Effects chain – Example presentation from the ‘soil’ action field | Umweltbundesamt

Climate changes relevant to the action field

State: Precipitation and drought periods

Although the mean precipitation amounts have changed little over recent years, there have been repeated phases regionally of extreme water shortages as well as violent heavy-rain events. Soils can dry out whenever the evaporation in summer increases as a result of high temperatures. Since 2003 there have been particularly frequent incidents of dry phases in summer. As far as heavy-rain events are concerned, high spatial and temporal variability make statistically backed trend statements difficult. However, the general understanding is that heavy rain events have increased as a result of climate change. Especially in warm years, extreme convective precipitation events can occur repeatedly (cf. Changes regarding extremes).

Impacts of climate change

Impact: BO-I-1 Soil water in agriculturally used soils

There are critical development phases in the cultivation of agricultural crops which will incur yield losses, if the crops are subject to water shortages during those phases. DWD modelling has demonstrated that the amount of water available to plants during their growth period has diminished in the past 60 years; the trend observed is significant. The decline has been conspicuous above all in the years that have passed since the turn of the millennium.

Impact: BO-I-3 Rainfall erosivity

Given the presumably increasing frequency and intensity of heavy rain events due to climate change, the risk of soil erosion by water is rising. Especially in cases where heavy rain falls on to bare or very dry soils, unable to seep through, this situation can rapidly trigger soil removal processes. In particular, erosion leads to the removal of topsoil, which plays an important role regarding the water retention capacity and the nutrient balance of soils. It takes lengthy and complex processes for this topsoil to be replenished. Erosion weakens the resilience of soils towards climate change while strengthening the associated adverse impacts.

Adaptations – activities and results

Response: BO-R-2 Permanent grassland terrain

Under permanent grassland, agriculturally used soils are protected relatively well from adverse impacts of climate change such as erosion or the decomposition of humus. At the same time, moist grassland in particular, helps to stabilise a landscape’s water balance. Since 2013, there has been a precept in force nationwide requiring the conservation of grassland. According to this precept, it is not permitted to plough up grassland unless new grassland is created elsewhere in the territory concerned. Up until 2013 the grassland terrain was diminishing continuously and significantly. After 2013 this trend was reversed. Since then, the grassland terrain and its share of the terrain used for agricultural purposes has been increasing very slowly.