The growing use of nitrogen fertilisers in the production of food worldwide is increasing concentrations of nitrous oxide — a greenhouse gas 300 times more potent than carbon dioxide — which remains in the atmosphere longer than a human lifetime. Rising nitrous oxide emissions are jeopardising climate goals and the Paris Accord, a study published in Nature, and led by an Auburn University researcher, has found.
This finding is part of a study co-led by professor Hanqin Tian, director of the International Center for Climate and Global Change Research at Auburn University’s School of Forestry and Wildlife Sciences, and Andrew Carnegie Fellow. The study was published on Wednesday in Nature, the world’s most highly-cited interdisciplinary science journal.
Tian co-led an international consortium of scientists from 48 research institutions in 14 countries under the umbrella of the Global Carbon Project and the International Nitrogen Initiative. The objective of the study, titled ‘A comprehensive quantification of global nitrous oxide sources and sinks,’ was to produce the most comprehensive assessment to date of all sources and sinks of the potent greenhouse gas nitrous oxide.
The study points to an alarming trend affecting climate change: Nitrous oxide has risen 20 per cent from pre-industrial levels and its growth has accelerated over recent decades due to emissions from various human activities.
“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,” Tian said. “There is a conflict between the way we are feeding people and stabilising the climate.”
The study also determined that the largest contributors to global nitrous oxide emissions are countries in East Asia, South Asia, Africa and South America.
Emissions from synthetic fertilisers dominate releases in China, India and the US, while emissions from the application of livestock manure as fertiliser dominates releases in Africa and South America, the study found. The highest growth rates in emissions were found in emerging economies, particularly Brazil, China and India, where crop production and livestock numbers have increased.
The co-authors agreed that the most surprising result of the study was the finding that current trends in nitrous oxide emissions are not compatible with pathways consistent to achieve the climate goals of the Paris Climate Agreement, or Paris Accord.
Signed by 195 nations, the agreement aims to strengthen the global response to the threat of climate change by keeping the global temperature rise in the 21st century well below 2 degrees Celsius above pre-industrial levels, and to pursue efforts to limit the temperature rise even further, to 1.5 degrees Celsius.
“Current emissions are tracking global temperature increases above 3 degrees Celsius, twice the temperature target of the Paris accord,” said Robert Jackson, a professor and co-author from Stanford University, and chair of the Global Carbon Project.
Experts have said that these findings underscore the urgency of the issue, and the need to find opportunities to mitigate nitrous oxide emissions worldwide to avoid the worst of climate impacts.
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