Taking into account both their direct and indirect impacts – including deforestation – agriculture and the world food system are currently responsible for nearly half of global warming. The aim of keeping global warming below 2°C implies drastically reducing net greenhouse-gas (GHG) emissions and then ending and reversing these in the second half of the 21st century. Agriculture has so far played only a minor role in international climate negotiations. However, the aim of keeping global warming below 2°C cannot be achieved without changes to agricultural practices and the food system. Climate change also poses a major threat for world food security. Agro-ecology will contribute to achieving targets for GHG emissions and ensure the adaptation of populations that are most affected by climate change. There is an urgent need to recognise this and anticipate remuneration policies for positive externalities of agriculture.