Key greenhouse emissions spike by 40 percent

Tractor spreading fertiliser. | Newsreel
N2O greenhouse gas emmisions are driven by the use of fertilizer in the agriculture sector. | Photo: Fotokostic

The human-induced emissions of a key greenhouse gas have increased by more than 40 percent in the past 40 years, according to new research.

The Global Nitrous Oxide (N₂O) Budget, released today, revealed that anthropogenic (human-induced) N₂O emissions had increased, with the period between 2020-2022 showing an accelerated rate of growth.

Dr Pep Canadell, from the CSIRO, said N₂O was one of the three key greenhouse gases, along with carbon dioxide and methane, contributing to climate change.

Dr Canadell said the paper was a core component of global greenhouse gas assessments, coordinated by the Global Carbon Project, and was authored by an international team of researchers, including CSIRO.

He said the report incorporated both natural and human-induced N₂O sources using data from 1980 to 2020.

“N₂O in the atmosphere contributes to global warming as well as depleting the ozone layer. It is a long-lived potent greenhouse gas and has been accumulating in the atmosphere since the pre-industrial period,” Dr Canadell said.

“Our report shows N₂O accumulation in the atmosphere has accelerated in the last four decades (with) growth rates over the past three years – from 2020-2022 – 30 per cent higher than any previously observed year since 1980.”

Dr Canadell said agricultural production, due to the use of nitrogen fertilisers and animal manure, contributed 74 percent of the total anthropogenic N₂O emissions in the last decade.

“This was followed by fossil fuels, waste and wastewater, and biomass burning.”

Dr Hanqin Tian, from Boston College, who led the study, said the report provided a comprehensive quantification of global N₂O sources and sinks in 21 natural and anthropogenic categories from countries across the globe.

“The once top emitter, Europe, has reduced its emissions since the 1980s by 31 percent, through industrial emission reductions. However, emerging economies have grown in response to growing population and food demand,” Dr Tian said.

“The top five country emitters by volume of anthropogenic N₂O emissions in 2020 were China (16.7 percent), India (10.9 percent), USA (5.7 percent), Brazil (5.3 percent), and Russia (4.6 percent).”

He said Australia’s anthropogenic N₂O emissions had been stable over the past two decades.

The Global Nitrous Oxide Budget was published in Earth System Science Data.