Rising nitrous oxide (N2O) emissions are jeopardizing the climate goals of the Paris Agreement, according to a major new study. The growing use of nitrogen fertilizers in the production of food worldwide is increasing atmospheric concentrations of the greenhouse gas N2O.
N20 is 300 times more potent than carbon dioxide (CO2) and remains in the atmosphere for more than 100 years. A major global study has now produced the most comprehensive assessment to date of all global sources and sinks of N2O.
Their findings show N2O emissions are increasing faster than any emission scenario developed by the Intergovernmental Panel on Climate Change (IPCC), consistent with greenhouse gas scenarios that lead to global mean temperature increases well above 3°C from pre-industrial levels. The Paris Agreement aims to limit warming to less than 2°C but ideally no more than 1.5°C.
N2O has risen 20 per cent from pre-industrial levels – from 270 parts per billion (ppb) in 1750 to 331ppb in 2018 – with the fastest growth observed in the last 50 years due to emissions from human activities.
Prof Hanqin Tian, director of the International Center for Climate and Global Change Research at Auburn University’s School of Forestry and Wildlife Sciences, co-led the study.
“The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions,” said Prof Tian in a statement. “There is a conflict between the way we are feeding people and stabilizing the climate.”
The study found that the largest contributors to global N2O emissions come from East Asia, South Asia, Africa and South America. Emissions from synthetic fertilizers dominate releases in China, India and the US, while emissions from the application of livestock manure as fertilizer dominates releases in Africa and South America.
The highest growth rates in emissions are in emerging economies, particularly Brazil, China and India, where crop production and livestock numbers have increased. However, N2O emissions in Europe decreased in agriculture and the chemical industry. This was due to a combination of factors, including voluntary measures to remove N2O from flue gases in the Nylon industry.
Photo credit: UN Photo/John Isaac