Nitrous Oxide – Nothing to Laugh About

Also known as laughing gas, nitrous oxide seems less funny since scientists branded it as the third most important greenhouse gas emitted through human activities.


A woman sprays fertilizer on her field in Nakornsawan, Thailand. Fertilizers are the single most important source for man-made nitrous oxide emissions (Photo: Reuters)


Contribution to Human-Induced Climate Change: 7 percent

Global Warming Potential (100 years): 298 times stronger than CO2


Like most other greenhouse gases, nitrous oxide is neither toxic nor destructive but a fundamental part of the mechanisms that keep our planet healthy and green. Produced by digesting bacteria, nitrous oxides are part of the nitrogen cycle, one of the most important chemical reactions on Earth.


Nitrogen is the chemical basis for proteins and DNA; plants need it for photosynthesis and growth. While the gas is the most abundant element of our atmosphere, it cannot be used. Higher organisms have to rely on tiny bacteria to turn it into ammonia or nitrates. Once a plant dies, other bacteria feed on the leftovers and turn nitrates back into gases like nitrous oxide or nitrogen.


This benevolent cycle went on for millions of years until chemists and farmers realized that nitrogen fertilizers greatly increase crop yields. Since then, more and more nitrogen has been added to the cycle. Farmers around the globe use more than 70 million tons of nitrogen fertilizers annually. According to a study conducted by Nobel prize-winning chemist Paul Crutzen in 2007, some 3 to 5 percent of this nitrogen is converted directly into nitrous oxide, twice the amount previously thought.


Fertilizer application will increase with a growing world population. Over the next three decades food production will need to increase by about 60 percent, estimates the UN’s Food and Agricultural Organization. In the same period, nitrous oxide emissions could double, especially in developing countries.

Developing more effective ways of adding nitrogen to the soil will be a key challenge. Today, fertilizers are often washed away by rain into lakes and seas where algae feed on them, bloom uncontrollably, and starve the water of oxygen. Every summer, nitrogen-rich river flow from the Mississippi River creates a “dead zone” in the Gulf of Mexico the size of Massachusetts.


reference: http://knowledge.allianz.com/en/globalissues/climate_change/global_warming_basics/nitrous_oxide_greenhouse_gas_profile.html