14 DAY TRIAL // While carbon dioxide is undoubtedly the most renowned greenhouse gas, it's not by far the strongest. Nitrous oxide is a lot more efficient at heating up the atmosphere, and now experts determined that rivers produce three times more of the stuff than originally thought.
According to the new investigation, the estimates on which the Intergovernmental Panel on Climate Change (IPCC) bases its analysis of how climate change will evolve are too conservative.
The new numbers show that rivers and adjacent networks are responsible for emitting as much as 10 percent of all human-produced nitrous oxide. That is nearly three times more than the IPCC calculated.
In addition to contributing to the heating of the atmosphere, the potent greenhouse gas also contributes to the destruction of stratospheric ozone, right alongside chemicals such as chlorofluorocarbons.
As runoff nitrogen from activities such as agriculture makes its way into rivers and streams, it contaminates them, and then triggers a reaction called denitrification. This reaction produces nitrous oxide and dinitrogen, which is an inert gas.
While the individual river may not contribute with vast amounts of the gas to global warming, the situation changes when rivers around the world are taken into account,
The team behind the investigation published the results of its findings in this week's issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS).
“Human activities, including fossil fuel combustion and intensive agriculture, have increased the availability of nitrogen in the environment,” explains researcher Jake Beaulieu.
The expert, who is the lead author of the PNAS paper, holds joint appointments at the University of Notre Dame and at the US Environmental Protection Agency (EPA) in Cincinnati, Ohio.
“Much of this nitrogen is transported into river and stream networks, where it may be converted to nitrous oxide, a potent greenhouse gas, via the activity of microbes,” the expert goes on to say.
Together with his team, the expert looked at samples collected from over 72 locations. Denitrification rates at all these spots were then analyzed and cataloged.
“This multi-site experiment clearly establishes streams and rivers as important sources of nitrous oxide,” explains the program director of the Division of Environmental Biology (DEB), Henry Gholz.
"This is especially the case for those draining nitrogen-enriched urbanized and agricultural watersheds, highlighting the importance of managing nitrogen before it reaches open water,” the expert adds.
The DEB is the organization which funded the new research, and it is a part of the US National Science Foundation (NSF). “This new global emission estimate is startling,” Henry Gholz concludes.