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.

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