© Science/AAASFluxes of CH4 venting to the atmosphere over the East Siberian Arctic Shelf.
Ancient permafrost submerged in the Arctic Ocean is releasing methane gas into the atmosphere at rates comparable to previous estimates for all the world's oceans combined, researchers say. This underwater permafrost represents a large but previously overlooked source of methane, and experts say that similar but more widespread emissions of the gas could have dramatic effects on global warming in the future.
The discovery creates "an urgent need" for further research to understand the methane release and its possible impact, researchers say in the new issue of
Science.In order to make this discovery, Natalia Shakhova from the Russian Academy of Sciences, along with colleagues from the University of Alaska and Stockholm University, traveled on Russian ice-breaker ships each year from 2003 to 2008 to survey the waters above the remote East Siberian Arctic Shelf; they also made one helicopter survey and an over-ice winter expedition to the region. After more than 5000 painstaking observations at sea, the researchers found that 80% of the bottom water and more than 50% of the surface water over that continental shelf is supersaturated with methane originating from the permafrost below.
After water vapor and carbon dioxide, methane is the third most important greenhouse gas in the atmosphere, and the researchers warn that this unforeseen flux of the gas into the atmosphere could alter the global climate in unexpected ways.