Causes: Nitrous oxide N20
Today, nitrogen pollution is one of the most pressing pollution issues facing humanity, threatening our environment, health, climate and ecosystems. – UN
Nitrous oxide (N2O) is around 300 times worse for the climate than carbon dioxide. Overall, it’s the third-largest contributor to man-made (anthropogenic) greenhouse gases after carbon dioxide and methane. It also contributes to the destruction of the ozone layer. And the amount in the atmosphere is dramatically increasing (Fig. 1).
The recent growth in N2O emissions exceeds some of the highest projected emission scenarios, underscoring the urgency to mitigate N2O emissions. – Tian et al, 2020
Most emissions come from agriculture: manure, dung and urine from livestock and adding excessive nitrogen fertiliser to soils. Once in the ground, microorganisms reduce nitrogen oxides to nitrogen gas (denitrifying microbes) or by converting soil ammonium to nitrate (nitrifying microbes). One of the biproducts is carbon dioxide.
It’s also produced in meat and dairy processing, and through poor management of manure.
When excess nitrogen enters our waterways, it causes suffocating algae blooms, and creates dead zones in the ocean.
While it is possible for farmers to measure their emissions, under the National-led government the agricultural sector does not have to account for emissions.
Fig. 1: Instructions for this interactive graph (Credit: The 2°
- Mouse over anywhere on the graph to see the changes in global atmospheric N2O over the last thousand years.
- To see details for time periods of your choice, hold your mouse button down on one section then drag the mouse across a few years, and release it.
- To see how this compares to the past 771,000 years, click on the ‘time’ icon on the top left.
- Compare this to rising global temperatures by clicking the planet/thermometer icon at the top left corner.
- To return the graph to its original position, double-click the time icon to the left of the thermometer/planet icon
