I think that this paper: http://www.esrl.noaa.gov/gmd/ccgg/aircraft/miller_2012_jgr_c14.pdf will go some distance in reducing the possibilities. -Greg
From: Nathan Currier <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> To: geoengineering <[email protected]<mailto:[email protected]>> Cc: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Re: [geo] 400 ppm and rising Hi, all - Going back to Stephen's suggestion, re arctic methane escape, elevated arctic CO2, and then the subsequent comments on OH, etc.: first, if there were a chronic release of CH4 to the arctic atmosphere, I don't think you would expect to see any elevated CO2 there at all, since the atmospheric mixing and CH4 lifetime are so different. On the other hand, the one case in which you would see this is that suggested by John Nissen's comment. I had written something once to AMEG suggesting there be a search for a small perturbation in CO2, as a test against just the same data he mentions from Shakhova et al. What John is discussing comes from sonar data, and if the observed seabed release rates were extrapolated over estimated ESAS taliks, it would give a few Gt/CH4 yr. But John then says that the water is too shallow there for much oxidation. Clearly those sonar readings, though, could only be meaningful if there were almost 100% oxidation of the methane in the water, since the growth in the atmosphere has been nothing on that scale. There is, surely, much about arctic microbial communities we don't know, so, just to speculate, if there really were such gigantic releases getting methanotrophically oxidized to CO2, how much of a CO2 anomaly might you expect to see locally? Crudely, if ~30Gt CO2 =+2ppm/yr, then you might expect that over ~3% of the atmosphere (arctic), 1 Gt/yr CO2 might equal ~2ppm. Microbes would be using some proportion of the carbon for biomass, but on the other hand 1Gt CH4 oxidizes >1Gt CO2, since the molecular weights are different, so if you imagine those factors roughly canceling each other out, then 1Gt methane oxidized in the water crudely gives ~1Gt CO2, and so you might expect a few Gt /yr could +~4-6ppm, which is about what you're seeing. All that being said, given that these readings are all over the place, in Mongolia, Finland, Iceland, etc., I agree with Mike and transport is the easier explanation. At least let's hope so, because it would take an awful lot of methane, in other words, to make that small CO2 anomaly. One could test Stephen's suggestion, in any case, by looking locally at CO2 around hotspots of seabed release. In terms of what Robert Socolow asks, which one also needs to know, I remember reading some years ago speculation on whether the annual (globally averaged) Mona Loa oscillation might be growing, perhaps as a signature of the fertilization effect. Could the arctic amplitude be increasing in this way, from things like the "pop up forests" that I just saw mentioned in the news yesterday, where tundra is rapidly changing in response to warming? Cheers, Nathan On Tuesday, June 5, 2012 2:17:35 PM UTC-4, John Nissen wrote: Hi Albert, You make an interesting point about the storm surges mixing the water. This will take warmer surface water down to the seabed - adding to other mixing phenomena that Shakhova and Semiletov have been observing. They believe it is this warming that is causing rapid release of methane, whether it is from hydrates or from free gas previously trapped below subsea permafrost. This is a mechanism for rapid methane release that David Archer says does not and cannot exist, see extract from [1]. The Russians estimated that, if one could imagine the methane release that they were observing from one part of the ESAS happening continuously over the whole of the ESAS, it would amount to several gigatonnes of methane per annum [2]. The global warming from that would quickly dwarf global warming from CO2, and we'd be liable to experience run-away global warming. One does not need hundreds of Gigatonnes of methane over a few years to obtain a catastrophe, as Archer maintains, see extract from [1]. A gigaton of methane release per year for a few years could build up to several Watts per square metre of global climate forcing, compared to under one W/m2 for the current net climate forcing [3]. (BTW, I think you are wrong about the OH. It is bacterial action by methanotrophs [4] that oxidises the methane as it ascends through a water column. In shallow seabed, such as ESAS where it is less than 50 metres deep, most of the methane reaches the atmosphere without oxidation. As Stephen points out, this methane digestion produces significant warming of the water column.) So what can we reduce the risk of such a catastrophe? One absolutely requirement is to cool the Arctic using geoengineering and other means. As well as cooling the Arctic, we need to develop methods to capture (or flare) methane from the ocean seabed, preferably before (or as) it reaches the atmosphere. The Arctic emergency situation, and measures to deal with it, will be considered by the Arctic Methane Emergency Group (AMEG) at the conference organised by the Campaign against Climate Change, in London, on the weekend June 16-17th. Details are available on the AMEG web site here [5]. All are welcome. Cheers from Chiswick, John [1] http://www.realclimate.org/index.php/archives/2012/01/much-ado-about-methane/ [extract] Archer: "The methane bubbles coming from the Siberian shelf are part of a system that takes centuries to respond to changes in temperature. The methane from the Arctic lakes is also potentially part of a new, enhanced, chronic methane release to the atmosphere. Neither of them could release a catastrophic amount of methane (hundreds of Gtons) within a short time frame (a few years or less). There isn’t some huge bubble of methane waiting to erupt as soon as its roof melts." [2] http://www.sciencemag.org/content/327/5970/1246.abstract [3] http://www.columbia.edu/~jeh1/mailings/2011/20110415_EnergyImbalancePaper.pdf<http://www.columbia.edu/%7Ejeh1/mailings/2011/20110415_EnergyImbalancePaper.pdf> [4] http://en.wikipedia.org/wiki/Methanotroph [5] http://ameg.me/ -- On Tue, Jun 5, 2012 at 1:08 PM, Veli Albert Kallio <[email protected]<mailto:[email protected]>> wrote: Dear Stephen, I think that the metamorphosis of ice covered Arctic Ocean to open water plays the decisive role in the hydroxyl-driven methane oxidation: Lets just take a relatively moderate storm surge with the crest between 2-3 metres along Yakutian coast. While the wind propelled storm surge current advances, the reverse current on the bottom of storm surge (which drains the water back into ocean) pulls loose sediments and silt away along the water. This rapidly excavates and exposes methane clathrates to warm water. Furthermore, as East Siberian Sea is so shallow, storm surges can form on sideway directions as well which might be strong enough to disturb bottom mud. This explains entirely the observed rapid methane clathrate losses on East Siberian Sea seabed last autumn. The sea bed responds to warming far faster than terrestrial permafrost due to higher thermal inertia of sea water to air above land. The hydrodynamical factors played key role in excavating those 22,000 methane craters along Siberian sea bed, many of which are one kilometre wide, largest ones 750 km2. As storm surges and rising bottom currents excavate methane clathrates rapidly, the hydroxyl supply is unlikely to keep up with these. Temperatures surge, winds rise and erosion grows. As a result the hydroxyl radical disappears due to large surges of methane, just the same way carbon-14 isotope will get increasingly diluted the more CH4 and CO2 come from Eurasian and Arctic frozen soils and seabed. Stephen, thus the answer to your question must necessarily be: Yes, methane from the Arctic does not get oxidised as warming and storm surges driven supply of methane quickly overwhelms the supply of methane oxidising OH-. It is crucial to understand that wind driven storm surges drive the loss of methane clathrates, unlike a steady loss of methane ice, this occurs rather rapidly in pulses thus encapsulating most of methane in a hydroxyl-protected enviroment. Regards, Albert > Date: Tue, 5 Jun 2012 11:10:24 +0100 > From: [email protected]<mailto:[email protected]> > To: [email protected]<mailto:[email protected]> > CC: [email protected]<mailto:[email protected]> > Subject: Re: [geo] 400 ppm and rising > > Mike > > Both diffusion and oxidation are involved. Are you saying that methane > released from the Arctic does not get oxidised? > > Stephen > > Emeritus Professor of Engineering Design > Institute for Energy Systems > School of Engineering > Mayfield Road > University of Edinburgh EH9 3JL > Scotland > Tel +44 131 650 5704 > Mobile 07795 203 195 > www.see.ed.ac.uk/~shs<http://www.see.ed.ac.uk/%7Eshs> > > > On 04/06/2012 14:46, Mike MacCracken wrote: > > Hi Stephen--I think there is a simpler explanation, and that is that the > > planetary boundary layer is shallow due to the typical inversion, so CO2 > > tends to build up near the ground during the non-growing season. My guess is > > that the late summer values also tend to be a bit lower than Mauna Loa due > > to the CO2 being pulled out from a thinner layer (you see a much larger > > seasonal variation in high latitude CO2 than at Mauna Loa). > > > > Mike > > > > > > On 6/4/12 6:30 AM, "Stephen > > Salter"<[email protected]<mailto:[email protected]>> wrote: > > > >> Hi All > >> > >> There are not many large coal-fired power stations in the Arctic and so > >> the question arises about where this extra CO2 in the Arctic has come > >> from. One possibility is that it is the product of methane > >> decomposition and would be in line with the report to this group from > >> Greg Rau of 22 May. > >> > >> We know that the atmosphere weighs about 5 E18 kilograms. If we know > >> the plan area represented by the observing stations and the decay rate > >> of methane to CO2 we could get an approximate figure for the mass of > >> methane causing the rise in CO2. We could then compare this with the > >> scary rate of methane increase reported by Semiletov and Shakhova. > >> > >> Stephen > >> > >> > >> Emeritus Professor of Engineering Design > >> Institute for Energy Systems > >> School of Engineering > >> Mayfield Road > >> University of Edinburgh EH9 3JL > >> Scotland > >> Tel +44 131 650 5704 > >> Mobile 07795 203 195 > >> www.see.ed.ac.uk/~shs<http://www.see.ed.ac.uk/%7Eshs> > >> > >> > >> On 02/06/2012 17:41, Rau, Greg wrote: > >>> Greenhouse gas levels pass symbolic 400ppm CO2 milestone > >>> Monitoring stations in the Arctic detect record levels of carbon dioxide, > >>> higher than ever above 'safe' 350ppm mark > >>> Associated Press > >>> guardian.co.uk<http://guardian.co.uk>, Friday 1 June 2012 07.50 EDT > >>> > >>> The Arctic Ocean with leads and cracks in the ice cover of north of > >>> Alaska. > >>> Photograph: Courtesy Eric Kort/Jet Propulsion Laboratory/NASA > >>> The world's air has reached what scientists call a troubling new milestone > >>> for carbon dioxide, the main global warming pollutant. > >>> > >>> Monitoring stations across the Arctic this spring are measuring more than > >>> 400 > >>> parts per million of the heat-trapping gas in the atmosphere. The number > >>> isn't quite a surprise, because it's been rising at an accelerating pace. > >>> > >>> Years ago, it passed the 350ppm mark that many scientists say is the > >>> highest > >>> safe level for carbon dioxide. It now stands globally at 395. > >>> > >>> So far, only the Arctic has reached that 400 level, but the rest of the > >>> world > >>> will follow soon. > >>> > >>> "The fact that it's 400 is significant," said Jim Butler, the global > >>> monitoring director at the National Oceanic and Atmospheric > >>> Administration's > >>> Earth System Research Lab. "It's just a reminder to everybody that we > >>> haven't > >>> fixed this, and we're still in trouble." > >>> > >>> "The news today, that some stations have measured concentrations above > >>> 400ppm > >>> in the atmosphere, is further evidence that the world's political leaders > >>> > >>> with a few honourable exceptions are failing catastrophically to address > >>> the climate crisis," former vice president Al Gore, the highest-profile > >>> campaigner against global warming, said in an email. "History will not > >>> understand or forgive them." > >>> > >>> Carbon dioxide is the chief greenhouse gas and stays in the atmosphere for > >>> 100 years. Some carbon dioxide is natural, mainly from decomposing dead > >>> plants and animals. Before the industrial age, levels were around 275 > >>> parts > >>> per million. > >>> > >>> For more than 60 years, readings have been in the 300s, except in urban > >>> areas, where levels are skewed. The burning of fossil fuels, such as coal > >>> for > >>> electricity and oil for gasoline, has caused the overwhelming bulk of the > >>> man-made increase in carbon in the air, scientists say. > >>> > >>> It's been at least 800,000 years probably more since Earth saw carbon > >>> dioxide levels in the 400s, Butler and other climate scientists said. > >>> > >>> Readings are coming in at 400 and higher all over the Arctic. They've been > >>> recorded in Alaska, Greenland, Norway, Iceland and even Mongolia. But > >>> levels > >>> change with the seasons and will drop a bit in the summer, when plants > >>> suck > >>> up carbon dioxide, NOAA scientists said. > >>> > >>> So the yearly average for those northern stations likely will be lower > >>> and so > >>> will the global number. > >>> > >>> "It's an important threshold," said the Carnegie Institution ecologist > >>> Chris > >>> Field, a scientist who helps lead the Nobel Prize-winning > >>> Intergovernmental > >>> Panel on Climate Change. "It is an indication that we're in a different > >>> world." > >>> > >>> Ronald Prinn, an atmospheric sciences professor at the Massachusetts > >>> Institute of Technology, said 400 is more a psychological milestone than a > >>> scientific one. We think in hundreds, and "we're poking our heads above > >>> 400," > >>> he said. > >>> > >>> Tans said the readings show how much the Earth's atmosphere and its > >>> climate > >>> are being affected by humans. Global carbon dioxide emissions from fossil > >>> fuels hit a record high of 34.8 billion tonnes in 2011, up 3.2%, the > >>> International Energy Agency announced last week. > >>> > >>> The agency said it's becoming unlikely that the world can achieve the > >>> European goal of limiting global warming to just 2 degrees based on > >>> increasing pollution and greenhouse gas levels. > >>> > > > > > > -- > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to > [email protected]<mailto:[email protected]>. > To unsubscribe from this group, send email to > [email protected]<mailto:geoengineering%[email protected]>. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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