Rapid Rise of Atmospheric Nitrous Oxide

Rapid Rise of Atmospheric Nitrous Oxide

Context: India is the world’s second-largest emitter of nitrous oxide (N2O) after China.

• Though N2O concentration in the atmosphere (336 parts per billion in 2022 – which is about 25% higher than pre-industrial levels) is lower than CO2, N2O stays longer and rises rapidly.
• It has a high Global Warming Potential as N2O remains in the atmosphere for an average of 117 years.
• N2O emissions account for 6.4% of GHG radiative forcing, contributing about 0.1°C to global warming.
• GHG radiative forcing is a measure of the difference between the amount of energy (in the form of radiation) that enters the Earth’s atmosphere and the amount that is radiated back into space.

Agriculture and N2O Emissions

• Human activities have increased N2O emissions by 40% in the past four decades.
• Agricultural production, particularly the use of nitrogen fertilisers and animal manure, contributed 74% of the total anthropogenic N2O emissions in the last decade.
• The growing demand for meat and dairy products has also led to increased emissions through manure production and the use of nitrogen fertilisers in animal feed production.
• Emissions from aquaculture are growing rapidly, especially in China.
• The inefficient use of synthetic nitrogen fertilisers and animal manure also contributes to the pollution of groundwater, drinking water, and inland and coastal waters.

Way Forward

• To meet the Paris Agreement’s goals (to stabilise global temperatures below 2°C from pre-industrial levels), anthropogenic N2O emissions must decrease by at least 20% from 2019 levels by 2050.
• Experts call for a reduction in fertilizers subsidies and a shift towards sustainable agricultural practices.
• Also, India should seriously consider changing cropping systems and production practices. They also recommend repurposing fertilizer subsidies to support alternative production systems.
• Global Warming Potential (GWP)
• Global Warming Potential (GHP) measures the relative impact of a greenhouse gas on the Earth’s warming compared to carbon dioxide (CO2) over a specified period.
• By definition, the GWP of CO2 is set to 1 for all time periods. The GWP values for other GHGs are expressed relative to CO2. For example, if a gas has a GWP of 25, it means that one ton of this gas will absorb 25 times more energy than one ton of CO2 over the specified time period.