Climate sensitivity is now irrelevant
Thanks to Professor Jennifer Browdy de Hernandez (Transition Times blog), I have been alerted to an article by Andrew Revkin in the New York Times, in which he takes A Closer Look at Moderating Views of Climate Sensitivity (where climate sensitivity is the amount of temperature change expected per doubling of atmospheric CO2).
This even includes an update wherein Revkin reports an exchange of emails with Gavin Schmidt (NASA), in which the latter suggests that Revkin has implied that “the wishful thinking of people like Ridley and Lindzen for a climate sensitivity of around 1 deg C is tenable”. For the record, I think this criticism was unjustified because, at the beginning of his article, Revkin clearly states that:
There’s still plenty of global warming and centuries of coastal retreats in the pipeline, so this is hardly a “benign” situation, as some have cast it.
However, with the greatest of respect to both Revkin and Schmidt, all this arguing about climate sensitivity (to CO2) may be moot, if, as many scientists are now saying, the warming that has already occurred is now very close to triggering widespread methane release:
– from permafrost (which is already happening); and
– sediments on the deep ocean floor (also already happening).
If these things are already happening, it is almost certainly too late to stop them. It is tantamount to trying to stop an avalanche that has already started. This is because, as a greenhouse gas (GHG), methane is over twenty times more powerful than CO2. Therefore, the warming effect of all this methane could be many times more than all the CO2 humans will ever emit as a result of burning fossil fuels. We could of course try and trap this methane and burn it. This would still not be good (but it would be better than uncontrolled release). However, trapping and burning all this methane would make the technological achievement of landing a man on the Moon look like child’s play by comparison.
In essence then, the widespread release of geospheric methane back into the biosphere, which has already started, renders discussion of climate sensitivity to CO2 irrelevant; and means that significant climatic change is now inevitable and irreversible. Sadly, just as Bill McKibben noted over a year ago (thanks to Learning from Dogs for the reminder), we continue to be deafened by:
– climate change denial from the fossil fuel lobby;
– denial of the problem from our politicians.
Whichever way you slice the cake, it is not good news. With my thanks to another British blogger, Pendantry, for alerting me to it, here is the bad news in full from Guy McPherson (ecological biology Professor Emeritus at University of Arizona)…
I guess I should have called this post, “Confessions of an environmental alarmist” but, I do not see that I have much choice because… Denial is not a river in Egypt.
UPDATE (1500 GMT): Thanks to the fact-checking of Jules (see comment below), it has been pointed out to me that the release of methane from the seabed may not be the massive problem McPherson makes it out to be above, because:
Methane emitted at the seafloor only rarely survives the trip through the water column to reach the atmosphere. At seafloor depths greater than ~100 m, O2 and N2 dissolved in ocean water almost completely replace CH4 in rising bubbles (McGinnis et al. 2006). Within the water column, oxidation by aerobic microbes is an important sink for dissolved CH4 over some depth ranges and at some locations (e.g., Mau et al. 2007).
Ruppel, C. D. (2011) Methane Hydrates and Contemporary Climate Change. Nature Education Knowledge 3(10):29.
However, this does not change the fact that methane is already being released direct to the atmosphere across vast areas of formerly-frozen permafrost in the north of Canada and Siberia.
UPDATE (1845 GMT): In responding to my comment on the NYT website, Andy Revkin claims most scientists doubt that methane release is the game over scenario some claim it to be; and he refers to a David Archer piece on the Real Climate blog a year ago. My response to that would be: So what, this is not – nor was it ever – a reversible laboratory experiment!