23rd February, 2010 - Posted by admin - Comments Off
The Rise in Methane
The Independent (22 February 2010) reports the work of Professor Euan Nisbet and Dr Ed Dlugokencky on the levels of methane in the atmosphere:
Both men are leading experts on CH4 in the atmosphere, and Dr Dlugokencky in particular, who is in charge of NOAA’s global network of methane monitoring stations, is sometimes referred to as “the keeper of the world’s methane”. In a presentation on “Global atmospheric methane in 2010: budget, changes and dangers”, the two scientists will reveal that, after a decade of near-zero growth, “globally averaged atmospheric methane increased by [approximately] 7ppb (parts per billion) per year during 2007 and 2008.”
They go on: “During the first half of 2009, globally averaged atmospheric CH4 was [approximately] 7ppb greater than it was in 2008, suggesting that the increase will continue in 2009. There is the potential for increased CH4 emissions from strong positive climate feedbacks in the Arctic where there are unstable stores of carbon in permafrost … so the causes of these recent increases must be understood.”
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.”
The Climate Change Committee
An email from the Climate Change Committee (13 Nov 2009) tells CCQ:
On the subject of methane and climate feedback; we do not assign probabilities to methane release because we do not yet know enough about these processes to include them in our models projections.
“Not assigning a probability” really means assigning a probability of zero. How then can Lord Turner claim that the CCC are formulating policies to limit the chance of “dangerous” climate change to a 1% probability when they set to zero the probability of the methane releases from the unstable stores of carbon in permafrost – sometimes called the “methane time bomb”?
What we would absolutely like to do is keep very small the chances of really hardcore planet change. We suggest that at any one time, based on the latest scientific information, we ought to be designing public policies so as to keep the chances of going above 4%C below 1%.
Lord Turner Speech to the Overseas Development Institute (03 June 2009)
CCQ will ask.
Postscript 4th April 2011
Recieved from the Climate Change Committee:
We still do not assign probabilities to methane release. As we have stated before, this is because we find no such quantitative information available in large-scale reputable assessments.
Perhaps they haven’t noticed the paper by Shaffer et. al. from the National Snow and Ice Data Centre, University of Boulder Colarado, Amount and timing of permafrost carbon release in response to climate warming.
Postscript 30th May 2011 … Methane still on the rise
This leaves little doubt that methane concentration, averaged over these 10 stations, has continued to increase since its rise began in 2007. We can even take the post-2007 data and fit a linear regression line to estimate the rate of increase:
It appears that atmospheric CH4 concentration is increasing at a rate of 5.9 +/- 1.6 ppb/yr.
As usual, Tamino’s analysis is very convincing. There is some discussion as to whether the increase might come from the tropics. Where-ever it comes from it’s bad news.
Another worrying item is a paper by Joye et.al. Comment on “A Persistent Oxygen Anomaly Reveals the Fate of Spilled Methane in the Deep Gulf of Mexico”. It suggests that previous work after the oil spill iin the Gulf of Mexico overestimated the effect of methanatrophic bacteria in preventing the escape of methane to the atmosphere.