Enlarge / We'd like to replace you with a forest. (credit: Peter Cade) By shifting to more plant-rich diets, wealthy nations could cut their agricultural emissions by 61 percent—and sequester nearly 100 gigatons of CO2 equivalent if the surplus farmland is left to rewild. The global food system is the second-biggest source of anthropogenic greenhouse gases (GHGs), accounting for up to a third of emissions.