Constant rain and floods in Germany give a different impression. But climate change has made the air across Europe significantly drier in recent decades. The Alps and the Pyrenees as well as Central Europe are mainly affected, writes an international research group with German participation in the magazine Nature Geoscience. The dry air increases the risks for both forest fires and agriculture, reports the group led by Kerstin Treydte from the Federal Research Institute for Forest, Snow and Landscape (WSL) in Birmensdorf.
The research team determined air dryness since 1600 primarily by analyzing tree rings from 45 forests across Europe. Here the scientists examined the ratio of two isotopes of oxygen (O) of different weights – O-18 and O-16. The team also evaluated meteorological data and carried out model simulations.
The group used the so-called vapor pressure deficit as a measure of dryness. This means the difference between the actual and the maximum possible water content in the air; it is also described as the “thirst of the atmosphere”. When there is a high vapor pressure deficit, the “thirsty” air draws more water from the soil and plants. This can affect vegetation growth and increase the risk of wildfires.
Farmers have to irrigate more, yields fall
According to the analyses, the air over all regions of Europe examined has been drier since the beginning of the 21st century than ever before during the study period. However, the trend is different in different areas and mainly affects the Pyrenees, the Alps and the Central European lowlands. However, it is weaker in southern Scandinavia. There is a 98 percent probability that the development is a result of human-caused climate change, it goes on to say.
In June 2023, hundreds of hectares of forest burned south of Berlin, here near Jüterborg.
(Photo: Thomas Schulz/dpa)
“Drying out vegetation and soils increase the frequency of forest fires, such as those we recently experienced in Brandenburg,” co-author Gerhard Helle from the German Georesearch Center is quoted as saying in a statement from the institution. But the agricultural sector could also feel the effects of the development: “The vapor pressure deficit is particularly important for agriculture, because the higher it is, the greater the plants’ water requirements,” says lead author Treydte. “More irrigation is needed and crop yields are declining. In forests, wood supplies and carbon storage are at risk, leading to uncertainties about the climate regulation and carbon storage of these ecosystems in the future.”