Farm animals account for between 20% and 30% of global greenhouse gas (GHG) emissions. That figure includes the clearing of land to feed and graze the animals. Clearing land of trees, and cultivation, are the main drivers of farming emissions. Deforestation eliminates carbon sinks, accelerating the process of climate change. Cultivation, including the use of synthetic fertilisers, releases greenhouse gases such as nitrous oxide. Nitrogen fertiliser is especially demanding of fossil fuels, as producing a tonne of it takes 1.5 tonnes of oil.