Another tipping point passed: methane plumes from Arctic seabed

Graph and research report 6 Aug 09 by National Oceanography Centre Southampton, UK.
The following is a summary of a geochemist's report on DailyKos 19 Aug 09:

Oil and coal companies more than doubled their millions to K Street lobbyists over two years to pressure the US Congress to weaken climate legislation. The companies argue that global warming is not an immediate problem.

Scientists' discovery of methane plumes from the Arctic seabed, just announced, shows otherwise. Frozen methane is now being released as a gas. This is another major tipping point passed. Methane has 23 times the warming power of CO2, and the USGS says the volume of methane frozen in clathrates is "conservatively" twice the volume of all known fossil fuels on earth.

Scientific conclusion: world leaders must act immediately to reduce greenhouse gas emissions, in order to stop ocean warming from triggering massive releases of methane.

Methane release from a frozen lake: U of Alaska Nov 2007. For details of this research see "The Peril below the ice" in Scientific American Earth 3.0 June 2009