I vowed not to talk about this because it literally makes me sick to my stomach, but it's too important to deny. We all know about the vast deposits of methane clathrates on the Siberian continental shelf. They are kept in place by pressure and low temperatures. However, the temperatures (SAT as well as SST) are getting less and less low in the Arctic, so in theory it could mean that these deposits come loose and leave the ocean floor to end up in the atmosphere. Methane is a much more potent greenhouse gas than CO2 and some extinction events in the distant past have been linked to the deadly feedback of warming->methane release->more warming->more methane release->etc.
No one is really sure what is going on exactly with those methane deposits, but in the past years there has been much speculation (undoubtedly caused by the spectacular retreat of summer sea ice in the region) and reporting of a probable increase of methane bubbling up from the Siberian continental shelf. And so the results of this year's Russian research mission were eagerly awaited. Mind you, not by me.
It seems the results are in and were reported at AGU last week.
The Independent reports with this article:
Shock as retreat of Arctic sea ice releases deadly greenhouse gas
Russian research team astonished after finding 'fountains' of methane bubbling to surface
Dramatic and unprecedented plumes of methane – a greenhouse gas 20 times more potent than carbon dioxide – have been seen bubbling to the surface of the Arctic Ocean by scientists undertaking an extensive survey of the region.
The scale and volume of the methane release has astonished the head of the Russian research team who has been surveying the seabed of the East Siberian Arctic Shelf off northern Russia for nearly 20 years.
In an exclusive interview with The Independent, Igor Semiletov, of the Far Eastern branch of the Russian Academy of Sciences, said that he has never before witnessed the scale and force of the methane being released from beneath the Arctic seabed.
"Earlier we found torch-like structures like this but they were only tens of metres in diameter. This is the first time that we've found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It's amazing," Dr Semiletov said. "I was most impressed by the sheer scale and high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them."
Scientists estimate that there are hundreds of millions of tonnes of methane gas locked away beneath the Arctic permafrost, which extends from the mainland into the seabed of the relatively shallow sea of the East Siberian Arctic Shelf. One of the greatest fears is that with the disappearance of the Arctic sea-ice in summer, and rapidly rising temperatures across the entire region, which are already melting the Siberian permafrost, the trapped methane could be suddenly released into the atmosphere leading to rapid and severe climate change.
Dr Semiletov's team published a study in 2010 estimating that the methane emissions from this region were about eight million tonnes a year, but the latest expedition suggests this is a significant underestimate of the phenomenon.
Continue reading here...
I guess this is the graph to keep an eye on (courtesy of Al Rodger):
The numbers for this graph were derived from NOAA's Earth System Research Laboratory.
Methane (CH4) contributes about 18% to the overall global increase in radiative forcing since 1750 and is the second most important greenhouse gas after carbon dioxide.
Before the start of the industrial era, atmospheric methane was about 700 parts per billion (number of molecules of the gas per billion molecules of dry air) Since 1750, it has increased 158%, mostly because of activities such as cattle-rearing, rice planting, fossil fuel exploitation and landfills. Human activities now account for 60% of methane emissions, with the remaining 40% being from natural sources such as wetlands.
After a period of temporary relative stabilization from 1999 to 2006, atmospheric methane has again risen. Scientists are conducting research into the reasons for this, including the potential role of the thawing of the methane-rich Northern permafrost and increased emissions from tropical wetlands.
There's more info in this excellent SkS post from earlier this year: Wakening the Kraken
And from last year this blog post on Hot Topic: Siberian seabed methane, first numbers