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What if we stopped cutting down forests to produce palm oil and cattle? What if we grew new forests on vacant city lots, old industrial buildings — even golf courses?

For the first time, scientists have sought to quantify this thought experiment. How many trees could be planted on every available parcel of land on Earth , where they could go, and what impact could that have on our survival ?

They concluded that the planet could support nearly 2.5 billion additional acres of forest without shrinking our cities and farms, and that those additional trees, when they mature, could store a whole lot of the extra carbon — 200 gigatons of carbon, to be precise — generated by industrial activity over the last 150 years.

Parts of the study — led by researchers at ETH Zurich, a university that specializes in science, technology and engineering — were immediately criticized.