Aug 15, 2021 12:00:00

Simulation results are reported that 'planting increases precipitation', why forests rain?

As trees grow,

they absorb a lot of carbon dioxide and have the effect of lowering the ambient temperature, so it is said that tree planting is the most powerful countermeasure against global warming. New simulations by Swiss and British research teams have shown the possibility of 'increasing precipitation' by planting trees and increasing forests.

Empirical estimate of forestation-induced precipitation changes in Europe | Nature Geoscience
https://www.nature.com/articles/s41561-021-00773-6

Planting forests can increase rainfall and help fight drought in Europe, study shows
https://www.france24.com/en/europe/20210709-planting-forests-can-increase-rainfall-and-help-fight-drought-in-europe-study-shows

Bringing Back Forests Could Boost Summer Rainfall Across Europe by 7.6%, Study Shows
https://www.sciencealert.com/making-this-change-could-increase-summer-rainfall-in-europe-by-7-6

A research team led by Dr. Ronnie Meyer of the Institute of Atmospheric Climatology at the ETH Zurich has used statistical models trained with real-world observational data to explain the impact of planting trees on available farmlands in Europe. I analyzed it. Then, the simulation result was obtained that 'If 20% of the land judged to be available from satellite images is planted, the summer precipitation in Europe as a whole will increase by an average of 7.6%.'

'Our findings suggest that tree planting can cause significant changes in precipitation throughout Europe,' the research team wrote in a treatise. In addition, the rainfall that increases due to tree planting does not necessarily fall on the forest itself, and it seems that precipitation will increase even on the leeward side of the forest, especially during the summer. Also need to be considered carefully.

For example, in the southern half of France, tree planting could increase precipitation by 24% in winter and 13% in summer, but this is also affected by tree planting in areas other than southern France. It is a thing. Water availability is one of the most important climatic factors along with rising temperatures, so increasing precipitation due to tree planting is important in coping with climate change.

There are several possible reasons for the increase in precipitation due to the increase in forests, one of which is '

transpiration from leaves'. As a result of transpiration releasing a large amount of water from the forest into the air, a humid climate may be created and precipitation may increase.

Another factor that the research team cites is that 'forests have a larger surface roughness than agricultural land.' 'Forests generally have a larger surface roughness than farmland, which creates more eddy and slows the movement of air masses that cause rain,' the research team explains in a treatise.

On the other hand, the surface roughness of forests may also be involved in the phenomenon of reduced precipitation in areas leeward of forests in winter. 'Moist air masses and fronts coming from the ocean and the west may be slowed down by forests, which may have the effect of not reaching the interior of the continent,' Meyer said.

The findings provide policy makers with the benefits of implementing reforestation and warn of the disadvantages of forest loss. 'Our job as a scientist is to provide information so that policy makers can make informed decisions,' Meyer said. 'Our research is an effort to protect forests.' It can be seen as a small warning to, because the effects of forests can be reversed, and once forests are lost and precipitation is reduced, more and more forests are lost. ' Said.