Planting trees and replenishing forests are among the simplest and most appealing natural climate solutions, but the impact of trees on atmospheric temperature is more complex than meets the eye.
One question among scientists is whether reforesting midlatitude locations such as North America or Europe could in fact make the planet hotter. Forests absorb large amounts of solar radiation as a result of having a low albedo, which is the measure of a surface’s ability to reflect sunlight. In the tropics, low albedo is offset by the higher uptake of carbon dioxide by the dense, year-round vegetation. But in temperate climates, the concern is that the sun’s trapped heat could counteract any cooling effect forests would provide by removing carbon dioxide from the atmosphere.
But a new study from Princeton University researchers found that these concerns may be overlooking a crucial component — clouds. They report in the Proceedings of the National Academy of Sciences that the denser cloud formations associated with forested areas means that reforestation would likely be more effective at cooling Earth’s atmosphere than previously thought.