Ecological dimensions of agricultural intensification and extensification across regions

Agriculture currently causes >35% of greenhouse gas emissions and most land clearing. The impacts of doubling crop demand depend on how agriculture expands. About 4-times more greenhouse gas would be released by extensification (land clearing) than by intensification on the already-cleared lands of low-yielding nations. Intensification also prevents destruction of about 800 million hectares of tropical forest and savanna. Although nitrogen fertilizer also causes eutrophication, precise application of nitrogen can decrease its use with no harm to yields, as recently achieved in Mexico, Germany and other nations. Higher yields on existing croplands of under-yielding nations offer immense environmental benefits.