Scientists have long worried that thawing permafrost would free vast amounts of methane, a potent greenhouse gas, once locked in the frozen soil.
But now a team of researchers is suggesting the possibility that methane-eating bacteria that like the warmer weather might offset those emissions.
A group of scientists in April published an article in the International Society for Microbial Ecology suggesting there are carbon-hungry bacteria trapped in the frozen soil, waiting to counteract the discharge when the ground temperatures rise above freezing. As temperatures warmed further, up to about 64 degrees, the bacteria ate increasing amounts of methane.
"Most of the methane emissions happen in the Northern Hemisphere, but the methane level at the Arctic is pretty constant," said lead scientist Maggie Lau of Princeton University's Department of Geosciences. "That's possibly because the bacteria (are) working ... they can only be active when the ground is thawed."
Lau said her colleagues in Canada studied this flux over the course of three years by taking permafrost measurements at Axel Heiberg Island. They also incubated soil in test tubes to replicate the process. They found that the carbon in the soil became richer as the temperature rose, while methane in the atmosphere above it whittled to as little as a quarter of the measurement taken before it was released. The bacteria oxidize what they can of the methane and let the rest go, she said.
She said it's too soon to know whether this is happening across the Arctic or even the world, because they just studied one site, but that she is collaborating with others to figure out where it applies.
"By further investigation at other sites, we may be able to generalize this phenomenon more accurately to estimate the global impact," she said.