Drained swamps and wetlands across the world are bubbling with laughing gas, and it’s no joke: nitrous oxide, or N2O, is a potent ozone depleting gas and contributor to global warming. Nitrogen-rich fertilisers and the destruction of peatland for agricultural use are to blame.
A team of geographers led by Professor Ülo Mander at the University of Tartu in Estonia studied gas emissions from peatlands around the world, to build the first global database of N2O emission from organic soils.
They published their findings in the journals Nature Communications and Scientific Reports this week, calling for the protection of existing peatlands, re-wetting of drained marshes and bogs, and the avoidance of nitrogen-rich fertilisers.
Nitrous Oxide, also known as laughing gas, is used in dentistry and surgery as an anaesthetic and analgesic. But N2O in the atmosphere is no laughing matter: it’s one of the most potent greenhouse gases, trapping around three hundred times more heat than CO2. It is also the most significant contributor to ozone depletion.
Peatlands doesn’t typically release N2O unless the water is drained or the soil turned over, according to the study. The researchers discovered that, clearing wetlands for crops, grazing or development triggers microbial processes that release significant quantities of Nitrous Oxide.
The effect is particularly strong where the soils are nitrogen rich due to past grazing, or from floodwaters carrying nitrates from fertilised land.