(AFP) – Planting trees, a classic tool in the fight against global warming, may have the opposite effect if it turns bright areas that reflect the sun’s energy into dark forest that absorbs it, warns a study published Tuesday that maps places suitable for reforestation .
By absorbing carbon dioxide, trees play a vital role in absorbing greenhouse gases from human activity that cause global warming.
But reforestation also has the effect of reducing albedo – the surface’s ability to reflect solar radiation – to a maximum on snow-covered land and to a minimum on water bodies or forests.
A study published in the journal Nature Communications shows that afforestation projects that do not factor albedo into the equation overestimate the climate benefits of additional trees planted by 20 to 80%.
“There are places where putting trees back has a net negative effect on the climate,” study co-author Susan Cook-Patton told AFP.
At a time when many countries have pledged to plant billions of trees, the maps provided by this study should help policymakers determine the best places for reforestation with the maximum impact on limiting global warming, explains a forest restoration researcher.
Humid and tropical environments such as the Amazon and Congo allow for high carbon storage with only a small reduction in albedo, making them ideal sites for reforestation.
Conversely, afforestation of temperate grasslands and savannas would be counterproductive, explains Ms Cook-Patton.
“We really don’t want our work to be a general critique of the global afforestation movement,” insists the researcher, emphasizing the undeniable benefits for people and the planet, particularly through improving air quality and some water.
“But we can’t plant trees everywhere. We don’t have enough money, time, resources, people or seeds. So it’s about making the most of limited investment and getting the best climate return per hectare of investment,” concludes Ms. Cook. -Patton.