Forests are extremely important for the environment. They are dense habitats for animals and plants, they clean groundwater, and provide us with oxygen. Now scientists from ETH Zurich have shown for the first time that forests lead to a rise in precipitation. In other words, forests help fight droughts.
Forests clean our air, stop land erosion, filtrate water and, as this new study has shown, make it rain. Image credit: Luc Viatour via Wikimedia (CC BY-SA 3.0)
Due to climate change, we are bound to experience more and more devastating droughts. And that is extremely bad news because our farms depend on rain and wildlife is struggling in droughts as well. Scientists knew for a long time that forests affect regional climates. They help regulate local temperatures and relative humidity. However, up until now scientists didn’t know how exactly forests affect precipitation locally and regionally.
Swiss scientists now analysed precipitation data from over 5,800 measuring stations belonging to different measuring networks in five European regions – Great Britain, Germany, the Netherlands, Sweden and Finland. And they made some interesting findings – precipitation in forested lands is considerably higher than in agricultural fields. Surprisingly, scientists found that this effect was more pronounced in winter. But how do forests make it rain?
Scientists hypothesize that increase in precipitation is due to the roughness of the surface of the forest. Forests hold up air masses longer and induce more turbulence, which favours precipitation. They are also warmer in winter than their surroundings and different local temperatures increase precipitation as well. This does mean that planting new forests could help us combat droughts, but what kind of effects could we expect?
Researchers estimate that reforestation of 14.4 % of the total area included in the study would increase average precipitation by as much as 7.6 %, which is a significant amount of rain. On the other hand, this area corresponds to an area slightly larger than France. Allocating so much land to a new forest would not be easy, but it would also help us reduce CO2 concentrations. However, scientists are not too optimistic.
Ronny Meier, first author of the study, said: “A forest does not grow overnight; it takes 20-30 years. The increased evaporation caused by adding forests in one location might draw water away from streams and rivers needed for agricultural irrigation elsewhere.” This means that reforestations efforts should be well-planned and strategic. However, the efforts would be worth it, because it is very likely that forests would help us avoid extreme weather events as well.
Earth needs forests, but humans prefer agricultural fields. The problem is that without the forests our fields are not going to flourish, bees will die and weather will become more and more extreme. We need to be smart about it and plant more forests.
Source: ETH Zurich
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