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Klimawandel in Deutschland - Entwicklung, Folgen, Risiken und Perspektiven


Titelseite Klimabericht

Executive summary

Characteristics of climate change in Germany and extreme events

Climate-related natural dangers are of great importance for Germany. During the period between 1970 and 2014, such dangers accounted for economic losses of over ninety billion Euros. Climate change affects the frequency and intensity of such events: this influence, however, heavily varies depending on the process and region. In addition, the level of knowledge differs depending on the issue.

Temperatures
Observations show that from 1881 to 2014, temperatures – averaged across Germany – have considerably increased by around +1.3° C for the annual average (see fig. 1). Projections up to the end of the 21st century show an even stronger trend: compared to the reference period 1971 to 2000, the near-surface air temperature averaged for the region is accordingly becoming warmer, depending on the emission scenario, by between 1.2 and 3.2° C (moderate, intermediate scenario) or between 3.2 and 4.6° C (continuation of the current high emissions). In the summer – assuming the two aforementioned scenarios – temperature increases are projected between 1.3 and 2.6° C or, respectively, 2.7 and 4.8° C.

Fig. 1: The linear trend for the annual average temperatures is highly significant at 1.3 degrees Celsius within the 134 years represented.

The upper temperature extremes could increasingly become a problem: observations, partially dating back to the 19th century show an increase in warm temperature extremes while at the same time cold extremes decrease. It is of particular significance from a medical standpoint that the duration of summer heat waves across western Europe since 1880 has roughly tripled. Climate projections for the future, particularly under unabated greenhouse gas emissions, suggest considerable intensification of this development. With the increasing number of warm days and heat waves as well as the increase in ground-level ozone and particulate matter concentrations, the chronically ill, the elderly and allergy sufferers will especially be adversely affected in the future. This requires climate-conscious urban planning.

With higher temperatures, also comes a substantial decrease in snow cover, mainly in the lowlands of Germany.

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Fig. 2: The average precipitation during the winter months (December until February) increased between 1881 and 2014 by 47 mm, that is, by 26%.

Precipitation
Observations from 1881 to 2014 show an increase in annual precipitation: based on the long-term average from 1961 to 1990, the increase at the end of the observation period amounted to 10.2% (fig. 2).

In comparison to the reference period 1971 to 2000, most simulations for the next hundred years show an increase in precipitation during winter with a range for the moderate scenario of -3 to +17 %, and for a scenario with unabated greenhouse gas emissions from +8 to +32 %.

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Fig. 3: The changes in days with hail across all of Germany were projected by seven regional climate models. The figure shows the number of simulations from this ensemble of seven, which depict an increase.

Precipitation has not only increased altogether in Germany, but a change in precipitation patterns can also be observed. Strong winter precipitation has become more severe in many regions.

In addition, data indicates there is increased potential for severe storms and hail (fig. 3) which may play an important role in agricultural and urban hydrological issues.

Severe wind events
It is also likely that severe wind events and strong gusts, mainly in winter, will become more frequent over the North Sea and in northwestern Germany as early as by the middle of the 21st century.

Effects of climate change on particular sectors

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Fig. 4: Which action fields are particularly heavily affected and which areas experience only little negative or even positive effects of climate change? Statements, in terms of number and trend, obtained from a German nationwide literature study.

In scientific literature, it is assumed that all economic sectors and action fields will be affected by climate change, whereby the negative effects will heavily outweigh the positive (fig. 4).

Water supply
Climate change will influence the ground surface water supply. Most importantly, the average runoff on the Rhine and Danube will increase in winter and will continue to decrease in summer. Both the decreasing runoff as well as the rising air and water temperatures would lead to increased restrictions on thermal power plant production in the long term if the existing power plant stock continued operation (fig. 5).

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Fig. 5: If air temperature would rise by 2° C, continued operation of the power plant stock that existed in 2010 would be detrimental to thermal power plants with stream cooling due to high water temperatures. Projected capacity utilization until 2055 shows an average decrease throughout the year between 0.1 and 4% compared to 2010, which would be between eight hours and more than fourteen days [d].

Agriculture, forest management, soil quality, ecosystems
Increasingly extreme weather conditions can pose challenges for the agricultural sector, whereby the development of the agricultural markets also plays a role. Increasingly climate-adapted forest management is required as trees become more vulnerable. As a result of climate change, soil productivity is impaired by regionally varying changes in soil moisture or through more intense soil erosion. Ecosystem biodiversity should not only be preserved in isolated protective areas, but also generally in the cultural landscape.

Tourism
Regarding demand the tourism sector is expected to be heavily impacted in the long term by climate change. This impact mainly concerns the choice of destination and the time of travel (e.g., due to shifting snow lines, or unbearable summer heat in the Mediterranean).

Economy
Due to climate change, negative overall economic effects in Germany are expected — which are, however, mostly driven by international feedback effects. Without such effects, the overall economic impact could even be positive.

Overarching risks and uncertainties

Climate consequences arise from the interplay of physical events and the social conditions that prevail locally: heavy precipitation in a region with a robust sewage system will have a different and lesser impact than in a place with dilapidated infrastructure, dense population and therefore higher vulnerability. This means that part of comprehensive climate protection is to enable affected populations in regard to efficient adaptation measures and effective risk management in the face of unavoidable climate consequences.

Cost risk analysis and the precautionary approach
To estimate possible impacts of climate change in Germany, it is important toalso consider remote effects. Not only local changes are relevant for Germany, but also changes that occur in the rest of the world, as trade, production, supply chains and migration are closely intertwined. On the one hand, this means that a purely national assessment of climate consequences is too optimistic. On the other hand, such complex interplays of various processes are difficult, if not impossible, to quantify, which limits the conventional decision-making method to optimise the expected utility and requires alternative approaches, such as cost risk analysis or the precautionary approach.

Risk management in regard to exchange between social groups
Successful climate policy must combine technical possibility with socially desirability. Integrated risk management can contribute in this regard, which should be based on a close exchange between scientists, practitioners in companies, administration and politics as well as civil society. When assessing risks, it is therefore not only the objectively definable damages that are important, but also their subjective assessment by those affected.

Integrated strategies for climate change adaptation

Consistent decarbonisation
Limiting global warming to well below two degrees requires comprehensively transforming national and global economies. This means that we need consistent decarbonisation in energy systems, land usage, housing and mobility.

Transformation through integration
Adaptation to climate change must be embedded in this transformation and, in particular, requires stronger integration of municipalities, companies and civil society. Awareness of the challenges, however, is growing too slowly in many areas to keep up with the rapid pace of climate change and this delays or prevents effective measures such as protection in the event of severe rain or heat. This gives rise to considerably higher and unnecessary (as they are avoidable) adaptation costs and climate damage in the future.

Carefully plan and regularly review adaptation measures
Adaptation to climate change means always changing that to which you are accustomed. In order for this process of change to contribute to sustainable development, the environmental, economic and, above all, social aspects of the adaptation measures should be taken into consideration early in the planning process. Only if the impact of the measures is reviewed on a regular basis policy frameworks –such as standards, norms, support structures or legal regulations – can be improved by adjustments through policy making.

This information fact sheet was developed as a supplement to the book: Brasseur et al. (Editors): Klimawandel in Deutschland, Springer Verlag, 2017. The book serves as the source of the figures, and the book cover has been used.
English Translation: Anupa Srinivasan and GERICS experts

Figs. 1 and 2: Using data from the Deutscher Wetterdienst (German Weather Service)
Fig. 3: Susanna Mohr
Fig. 4: adelphi; PRC; EURAC (2015): Vulnerabilität Deutschlands gegenüber dem Klimawandel. Umweltbundesamt. Climate Change 24/2015, Dessau-Roßlau
Fig. 5: Hagen Koch

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