Researchers estimate that between 44% and 57% of all greenhouse gas emissions (GHGs) come from the global food system. Agriculture and deforestation caused by agriculture account for 26-33% of total emissions, is making it one of the major contributors of climate change.

Chemical fertilisers are the main source of climate-changing gases. No country uses them more than China, which now accounts for a third of global fertiliser use. These are mostly nitrogen fertilizers, which are produced from coal. A Chinese farmer applies over 600 kilogrammes of chemical fertilisers per hectare - more than triple of a farmer in Brazil and nearly five times more that the one used in the US, where fertilizers' use is also a growing problem. 

Furthermore, only a third of the nitrogen fertilizer applied to China's wheat and rice crops is absorbed by plants. The rest ends up in rivers or in the atmosphere.