Fertilizer Use Driving Rapid Rise in Potent Nitrous Oxide Emissions

A woman applies fertilizer on a maize crop in Kenya.

A woman applies fertilizer on a maize crop in Kenya. B. Das/CIMMYT

Emissions of nitrous oxide (N2O) have surpassed projections by the Intergovernmental Panel on Climate Change (IPCC), jeopardizing the goals of the Paris Agreement. In a recent study published in the journal Nature, an international team of scientists discovered that N20 emissions are increasing at a faster rate than any other type of greenhouse gas emission, mainly due to a rise in nitrogen fertilizer application for food production.

Not only does nitrous oxide have 300 times more heat-trapping power than carbon dioxide, it also depletes the stratospheric ozone layer, which protects the Earth from most of the sun’s ultraviolet radiation. N2O persists in the atmosphere an average of 114 years and creates a positive climate feedback in which climate change enhances N2O emissions from soils. Industrial processes, fuel combustion, agriculture, and other human activities such as wastewater treatment are responsible for N2O emissions, though nitrous oxide is also naturally present in the atmosphere.

The new study aimed to create a comprehensive assessment of global sources and sinks of nitrous oxide, since previous assessments failed to account for natural sources of N2O or failed to gather sufficient data from South American and African nations. The research, led by scientists at Auburn University, found that nitrous oxide has risen 20 percent from pre-industrial levels, from 270 parts per billion (ppb) to 331.

“This new analysis calls for a full-scale rethink in the ways we use and abuse nitrogen fertilizers globally,” Josep Canadell, a climate scientist at the Commonwealth Scientific and Industrial Research Group (CSIRO) in Australia and coauthor of the study, said in a statement.

The growing demand for food and livestock feed is the dominant driver of the N2O increase, the report found, with farmers increasingly relying on synthetic nitrogen fertilizer to boost productivity. Emerging economies in Asia, Africa, and South America are the largest contributors to global nitrous oxide emissions, the study found.

Genevieve Tarino