Earth and Habitat (Commonwealth Union) _ Nitrous oxide (N2O), a potent greenhouse gas, has seen a dramatic increase in emissions over the past four decades, largely due to human activities. This is the alarming finding from the Global Carbon Project’s second “global nitrogen budget,” published in Earth System Science Data. The study highlights the urgent need to address N2O emissions to meet global climate goals, particularly those outlined in the Paris Agreement.
The research reveals that nitrous oxide emissions from human activities have risen by 40% since 1980. This increase is partly driven by the growing global demand for meat and dairy, which necessitates more nitrogen fertilizers and manure management in agriculture. As a result, human-caused emissions now account for 35% of total nitrous oxide emissions, with natural sources like ocean and soil microorganisms contributing the remaining 65%.
The lead author, Prof. Hanqin Tian from Boston College, warns that continuing emissions at current rates will significantly hinder efforts to limit global warming to “well below” 2°C. The study finds that nitrous oxide concentrations in the atmosphere have risen faster in the past three years than at any time since 1980, surpassing even the highest projections for future emissions.
Nitrous oxide is around 270 times more potent than carbon dioxide (CO2) as a greenhouse gas and is the third-largest contributor to climate change, following CO2 and methane. Despite its significant impact, nitrous oxide often receives less attention. Prof. Dave Reay from the University of Edinburgh, who was not involved in the study, emphasizes that every missed opportunity to cut nitrous oxide emissions moves the world further from achieving climate goals.
Agriculture is the main driver of increased human-caused nitrous oxide emissions, responsible for 74% of these emissions between 2010 and 2019. While agricultural emissions have surged, those from fossil fuels and industry have slightly decreased over the same period. Cutting nitrogen use in agriculture is complex, involving food production, security, and environmental issues. However, reducing nitrogen use can benefit climate change mitigation, food production, air and water quality, and biodiversity.
The study examines nitrous oxide emissions in 18 regions, noting significant increases in countries like China, India, and Brazil. China alone accounted for 40% of the overall increase in global human-caused emissions between 1980 and 2020. Conversely, regions like Europe, Russia, and Australia have seen decreases in emissions due to improved nitrogen use efficiency and reductions in fossil fuel and industrial emissions.
The researchers compared current nitrous oxide emissions with future climate projections, finding that recent emissions have exceeded even the highest projected levels. This underscores the urgent need for better monitoring and reduction strategies. The study calls for a global network to better track and model nitrous oxide emissions, which Prof. Reay supports, noting the potential for improved reporting and emission reduction efforts ahead of COP30 in Brazil next year.
The rise in nitrous oxide emissions poses a significant threat to global climate goals. Addressing these emissions requires coordinated efforts to improve nitrogen use efficiency, particularly in agriculture, and robust monitoring systems to track progress. The findings of this study serve as a critical reminder of the urgent need to act on all fronts of greenhouse gas emissions to protect our climate.
