Tree Planting Location Matters More Than Quantity for Cooling

Planting trees to fight climate change works best when we plant them in the right spots, according to groundbreaking research from ETH Zurich that challenges the "more is better" mindset.

Researcher Nora Fahrenbach and her team compared three different global tree planting scenarios to see which would cool the planet most effectively by 2100. What they found surprised even climate experts.

One scenario planted 926 million hectares of forest, mostly in tropical regions, and cooled Earth by 0.25°C. Another planted 894 million hectares but included northern areas like parts of Alaska and Siberia. Despite covering almost the same area, it only cooled the planet by 0.13°C.

The real eye-opener was the third scenario. Planting just 440 million hectares of strategically placed tropical and subtropical forest achieved the same 0.13°C cooling as nearly double that area planted elsewhere.

The reason comes down to basic physics. Trees in snowy regions actually make the land darker, causing it to absorb more sunlight and heat up. Meanwhile, tropical trees absorb carbon while keeping the land surface cooler through shade and water evaporation.

"We show that planting a trillion trees doesn't automatically mean more cooling," Fahrenbach explains. "Where you plant matters just as much, if not more."

The effects ripple across the entire planet too. The researchers found that planting trees in one location changes temperatures and wind patterns thousands of miles away, including over the Atlantic and Indian Oceans.

The Bright Side

Forest ecologist Emilio Vilanova from climate nonprofit Verra sees this research as a game changer for how we approach reforestation projects worldwide.

The findings mean we can achieve meaningful climate benefits with fewer resources by simply choosing better locations. Countries can now design smarter reforestation programs that maximize cooling while avoiding the unintended warming effects that come from planting in the wrong places.

Current international policies like the Paris Agreement focus almost entirely on how much carbon trees absorb. This research shows policymakers need to also consider the physical effects of changing the landscape, from albedo to wind patterns.

The cooling potential might seem modest at 0.13 to 0.25°C by century's end. But climate scientists stress that every fraction of a degree matters for preventing extreme weather, protecting ecosystems, and safeguarding human communities.

The message is clear: we can't plant our way out of climate change alone, but smart reforestation remains a powerful tool when we plant the right trees in the right places.