Nitrous Oxide Emissions: Causes, Impacts, and Climate Solutions

By Abdul Ahad NazakatReviewed by Laura ThomsonJan 28 2026

Carbon dioxide (CO₂) and methane (CH₄) dominate the global climate conversation, leaving nitrous oxide (N₂O) frequently dubbed the "forgotten greenhouse gas." Despite its lower atmospheric concentration, its impact is disproportionately severe. According to the Global Nitrous Oxide Assessment 2024 published by the United Nations Environment Programme (UNEP) and the Food and Agriculture Organization (FAO), N₂O is currently the third most significant greenhouse gas and the primary driver of stratospheric ozone depletion.¹

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What Are Nitrous Oxide Emissions?

Nitrous oxide is a long-lived greenhouse gas produced through both natural and anthropogenic processes. It is naturally released by microbes in soils and oceans. However, human activities have significantly disrupted the nitrogen cycle.

Since the pre-industrial era, atmospheric levels have risen from approximately 270 parts per billion (ppb) to over 336 ppb in 2024.¹ Unlike short-lived pollutants, N₂O remains in the atmosphere for approximately 120 years, meaning the emissions released today will continue to affect the climate for over a century.

A Super Pollutant: Why Nitrous Oxide is a Critical Climate Concern

The climate concern regarding N₂O originates from its high Global Warming Potential (GWP). On a molecule-for-molecule basis, N₂O is approximately 270 times more effective at trapping heat than CO₂ over a 100-year period.¹ While CO₂ is emitted in much larger quantities, the sheer potency and longevity of N₂O make it a "super pollutant” and the most significant ozone-depleting substance (ODS) currently being emitted.

While the Montreal Protocol successfully phased out chlorofluorocarbons (CFCs), N₂O remains largely unregulated. It reacts in the stratosphere to produce nitrogen oxides that catalytically destroy the ozone – a layer protecting life on Earth from harmful ultraviolet (UV) radiation.¹

Distinguishing N₂O from NO_x

It is essential to distinguish between N₂O and nitric dioxide (NO_x). While they are often co-emitted, they play different roles. NOx gases are short-lived air pollutants that contribute to smog, acid rain, and ground-level ozone, which harm human respiratory health. In contrast, N₂O is a well-mixed greenhouse gas. While NO_x does not have the same direct long-term GWP as N₂O, its presence in the lower atmosphere influences the formation of other climate-active compounds.^{1, 2}

Agriculture and N₂O Pollution

Agriculture is the largest contributor to N₂O pollution, accounting for approximately 75 % of anthropogenic emissions.¹ This is primarily driven by the use of synthetic nitrogen fertilizers and the management of livestock manure.

When nitrogen fertilizers are applied to crops, soil microbes undergo nitrification and denitrification. If the nitrogen application exceeds what the plants can absorb, a common occurrence in many industrial farming systems, a significant portion is lost to the atmosphere as N₂O.

Further Reading: An Overview of Sustainable Fertilizer Developments

Research indicates that N₂O emissions are accelerating faster than previously projected due to the global expansion of intensive agriculture.² Manure management contributes an additional 10 % of agricultural emissions, particularly through storage and spreading practices.¹

Industrial and Urban Sources of N₂O

Beyond agriculture, industrial processes account for around 5 % of global anthropogenic emissions. The chemical industry, specifically the production of adipic acid (used in nylon and foam) and nitric acid (used in fertilizers and munitions), produces N₂?O as an unintended byproduct.¹

Wastewater treatment is another growing source. The biological processes used to remove nitrogen from sewage can release N₂?O if treatment plants are not optimized. In the United States, N₂?O emissions from wastewater increased by 42 % between 1990 and 2019 due to population growth and high-protein diets.¹ Additionally, while vehicle emissions have been reduced through catalytic converters, these devices can sometimes inadvertently increase N₂O output as a byproduct of reducing NO_x?.¹

Measurement and Monitoring of N₂O

Accurately measuring N₂?O is challenging because emissions are highly variable across space and time. Scientists use two primary methods:

1. Bottom-up estimates: Using inventory data (such as fertilizer sales and livestock numbers) and small-scale flux measurements from soil chambers.¹
2. Top-down estimates: Using atmospheric measurements from global monitoring networks and satellites to track concentrations and use chemical transport models to trace them back to sources.¹

Recent studies suggest that bottom-up inventories often underestimate emissions, particularly in regions with high nitrogen inputs, underscoring the need for more granular satellite data and better modeling of soil microbial responses.^2,3

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Pathways to Reduction and Clean Technologies

The Global Nitrous Oxide Assessment identifies that a 40 % reduction in anthropogenic emissions is possible by 2050 using existing technologies.¹

Precision agriculture

Adopting the "4R" framework, applying the right fertilizer at the right rate, right time, and right place, can significantly reduce nitrogen waste. Tools such as soil-nitrogen testing and variable-rate technology allow farmers to match fertilizer application with real-time crop needs.¹

Green fertilizers and inhibitors 

The use of nitrification inhibitors can slow the microbial conversion of nitrogen in the soil, keeping it available for plants longer and reducing N₂O release. Furthermore, transitioning to "green ammonia", produced using renewable energy rather than natural gas, reduces the carbon footprint of the fertilizer production process itself.³

Industrial abatement

This is considered the "low-hanging fruit" of N₂O mitigation. Thermal destruction and catalytic reduction technologies can eliminate up to 99 % of N₂O emissions from adipic and nitric acid plants at a relatively low cost (USD 6–22 per ton of CO₂ equivalent).¹

Global Policies and Agreements

Currently, N₂O is included in the "basket" of greenhouse gases under the Paris Climate Agreement, but it lacks the specific, high-level focus directed at CO₂? and methane. While the Montreal Protocol does not currently control N₂O, there are increasing calls to use its framework to address the gas as a threat to the ozone layer.¹

Effective governance must balance food security with environmental protection. This requires shifting agricultural subsidies toward sustainable nitrogen management and implementing mandatory emissions limits for the chemical industry, similar to the Emissions Trading Scheme (ETS) used in the European Union.¹

A Dual Threat

Nitrous oxide can no longer remain a secondary priority in climate policy. Its role as a potent greenhouse gas and an ozone-depleting substance makes it a dual threat.

The global community can achieve deep emissions reductions that provide immediate benefits for both the climate and human health by implementing precision agriculture, scaling industrial abatement, and optimizing wastewater treatment.

References and Further Reading

1. United Nations Environment Programme and Food and Agriculture Organization of the United Nations. (2024). Global Nitrous Oxide Assessment. Nairobi. https://openknowledge.fao.org/items/cf38b56b-bbb2-455c-8ce6-58d0c9fb0d6b
2. King, A. (2025, November 10). Nitrous oxide emissions accelerate as agriculture drives climate threat. Chemistry World. [Online] Available at: https://www.chemistryworld.com/features/nitrous-oxide-emissions-accelerate-as-agriculture-drives-climate-threat/4022460.article
3. Wang, Q., Yao, D., & Tang, X. (2026). Maximizing nitrous oxide mitigation potential of straw-derived biochar in China with optimal application strategies. Biochar. https://link.springer.com/article/10.1007/s42773-025-00544-1

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