Nitrous oxide emissions rise with climate threat: study June 13, 2024

The vast majority of nitrous oxide emissions are generated by agriculture, with most of the blame going to nitrogen-based fertilizers and animal waste (William WEST)

By AFP - Agence France Presse

Nitrous oxide emissions rise with climate threat: study

Global emissions of nitrous oxide - a potent greenhouse gas - are exceeding expectations and putting climate change targets at risk, according to a major study published on Wednesday.

Based on millions of atmospheric measurements from around the world, the report revealed a sharp increase in human-related nitrous oxide levels.

The findings have raised concerns among researchers that too little is being done to control the gas, the vast majority of which is produced by agriculture.

Nitrous oxide warms the Earth's atmosphere 300 times more effectively than carbon dioxide, according to scientists, and could remain for more than a century.

Emissions increased by 40% in the four decades to 2020, according to the Global Nitrous Oxide Budget, which drew on the expertise of 58 international researchers.

As a result, levels of the gas in the atmosphere rose to 336 parts per billion in 2022, a 25% increase from pre-industrial levels.

The increase was much higher than previous predictions by the UN's panel of climate scientists, the IPCC, said the report's lead author, Hanqin Tian of Boston College.

Nitrous oxide emissions must fall if global warming is to be limited to the Paris Agreement's target of 2 degrees Celsius, Tian said.

“Reducing nitrous oxide emissions is the only solution because so far there are no technologies capable of removing nitrous oxide from the atmosphere.”

Nitrous oxide, or laughing gas, is one of the three main greenhouse gases, along with carbon dioxide and methane, that contribute to man-made climate change.

It also pollutes the soil, water, and air and reduces the ozone layer.

- The main culprit is agriculture.

“This increase in emissions is occurring when global greenhouse gases should be declining rapidly towards net zero emissions if we have any chance of avoiding the worst effects of climate change,” said Tian.

Agriculture is the biggest offender, accounting for almost three-quarters of human-related, or anthropogenic, nitrous oxide in the 10 years to 2020, according to the report.

Other culprits were fossil fuels, waste and wastewater, and the burning of biomass.

In the four decades to 2020, agricultural emissions of the gas increased by 67%, according to the report, with most of the blame going to nitrogen-based fertilizers and animal waste.

Although there are global policies to reduce other greenhouse gases, nitrous oxide emissions are increasing almost unchecked, said Pep Canadell, co-leader of the study.

“We need to be more aggressive with nitrous oxide - we don't have policies anywhere and efforts are very limited,” said Canadell, chief researcher at Australia's national science agency, CSIRO, in an interview with AFP.

The UN's Intergovernmental Panel on Climate Change has estimated that nitrous oxide is responsible for 6.4% of total greenhouse gas emissions.

This figure is expected to rise in the coming years.

However, for global warming to remain below 2ºC, anthropogenic nitrous oxide emissions need to decrease by around 20% by 2050, according to a new study.

- Farmers are taking action

China, India, the United States, Brazil, Russia, Pakistan, Australia, and Canada were the biggest emitters of nitrous oxide, driven in part by the rapid growth of their populations and increased demand in the food sector, according to the report.

Europe, once the world's biggest nitrous oxide emitter, has achieved the biggest reduction by cutting its use of fossil fuels. Its emissions related to agriculture are also decreasing slowly.

Emissions in Japan and South Korea have also fallen.

New policies to limit nitrous oxide emissions could take up to 10 years to take effect, said Canadell.

However, many farmers were already trying to reduce their emissions, including through more precise use of nitrogen fertilizers, genetic modification of crops, better management of animal waste, and more sustainable farming practices.

“If these emissions are reduced at any level, it will have a huge impact,” said Canadell.

lec/djw/mtp