Laughing Gas Is A Growing Serious Concern For The Climate, Says International Team

Nitrous oxide is a growing concern for the climate, says an international team. Stockr/Shutterstock.com

There is a time and place for when laughing gas is for giggles and when it is a serious matter. Laughing gas is used often in the dentist’s chair or can come wafting from potent penguin poo to make scientists loopy. It’s also used in our fertilizers. That’s right, laughing gas, or nitrous oxide (N2O), is a key ingredient in fertilizers for the production of food worldwide. 

While carbon dioxide (CO2) is responsible for about 10 times more warming than nitrous oxide, laughing gas is 300 times more potent and stays in the atmosphere for a century or more. To get serious about the matter, an international team of scientists from 48 research institutions banded together to investigate the impact of this versatile chemical compound. The team have called the study the most comprehensive picture to date of N2O emissions.

For the study published in Nature, the team measured natural and human-caused N2O emissions between 1980 and 2016. Overall, global N2O levels have risen by 20 percent from pre-industrial levels, with a surge in the last half-century.

These emissions are increasing at a faster rate than the goal set by the Intergovernmental Panel on Climate Change (IPCC) to limit warming by less than 2°C (3.6°F), with an ideal scenario tightening that limit to less than 1.5°C (2.7°F). Instead, emissions are in line with a scenario that is above 3°C (5.4°F) from pre-industrial levels.

"The co-authors agreed that the most surprising result of the study was the finding that current trends in nitrous oxide emissions are not compatible with pathways consistent to achieve the climate goals of the Paris Climate Agreement," Professor Hanqin Tian, a co-author from Auburn University, told IFLScience.

So where are these N2O emissions coming from? It certainly isn’t just the dentist’s chair. It’s agriculture and cows – again.

Up to 71 percent of the increase in N2O emissions comes from the use of nitrogen-based fertilizers in agriculture, with 16 percent coming from cow manure and aquaculture. The impact factor of cows is compounded by the need to feed them grain that uses nitrogen-based fertilizer. 

"The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions," said Professor Tian. "These findings underscore the urgency and opportunities to mitigate nitrous oxide emissions worldwide to avoid the worst of climate impacts."

Yet it seems we just can’t get enough of the stuff, with nitrous oxide increasingly being used in both crop and livestock production, particularly in emerging economies. Brazil, for example, has increased cow production in recent decades to become one of the world’s top producers of beef. In the United States and China, synthetic fertilizers are the main source of emissions. Their analyses also found that the increase in N2O emissions have resulted in a feedback loop, with warmer temperatures increasing nitrous oxide emissions.

Now that we know poop of all sorts, from penguins to cows, is responsible for warming emissions, what can we do about it? Professor Tian gave IFLScience a few tips.

"N2O emission can be reduced by improving nitrogen use efficiency and reducing food waste. Choosing organic food may help reduce N20 emissions. Large amounts of N2O emission is from nitrogen fertilizer application to farmland. However, some organic farming practices such as the use of cover crops and nitrogen-fixing plants can improve soil fertility and release less nitrous oxide."

Co-author Rob Jackson, a professor of Earth system science from Stanford University, added: "Cattle are responsible directly and indirectly for considerable N2O emissions (and are one of the largest sources of methane, too). Eating less beef and cheese will make most of us healthier and reduce everyone’s greenhouse gas footprint. Fish is better than beef for emissions, and plants are better than fish. Also, the Department of Agriculture estimates that Americans waste a shocking 30 to 40 percent of all the food we produce – more than a hundred billion pounds and a hundred and fifty billion dollars’ worth of food each year. Food waste leads to unnecessary greenhouse gas emissions."

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