Has runaway climate change begun?

The UK’s Independent reported today some pretty shocking news in “Exclusive: The methane time bomb”:

The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists.

The Independent has been passed details of preliminary findings suggesting that massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.

Assuming these findings are published in a peer-reviewed publication, as is planned, they should be taken quite seriously for four reasons. First, many fear that a huge methane release is what happened during the Permian-Triassic extinction event and the Paleocene-Eocene Thermal Maximum. Second, releasing even a small fraction of the sub-sea methane would make a stabilizing greenhouse gas emissions at non-catastrophic concentrations all but impossible.

Third, as NOAA reported earlier this year, levels of methane rose sharply last year for the first time since 1998:

Fourth, the findings are apparently based on very new and credible in situ measurements:

Scientists aboard a research ship that has sailed the entire length of Russia’s northern coast have discovered intense concentrations of methane — sometimes at up to 100 times background levels — over several areas covering thousands of square miles of the Siberian continental shelf.

In the past few days, the researchers have seen areas of sea foaming with gas bubbling up through “methane chimneys” rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a “lid” to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age.

They have warned that this is likely to be linked with the rapid warming that the region has experienced in recent years….

Since 1994, Igor Semiletov of the Far-Eastern branch of the Russian Academy of Sciences “has led about 10 expeditions in the Laptev Sea but during the 1990s he did not detect any elevated levels of methane. However, since 2003 he reported a rising number of methane “hotspots,” which have now been confirmed using more sensitive instruments.” Why now?

Dr Semiletov has suggested several possible reasons why methane is now being released from the Arctic, including the rising volume of relatively warmer water being discharged from Siberia’s rivers due to the melting of the permafrost on the land.

The Arctic region as a whole has seen a 4C rise in average temperatures over recent decades and a dramatic decline in the area of the Arctic Ocean covered by summer sea ice. Many scientists fear that the loss of sea ice could accelerate the warming trend because open ocean soaks up more heat from the sun than the reflective surface of an ice-covered sea.

The article notes that the “preliminary findings of the International Siberian Shelf Study 2008” are “being prepared for publication by the American Geophysical Union.” Until that happens, it will be difficult to know what to make of all this. You can read what some other scientists say about these preliminary reports here. Stay tuned.

The time to act is yesterday.

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