Thanks Tom. Here is the abstract. Unfortunately the paper itself is 
locked away.

It sure looks like there is a major source of methane here. But what we 
do not know is how long it has been going on for. It may be that we have 
got global methane completely wrong in the past, and that for more of it 
has been produced from sediments and degraded in the atmosphere than we 
ever realised until we bothered to look.

But even if that is true, the last thing we want to do is to increase 
methane production as warmer Arctic sea temperatures will surely do.

Oliver.

Extensive Methane Venting to the Atmosphere from Sediments of the East 
Siberian Arctic Shelf
Shakhova, Natalia | Semiletov, Igor | Salyuk, Anatoly | Yusupov, 
Vladimir | Kosmach, Denis | Gustafsson, Orjan
Science (Washington). Vol. 327, no. 5970, pp. 1246-1250. 26 Feb. 2010

Remobilization to the atmosphere of only a small fraction of the methane 
held in East Siberian Arctic Shelf (ESAS) sediments could trigger abrupt 
climate warming, yet it is believed that sub-sea permafrost acts as a 
lid to keep this shallow methane reservoir in place. Here, we show that 
more than 5000 at-sea observations of dissolved methane demonstrates 
that greater than 80% of ESAS bottom waters and greater than 50% of 
surface waters are supersaturated with methane regarding to the 
atmosphere. The current atmospheric venting flux, which is composed of a 
diffusive component and a gradual ebullition component, is on par with 
previous estimates of methane venting from the entire World Ocean. 
Leakage of methane through shallow ESAS waters needs to be considered in 
interactions between the biogeosphere and a warming Arctic climate.

On 14/02/2011 10:13, Barker, Tom wrote:
> Shakhova N., Semiletov I., Salyuk A., Yusupov V., Kosmach D. and
> Gustafsson Ö. 2010.  Extensive Methane Venting to the Atmosphere from
> Sediments of the East Siberian Arctic Shelf. /Science/ *327* 1246. DOI:
> 10.1126/science.1182221