A few weeks ago news came though that “the climate threat posed by methane trapped at the bottom of the world’s oceans is not as bad as first thought.” We all breathed a little easier.
The CSIRO and other scientists around the world examined ice cores in Greenland and found that during the Younger Dryas event between approximately 12,800 to 11,500 years ago the increase in atmospheric methane of that time was not sourced from clathrates under the ocean “but from ecological sources such as wetlands”.
That’s good as far as it goes, but I’m not sure it is a get out of jail card.
Lets look briefly at the Younger Dryas event. It is one of a category of Heinrich or Dansgaard/Oeschger events, of which there has been a number in the past 50,000 years. (See Figure 3 here.) The temperature change over central Greenland is quite striking:
Figure 1: Temperature over Greenland
I don’t have a link for the source of the graph, but it was in a report on security and sourced to NASA. There is a similar one here but I chose the first because the x axis is less compressed.
It is important to note that the temperature is over Greenland. The question has been raised as to whether the Younger Dryas was a global event. The short answer seems to be “no”, although there were traces as far south as New Zealand. Have a look at the temperature of Greenland overlayed with that of Antarctica:
Figure 2: Temperature over Greenland and Antarctica
That graph is courtesy of a post on the Younger Dryas by Tamino at Open Mind. Tamino thinks that on balance the latest evidence indicates that the Younger Dryas was triggered by the explosion of an extraterrestrial object over the Laurentide ice sheet. The thermal blast could have caused a fresh water pulse that interrupted the thermohaline circulation blocking heat transport from the tropics to the Northern Atlantic.
The CSIRO research looks at the methane sources during the also very rapid warming at the end of the Younger Dryas. What caused this warming I don’t know, but by examining the chemical tracers on the molecules of methane trapped in the ice the new research found that the methane came from the melting of permafrost weltlands rather than from methane clathrates under the ocean.
The bottom line to me is that all this took place at temperatures lower than the present where you wouldn’t expect the underwater clathrates to be involved. So I’m not sure exactly why we should be relieved.
Methane is produced right now from sources such as bacteria in wetlands and bogs, especially where the permafrost is melting, from cattle and other ruminant livestock, rice paddies, termites, landfills, and ‘fugitive’ emissions from coal mining. This is what is worrying scientists:
Figure 3: Methane emissions
That graph was from Nature; this one is from the New Scientist:
Figure 4: Methane emissions and warming trends
It’s easy to see, I think, that Siberian permafrosts and peat bogs is where there is significant action, leaving aside underwater clathrates. There have been numerous reports, for example here and here.
The UNEP 2009 Report chapter on climate change (pdf) tells us that latest estimates say the northern tundras contain twice as much carbon as the atmosphere. In addition a study of unfrozen bogs in Manitoba suggest that with a 4C rise:
“Over several centuries, some 40 percent of carbon could be lost from shallow peat bogs, while the losses could total as much as 86 percent in deep bogs.”
All of this is scary enough and well before all that happens there is a risk that methane clathrates could be brought into play.
I don’t know about you, but I’m still worrying.
Agreed. There’s more than enough in the permafrost to send us all to hell. This said, it’s nice to be able to cross clathrates off the list as a potential near-term ‘runaway’ contributor.
Good, we’ve dodged one bullet. But expect a hail of them coming our way from now on.
I doubt we have dodged any bullets. I always thought the interpretation of the study results were a bit generous. So the methane from permafrost gets released quicker/earlier than the methane from the calthrates. I think we knew that anyway. We should be less concerned now because…
because… it’s so depressing being concerned!
Just accept that the world we know 50 years from now will be nothing like the world we know today. Certainly, we should make the most of the opportunities presented for savvy property investors/developers to grab a bit of ‘soon to be ocean views’…
The release of methane from clathrates (or hydrates) will depend upon where the knee of the temperature/pressure curve is located. This will depend upon the rate of mixing in the sea and the temperature rise and of course the depth. Most models suggest that liberation will take a long time. Very roughly, the stability curve has a very soft knee and even a small change in temperatiure will alter the depopth at which methane will be liberated. There is alot of it BTW – 10,000 gigatonnes of carbon.
http://www.nature.com/nature/journal/v420/n6916/full/nature01263.html
Huggy
This is an excellent overview, which has saved me the trouble. I was going to write about this on my blog, but now I can highlight what you have and add the little I have.
I’ve had e-mail contact with a researcher on this topic, and got the same response. I tried to clarify the issue of lower temps during the YD and got a response about it being pressure, temps AND speed of temperature change.
With regard to pressure, SLR leading up to the YD would have increased pressure on any and all sea bed clathrates. Yes, temperatures for those clathrates created during the YD and before on what is now shallow sea floor would have raised as covered with sea water, but to on;y within 2C of their melting point.
The problem is that temps, both air and ocean, temps have risen since then and, according to Romanovsky, leaves both clathrates and permafrost methane deposits within a degree or two of melt. Of course, we know they are already melting in places.
I tried to get a response to this from Dr. Katey Walter and Dr. Romanovsky who were involved on the thermokarst and permafrost methane emissions studies from last summer, but got no response.
My point on the YD comparison is that it is simply not a proper comparison. If temps were lower than the melting point for these deposits, how can it be an issue?
I think there is plenty to be concerned about. When we consider the science has been well behind the observed changes in the natural world, all the more so.
Hope you don’t mind if I quote liberally from you on my blog?
Cheers
ccpo, quote away with acknowledgement, of course, but just remember I’m not a scientist, so not an authority as such. Thanks also, and to Huggy, for the informed comment.
Polyquats, I agree. That was my point. I can’t see where we’ve dodged any bullets.
I did see a recent estimate of how much methane might be released from permafrost by 2100 and it was smaller than I’d imagined it might be. There are problems, though, in how it is measured if just in tonnes of carbon. Normally methane is converted to CO2 equivalence in terms of about 23 times CO2. But as Barry Brook keeps pointing out, especially in relation to cattle and sheep, methane is gone after 20 years and if the effect is calculated over 20 years then it is 72 times more potent than CO2:
Ouch!
The irony of the leaking coal mines is that it is better to burn the methane in a combined cycle gas turbine than to actually mine the coal. People I know who are doing the survey work tell me that there is no shortage of the stuff. Already it is a large proportion of the gas grid. You get almost twice the efficiency with the CCGT and some of the energy comes from hydrogen. It’s an absolute no-brainer.
Huggy
Methane oxidiizes to CO2 over time with Wikapedia quoting a half life due to this oxidation of 7 years. The big risk then is large surges in methane emission over arelatively short time. One crucial question then is: “How fast might warming related methane surges be? It may also be worth asking whether the size of these surges might be large enough to give CO2 surge due to methane oxidation that is enough to be significant? Wikapedia gave 1998 atmospheric concentrations of 1.7 ppm for methane compared with 365 ppm for CO2. (CO2/CH4=209)
A second crucial question: Is there a store of methane has been building up that hasn’t been released during the warm part of past climate cycles?” If this is true, we may have a crisis if the current round of global warming reaches high enough temperatures to release methane from this old store.
I am sadly bemused by the “there have always been fluctuations in climate” brigade who completely missed the part where within those fluctuations entire species die out, and, if there were highly tuned civilsations such as ours around at the time, they would fade in the first moments of the fluctuations.
I have adjusted to the inevitability, now. Still joining the street marches, though. And the sacking of Labour headquarters, if necessary.
John D @ 9, those are good questions and I don’t know the answers.
It seems the Holocene Climatic Optimum 5-8,000 years ago was similar to now and during the Eemian interglacial 125kya the temperature was said to be 1-2C higher.
We are forcing harder now than then which means that as the temperature rises the sea level now would lag what it achieved then. What this says to my untutored eye is that we may now have storms etc of equal severity causing deep mixing, but lack a bit of the protection granted by sea level and pressure.
But really, I don’t know.
I did read somewhere that there was a concern over severe monsoons going close to disturbing clathrates in the Northern Indian Ocean.
There was a mini Tsunami on the north coast of PNG around 1997 during the severe drought that was caosed by a huge pool of hot water that sat over the North Coast.
there was speculation at the time that the Tsunami haad been caused by hot water destabilising the Methane Hydrates on the walls of the deep ocean trench there. The resulting “seaslide” caused abackwash that wiped out at least one village.
Huggy
I think this is good news:
a 2000hp drilling rig arrived at Port Pirie late yesterday .. will be transported to site this week…(where) exploratory drilling results indicate… the
highest recorded heat flow of all geothermal projects on mainland Australia … to drill 4km below the earth’s surface creating a deep injection well that, in tandem with a soon-to-be-drilled second well, will establish an underground “heat exchanger” capable of circulating super-heated water by early 2010..(on track to) deliver Australia’s first commercial geothermal energy supply by early 2011 … other geothermal energy developers across Australia will subsequently have access to (drilling rig)…The project has already received significant Federal Government support, including a $7 million grant last month through the Government’s $50 million Geothermal Drilling Program… (and it has )applied for funding via the Government’s $435 million Renewable Energy Demonstration Program to help finance a 30MW commercial demonstration project.
Mar’n's mob has been dragging the chain about announcing the winners in the redp grant round, but plonking some money down on shares in this project’s partners would be a pretty safe bet on the strength of the likeliehood the Mar’n will eventually announce what the gov’t is kicking in…he who gets the rig here is first cab of the grants rank? A
Danny, that sounds like the Flinders Ranges project and, yes, good news.
Huggy, I remember that mini tsunami. It brought to mind what I thought was a catastrophe involving methane arising from a lake in Africa and killing a whole village. The culprit turned out to be CO2 suffocation in what is termed limnic eruption which has killed twice:
Lake Kivu is the third known ‘exploding lake’ and could be the worst of the lot when it goes.
I looked in Mark Lynas’s book Six degrees, which is where I thought I read it. Couldn’t find it, but found a story about the Holocene Storegga Slide Tsunami off Norway about 8,000 years ago. Much methane was released, and may have been implicated in the cause.
Methane clathrates seem to be the prime suspect for the Paleocene-Eocene Thermal Maximum (PETM) event 55 mya. The account of the mechanism indicates why the process was dragged out over thousands of years.
There is some comfort in that because it means the process could be interruptible and warming reversed.