Forests for rain
Keskiviikko 10.6.2020 klo 19:46 - Mikko Nikinmaa
When the importance of forests for environmental well-being is brought forward, the media invariably brings forward them as a carbon dioxide sink. While oxygen production and carbon dioxide removal are undoubtedly of major importance in combatting climate change, and planting trees because of this an important deed, the importance of forests and consequently planting trees is not restricted to that.
Recent studies indicate that rain is not only the result of moist air rising up from water (mainly seas but also lakes) but also caused by the evaporation from trees. The evaporation gives out moisture and keep the vicinity much moister than if the forests are cut. Cutting trees dries up the environment, and as a result the fertility of land decreased. Initially, only small effects are seen, but after a tipping point is reached a green forest can turn into a dry area, not able to sustain a further forest growth. This is envisioned as the first possible nightmare resulting from forest clearing in Amazonas.
Many areas which are now desert or semidesert had large forests not so long ago. The flag of Lebanon has a tree. About two thousand years ago the land was filled with huge forests. The trees were cut to make ships, and once enough trees were cut, the tipping point was reached, and the environment became too dry for the growth of trees. Many semi-desert areas in Sahara were the home of rich African culture until the trees were cut down.
So, planting trees, and making certain that they continue to grow to forest may be important to increase the moisture of nearby areas, and should be supported because of this in addition to being important for carbon dioxide removal. Also, clearing forests should be stopped both because of carbon dioxide and because of water balance. Although the clearest examples are from tropical areas because of their high temperatures, making the changes in moisture rapid, forest clearing dries up environment also in temperate areas.Thus, in addition to being carbon dioxide sinks, forests are important in maintaining wter balance.