Planting trees to save the environment has been chanted like a mantra for decades now, but the extent to which trees could actually make a difference was still not clear until recently when Tom Crowther, a professor of global ecosystem ecology at the Swiss Federal Institute of Technology in Zurich, published a study in Science that finally quantified what an investment in trees would have to offer.
The research explained that planting the right trees in the right places could reduce 205 gigatons of carbon dioxide in the atmosphere. The team studied over 80,000 satellite images of tree-cover worldwide. Pairing those photos with databases on climate and soil conditions helped them calculate that the earth could naturally support 4.4 billion hectares of forest. Next, they subtracted urban areas, land used for agriculture, and area already covered with forests, resulting in a calculated area of 0.9 billion hectares that can be forested, which hasn’t been utilized yet.
If all that area were reforested, in about 40 to 100 years, the carbon dioxide level in the atmosphere could be maintained at a level 205 gigatons lesser than it is now. While the results look promising, climate change could compromise forests’ ability to grow. Forests could also threaten water reserves in dry areas, or become a hurdle for people earning off herding or farming. With all such factors taken into consideration, Robin Chazdon, an ecologist and evolutionary biologist at the University of Connecticut, who was not involved in the study, says any replanting should begin as soon as possible.
All the new tree work, Chazdon says, signals that “we’re entering into the practicality stage” of smart reforestation. “We can bring a lot of interdisciplinary science to bear. I hope there will be more interaction between scientists and politicians, realizing that the tools we now have can guide reforestation that is the most cost-effective, and has multiple benefits and fewer tradeoffs.”