Field of Action Biological Diversity

colourful flowering summer meadowClick to enlarge
Changes in climate can have negative consequences for many species and ecosystems.
Source: patzita/

Impacts of Climate Change

Table of Contents


Effects of climate change on plants and animals

Changes in temperature, altered precipitation and extreme weather events influence the living conditions of plants and animals.

Thus, in Germany, on average, it has become approximately 1.6 degrees warmer over the last 139 years. As a consequence, the number of cold and very cold days decreased and the number of warm and very warm days increased. This results in changes and shifts in vegetation phases as a whole. The phenological spring already begins today, on average, around two weeks earlier than some decades ago. The phenological autumn lasts longer while the phenological winter has shortened from an average of 120 days per year to only 102 days.

If these important basic conditions change, many animals and plants change their behavior and their characteristics:

  • periodically recurring growth and development processes of plants and animals adapt to the new conditions,
  • food relationships shift,
  • animals display new behavioral patterns,
  • shift in the reproductive cycles of animals and plants,
  • animals and plants settle in new distribution areas and habitats,
  • native species are increasingly in competition with newly immigrated species.

Such changes in the living conditions and behavior of animals and plants can have profound effects on complex biotopes, habitats and ecosystems.


Consequences for species and populations

If the climate changes, it also influences the composition of biocoenoses and the habitats of species. Against this background, temperature and precipitation trends have a significant impact on biodiversity.

Species that have a very narrow tolerance range with regard to their requirements for living conditions may decline in number and distribution or even become extinct. These species can only poorly adapt as it is hardly possible for them to move to new habitats. Also, species that are less mobile cannot reach new, suitable habitats. In the course of climate change, habitats for species that love the cold and moisture are becoming scarcer in Germany. However, conditions are improving for warmth-loving species, which will become more widespread.

The increase in temperature and the prolonged vegetation period allows the spread of new species that form new communities or influence the composition of existing communities. This can increase the number of species in a biotope. However, the spread of new, so-called invasive species, which are very competitive, can also displace native flora and fauna and thus lead to a shift or even loss of biodiversity.

The climate sensitivity of a species depends on many other factors, including biotope connectivity, area size, current population situation and reproduction rate.

Climate change also threatens biodiversity. An analysis of 500 selected indigenous animal species commissioned by the Federal Agency for Nature Conservation, showed that climate change poses a high risk for 63 species, with butterflies, molluscs (e.g. snails) and beetles most affected.

In addition to direct impacts, climate change also has indirect effects on biodiversity. Triggers are adaptations in land use, for example in agriculture and forestry, or measures to protect the population and infrastructure, such as modified water management. The implementation of climate protection measures, such as the expansion of renewable energies or the insulation of buildings, also influences the occurrence of species and the quality of habitats. However, in most cases, it is difficult to demonstrate the extent to which these developments influence biodiversity since numerous other factors besides climate change usually have an additional impact.


Consequences for biotopes, habitats and ecosystems

Biotopes and ecosystems live on the interrelation of different plant and animal species. A modified species composition, as well as changes in the characteristics and behavior of individual species, endanger this complex interaction. Since, for example, shifts in life cycles do not occur in the same way for all species, interdependent species (e.g. predator-prey, flower-pollinator dependencies) can be decoupled in time and space.

An example of such a spatial decoupling is the caterpillars of many butterfly species, which require the leaves of special tree species as food. This interrelation is lost due to the progressively divergent distribution of animals and plants as a result of climate change.

Temporal decoupling of food chains can be observed in the example of migratory birds. Some species do not find enough larvae as food when they return in spring, because the insects have already developed.
It has been proven that fish begin their spawning earlier. The flowering times of plants also shift, so that they no longer match the life cycle of the insects pollinating them.

Even changes in individual species and small variances of just a few days can throw an ecosystem out of balance and seriously disrupt food chains.

The beginning of the phenological spring, summer and autumn has shifted forward on average during the last 70 years. The winter has become significantly shorter, and early autumn significantly longer. These changes are an expression of the ability of plants to adapt to a changing climate, but they can also have more far-reaching consequences for biodiversity and even endanger animal and plant species.

Die Grafik zeigt eine phänologische Uhr. Konzentrisch sind drei Zeiträume 1951 bis 1980 und 1981 bis 2010 und 1988 bis 2017 abgetragen. Dargestellt sind die Veränderung der folgenden zehn durch Wildpflanzen repräsentierten Leitphasen.
BD-I-1: Phänologische Veränderungen bei Wildpflanzenarten

Die Grafik zeigt eine phänologische Uhr. Konzentrisch sind drei Zeiträume 1951 bis 1980 und 1981 bis 2010 und 1988 bis 2017 abgetragen. Dargestellt sind die Veränderung der folgenden zehn durch Wildpflanzen repräsentierten Leitphasen; im Folgenden werden die Zahlenwerte der drei Zeiträume jeweils gelesen: Stieleiche (Beginn des Blattfalls) Winter: 143, 135 und 133 Tage, Huflattich (Beginn der Blüte) für den Vorfrühling: 14, 14 und 13 Tage, Buschwindröschen (Beginn der Blüte) für den Erstfrühling: 31, 31 und 31 Tage, Stieleiche (Beginn der Blattentfaltung) für den Vollfrühling: 30, 28 und 28 Tage, Schwarzer Holunder (Beginn der Blüte) für den Frühsommer: 20, 22 und 23 Tage, Sommerlinde (Beginn der Blüte) für den Hochsommer: 49, 43 und 44 Tage, Eberesche (Entwicklung erster reifer Früchte) für den Spätsommer: 21, 24 und 23 Tage, Schwarzer Holunder (Entwicklung erster reifer Früchte) für den Frühherbst: 29, 39 und 43 Tage, Hängebirke (Beginn der Blattverfärbung) für dem Vollherbst: 20, 22 und 22 Tage, Rotbuche (Beginn des Blattfalls) für den Spätherbst: 7,7 und 7 Tage.

Source: DWD (Phänologisches-Beobachtungsnetz)

Various ecosystems are differently sensitive to climate change. Dry habitats such as dunes, dry grasslands and heathlands are considered relatively resistant because they are not very sensitive to water shortages. On the other hand, moors, swamps, spring areas and wet grassland are particularly sensitive to water shortages. This applies increasingly to forests as well. Further information can also be found in the fields of action Soil and Forestry.

Habitats near and in the water are also highly endangered since warming and a negative climatic water balance (evaporation exceeds the water supply by precipitation) lead to more frequent low waters. This increases the risk of dehydration or eutrophication, that is an excessive input of nutrients into the water body and the accompanied lack of oxygen, especially for smaller standing waters. More information can also be found in the field of action Water, Floods and Coastal Protection.

Adaptation to Climate Change

Technical measures

Nature reacts to changes in climatic conditions: It adapts. However, it is often hindered by the human way of life and economy. If this is the case, dynamic, spatial and temporal adaptation processes are often only possible to a limited extent.

Humans should therefore support the naturally existing dynamics and adaptation potential of nature by preserving and promoting the functionality of ecosystems. In order to preserve those animal and plant species that are bound to specific site and habitat conditions, they must be allowed to escape to their most favourable habitat. It is therefore important to look beyond the boundaries of protected areas to identify possible interlinked biotope systems. These are necessary conditions for the preservation of biodiversity.

Technical solutions play an important role in such a biotope network system. For many species, an interconnected system is a crucial prerequisite for adaptation to climate change.
Corridor areas, guiding structures such as hedges and stepping stone habitats, migration corridors and green bridges are used to connect habitats. These form the central building blocks of the network and are specifically geared to the species to be supported. The diversity of habitat structures in the landscape supports the networking of biotopes. At the same time, technical measures can reduce the barrier effect of traffic routes, river engineering and intensively used areas.

Ecosystem Measures

The creation of an effective system of interlinked biotopes, which is also the aim of Natura 2000, is probably one of the most important measures in the area of "green infrastructure". According to the Nature Conservation Act (BNatSchG § 4), states must make at least 10 percent of their land area available for a biotope network. Therefore a large scale view is important.

By networking habitats, the migration and spread of species into future habitats should be made possible. Only through these territorial links can species affected by climate change find new suitable habitats. An effective system of interlinked biotopes is to be developed and established on a cross-border basis. The fragmentation of natural systems and land consumption must be reduced and sectoral planning - for example for settlements, infrastructure and transport - must be adapted accordingly.

Other "green" measures include the creation and maintenance of near-natural green spaces in cities and alternative habitats. This also includes process protection as a nature conservation strategy based on non-intervention in the natural processes of ecosystems.

In addition, the protection of wetland habitats such as marshes and floodplains is an important measure that also contributes to climate protection. Targeted stabilization and improvement of the water balance, renaturation, rewetting, nature-conserving alternative uses and other measures should protect the particularly climate-sensitive habitats, not only in protected areas but already in their drainage basin.
One measure for flood protection and at the same time species protection is the transfer to areas with natural flood dynamics, which allows a re-colonization with many floodplain-typical plant and animal species. By dismantling, relocating or slitting dikes at 79 rivers nationwide in the years from 1983 to 2017, 4,080 hectares of former floodplain area have been reconnected to the natural flood dynamics of running waters and are uncontrollably flooded during flood events.

In agriculture, further measures are possible that contribute to nature conservation. Gentle soil cultivation, protection of agricultural biodiversity and reduction of stress factors are to improve the synergy between agriculture, nature conservation, soil protection, water protection and climate protection. Organic farming represents an extremely environmentally friendly alternative to conventional agriculture.

Legal, political and management measures

National and international policy-makers are called upon to ensure the right framework conditions for the adaptation of nature conservation. To this end, the concept of nature conservation needs to be further developed in view of climate change. The aim must be to align nature conservation in such a way that as many functional ecosystems as possible are preserved, in order to provide an intact habitat for as many species as possible. The focus on small-scale protected areas should be reconsidered. Flexible protected area boundaries can also be an effective solution in view of migrating species.

Special precautions are necessary for those species whose future habitats do not overlap with current distribution areas. In addition, species that are only capable of limited migration need special protection. In their case, targeted measures for settling in new habitats are conceivable.

The further development of the protected area system must take into account the requirements of climate change. The area of strictly protected areas has statistically significantly increased from 1,129,225 hectares in 2000 to 1,591,580 hectares in 2016. In terms of Germany's land area, this means an increase from 3.2% in 2000 to 4.4% in 2016. The increase in the area of strictly protected areas is partly due to the implementation of the Natura 2000 network.

The responsible state and nature conservation authorities can also take the changing climate conditions into account when drawing up maintenance and development plans and management plans for protected areas and adapt them on an ongoing basis. For example, more than two-thirds of the landscape programs now mention topics of climate protection and adaptation to climate change in connection with nature conservation issues. An important instrument is adaptive management, which enables dynamic management of protected areas. Protection goals can be continually be evaluated and adapted to changing conditions.

The monitoring of climate impacts on biodiversity plays an important role. The conservation of biological diversity requires cross-national cooperation and early exchange of information. Against this background, a monitoring system for climate impacts and measures already initiated as well as the precise definition of target criteria is important. Monitoring and early warning systems are also useful for supporting particularly affected species and biotopes and for dealing with invasive species. Based on their results, risk assessments can be made and recommendations for action can be issued. Only in this way can climate-related risks and new requirements be addressed in a targeted and efficient manner.

In mid-2020, the EU Commission presented a new biodiversity strategy for 2030. The aim is to develop a restoration plan for nature with binding targets. 30 percent of land and sea areas are to be placed under nature conservation, building on the existing Natura 2000 areas. The decline of insects and birds on agricultural land is to be curbed, as is the bycatch of protected species in the oceans. Other targets include 25,000 kilometers of free-flowing rivers and three billion newly planted trees. The EU wants to promote research on biodiversity more strongly. According to the Commission, at least 20 billion euros per year are to be invested in nature conservation and the restoration of ecosystems to achieve these goals.