As we turn the world’s wetlands to farming, we could be unleashing a hidden source of greenhouse gas into the atmosphere. No, this isn’t carbon dioxide, but actually laughing gas.
Much of the planet's wetlands – which are incredibly fertile and productive lands – are actually made up of peatland. These are water-logged areas of partially decaying vegetation that lock in much of the gasses that are released when organic matter rots.
The problem comes when these bogs are drained and then again when they’re irrigated to grow crops on. As a new study published in Nature Communications has found, this process releases significant amounts of nitrous oxide, also known as laughing gas.
“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,” explains co-author Ülo Mander in a statement. “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.”
The study has found that if things carry on as usual, then the draining of peatlands – particularly in the tropics – will become the primary source of nitrous oxide.
While many might associate peat with the northern latitudes of the Americas and Europe, significant peatlands are also found in the tropics. Much of the rainforest in Indonesia is growing on top of thick peat deposits, but as more and more deforestation occurs for palm oil plantations, the risk of the peat setting alight increases, as was seen when massive wildfires teared through the region in 2015.
Surprisingly, the largest tropical peatland in the world was only discovered last year. It was found hidden in the middle of the Congolese rainforest, covering an area of 145,500 square kilometers (56,000 square miles), about equivalent to the entirety of England. The only problem is that it is now threatened with both climate change and agricultural use.
The authors of this research say that the best way to cut our nitrogen oxide emissions from growing is to try and protect as much of this peatland as possible and to restore those areas that have already been significantly degraded, such as in Southeast Asia.