Addressing N2O emissions key to meeting 1.5°C target, protecting human health, biodiversity: Report

Addressing N2O emissions key to meeting 1.5°C target, protecting human health, biodiversity: Report

Sub : Env

Sec : Climate change

Context:

• Experts at COP29 emphasized the urgency of addressing nitrous oxide (N₂O), a powerful but often overlooked greenhouse gas.
• As the third most impactful greenhouse gas after carbon dioxide (CO₂) and methane (CH₄), and the leading ozone-depleting substance, reducing nitrous oxide emissions is crucial for limiting global warming to 1.5°C.

About Nitrous Oxide (N₂O):

• Warming Potential: N₂O is 270 times more potent than CO₂ in its warming effect per tonne of emissions.
• Longevity: The gas remains in the atmosphere for about 120 years, causing long-term impacts.
• Contribution to Global Warming: N₂O has already contributed to 0.1°C of net global warming since the industrial era. If left unchecked, it could add 0.2°C of warming by 2100.

Main Sources of Emissions

1. Agriculture (75%):
   • Overuse of nitrogen-based fertilizers.
   • Poor manure management in livestock farming.
2. Industrial Sources (5%):
   • Emissions from chemical manufacturing, including nitric acid production.
3. Other Sources (20%):
   • Fossil fuel combustion.
   • Wastewater treatment.
   • Biomass burning and aquaculture.

Challenges and Solutions:

1. Policy Gaps:
   • Unlike other ozone-depleting substances, N₂O is not covered under the Montreal Protocol, a key international agreement aimed at protecting the ozone layer.
2. Available Abatement Measures:
   • Controlled-release fertilizers: These can minimize nitrogen loss, reducing N₂O emissions from soil.
   • Improved manure management: Better handling and storage can cut emissions from livestock waste.
   • Industrial reductions: Adopting existing technologies could eliminate industrial N₂O emissions at costs ranging from $1,600 to $6,000 per tonne.
3. Systemic Changes:
   • Transforming food systems: Reducing reliance on nitrogen-heavy fertilizers and decreasing animal protein consumption could lead to deeper reductions in N₂O emissions.
   • Behavioural shifts: Promoting plant-based diets can reduce agricultural demand for livestock, lowering associated emissions.

Addressing nitrous oxide emissions is essential for:

• Limiting global warming to below 1.5°C.
• Protecting the ozone layer and reducing the risk of UV-related health issues.
• Improving air quality and public health outcomes.

Co-Benefits of N₂O Abatement:

1. Climate and Health:
   • Reducing N₂O emissions could cut global warming by 1°C by late this century, aligning with climate goals.
   • Since N₂O depletes the ozone layer, reducing emissions can prevent 2–0.8% increases in cataract cases and 2–10% increases in skin cancers by 2080-2090, depending on latitude.
2. Air Quality:
   • Abating N₂O would also yield benefits for air quality, reducing the health impacts of air pollution.

Potential Risks and Trade-offs

• Emerging technologies like ammonia fuel for shipping and biofuels from fertilized crops could unintentionally increase N₂O emissions, potentially offsetting their intended climate benefits. More studies are needed to assess these trade-offs across CO₂, CH₄, and N₂O emissions in various sectors.