As heat records fall, experts call for reductions in this often-overlooked greenhouse gas

Last week, leading scientific organizations confirmed a long-anticipated reality: 2024 was officially the hottest year on record. This announcement reignited urgent calls for countries to address greenhouse gas emissions that are intensifying the climate crisis. Among these gases, experts highlighted nitrous oxide, an often-overlooked but highly destructive compound. Martina Otto, Head of Secretariat for the Climate and Clean Air Coalition at the United Nations Environment Programme (UNEP), emphasized its threat: “Nitrous oxide is not as well known by the public as some other greenhouse gases, but it can be a remarkably destructive substance.” She added, “The good news is that with strong policymaking and international cooperation, it is possible to slow emissions of this super pollutant – and save millions of lives around the world.”
Nitrous oxide, commonly known as laughing gas in medical contexts, becomes a super-pollutant at elevated levels. It traps heat in the atmosphere, exacerbating global warming, and breaks down the ozone layer, the Earth’s shield against harmful ultraviolet rays. The compound’s sources include natural processes, such as nitrification and denitrification in soil and water, but human activities are accelerating its emissions. Agriculture is the dominant contributor, responsible for 75% of human-made nitrous oxide emissions since 1980, primarily through overuse of nitrogen-based fertilizers. Industrial processes, fossil fuel combustion, and wastewater treatment account for the rest.
Alarmingly, nitrous oxide emissions are increasing faster than previously thought. A UNEP and Food and Agriculture Organization (FAO) report revealed that over 28 million tonnes of nitrous oxide were emitted in 2020, compared to an average of 17 million tonnes annually before the industrial revolution. This surge is largely attributed to the expanded use of synthetic fertilizers to support a growing global population.
While nitrous oxide ranks third among human-produced greenhouse gases, behind carbon dioxide and methane, its effects are disproportionately severe. David Kanter, co-chair of the Global Nitrous Oxide Assessment, explained, “It has been responsible for around 10 per cent of global warming since the industrial revolution.” Despite remaining in the atmosphere for about 120 years, far less than carbon dioxide, nitrous oxide traps 270 times more heat per tonne. Additionally, it is the most significant ozone-depleting substance not covered by the Montreal Protocol, underscoring its environmental impact.
Compared to carbon dioxide and methane, nitrous oxide receives less attention. Carbon dioxide is the primary driver of global warming and has long been a focus of climate activism. Methane, while short-lived, is 80 times more potent than carbon dioxide during its first 20 years in the atmosphere, and it contributes to at least one-third of current warming. Consequently, nitrous oxide has largely “fallen through the cracks,” according to Kanter. However, he stressed the importance of addressing all three gases to meet the Paris Agreement’s goal of limiting global warming to 1.5°C above pre-industrial levels. “Only through addressing all three of these greenhouse gases do we stand a chance of staving off the most devastating effects of climate change, from extreme heat, to droughts, to more frequent and more intense storms,” he said.
Countries can reduce nitrous oxide emissions through several strategies. Industrial emissions can be cut quickly and cost-effectively with existing technologies, potentially reducing emissions by 2.5 billion tonnes of carbon dioxide equivalent by 2050. In agriculture, optimizing fertilizer use and improving crop management are critical steps that could mitigate emissions without compromising food security. Nitrous oxide reduction targets can also be integrated into international climate agreements like the Paris Agreement.
The benefits of addressing nitrous oxide extend beyond climate mitigation. Otto highlighted the public health advantages, noting that reducing emissions would improve air quality and prevent deaths. Furthermore, protecting the ozone layer would decrease cases of skin cancer and cataracts caused by increased ultraviolet radiation. These measures represent an opportunity for nations to safeguard both the environment and human health through coordinated action.