A tree planting in the Democratic Republic of the Congo. Axel Fassio / CIFOR
Though oft touted as a fix for climate change, planting trees could, in some regions, make warming more severe, a new study finds.
Trees draw down carbon dioxide from the atmosphere, helping to keep warming in check. But their dark, green leaves also absorb heat from sunlight. Snow and sand, by virtue of their light color, reflect more sunlight back into space. As such, trees planted in snowy areas or in the desert will absorb more sunlight than their surroundings, which may negate the climate benefits of soaking up carbon dioxide.
For a new study, scientists mapped the climate impact of tree planting across the globe, determining where it would be most and least beneficial. The study, published in Nature Communications, found that because of their low reflectivity, trees planted in arid, desert regions or in the snowy Arctic would, on balance, worsen warming.
Regions where tree planting would curb warming on balance are shaded in blue, while regions where tree planting would intensify warming are shaded in red. Hasler, et al.
The authors say that prior research into tree planting, which looked solely at how much carbon trees would draw down, grossly overstated how much warming plantings could prevent. They say the new study could help direct tree planting to those areas where it will do the most good.
Encouragingly, the new study showed, planting projects now underway or in the pipeline around the globe are largely concentrated in regions where they will help slow warming.
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