Planting trees in the wrong places can actually contribute to global warming

Scientists revealed on Tuesday that planting trees in inappropriate locations can exacerbate global warming, but a novel map has been devised to pinpoint the optimal areas for forest regeneration, which could help mitigate the planet's rising temperatures.

While trees are renowned for absorbing carbon dioxide and are a vital tool in combating climate change, there are instances where their proliferation can lead to unintended consequences. A study published in the journal Nature Communications highlighted that in certain scenarios, increased tree cover results in reduced sunlight reflection from the Earth's surface, causing the planet to absorb more heat.

Susan Cook-Patton, a co-author of the study, explained to AFP, "There are some places where putting trees back leads to net climate negative outcomes." Scientists had previously recognized the impact of reforestation on albedo—the reflection of solar radiation—but lacked the means to effectively account for it.

Utilizing innovative mapping techniques, researchers could now assess both the cooling effect of trees and the warming induced by changes in albedo simultaneously. Their findings revealed that projects overlooking albedo considerations overestimated the climate benefits of tree planting by a considerable margin—ranging from 20 to 80 percent.

Despite these challenges, the maps offer valuable insights for policymakers seeking to optimize resource allocation for maximum climate impact, emphasized Cook-Patton, who serves as the senior forest restoration scientist at The Nature Conservancy. She noted, "There's also lots of places still where restoring tree cover is a great idea for climate change. We're just trying to help people find those spots."

The study underscored the significance of albedo, particularly in frozen regions where pristine snow and ice exhibit high reflectivity, effectively cooling the planet. Conversely, moist tropical environments like the Amazon and Congo Basin were identified as ideal regions for forest restoration due to their high carbon storage and minimal changes in albedo. However, temperate grasslands and savannas exhibited contrasting patterns, posing challenges for reforestation efforts.

Cook-Patton emphasized that while the study sheds light on the complexities of tree planting initiatives, the undeniable benefits of forest restoration extend beyond climate mitigation, encompassing ecosystem support and provision of clean air and water. She stressed the importance of strategic resource allocation to maximize the climate benefits per hectare of investment, acknowledging the limitations in terms of funding, time, and resources available for such endeavors.