Nitrous Oxide (N2O), more popularly known as laughing gas, has adverse effects on our environment that are no laughing matter and these effects are far worse than first assumed.

As the third most persistent greenhouse gas (GhG) after carbon dioxide and methane, nitrous oxide contributes considerably to global warming. Climate scientists estimate that 30 percent of the N2O in the atmosphere is the result of human activity, and is mostly produced by agriculture because it uses enormous quantities of nitrogen-based fertilizers.

Now, new research found people and their farming are releasing more N2O into the atmosphere than previously thought. There are higher N2O levels in the atmosphere today and this uptick has been steadily rising since the mid-20th century, according to a new study published this week in the scientific journal, Nature Climate Change.

The study was conducted by team that also included lead scientist Rona L. Thompson from NILU-Norwegian Institute for Air Research and Eric Davidson of the University of the Maryland Center for Environmental Science.

"We see that the N2O emissions have increased considerably during the past two decades, but especially from 2009 onwards. Our estimates show that the emission of N2O has increased faster over the last decade than estimated by the Intergovernmental Panel on Climate Change (IPCC) emission factor approach," Thompson said

The study strongly links this N2O rise to an increase in nitrogen substrates released into the environment. The amount of nitrogen substrates in the environment has increased enormously since the mid-20th century due to the production of nitrogen fertilizers. It's also due to the widespread cultivation of nitrogen-fixing crops such as soybeans, lupins and peanuts, and the combustion of fossil and biofuels.

"The increased nitrogen availability has made it possible to produce a lot more food," Thompson noted. "The downside is of course the environmental problems associated with it, such as rising N2O levels in the atmosphere."

The study shows that global N2O emissions have now risen to 10 percent of the global total from 2000 to 2005 and 2010 to 2015. This is twice the amount reported to the United Nations Framework Convention on Climate Change based on the amount of nitrogen fertilizer and manure used and the default emission factor specified by the IPCC.

The new study contended this discrepancy is due to an increase in the emission factor (or the amount of N2O emitted relative to the amount of nitrogen fertilizer used) associated with a growing nitrogen surplus. This suggests the IPCC method, which assumes a constant emission factor, actually underestimates emissions when the rate of nitrogen input and nitrogen surplus are high.

Davidson said their new study demonstrates both how we can solve a problem of growing GhG emissions and how current efforts are falling short in some regions of the work. He said these emissions come primarily from using fertilizers to grow food and the increasing number of livestock herds.

"In Europe and North America, we have succeeded in decreasing growth in nitrous oxide emissions, an important contributor to climate change and stratospheric ozone depletion," Davidson added. "Unfortunately, the same can't be said for Asia and South America, where fertilizer use, intensification of livestock production, and the resulting nitrous oxide emissions are growing rapidly.

According to Davidson, the good news is this problem can be solved, "but the less good news is that it will take a global effort, and we are far from there yet."

RELATED STORIES