Soil and climate
Vulnerability of soil functions due to climate change
Soils and their numerous functions, e. g. as habitat for plants and animals, location for cultivated plants, water reservoir or filter, are affected by climate change in many ways. Climate change can, for example, lead to changes in soil properties as a result of degradation processes. They influence both the soils themselves and their performance in the ecosystem and thus their long-term usability, such as changes in yields in agriculture and forestry. BGR is developing methods to determine the vulnerability of soil functions to climate change.
Already in 2003, BGR and the Technical University of Berlin (TUB) developed a method for describing the mean seepage water rate from soil using climate data of the then standard period (1961-1990). In this context, numerous so-called linking rules were developed, e. g. for capillary rise or for the effective water balance during the main vegetation period (May-August).
In spring 2019, the German Weather Service (DWD) provided processed climate scenario data (https://www.dwd.de/ref-ensemble). Using this climate scenario data enables the application of the calculation methods developed. The ensemble comprises 16 bias-corrected spatial data sets (combination of global and regional climate models) with a spatial resolution of 5 x 5 km2, which describe the scenario RCP 8.5 (RCPs Representative Concentration Pathways) and assume an additional radiative forcing of 8.5 W/m². The mean, 15th and 85th percentiles were calculated for the time slices 1971-2000, 2031-2060 and 2071-2099.
The first step in this study was to analyse the soil functions that are directly related to the climate parameters of temperature, precipitation, wind speed and evaporation.
The following analyses were carried out in this context:
- Determination of the effective water balance in the main vegetation period (May-August)
- Determination of the annual seepage water rate from soil according to the TUB_BGR method
- Determination of the potential erosion risk through water according to pedological, morphological and climatic conditions
In the next steps of the project, it is planned to further develop numerous algorithms that were previously developed on the basis of the standard period (1961-1990) and are part of the linking rules and soil evaluation methods. Furthermore, the utilisation of current results using nationwide soil-water balance models will be examined in order to be able to better evaluate current conditions with their possibilities and risks.
The maps of the effective water balance in the main vegetation period (May to August) provide an overview of the ratio of precipitation to evaporation. The water balance is positive when precipitation is higher than evaporation and negative when evaporation exceeds precipitation. A look into the future generally shows that water stress is likely to increase significantly in large parts of Germany.