Planting too many trees can do more harm than good. The Verge has said this again and again with tree-planting schemes becoming a popular way for brands to paint themselves green. A big part of the problem was an initiative to plant a trillion trees spearheaded by the World Economic Forum and backed by a contested study from the Crowther Lab at ETH Zurich. Apparently, the lab’s namesake, Thomas Crowther, took the stage during the recent United Nations climate conference to push countries to protect existing forests instead. “If no one had ever said, ‘Plant a trillion trees,’ I think we’d have been in a lot better space,” Crowther tells Wired.