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Fact check: Why soils are getting drier despite more rain
Overall, the summers in Germany are becoming drier. photo
© Armin Weigel/dpa
For decades, the trend in total precipitation in Germany has been upwards. But a single statistic says little about the drought and dryness problem.
Claim: Because the annual precipitation in Germany has increased by seven percent compared to 1881, there are no problems with drought.
Rating: Wrong.
Facts: 57.7 millimeters or seven percent more annual precipitation in Germany: This has been reported by the German Weather Service (DWD) as a so-called linear trend since 1881. But the value alone has little meaning.
The increase is mainly due to more precipitation in the winter months. The Federal Environment Agency and the DWD themselves point this out. “In summer, on the other hand, precipitation has fallen by around five percent in a linear trend since 1881,” explains DWD agricultural meteorologist Andreas Brömser in an interview with the German Press Agency. Summer, together with spring, is the growing season that is important for agriculture. “We need more precipitation in the summer,” says Brömser.
In addition, it is not possible to draw conclusions about soil moisture or drought from the amount of precipitation alone, according to Brömser. He cites the rise in average temperatures since 1881 as one reason for this: “The higher the temperatures, the more rain evaporates again quickly. The increase of 1.7 degrees Celsius recorded in Germany means around twelve percent more evaporation.”
The comparatively wet summer of 2023 can easily hide the fact that droughts in Germany have been exceptional in some cases in recent years. In 2020, researchers at the Helmholtz Center for Environmental Research wrote in the journal “Scientific Reports” that Central Europe experienced the worst summer droughts of the past 250 years in 2018 and 2019.
DWD meteorologist Brömser says: “The last ten years have been drier than the long-term trend.” However, one still has to be cautious about the question of whether this is a longer-term development or a fluctuation of a few years.
And what about the soil? The Federal Environment Agency wrote in a 2019 report, citing DWD information, that the number of days with low soil moisture had increased significantly since 1961. A look at the Helmholtz Center’s so-called drought monitor shows that the rain of the past few weeks has provided sufficient water in the upper soil layers in many places. But in the deeper layers, the drought persists in many regions.
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