Nitrous oxide human emissions increased 30% in 36 yrs: Report

Human emissions of nitrous oxide (N2O) — a greenhouse gas 300 times more potent than carbon dioxide (CO2) — increased by 30 per cent between 1980 and 2016, according to a research paper published in Nature October 7, 2020.

Nitrous oxide is a dangerous gas for the sustainable existence of humans on Earth. It has the third-highest concentration — after CO2 and methane — in our atmosphere among greenhouse gases responsible for global warming.

N2O can live in the atmosphere for up to 125 years.

Its global concentration levels increased from 270 parts per billion (ppb) in 1750 to 331 ppb in 2018 — a jump of 20 per cent. The growth has been the quickest in the past five decades because of human emissions.

The research was conducted through an international collaboration between the International Nitrogen Initiative (INI) and the Global Carbon Project of Future Earth, a partner of the World Climate Research Programme. It involved 57 scientists from 48 institutions in 14 countries.

“This is the most comprehensive study of global nitrous oxide emissions ever published, as it combines both natural and anthropogenic (man-made) sources,” said Nandula Raghuram, chair of INI and professor of biotechnology at Guru Gobind Singh Indraprastha University, New Delhi.

Source: Global Carbon Project

The study, which analysed 21 natural and human sources of N2O, found that 43 per cent of the total emissions came from human sources.

N2O is also the only remaining threat to the ozone layer, for it accumulates in the atmosphere over a long period of time, just like CO2. This is in addition to the fact that “right now, our emissions trajectory is higher than even the worst-case scenario anticipated”, said David Kanter, vice-chair of INI and aassistant professor at New York University.

The increase in its emissions means that the climatic burden on the atmosphere is increasing from non-carbon sources as well, while the major focus of global climate change negotiations is currently centred on carbon, its emissions and mitigation.

The paper also brought to the fore the dichotomy of the climate crisis and global food security: It found that a major proportion of the N2O emissions in the last four decades came from the agricultural sector, mainly because of the use nitrogen-based fertilisers.

“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,” said Hanqin Tian, lead author of the paper and professor, director of the International Center for Climate and Global Change Research at Auburn University’s School of Forestry and Wildlife Sciences, Alabama, United States.

Most N2O emissions have come from emerging countries like India, China and Brazil.

“The good news is that there are well-established practices and technologies to mitigate nitrous oxide emissions. Industrial and agricultural policies in Europe reduced such emissions considerably. Still, further efforts will be required, in Europe as well as globally,” said Wilfried Winiwarter, co-author of the study and a member of the INI steering committee.

“Moreover, reducing greenhouse gas emissions also has the co-benefits of reduced air and water pollution,” he added.

Raghuram and Kanter said it is possible to slow down N2O emissions if countries implement the 2019 United Nations resolution on sustainable nitrogen management.

India had led the first-ever nitrogen resolution adopted in the fourth UN Environment Assembly with the help of INI.

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