The simplest solution is to let tropical forests grow. Protect them from degradation and let them be. Older, larger tropical trees can absorb as much as 3 times more carbon than younger.

Time is short. Of the three largest rainforests on the planet, only one, in Africa’s Congo basin, remains a carbon sink and retains most of its accumulated carbon. A second, in Indonesia, has become a net source of carbon due to degradation and deforestation, and the third, in the Amazon basin, is teetering. Scientists estimate there is a temperature threshold for tropical forests beyond which they cease to function properly. According to model projections, the Amazonian forest will reach this threshold by 2040.