Emissions of planet-warming nitrous oxide gas rose 40% between 1980 and 2020, says study

While India has the lowest per capita emission of 0.8 kg N2O/person, the kg N2O/person figures for the other top emitters are China 1.3, US 1.7, Brazil 2.5 and Russia 3.3. (Wikimedia Commons)

High levels of nitrous oxide in the atmosphere can deplete the ozone layer and compound effects of climate change, the study said. On the earth, excess nitrogen contributes to soil, water and air pollution.

Agricultural production and livestock rearing were the two key human-driven sources of nitrous oxide. In the last decade agricultural production, chiefly owing to the use of nitrogen fertilisers and animal manure, contributed to 74 per cent of the total anthropogenic nitrous oxide emissions, according to the study.

“Agricultural emissions reached 8 million metric tons in 2020, a 67 per cent increase from the 4.8 million metric tons released in 1980,” said the study.

The world’s farmers used 60 million metric tonnes of commercial nitrogen fertilisers in 1980. By 2020, the sector used 107 million metric tonnes. That same year, animal manure contributed 101 million metric tonnes for a combined 2020 usage of 208 million metric tonnes, as per the study.

Among the 18 regions considered in this study, only Europe, Russia, Australasia, and Japan and Korea had decreasing nitrous oxide emissions. Europe had the largest rate of decrease between 1980 and 2020, resulting from reduced fossil fuel and industry emissions. China and South Asia, on the other hand, had the largest increases in nitrous oxide emissions from 1980 to 2020 at 92 per cent.

“Nitrous oxide emissions from human activities must decline in order to limit global temperature rise to 2 degrees Celsius as established by the Paris Agreement,” said the report’s lead author, Hanqin Tian, the Schiller Institute Professor of Global Sustainability at Boston College. “Reducing nitrous oxide emissions is the only solution since at this point no technologies exist that can remove nitrous oxide from the atmosphere.”

Nitrous oxide is also emitted from natural sources such as oceans, inland water bodies and soil. These sources contributed to 11.8 per cent of the global emissions of the gas between 2010 and 2019. Agriculture activities and related waste generation, biomass burning, fossil fuels and industries together contributed to around six per cent of the global nitrous oxide emissions in 2010-2019, the study noted.

The study involved examination of global data for all major economic activities that lead to nitrous oxide emissions and 18 anthropogenic and natural sources and three absorbent “sinks” of global nitrous oxide.

The Global Carbon Project analyses the impact of human activity on greenhouse gas emissions and earth systems and quantifies emissions of carbon dioxide, methane and nitrous oxide—three major planet-warming gases—to inform public policy and international action.