N2O Emissions are Increasing at a Faster Rate than Global Predictions

The term "greenhouse gas" is often used interchangeably with carbon dioxide, due to its prevalence in our atmosphere - more than 80 percent of all greenhouse gas emissions, estimates the Environmental Protection Agency. But another greenhouse gas, nitrous oxide (N₂O), can have effects with far greater impact.

And, according to a recent study, N₂O emissions are increasing at a "devastating" rate, faster than predictions introduced by the Intergovernmental Panel on Climate Change.

In a paper published in Nature, a large, multinational team of researchers associated with the Global Carbon Project -- including Peter Raymond, professor of ecosystem ecology at Yale School of the Environment (YSE), and postdoctoral fellow Taylor Maavara -- explains that existing inventories of N₂O emissions don't provide a full picture of its prevalence. Using "bottom-up" and "top-down" approaches, the researchers have provided a global look at N₂O emissions, accounting for naturally occurring sources of nitrous oxide and attributing anthropogenic sources that had both been omitted in previous inventories.

"Nitrous oxide is often seen as the third most important greenhouse gas" behind carbon dioxide and methane, says Maavara. "Not as much attention is paid to nitrous oxide, but it's extremely important." In addition to being an ozone depleting chemical, nitrous oxide, she explains, can take more than a century to completely break down in the atmosphere and has a climate warming potential nearly 300 times higher than carbon dioxide.

Developing a more comprehensive inventory, the researchers found growing N₂O emissions in emerging economies -- particularly Brazil, China and India -- due in large part to agricultural activity, the cause of nearly 70 percent of global human-derived N₂O emissions over the past decade. As populations grow and more food is needed, the researchers predict that N₂O emissions will continue to grow if not mitigated.

"It's going to be difficult because we need food," says Maavara, who suggests more sustainable practices, such as best management practices for farming that focus on more precise timing and applications of fertilizer.

But, even then, Maavara says positive results could take decades.

"Even if the world is willing, there's not a quick fix. It's going to take a long time to change what's been done to the soil. We want to emphasize that this is a problem now so we can begin developing the incremental solutions."