The Climate Threat You Probably Didn't Know About: Laughing Gas Hotspots

Laughing gas invariably conjures up uncomfortable thoughts of the dentist chair, but rarely does it evoke a sense of danger. But researchers say laughing gas, or nitrous oxide, is a threat to the well-being of the planet.

According to a study published earlier this month in Nature Communications, draining fertile peatlands for agricultural purposes significantly increases laughing gas emissions. 

Researchers with the University of Tartu in Estonia and U.K.'s University of Birmingham studied nitrous oxide emissions and the potential driving factors behind the emissions at 58 sites around the world, including locations in the United States, Australia, Brazil, South America, Australia, New Zealand, East Africa, Southeast Asia, Siberia and Europe.

The researchers found that draining wet soils for agricultural purposes or irrigating already well-drained cultivated soils create laughing gas hotspots.

Perhaps the most talked-about greenhouse gas is carbon dioxide (CO2) and rightly so because it makes up 82 percent of all greenhouse gases, but it is just one of many greenhouse gases depleting the ozone layer and driving global warming. While not as abundant as carbon dioxide, nitrous oxide (N20), which makes up 5 percent of all greenhouse gases, is 300 times more efficient at trapping heat in the atmosphere than CO2 over a 100-year period. 

“Nitrous oxide is no laughing matter — it is a significant contributor to global climate change and depletion of the ozone layer, which protects our planet from cosmic radiation," Ülo Mander, senior lecturer in biogeochemistry at the University of Tartu, said in a press release. "Organic soils, such as fens, swamps, bogs and drained peatlands, make up more than one-tenth of the world’s soil nitrogen pool and are a significant global source of laughing gas. They are significant sources of nitrous oxide when drained for cultivation.”

According to the study, the amount of nitrous oxide released into the atmosphere is determined by a combination of soil nitrate concentration, which is a by-product of agriculture and industrial activities, water content and temperature. The higher the nitrate concentration in the soil, the greater the amount of nitrous oxide gas released, the authors said. 

A separate study published in Biogeosciences in 2013 noted that draining naturally occurring bogs, swamps and fens increases the amount of nitrate found in the soil.

Peat is organic material that accumulates in water-saturated environments. When wetlands containing peat are drained, the soil that remains is rich in nitrates. 

Jaan Pärn, co-author of the study and joint exchange postdoctoral fellow at the University of Birmingham, said the artificial drainage of natural wetlands will become the "primary driver of future changes in laughing gas emission from organic soils," noting that the effect will be more pronounced in tropical zones because of the warmer temperatures.

The researchers say measures should be taken to conserve peatlands to reduce the impact of climate change and protect the ozone layer.