Methane levels may see ‘runaway’ rise, scientists warn:
Atmospheric levels of methane, the greenhouse gas which is much more powerful than carbon dioxide, have risen significantly for the last three years running, scientists will disclose today – leading to fears that a major global-warming “feedback” is beginning to kick in.
For some time there has been concern that the vast amounts of methane, or “natural gas”, locked up in the frozen tundra of the Arctic could be released as the permafrost is melted by global warming. This would give a huge further impetus to climate change, an effect sometimes referred to as “the methane time bomb”.
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Now comes the first news that levels of methane in the atmosphere, which began rising in 2007 when an unprecedented heatwave in the Arctic caused a record shrinking of the sea ice, have continued to rise significantly through 2008 and 2009.
Although researchers cannot yet be certain, and there may be non-threatening explanations, there is a fear that rising temperatures may have started to activate the positive feedback mechanism. This would see higher atmospheric levels of the gas producing more warming, which in turn would release more methane, which would produce even further warming, and so on into an uncontrollable “runaway” warming effect. This is believed to have happened at the end of the last Ice Age, causing a very rapid temperature rise in a matter of decades.
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Professor Nisbet said at the weekend that the new figures did not necessarily mark a new excursion from the trend. “It may just be a couple of years of high growth, and it may drop back to what it was,” he said. “But there is a concern that things are beginning to change towards renewed growth from feedbacks.”
Huh? This multi-year run-up in methane levels is hardly news–I’vbe been beating a drum over it for a long time, and the data (see below) is openly available online. So any notion that this is “the first news that levels of methane in the atmosphere, which began rising in 2007 when an unprecedented heatwave in the Arctic caused a record shrinking of the sea ice, have continued to rise significantly through 2008 and 2009″ is simply wrong.
As for the source of that increase, my understanding is that the jury is still out. There’s evidence of increased methane emissions from Arctic as well as non-Arctic regions. Consider this yet further proof that we need to spend a lot more money, time, effort, and gray matter on figuring out what the hell is going on at the top of the planet.
The basic conclusion I think we should draw from all of this is that while we know with complete certainty that there’s more methane in the atmosphere, we’re not entirely sure if it’s just another run-up like the ones we’ve experienced serially since 1985 (see graph below), or if we’ve started melting enough permafrost (which we know for a fact is happening) that it’s cutting loose some of its gigantic methane stores. This is one time when a lack of evidence for something bad isn’t very comforting. It’s certainly good news that scientists aren’t saying, “the evidence is clear–the methane bomb is starting to go off”, but it’s very bad news that we don’t know exactly where that particular tipping point lies. Under the current warming trend we could have begun to trigger this methane release, or it could be decades away. The longer we continue business as usual in this state of ignorance, the greater the risk we’re taking of unleashing an immense feedback effect.
Oh — as for the latest methane graph:
