The spread of intensive farming is threatening to jeopardise the world’s chances of meeting the terms of the Paris agreement on the climate crisis, as the increasing use of artificial fertiliser and growing populations of livestock are raising the concentration of a key greenhouse gas to levels far beyond those seen naturally.

Nitrous oxide is given off by the overuse of artificial fertilisers, and by organic sources such as animal manure, and has a heating effect 300 times that of carbon dioxide. Levels of nitrous oxide in the atmosphere are 20% higher than in pre-industrial times, with most of that increase coming from farming.

Emissions of nitrous oxide are growing at a rate of 1.4% a year, outstripping the forecasts of the Intergovernmental Panel on Climate Change, and left untrammelled would put the world on track to exceed the 2C warming limit set under the Paris agreement, according to a paper published in the journal Nature.
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Hanqin Tian, a professor at Auburn University in the US and lead author of the study, said: “The dominant driver of the increase comes from agriculture and the growing demand for food and feed for animals will further increase global nitrous oxide emissions. There is a conflict between the way we are feeding people, and stabilising the climate.”

Current rates of nitrous oxide emissions were consistent with 3C of global heating above pre-industrial levels, the researchers found.

Artificial fertilisers make up about two-thirds of the emissions of nitrous oxide from farming. The gas is released when microbes in the soil break down the excess fertiliser, particularly in boggy or over-wet ground where there is less oxygen.

Farmers can reduce the amount of nitrous oxide produced by simple measures such as targeting their fertiliser use more carefully, avoiding excess and using fertiliser only in the right weather conditions.

An estimated 820 million people did not have enough to eat in 2018, up from 811 million in the previous year, which is the third year of increase in a row. This underscores the immense challenge of achieving the Sustainable Development Goal of Zero Hunger by 2030, says a new edition of the annual The State of Food Security and Nutrition in the World report released today.