Planting Trees in Wrong Places Worsens Global Warming

On Tuesday, scientists revealed that planting trees in unsuitable locations can exacerbate global warming. However, a newly developed map pinpoints optimal areas for reforestation, which can help in cooling the planet.

Trees play a crucial role in absorbing carbon dioxide, and efforts to restore degraded woodlands or expand forested areas are important strategies in combatting climate change.

However, a study published in the journal Nature Communications reveals that in certain situations, increasing tree cover can have unintended consequences. More trees can lead to reduced reflection of sunlight from the Earth’s surface, resulting in increased heat absorption by the planet.

Advancements in Understanding the Impact of Tree Restoration on Albedo

Susan Cook-Patton, a co-author of the study, explained that while scientists were aware of the impact of tree restoration on albedo (the reflection of solar radiation), they lacked the tools to accurately account for it. By utilizing new maps, researchers were able to incorporate both the cooling effect of trees and the warming effect caused by changes in albedo for the first time.

The study found that previous projects which neglected to consider albedo overestimated the climate benefits of tree planting by 20 to 80 percent. Cook-Patton emphasized that these maps offer valuable insights for policymakers, enabling them to prioritize areas where resources can be most effectively utilized to achieve maximum climate impact. She serves as the senior forest restoration scientist at The Nature Conservancy.

“We’re also identifying numerous locations where enhancing tree cover remains a beneficial strategy for addressing climate change. Our aim is to assist individuals in identifying these suitable areas,” she stated.

Return on investment

Albedo is at its peak in the frigid regions of the world, where pristine snow and ice act like mirrors, reflecting up to 90 percent of the sun’s energy. It serves as a significant cooling mechanism for the Earth, along with landmasses and oceans that absorb excess heat and greenhouse gas emissions, contributing to the planet’s warming.

Despite the pledges of numerous countries to plant billions of trees as a means to combat global warming, this study suggests that not all tree-planting efforts offer equal benefits to the planet. Moist, tropical environments such as the Amazon and Congo Basin, characterized by high carbon storage and minimal changes in albedo, emerge as optimal regions for forest restoration.

Conversely, temperate grasslands and savannas exhibit the opposite characteristics, with lower carbon storage and significant changes in albedo, making them less favorable for forest cover restoration efforts, according to Cook-Patton.

Tree-Planting Projects’ Anticipated Cooling Reduced by 20% Due to Albedo Changes

Even in the most favorable locations, tree-planting projects are likely delivering approximately 20 percent less cooling than anticipated once adjustments for changes in albedo are considered, she noted.

However, she emphasized that restoring forests brings indisputable advantages for both people and the environment, including ecosystem support and the provision of clean air and water, among others.

“We don’t intend for our research to criticize the overall movement,” she explained.

“But we can’t plant trees everywhere. There are limitations in terms of funding, time, resources, manpower, and seedlings available. Therefore, it’s crucial to optimize limited investments and achieve the highest climate impact per unit of investment,” she concluded.

Read the original article on: Science Alert

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