Plant trees and the planet will thank you, right? Not always | Biodiversity

Planting trees is an important strategy to combat climate change, due to their ability to absorb carbon dioxide, a greenhouse gas that is one of the main causes of warming temperatures. However, as revealed by a study recently published in the scientific journal Nature Communications, when planting is done in an inappropriate location, it can cause more harm than good.

Scientists from Clark University in the United States, The Nature Conservancy (TNC) and ETH-Zurich highlight that tree cover can, in some places, heat the Earth instead of cooling it, affecting the amount of sunlight that reaches the surface reflects, that is, the albedo.

EuroNews notes that other work has previously found that restoring tree cover could lead to changes in albedo, but this is the first time that this specific phenomenon has been described in simple terms.

Now, using new maps, researchers have been able to consider the cooling effect of trees and the warming caused by the decrease in albedo. They found that previous work did not include albedo in the equation, and overestimated the climate benefit of additional trees by between 20% and 80%.

“The balance between carbon storage and the change in albedo resulting from tree cover restoration varies from place to place, but until now we haven’t had the tools to differentiate good climate solutions from bad ones,” said lead author Natalia Hasler, in communicated. “Our study aims to change that by providing the maps needed to empower smarter decisions while ensuring limited funding is directed to the places where tree cover restoration can make the most positive difference as a natural climate solution. ”

The new study also identified locations in every biome on Earth where the climate mitigation benefits of tree planting can be achieved, and the good news is that most of the thousands of projects underway around the world to restore tree cover are concentrated in these areas. areas of greatest opportunity.

However, even in these locations, changes in albedo are expected to offset the net climate benefit by at least 20% in about two-thirds of cases.

“We addressed a significant research gap and gained a much more complete picture of how tree cover restoration can impact our global climate – both positively and sometimes negatively,” emphasized co-senior author Susan Cook-Patton.

According to her, it is important to remember that there are many other good reasons to restore tree cover, even in places where the climate benefits are not great: clean water, resilient food production, wildlife habitat, etc.

“We are simply calling on governments and land managers to more carefully integrate albedo into their environmental decision-making, and we are making this robust new set of tools available to help them do so.”

A EuroNews report points out that humid tropical environments such as the Amazon Basin and the Congo Basin are perfect for reforestation, thanks to their high carbon storage and low changes in albedo. In temperate grasslands and savannas, in turn, the opposite happens.