In the world’s effort to cut greenhouse gas emissions, the source of our food is coming into the spotlight. There’s good reason for that: Agriculture accounts for 16 to 27% of human-caused climate-warming emissions. But much of these emissions are not from carbon dioxide, that familiar climate change villain. They’re from another gas altogether: nitrous oxide (N2O).
Also known as laughing gas, N2O does not get nearly the attention it deserves, says David Kanter, a nutrient pollution researcher at New York University and vice-chair of the International Nitrogen Initiative, an organisation focused on nitrogen pollution research and policy making. “It’s a forgotten greenhouse gas,” he says.
Yet molecule for molecule, N2O is about 300 times as potent as carbon dioxide at heating the atmosphere. And like CO2, it is long-lived, spending an average of 114 years in the sky before disintegrating. It also depletes the ozone layer. In all, the climate impact of laughing gas is no joke. Scientists at the Intergovernmental Panel on Climate Change (IPCC) have estimated that nitrous oxide comprises roughly 6% of greenhouse gas emissions, and about three-quarters of those N2O emissions come from agriculture.