Study: Planting trees in the “wrong places” exacerbates global warming

France – Scientists have revealed that planting trees in the “wrong places” could actually contribute to global warming, so they have developed a new map identifying the best locations to replant forests and cool the planet.

Because trees absorb carbon dioxide, restoring degraded forest areas or planting seedlings to enhance forest cover is one tool to combat climate change.

But in some cases, more trees mean less sunlight is reflected from the Earth’s surface and the planet absorbs more heat, according to the study published in the journal Nature Communications.

“There are some places where bringing back trees leads to net negative climate outcomes,” study co-author Susan Cook Patton told AFP.

She pointed out that scientists already understood that restoring forest cover led to changes in reflectivity (albedo), which is the ability of an object to reflect light falling on it from a light source such as the sun, but they did not have the tools necessary to explain this.

Using new maps, scientists were able for the first time to look at the effect of cooling caused by trees and warming caused by reduced albedo.

They found that projects that did not factor albedo into the equation overestimated the climate benefits of additional trees by 20 to 80 percent.

The maps also provide tools to help policymakers determine the best places to direct scarce resources to maximize climate impact, said Cook Patton, senior forest restoration scientist at The Nature Conservancy.

“There are a lot of places where restoring forest cover is still a great climate change idea,” she added. “We’re just trying to help people find those locations.”

Albedo is usually higher in frozen regions of the world, and clean, mirror-like snow and ice with high levels of albedo reflect up to 90% of the sun’s energy.

It is one of the Earth’s main cooling agents, along with land and oceans that absorb excess heat and greenhouse gas emissions that cause global warming.

This study showed that many countries have promised to plant billions of trees as a bulwark against global warming, but not all efforts pay off equally for the planet.

Humid tropical environments such as the Amazon Basin and the Congo are characterized by high carbon storage and low changes in albedo, making them ideal sites for restoring forest cover.

Patton revealed that planting trees, even in the best locations, may have provided 20% less cooling than estimated when changes in albedo were taken into account.

She stressed that forest restoration has brought undeniable benefits to people and the planet, such as supporting ecosystems and providing clean air and water, among many.

She continued: “We don’t really want our work to be a criticism of the movement in general. But, we cannot plant trees everywhere. We don’t have enough money, time, resources, people or seedlings. “It is really about making the most of limited investments and getting the greatest climate return per hectare of investment.”

Source: ScienceAlert