SOURCE: ABC (Australia)

DATE: November 18, 2019

SNIP: Emissions of nitrous oxide — a greenhouse gas 300 times more potent than carbon dioxide — are going up faster than we thought.

Nitrous oxide is a greenhouse gas 300 times more potent than carbon dioxide.

This means each molecule of nitrous oxide in the atmosphere can capture 300 times more heat than a molecule of carbon dioxide.

Nitrous oxide is emitted predominantly from agriculture using nitrogen fertiliser, and to a lesser extent burning fossil fuels and biofuels.

It’s countries in east Asia and South America that are making the biggest contribution to the increasing emissions, according to a study published today in the journal Nature Climate Change.

Natural sources of nitrous oxide include our oceans and rainforests, but it’s the human sources that are of most cause for concern — specifically agriculture, including nitrogen fertiliser use and livestock manure.

We’ve known for decades that nitrous oxide emissions are increasing, but since 2009 there has been a “substantial increase” in these emissions, said Pep Canadell, executive director of the Global Carbon project and an author of the new research.

It’s been known for a while that there isn’t a linear relationship between nitrogen fertiliser input and nitrous oxide emissions, said Richard Eckard, director of the Primary Industries Climate Challenges Centre at the University of Melbourne.

“When you exceed the [plant] system’s capacity to use that nitrogen fertiliser, the efficiency goes out the window, and the nitrogen can leak out of the cycle,” Professor Eckard said.

“That plays out in some industries where the recommended amount of fertiliser is exceeded, and you get exponential loss of nitrogen.”

The big challenge with agriculture is that fertiliser is relatively cheap to use — so people put on a bit more to cover their bases, which is then lost to the environment (and atmosphere), Professor Eckard explained.

Because of global food insecurity, more countries than ever before are using nitrogen fertiliser.