from locally available groundwater resources, and only partly via bank filtration or from surface waters (for example, reservoirs), no fundamental problems in drinking-water supplies are expected even under changed climatic conditions. On the other hand, regional scarcities might occur in areas that suffer extensive periods of drought (20).
Low summer water levels in surface waters tend to increase water concentrations of undesirable substances. Such substances burden ecosystems and, where drinking water supplies are obtained via bank filtration, can increase overhead and expense in drinking-water purification. Increasingly frequent dry periods during summer months would tend to intensify drying of wetlands and bogs. Such trends would impair the ability of intact wetlands and bogs to buffer strong-rainfall events (20).
The definition of drought
Drought is a natural phenomenon defined as sustained and extensive occurrence of below average water availability. Drought should not be confused with aridity, which is a long-term average feature of a dry climate. It is also distinct from water scarcity, which constitutes an imbalance between water availability and demand (1).
Four different types of drought have been defined (28):
- Meteorological droughts relate to a deficiency of precipitation.
- Hydrological droughts reduce streamflow and low water levels of reservoirs and lakes. Hydrological droughts mainly affect water resources management, power plant cooling, irrigation, and inland navigation. Groundwater droughts are a special case of hydrological droughts (van Lanen and Peters 2000, Kumar et al 2016). They occur when water deficiencies reach deep subsurface storages resulting in exceptionally low groundwater levels, groundwater recharge and baseflow. They reduce the supply of fresh water, where groundwater is the major source for drinking water supply.
- Agricultural droughts are characterized by low soil water availability for plants, potentially leading to reduced biomass and yield or crop failure.
- Socioeconomic droughts can emerge from all of the aforementioned drought types. It is characterized by a shortfall of water supply (water scarcity) leading to monetary losses.
High temperatures are not a necessary component of drought conditions, dry winters can lead to water resources stress in the following summer.
Droughts might manifest themselves either as short but extreme single season droughts (such as the hot summer of 2003) or longer-term, multi-season droughts, and they might be local or widespread in nature (7).
Vulnerabilities in Europe
The European Commission has estimated that at least 11 % of Europe's population and 17 % of its territory have been affected by water scarcity to date and put the cost of droughts in Europe over the past thirty years at EUR 100 billion (1).The drought of 2003 caused a total economic cost of over €13 billion in around twenty European countries (2,7).
Vulnerabilities – European trends in the past
There is no clear evidence that a widespread change in droughts has occurred in Europe over the last century or over the last decades (6). There is no evidence that river flow droughts have become more severe or frequent over Europe in general in recent decades (3), nor is there conclusive proof of a general increase in summer dryness in Europe over the past 50 years due to reduced summer moisture availability (4). Strong increases in the area of combined severe dry and wet conditions in Europe over the last three decades have also been identified, though, and it has been suggested that without global warming droughts would have been smaller and less pervasive (13).
Despite the absence of a general trend in Europe, there have been distinct regional differences. In particular, more severe river flow droughts have been observed in Spain, the eastern part of eastern Europe and large parts of the United Kingdom (3). However, in the United Kingdom there is no evidence of a significant increase in the frequency of occurrence of low river flows (5).
Increasing drought deficits were observed in Spain, eastern Europe and large parts of central Europe with changes in precipitation cited as a major explanatory factor (11). Others (12) have indicated that the proportion of Europe experiencing extreme and/or moderate drought conditions has changed significantly during the twentieth century with fewer droughts over Scandinavia, Netherlands and the Ukraine and more in areas of eastern Europe and western Russia.
Water extraction as well as water management across catchments and changes in land use and management also make it very difficult to attribute changes in average water discharge, floods and droughts to climate-change forcing (8).
Changes in drought severity for western Europe have been attributed to a changing climate but for eastern European countries the increased extraction of water for economic expansion is also a significant factor (15). It has been suggested that the influence of increases in water consumption on future droughts may even be of the same magnitude as the projected impact of climate change (16).
Vulnerabilities – Future projections for Europe
River flow droughts are projected to increase in frequency and severity in southern and south‑eastern Europe, the United Kingdom, France, Benelux, and western parts of Germany over the coming decades. In snow-dominated regions, where droughts typically occur in winter, river flow droughts are projected to become less severe because a lower fraction of precipitation will fall as snow in warmer winters. In most of Europe, the projected decrease in summer precipitation, accompanied by rising temperatures which enhances evaporative demand, may lead to more frequent and intense summer droughts (9).
As a result of both climate change and increasing water withdrawals, more river basins will be affected by severe water stress, resulting in increased competition for water resources. The regions most prone to an increase in drought risk are the Mediterranean and south-eastern parts of Europe, which already suffer most from water stress (10).
According to research based on six regional climate models, there is not a simple north–south pattern of decreased–increased drought, with models projecting fewer events for parts of the Iberian Peninsula and parts of the Mediterranean. Considerable uncertainty exists at the regional scale. For example, for Britain and northern Spain, different models project both increases and decreases. … All models project longer and more severe droughts in the Mediterranean and shorter, less severe, events for Scandinavia with greater uncertainty as to the direction of change for the rest of Europe (14).
The use of six regional climate models has demonstrated the range of uncertainty in future projections of even mean precipitation across Europe, but also enables some generalizations to be made. Increases in precipitation are likely during winter and these are likely to be largest and most persistent for northern Europe. In contrast, large decreases in precipitation are likely during summer, these being largest in southern Europe (14).
For longer-duration droughts there is a clearer spatial pattern, which indicates fewer droughts in northern Europe due to larger increases in winter precipitation and more droughts of increasing severity in the south (14).
Droughts may strongly affect biodiversity all across Europe. Some examples (8):
- The environmental impacts of droughts can be exacerbated by unsustainable trends in water use. The worst combination appears when drought strikes freshwater ecosystems already weakened by excessive water withdrawals. For example, Lake Iliki, some 100 km northeast of Athens, has been reduced to a third of its original size, partly by a severe drought in 2000 but also as a result of increasing drinking water demand. Likewise, Lake Djoran, located between Greece and the Former Yugoslav Republic of Macedonia, is at risk of drying up, thus threatening one of the richest inland fishing stocks in Europe.
- Wetlands are particularly vulnerable to drought. The drought that affected Spain in the first half of the 1990s reduced by 97 % the flooded area of the Natural Park of the ‘Tablas de Daimiel’, the most important wetland area in the interior of the Iberian peninsula. Here too, water withdrawals, in this case for agricultural purposes, contributed to the loss.
- Droughts can cause the deterioration of water quality in rivers, lakes and reservoirs by exacerbating algal blooms that reduce the oxygen available for aquatic species. In the summer of 1999, for instance, these processes affected many lakes in Finland.
- Droughts may also weaken the resistance of certain plant species to plagues and increase their susceptibility to forest fires, as happened in the Greek island of Samos in the summer of 2000.
- Finally, drought can threaten the very survival of species in certain areas. The prolonged drought that affected southern Spain in the mid 1990s caused a high mortality rate among maritime pines and severely withered green oak and cork oak forests.
Droughts may also trigger soil erosion, mainly in Mediterranean areas. One way this happens is through a reduction in vegetation cover caused by forest fires or by increased plant mortality due to water stress. In addition, when the soil is very dry, the water infiltration rate decreases. Consequently, if a period of drought is followed by heavy storms, erosion is triggered by surface runoff. The problem is especially acute in the arid and semi-arid Mediterranean areas where the process may lead to desertification (8).
Europe should view 2003 as a wake-up call. The 2003 drought should be the catalyst for actions aimed at reducing drought impacts across all relevant sectors (7). Drought is not mentioned in European energy policies. Similarly European transport navigation policy makes no reference to low flow conditions, whereas health policies make few provisions for reduced water supplies and deteriorating water quality. Drought is one criterion for exemption to the requirements of the Water Framework Directive – an increasingly likely situation. It makes no provision for managing biodiversity protection during severe droughts (7).
In contrast to internal policy, drought is addressed as a real issue in EU development policies. Drought is seen as a threat to sustainable development, a humanitarian issue and a driver of mass migration and political instability (7).
EU policy orientations for future action
According to the EU, policy orientations for the way forward are (23):
- Putting the right price tag on water;
- Allocating water and water-related funding more efficiently: Improving land-use planning, and Financing water efficiency;
- Improving drought risk management: Developing drought risk management plans, Developing an observatory and an early warning system on droughts, and Further optimising the use of the EU Solidarity Fund and European Mechanism for Civil Protection;
- Considering additional water supply infrastructures;
- Fostering water efficient technologies and practices;
- Fostering the emergence of a water-saving culture in Europe;
- Improve knowledge and data collection: A water scarcity and drought information system throughout Europe, and Research and technological development opportunities.
Adaptation activities currently seem to be focused on flood management and defence, while adaptation measures related to the management of water scarcity and drought, although recognized as equally damaging, do not yet seem to be widespread (2).
The German drought monitor (GDM) focuses on agricultural droughts (26). Drought monitoring and early warning systems are designed to identify water deficiencies in climatic or hydrologic variables. They aim to detect emergence, probability of occurrence and the potential severity of drought events (27).
Several adaptation measures may be implemented to compensate for the future increase of the frequency and intensity of droughts (17):
- The likely occurrence of periods of low water and aridity call for sustainable land use management, which secures the retention of water in the landscape. Such improvement of the landscape water balance has additional advantages for flood protection;
- As a further measure of precaution the infrastructure should be built to store sufficient amounts of water in dams, and to open the possibility of transporting water through long-distance pipelines;
- Suitable water saving measures should be implemented in industry, agriculture, forestry and private households, to avoid restrictions of usage;
- Agriculture and forestry will have to prepare for water shortages by adapted cultivation techniques and modern water-saving irrigation devices;
- Further adaptation strategies to expected climate change in Germany are financial safeguarding through insurances against flood damage and drought-related yield losses, as well as the creation of reserve funds for damage reparation and future adaptation measures.
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Germany.
- EC (2007a), in: EEA (2009)
- Anderson (ed.) (2007)
- Hisdal et al. (2001), in:EEA, JRC and WHO (2008)
- Van der Schrier et al.(2006), in:EEA, JRC and WHO (2008)
- Hanneford and Marsh (2006), in:EEA, JRC and WHO (2008)
- Van Lanen et al. (2007), in: EEA (2009)
- Eisenreich (2005)
- EEA, JRC and WHO (2008)
- Douville et al. (2002); Lehner et al. (2006); Feyen and Dankers (2008), in:EEA, JRC and WHO (2008)
- Alcamo et al. (2003); Schröter et al. (2005), in: EEA, JRC and WHO (2008)
- Demuth and Stahl, 2001, in: Blenkinsop and Fowler (2007)
- Lloyd-Hughes and Saunders (2002), in: Blenkinsop and Fowler (2007)
- Dai et al. (2004), in: Blenkinsop and Fowler (2007)
- Blenkinsop and Fowler (2007)
- Lehner et al. (2006), in: Blenkinsop and Fowler (2007)
- Lehner and Döll (2001), in: Blenkinsop and Fowler (2007)
- Zebisch et al. (2005)
- Eisenreich (2005)
- Demuth (2004), in: Zebisch et al. (2005)
- Government of the Federal Republic of Germany (2010)
- Government of the Federal Republic of Germany (2006)
- Cramer et al. (2005), in: Government of the Federal Republic of Germany (2006)
- Commission of the European Communities (2007)
- Huang et al. (2015)
- COPA-COGECA (2003), in: Zink et al. (2016)
- Zink et al. (2016)
- WMO (2006), in: Zink et al. (2016)
- WMO (2006); Mishra and Singh (2010), both in: Zink et al. (2016)