More forests in Europe could alleviate drought through climate change. This is clear from the analysis Now featured in “Nature Geoscience”. A working group led by Ronnie Meyer of ETH Zurich also reported there that a 20 percent increase in forest area could increase precipitation in Europe by 7.6 percent. The team writes that the value of 20 percent is realistic given the extent to which land use in Europe has changed historically. The analysis is based on empirical data on rainfall across forests as well as a statistical analysis of potential impacts on the entire continent. However, the team notes that the analysis still contains uncertainties and does not capture many potentially influential variables.
Forests are known to influence the weather thousands of kilometers away. However, little research has been done to date on how these effects can be used in the context of climate change. However, the analysis shows that additional forest areas could offset part of the reduced rainfall due to climate change, according to the publication. However, the effects vary from region to region. Accordingly, new forests near the coasts create a rain shadow. The team believes this is simply because forests make the surface “rougher,” creating turbulence, and thus weather systems move slower. In contrast, the opposite effect works in areas with little rain: When trees slow down the wind, more rain falls through new forests.
In addition, forests also cause precipitation by themselves. Because trees allow a lot of water to evaporate, they bring water into the atmosphere, which can then fall back into areas behind the forest. In large parts of Europe, this effect will lead to an increase in the amount of precipitation, especially in the summer. Meyer’s team points out that the 7.6 percent calculated so far relates only to reforestation of farmland. In addition, it is assumed that it is possible to plant more trees in areas used for other purposes, for example in populated areas. Essentially, the analysis shows that reforestation of large areas not only constrains CO2, but can also partially mitigate the negative consequences of climate change. The task force wrote that the relationship between vegetation cover and water balance deserves further attention.