A new scientific study by the ECONICS Institute shows that it is not only large cities in Germany that are heat hotspots, but that there are now extensive heat landscapes. In partnership with NABU, the »Green-Wet-Cool Index« for Germany has now been presented, which illustrates that land cover has a significant influence on surface temperature and precipitation. The mutually influential triangular relationship between greenness, relatively cool temperatures, and humidity reflects the performance of landscapes and their sustainability in the face of climate change. Vegetation improves water retention, releases it back into the air through evaporation, and thus cools the environment. At the same time, these processes promote precipitation. Where trees, hedges, and meadows are lacking, soils dry out and heat up. This creates veritable heat landscapes.

»There are significant differences between the federal states and individual landscapes,« explains study leader Prof. Pierre Ibisch. »The critical regions include large parts of Saxony-Anhalt and the Thuringian Basin, Franconia in Bavaria, and the Rhine-Main area. As expected, forested mountain regions such as the Bavarian Forest, the Black Forest, Spessart, and the Palatinate Forest are above average in terms of greenery and coolness—but only as long as the forests remain healthy. In the Sauerland, Siegerland, and Harz regions, the decline of spruce forests has led to a noticeable decline in the productivity of ecosystems.«

With the help of high-resolution data on vegetation greenness, surface temperatures, precipitation, and additional parameters, statistical models were used to demonstrate the interactions between vegetation condition, temperature, and precipitation. Among other things, freely available satellite image data for the entire federal territory was used. The years 2018 to 2024 were examined, including the period of interconnected extreme weather events and the five warmest years since weather records began (2020, 2018, 2022, 2023, 2024).

The scientists and NABU agree that the findings can be put to practical use. NABU President Jörg-Andreas Krüger emphasizes: »The study highlights the significant benefits that intact ecosystems provide and demonstrates the potential of regional changes: for example, if we focus more on regenerative agriculture methods—through permanent soil cover, the promotion of agroforestry systems, or hedges—we can cool the region as a whole and keep it moister. And where nature is still intact, we should do everything we can to stabilize it, for example by promoting deciduous and mixed forests and sponge landscapes. These measures will help us retain water in the landscape.«

The results of the study have attracted considerable media interest. Prof. Ibisch met with Katrin Lindner in the Grumsiner Buchenwald forest in northern Brandenburg for ZDF’s “heute” news program. Here, it is clear to see that the dense vegetation and the associated high evaporation rates ensure relatively cool temperatures in the forest – even during heat waves. In contrast, the directly adjacent agricultural areas heat up by up to 10°C more on hot days. The entire report can be viewed here:

The study was also discussed on Deutschlandfunk radio. Here, Prof. Ibisch and Andreas Krüger from NABU explain how intensive land use—often in conjunction with urban areas—can create veritable heat and drought landscapes. These regions are not particularly hot because there is so little rain, but rather there is so little rain because the landscapes are not green enough. The entire conversation can be found here:

In “DIE ZEIT” it was made clear that agriculture is facing a similar rethink to that which urban planning has undergone. According to Prof. Pierre Ibisch, it is precisely fields with good soil, which are of particular economic importance, that are most vulnerable: »The land that was productive under certain conditions is now being lost very quickly.« However, awareness that agricultural landscapes also suffer from heat could be a turning point. There is room for action: diverse crop rotations, catch crops, hedges, and agroforests can help regulate the microclimate. Mixing, as in the city, but in a plant-based way.