The earth is losing its ability to store carbon, as rainforests are cut and burned to grow food, according to a study co-authored by a University of Minnesota professor.
The study's co-author, Jonathan Foley, who is the director of the university's Institute on the Environment, said it would be better to make farming more efficient on existing agricultural lands than expand farmland into the forest.
Burning a rainforest to clear land for crops puts out a lot of greenhouse gases. Cropland is not nearly as good at storing carbon as the forest was. It's also not very good at producing crops.
"What this really is about is the tradeoff between the need to grow food, which we absolutely need to do, but also to take care of the environment at the same time, and looking to avoid regions where we cause more harm than we create good," he said.
Foley says Russia and Eastern Europe have a lot of farmland that could be made more efficient.
The study was published online in the Proceedings of the National Academy of Sciences.