Rising Nitrogen Threat

GS3 – Environment

Context:

The United Nations’ Global Nitrous Oxide Assessment highlights a concerning spike in nitrous oxide (N₂O) emissions, calling for immediate global action to mitigate this potent greenhouse gas.

Nitrogen: Its Ecological and Biological Relevance

• Atmospheric Abundance: Nitrogen forms nearly 78% of Earth’s atmosphere, playing a crucial role in sustaining ecosystems and life processes.
• Biological Functions:
  • Integral to DNA, proteins, and ATP, which fuels cellular activities.
  • Supports nerve transmission, immune responses, and joint function via synovial fluid.
  • The familiar sound of knuckle-cracking comes from nitrogen bubbles in this fluid.
• Plant Growth & Nitrogen Cycle:
  • Crucial for synthesising chlorophyll and proteins in plants.
  • Circulates through the ecosystem—soil, flora, fauna, and atmosphere—via microbial processes.
• Natural Enrichment: Lightning helps convert atmospheric nitrogen into bioavailable forms like nitric acid, enhancing soil fertility.

Industrial Nitrogen Usage and Its Expansion

• Haber-Bosch Process: Revolutionised agriculture and warfare by mass-producing ammonia for fertilisers and explosives.
• Saltpetre (Potassium Nitrate): Historically used in gunpowder and fertilisers, increasing nitrogen’s presence in ecosystems.
• Explosives Industry: Nitrogen-based compounds such as TNT and nitroglycerine are widely used in industrial and military applications.

Drivers of Increasing Nitrous Oxide Emissions

• Agriculture as the Main Contributor:
  • Around 70% of N₂O emissions originate from farming, largely due to overuse of urea-based synthetic fertilisers.
  • Fertiliser inefficiency leads to leaching, volatilisation, and runoff, wasting up to 80% of applied nitrogen.
• Farming Patterns: Shift to monoculture, especially cereals, has reduced nitrogen-fixing legume crops.
• Fossil Fuels & Waste: Combustion of fossil fuels and organic waste from animals release various reactive nitrogen compounds into the environment.

Environmental and Health Impacts of N₂O

• Potent Greenhouse Gas:
  • N₂O stays in the atmosphere for around 120 years and has ~300 times more warming potential than CO₂.
  • It’s the third-most significant GHG and contributes nearly 10% to global warming.
• Ozone Depletion: Reacts with ozone molecules, aggravating stratospheric ozone layer thinning.
• Water and Air Pollution:
  • Leads to eutrophication, algal blooms, and aquatic dead zones.
  • Contributes to acid rain and smog, deteriorating air quality.
• Public Health Risks:
  • Linked to respiratory diseases and methemoglobinemia (“blue baby syndrome”) caused by nitrate-contaminated water.
• Economic Costs: Environmental and health-related damages from nitrogen pollution cost the world $340 billion to $3.4 trillion annually.

Global Action and Mitigation Strategies

• Paris Agreement Goals: Controlling N₂O emissions is vital to staying within the 1.5°C global temperature rise target.
• Potential Impact: Effective actions could cut up to 235 billion tonnes of CO₂-equivalent by 2100.
• Reforming Agriculture:
  • Promote precision farming, legume rotation, and better nitrogen-use efficiency.
• Technology Adoption:
  • Encourage slow-release fertilisers and nitrification inhibitors to reduce nitrogen loss.
• Policy Recommendations:
  • Establish a global nitrogen governance mechanism, akin to the Montreal Protocol.
• Research and Awareness:
  • Boost scientific understanding and stakeholder education on sustainable nitrogen practices.