Nitrous oxide emissions are a growing threat to human and planetary health

The 2024 United Nations Global Nitrous Oxide Assessment, unveiled at COP29 in Baku, Azerbaijan, highlights the accelerating impact of nitrous oxide (N₂O) emissions on climate change and the ozone layer. 

Conducted by the United Nations Environment Program (UNEP) and the Food and Agriculture Organization (FAO), the report raises serious concerns about the rapid rise in N₂O emissions, emphasizing that immediate action is required to mitigate its severe environmental and health consequences.

More potent than carbon dioxide

Nitrous oxide, a greenhouse gas approximately 270 times more potent than carbon dioxide in warming the planet, currently accounts for around 10% of net global warming since the start of the industrial era. 

While it’s predominantly released through agricultural practices like synthetic fertilizer and manure use, it’s also emitted by the chemical industry, making it the third most impactful greenhouse gas and the top ozone-depleting substance still entering the atmosphere.

N₂O emissions jeopardize climate goals

The report underscores that rising N₂O emissions jeopardize the ability to limit global warming to 1.5°C, warning that failure to reduce emissions could derail efforts to achieve the Paris Agreement’s climate targets. 

Without urgent action on rising N₂O emissions, there is no viable pathway to limiting global warming to 1.5°C, the report states, advocating for reductions that could lower emissions by over 40% from current levels.

The potential health impacts of unchecked N₂O emissions are equally alarming. Continued emissions could raise global UV exposure, leading to increased skin cancers and cataracts. 

Proactively addressing N₂O would also support the ozone layer’s recovery, which protects human health by reducing exposure to harmful ultraviolet radiation.

“Addressing nitrous oxide emissions is essential for ensuring sustainable, inclusive, and resilient agriculture that simultaneously helps countries achieve their climate and food security goals,” said Kaveh Zahedi, Director of FAO’s Office of Climate Change, Biodiversity, and Environment.

Reducing N₂O could prevent millions of deaths

In addition to its climate impact, reducing N₂O emissions would provide substantial public health benefits. The report estimates that simultaneously reducing N₂O, nitrogen oxides, and ammonia emissions could prevent up to 20 million premature deaths globally by 2050, largely due to improved air quality. 

By transforming agricultural practices and reducing excessive nitrogen use, societies could also improve water and soil quality, which are essential for ecosystem health.

“A sustainable nitrogen management approach not only reduces nitrous oxide emissions but also prevents the release of other harmful nitrogen compounds,” explained A.R. Ravishankara, Co-Chair of the Assessment and atmospheric scientist at Colorado State University. 

“This could improve air and water quality, protect ecosystems, and safeguard human health, all while maintaining food security.”

Pathways to reduce emissions 

The UN assessment outlines a series of cross-sectoral strategies to cut N₂O emissions significantly, including optimizing nitrogen use in agriculture and adopting cleaner practices in the chemical industry.

“Abating N₂O emissions could avoid up to 235 billion tons of CO₂-equivalent emissions by 2100 – this is equivalent to six years’ worth of current global carbon dioxide emissions from fossil fuels,” said David Kanter, Co-Chair of the Assessment and associate professor at New York University.

To achieve these reductions, the report advocates for a holistic approach to nitrogen management. By reducing nitrogen application and employing targeted fertilizer practices, the agricultural sector could decrease N₂O emissions while maintaining productivity. 

This would not only help to stabilize the climate but also reduce nutrient runoff that negatively impacts aquatic and terrestrial ecosystems.

Securing the ozone layer

The report emphasizes that reducing N₂O emissions would aid the recovery of the ozone layer, which has been a focus of global environmental protection since the Montreal Protocol’s inception. 

“The ozone layer is crucial for all life on Earth,” said Megumi Seki, Executive Secretary of the Montreal Protocol Ozone Secretariat. 

“For decades, parties to the Montreal Protocol have worked hard to safeguard it. This UN assessment highlights the need for continued vigilance, commitment, and action for the ozone layer to recover.”

Relatively forgotten super pollutant 

Martina Otto, head of the Secretariat of the UNEP Climate and Clean Air Coalition, stresses that immediate action could yield wide-ranging benefits across climate, air quality, and health. 

“This assessment sounds the alarm on a relatively forgotten super pollutant that contributes greatly to climate change and air pollution,” said Otto. “By using the abatement tools highlighted in the assessment that are already available to us, we can yield multiple benefits across climate, clean air, and health.”

The assessment calls for urgent implementation of these strategies, emphasizing that coordinated action to reduce N₂O emissions could bring about significant improvements in global health and environmental stability. 

With the tools and knowledge now available, governments, industries, and individuals can contribute to a cleaner, healthier planet, aligning efforts to meet critical climate, food security, and health goals.

The report can be found here.

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