BBC | Methane seeps from Arctic sea bedCan you say "feedback loop"? Or, to be more precise, "vicious circle"? This is what everyone who understands the situation has been dreading.
Scientists ... have evidence that the powerful greenhouse gas methane is escaping from the Arctic sea bed. ...
As temperatures rise, the sea bed grows warmer and frozen water crystals in the sediment break down, allowing methane trapped inside them to escape.
The research team found that more than 250 plumes of methane bubbles are rising from the sea bed off Norway. ...
Writing in Geophysical Research Letters, the team says the methane was rising from an area of sea bed off West Spitsbergen, from depths between 150 and 400m.
The gas is normally trapped as "methane hydrate" in sediment under the ocean floor.
"Methane hydrate" is an ice-like substance composed of water and methane which is stable under conditions of high pressure and low temperature.
As temperatures rise, the hydrate breaks down. So this new evidence shows that methane is stable at water depths greater than 400m off Spitsbergen.
However data collected over 30 years shows it was then stable at water depths as shallow as 360m.
Ocean has warmed
Temperature records show that this area of the ocean has warmed by 1C during the same period. ...
Their most significant finding is that climate change means the gas is being released from more and deeper areas of the Arctic ocean. ...
The team found that most of the methane is being dissolved into the seawater and did not detect evidence of the gas breaking the surface of the ocean and getting into the atmosphere.
They stress that this does not mean that the gas does not enter the atmosphere. They point out that the methane seeps are unpredictable and erratic in quantity, size and duration. ...
Most of the methane reacts with the oxygen in the water to form carbon dioxide, another greenhouse gas. In sea water, this forms carbonic acid which adds to ocean acidification, with consequent problems for biodiversity.
Graham Westbrook, lead author and professor of geophysics at the University of Birmingham said: "If this process becomes widespread along Arctic continental margins, tens of megatonnes of methane a year - equivalent to 5-10% of the total amount released globally by natural sources, could be released into the ocean."
At some point -- you never know when until it happens -- it won't just be us belching out greenhouse gases. So far, if we'd only stopped belching, that would have been the end of it. The greenhouse gases would have gradually been recycled out of the atmosphere and the climate could have returned to normal.
But the next phase is that the whole planet starts emitting extra CO2 and extra methane because it's warmer. That makes it even warmer. That makes the planet emit even more greenhouse gases.
At that point we can stop our own idiocy cold ... and it won't make much difference. When the permafrost in the Arctic tundras melts, it releases greenhouse gases. When the ocean warms, it releases greenhouse gases. Molecule per molecule, methane is about eight times stronger as a greenhouse gas than carbon dioxide. The best we can hope at that point is most of it will turn into CO2 in the ocean, and acidify that instead.
The grim news is that we've reached that point. The permafrost is melting (pdf). The shallower methane hydrates are bubbling up. Ocean circulation rates are changing. (There is variation.)
I'm beginning to think the saddest words a human being can say are, "I do not envy the young."
global warming, methane, methane hydrates