CHESTNUT HILL, Mass., June 11, 2024 (GLOBE NEWSWIRE) -- Emissions of nitrous oxide – a greenhouse gas more potent than carbon dioxide or methane – continued unabated between 1980 and 2020, a year when more than 10-million metric tons flowed into the atmosphere primarily through farming practices, according to a new report led by Boston College researchers for the Global Carbon Project.
Agricultural production accounted for 74 percent of human-driven nitrous oxide emissions in the 2010s – driven by chemical fertilizers and animal manure applied to croplands – according to the report “Global Nitrous Oxide Budget 1980-2020,” published today in the journal Earth System Science Data.
In an era when greenhouse gas emissions must decline to reduce global warming, nitrous oxide spewed into the atmosphere in 2020 and 2021 at the fastest rate in history. On Earth, excess nitrogen contributes to soil, water, and air pollution. In the atmosphere, it depletes the ozone layer and exacerbates climate change.
“Nitrous oxide emissions from human activities must decline in order to limit global temperature rise to 2°C as established by the Paris Agreement,” said lead author Hanqin Tian, Schiller Institute Professor of Global Sustainability at Boston College. “Reducing nitrous oxide emissions is the only solution since no technologies now exist that can remove nitrous oxide from the atmosphere.”
The concentration of atmospheric nitrous oxide reached 336 parts per billion in 2022, a 25 percent increase over pre-industrial levels that far outpaces predictions previously developed by the Intergovernmental Panel on Climate Change, said Tian, director of the Center for Earth System Science and Global Sustainability at BC’s Schiller Institute for Integrated Science and Society.
The top 10 nitrous oxide emission-producing countries are: China, India, the United States, Brazil, Russia, Pakistan, Australia, Indonesia, Turkey, and Canada, the researchers found.
Some countries have reduced nitrous oxide emissions. Emissions in China have slowed since the mid 2010s; as have emissions in Europe during the past few decades. In the U.S., agricultural emissions continue to rise while industrial emissions have declined slightly, steadying overall emissions, researchers found.
The world’s farmers used 60 million metric tons of commercial nitrogen fertilizers in 1980. By 2020, the sector used 107 million metric tons. That same year, animal manure contributed 101 million metric tons for a combined 2020 usage of 208 million metric tons.
Improved agricultural practices that limit the use of nitrogen fertilizers and animal waste can help reduce greenhouse gas emissions and water pollution. Tian said there is a need for more frequent assessments so mitigation efforts can target high-emission regions and activities. An improved inventory of sources and sinks will be required to meet climate policy goals.
Established in 2001, The Global Carbon Project analyzes the impact of human activity on greenhouse gas emissions and Earth systems, producing global budgets for the three dominant greenhouse gasses – carbon dioxide, methane, and nitrous oxide.
