Climate-Neutral Agriculture?

Abstract

Regarding the achievement of worldwide agricultural climate neutrality, the focus is on a worldwide net-zero emission of cradle-to-farmgate greenhouse gases (GHGs), while, when appropriate, including the biogeophysical impacts of practices on the longwave radiation balance. Increasing soil carbon stocks and afforestation have been suggested as practices that could be currently (roughly) sufficient to achieve agricultural climate neutrality. It appears that in both cases the quantitative contributions to climate neutrality that can actually be delivered are very uncertain. There is also much uncertainty about the quantitative climate benefits with regard to forest conservation, changing feed composition to reduce enteric methane emission by ruminants, agroforestry and the use of nitrification and urease inhibitors to decrease the emission of N2O. There is a case for much future work aimed at reducing the present uncertainties. The replacing of animal husbandry-based protein production by plant-based protein production that can reduce agricultural GHG emissions by about 50%, is technically feasible but at variance with trends in worldwide food consumption. There is a case for a major effort to reverse these trends. Phasing out fossil fuel inputs, improving nitrogen-use efficiency, net-zero GHG-emission fertilizer inputs and reducing methane emissions by rice paddies can cut the current worldwide agricultural GHG emissions by about 22%.