The thawing of the Arctic permafrost is releasing a potent greenhouse gas into the atmosphere that has rarely been considered as a threat despite its tremendous potential to drive global warming.

Nitrous oxide, or N2O, is more of a threat to the Arctic and global warming than previously believed, according to a study published yesterday in the journal Proceedings of the National Academy of Sciences. Currently, it's not usually considered when researchers create models to predict the future warming of the region, said Carolina Voigt, a researcher at the University of Eastern Finland and a lead author of the study.

"It is roughly 300 times more powerful in warming the climate than CO2 [carbon dioxide] on a 100-year time horizon, so it is a strong greenhouse gas, and even small amounts emitted can add to the total greenhouse gas budget of the area," she said.

"And so far, it hasn't been measured much in the Arctic, so we can't actually quantify the total N2O greenhouse gas budget for the Arctic."

As the permafrost thaws, emissions of nitrous oxide increase, researchers found. That's significant because naturally occurring nitrous oxide, which is locked inside the permafrost when it is frozen, is a potent greenhouse gas with 300 times the global warming potential of carbon dioxide.

The vast majority of climate scientists have determined that humans are chiefly responsible for climate change, pumping carbon dioxide into the atmosphere largely through the burning of fossil fuels. Of all the regions on Earth, the Arctic has seen some of the highest levels of warming, and scientists say it has already been transformed into a new state. Climate models show that the region, which broke records for low sea ice levels and high temperatures last year, will continue to warm.

Scientists are still studying some of the natural sources of carbon dioxide. The Arctic's permafrost, which is steadily thawing as the region keeps getting warmer, is also releasing carbon dioxide into the atmosphere, creating a feedback loop of transformation that drives further warming.

Currently, the world's largest source of terrestrial nitrous oxide is the tropical forest. However, the study found that emissions of nitrous oxide from a typical Arctic landscape, permafrost peatlands with little vegetation cover, could equal those from the tropics. About a quarter of the Arctic is permafrost peatlands, meaning the area has tremendous potential to be a major source of nitrous oxide release, researchers found.

Researchers have also begun to explore sources of methane, a more potent greenhouse gas than carbon dioxide, and how that drives climate change. But little research has been conducted on nitrous oxide as a source of warming, Voigt said. The study shows more research is needed to understand what is happening to the Arctic, she said.

"It's definitely understudied, and it's a large question mark, actually, in Arctic greenhouse gas research," she said.

The story of the Arctic is that so many different factors are all contributing to warming, said Jeremy Mathis, director of the Arctic Research Program at the National Oceanic and Atmospheric Administration. Mathis, who was not involved in the study, said the contributions of nitrous oxide and methane are largely hypothetical at this point, as observations have not yet shown either to be a significant contributor of greenhouse gases. Nonetheless, there is a growing body of research that shows both could drive warming in the future, he said.

Mathis said nitrous oxide will be "one of many players" driving the warming in the Arctic.

"It's just this cycle that starts to feed back on itself that is much more pronounced in the Arctic than it is down in the lower latitudes, so that's why we see the Arctic warming," he said. "Right now, it's warming at least twice as fast as the rest of the planet, and the trend is continuing to look upward from that perspective, so this warming effect and this exacerbation of the warming effect in the Arctic I think is going to continue, given all the complexities of the system that's in play."

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.