Restoration of the Earth's forests is the world's most effective solution to climate change available today, argues a new study in Science. The researchers calculate that reforesting 900 million hectares of land—an area about the size of the United States—would draw more than 200 gigatons of carbon from the atmosphere. Such extensive reforestation would reduce atmospheric carbon dioxide by 25 percent, essentially lowering it back to the level of a century or so ago. The researchers calculate that the additional tree cover could be added without affecting existing forests, agricultural land, and cities. The study finds that more than half the potential to restore trees can be found in just six countries: Russia (151 million hectares); the United States (103 million); Canada (78 million); Australia (58 million); Brazil (50 million); and China (40 million).
So much land reverting to nature would not only ameliorate the risks of climate change but also help protect and restore imperiled biodiversity.
The researchers in the Science article call for urgent global action. But it turns out that about half of their reforestation goals are already on the path to being realized as a result of market-driven technological progress that is boosting agricultural productivity.