Planting trees is a key strategy in the fight against climate change. Trees absorb carbon dioxide, regulate temperature, support biodiversity, and improve air and water quality, offering benefits that extend well beyond their boundaries.
But according to a new study by researchers from University of California – Riverside, where those trees are planted makes a big difference. The study, which was recently published in the journal Climate and Atmospheric Science, found that tree plantings are almost always a net positive for the climate because trees pull CO2 out of the atmosphere. But the impact of trees on temperature varies a lot by region.
In tropical regions, trees deliver the biggest cooling benefits. They not only absorb carbon but also cool the air through a process called evapotranspiration. Roots draw water from the soil, and when it evaporates from the leaves, it cools both the tree and the air around it. This also raises humidity, which can lead to more clouds. Both effects block some sunlight from reaching the ground, which adds to the cooling.
The researchers estimated that tropical tree plantings could cool regions like central Africa by as much as eight-tenths of a degree Fahrenheit.
In contrast, planting trees at higher latitudes may have a slight warming effect. Darker tree canopies absorb more sunlight, which can offset some of the cooling. In some places, such as Canada and the northeastern U.S., trees may even increase fire risk. But this does not mean trees in those regions are unhelpful. They provide many other benefits for biodiversity, ecosystems, and the environment.
But one thing is clear: planting trees in the tropics offers the strongest returns for the climate.
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Trees in the tropics cool more, burn less
Photo, posted September 15, 2024, courtesy of Jan Helebrant via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio
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