Open Mind

The Other Anthropogenic Greenhouse Gas

December 26, 2008 · 136 Comments

There are many greenhouse gases, i.e., constituents of the atmosphere which are infrared-active. The most potent in earth’s atmosphere (because it’s the most prevalent) is water vapor, but the concentration of water vapor is controlled by temperature and other natural factors. The next most potent, one whose atmospheric concentration has been dramatically increased by humanity, is carbon dioxide, which is responsible for most of the anthropogenic global warming. But next on that list after CO2, is methane, or CH4.


There’s not nearly as much methane in the atmosphere as there is CO2; the concentration of CO2 is over 380 ppm (parts per million) but that of methane is only about 1.8 ppm. However, more than half of that is due to human activity; we’ve more than doubled the pre-industrial methane concentration. And CH4 is a more potent greenhouse gas on a per-molecule basis, about 20 times as much as CO2. Methane only persists in the atmosphere about a decade (not nearly as long as CO2, which lasts for centuries), but when methane is broken down by natural atmospheric chemical processes (mostly involving the hydroxyl radical OH), the byproduct is: CO2. All told, methane is the 2nd-strongest anthropogenic contribution to global warming.

For about a decade, the concentration of methane in the atmosphere had stabilized; the emissions due to human activity were balanced by the processes which remove methane from the air. But recently, researchers announced that methane was on the increase again. Rigby et al. looked at methane concentration from a dozen stations around the globe (note: nmol mol-1 is the same as ppb, or parts per billion):


As discussed above, a relatively rapid growth of between 5 and 15 nmol mol-1 year-1 was observed at all sites during the El Nin˜o of 1998. In the following years, although some growth was seen in the Northern Hemisphere (NH) in 2002–2003 (possibly linked to biomass burning [Simmonds et al., 2005]), the global average mole fraction remained relatively stable between 1999 and 2006. However, from around early-2007 we see renewed global growth, the rate of which had reached almost 10 nmol mol-1 yr-1 at all locations by late-2007.

The CH4 concentrations at most of the stations in their study are plotted here (click for a larger, clearer view):

rigby1

They then apply a model for emission and destruction of CH4 to investigate the reason for the increase, and for its simultaneity in both hemispheres. Their model study is inconclusive, but two possibilities are suggested: a simultaneous increase in emissions in both hemispheres, or a decrease of OH concentration coupled with greater emissions increase in the northern hemisphere:


The pattern of this recent anomaly provides some information about the behaviour of the global sources and sinks that may be responsible. Positive annual average growth rate is found to first appear almost simultaneously at all latitudes around early-2007, and rises at a similar rate across the globe until the most recent measurements. Given that the inter-hemispheric mixing time is of the order of one year, we can infer that if an increase in CH4 emission is solely responsible, output must have risen almost simultaneously from both hemispheres. Alternatively, a decrease in the OH sink may have occurred, potentially reducing the required emissions rise in one or both hemispheres.

I’m not at all convinced that they’re correct about the simultaneity of the increase worldwide, or about the ubiquity of the increase at all stations. I took CH4 data (for most stations I only managed to find it through the end of 2007), isolated the data since 2000, and subtracted the annual pattern (as estimated by a 4th-order Fourier fit) to generate residuals. For Alert station (in the Northwest Territory, Canada) the increase occurs sharply in January 2007:

alert

For Trinidad Head station in California, the increase doesn’t occur unambiguously until September of 2007 (for this station, the available data go to March 2008):

trinidad

Finally, for Mauna Loa station in Hawaii, the increase appears likely but is far from certain; the recent upswing is within the range of variation exhibited in the last 8 years:

maunaloa

Despite these uncertainties, this much is certain: methane is on the rise again. Most of the stations studied by Rigby et al. show a sure-fire increase in atmospheric methane concentration during 2007. Whether this is due to global warming itself, and therefore represents a feedback in the climate system, I don’t know. One might even hypothesize that this recent increase represents crossing one of the “tipping points” of global warming, although again, that’s merely speculation on my part.

Categories: Global Warming
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136 responses so far ↓

  • co2ch4 // December 26, 2008 at 5:56 pm

    Could you please give a brief explanation (or a short treatment) on how and why this is so: “And CH4 is a more potent greenhouse gas on a per-molecule basis, about 20 times as much as CO2..” Thanks in advance.

    [Response: I don't know. I suspect it may be related to the fact that CH4 doesn't have as much overlap with water vapor absorption bands, and that CH4 infrared absorption is nowhere near saturation in the atmosphere. But it's really a question for a radiation physicist. Ray?]

  • Hank Roberts // December 26, 2008 at 6:14 pm

    Excellent. I hope you’ve invited, or will invite, Dr. Rigby et al. to look in. It’d be very interesting to know more about the patterns.

    Is there a separate annual/seasonal pattern for each station, that you subtracted? Correlation with anything else?

    [Response: Yes, the annual pattern is very different for different stations. I haven't looked thoroughly, but my first impression is that the arctic stations show the strongest (largest amplitude) annual pattern.]

  • co2ch4 // December 26, 2008 at 6:18 pm

    Chris Coloze’s post on this question maybe of interest: Is methane a ‘better’ greenhouse gas than CO2?, November 10, 2008

  • Nick Zervos // December 26, 2008 at 7:19 pm

    I find it interesting that AGW alarmists never hesitate to add remarks in these discussions such as “One might even hypothesize that this recent increase represents crossing one of the ‘tipping points’ of global warming” . There’s no reasonable basis even to speculate we’re anywhere near a tipping point. So why say it?

    The earth has recovered before from atmospheric CO2 and CH4 concentrations much higher than they are now. A prominent example: it’s been estimated that the CO2 concentration during the Paleocent-Eocene thermal maximum was about 2000 ppm. The only plausible explanation scientists can offer for that excursion was a release of methane, presumably from clathrate deposits. Yet the earth’s negative feedback mechanisms allowed the earth to recover. Even that extreme event wasn’t a “tipping point” in the Al Gore, climate-of-Venus sense of the term. In fact, mammalian life on earth flourished and diversified during that geologic period.

    I’d like to see what the IPCC-referenced climate models predict with the Paleocene-Eocene thermal maximum as an initial condition. Any model that predicts we’re near a tipping point now evidently understates or omits the relevant negative feedback mechanisms.

    [Response: The Paleocene-Eocene Thermal Maximum was 55 million years ago; earth certainly wasn't carrying the load of 6.5 billion human beings and their infrastructure. It was also a major extinction event; maybe extinction is your idea of a negative feedback.

    And why mention Al Gore, or "climate-of-Venus"? That's just a straw man argument.]

  • Hank Roberts // December 26, 2008 at 7:28 pm

    http://www.sciencemag.org/cgi/content/abstract/239/4844/1129

  • chriscolose // December 26, 2008 at 8:04 pm

    Yes, my post covers the question posed in #1. The answer has more to do with its current atmospheric concentration and context than anything special about the gas itself. Tamino’s answer on saturation is pretty much right.

  • dhogaza // December 26, 2008 at 8:31 pm

    Even that extreme event wasn’t a “tipping point” in the Al Gore, climate-of-Venus sense of the term.

    Sigh, climate science, and AFAIK Al Gore, doesn’t predict a “climate-of-Venus” future for the planet.

    And we all know that the earth will survive. “Save the Planet” is secret code for “Save our own ass”.

  • cce // December 26, 2008 at 9:12 pm

    The earth can recover from just about any calamity. The PETM lasted about 20,000 years and it took about 100,000 years for the atmosphere to “recover”. That will be little comfort to the next ~thousand generations of humans.

    The Venus-like runaway effect that Hansen has been talking about lately requires very rapid GHG release to overwhelm the negative feedbacks that ordinarily pull this stuff out of the air.

  • grenow // December 26, 2008 at 9:16 pm

    The chapter on methane in the recent USGS Abrupt Climate Change report (PDF here) gives a very good overview of the radiative forcing effects of methane, and its various sources. For those of us who are worried by the possibility of large methane releases, it is somewhat reassuring in its conclusions, but reads as though it was written a year or two ago, before the latest news on methane releases on the East Siberian shelf.

  • Ray Ladbury // December 26, 2008 at 9:35 pm

    Tamino, I, along with Chris, think it’s more likely relative concentration than the particular position of the absorption band. If you look here:
    http://www.globalwarmingart.com/wiki/Image:Atmospheric_Transmission_png

    You can see the relative strengths of the CH4 and CO2 lines, along with their position relative to each other and water. CH4 is still absorbing in the central portion of the band, while incremental increases in CO2 increase absorption in the wings.

    Chris, have you looked at CH4 sensitivity–degrees per doubling? That might be a good way of making the point?

  • David B. Benson // December 26, 2008 at 9:37 pm

    How far back do records of methane concentrations extend? Its not something I’ve looked into.

    [Response: Ice core measurements go back at least 400,000 years (Vostok), maybe more (EPICA?). I haven't yet found direct measurements prior to 1983.]

  • Ray Ladbury // December 26, 2008 at 10:05 pm

    Nick Zervos, You know, when you try to reassure us by conjuring visions of the PETM–a pretty nasty mass extinction event–you really don’t help your case. It’s a bit like the President in “Mars Attacks” saying after the incineration of Congress “We’ve still go 2 branches of government left, and I think that’s pretty darn good.”
    To which I reply, “Ack-Ack!”

  • Kipp Alpert // December 26, 2008 at 11:55 pm

    Chris Colose has mentioned methane in his article about Global Warming. Chris said that methane was not more potent than co2, but the reason methane is quantified that way is that less methane is in the troposphere. Above they say it is more potent per molecule, and is truly the second largest greenhouse gas. Water vapour being the first? The U.S.Geological Surevey new report said that by 2100, methane clathrates would still not be likely to melt. They said that the IPCC was too conservative about the melting of the Arctic and Greenland. The models didn’t take into acccount the lubricating effect of water underneath the ice. They said this would be sufficient to stop the thermohaline
    circulation. Chris, could you clarify the suggestion that per molecule methane is stronger than CO2.Thanks,Kipp

  • Kipp Alpert // December 27, 2008 at 12:15 am

    Chris Colose:Absorption bands in organic molecules show that CO2@2′380three bands at 100to300 OT2380 and methane@from2,800 to 3,200OT four bands. Could you explain their difference.Thanks again,KIPP

  • Kipp Alpert // December 27, 2008 at 12:18 am

    Ray Labury:Don’t worry, that President that you talk about will be leaving us in twenty days,Thank God.

  • Kipp Alpert // December 27, 2008 at 1:17 am

    To the Author;your reponse, The Paleocene-Eocene Thermal Maximum was 55 million years ago; earth certainly wasn’t carrying the load of 6.5 billion human beings and their infrastructure. It was also a major extinction event; Since I am not a scientist, during this mass extinction, what did survive or are we just talking about trilobites.Some mammals did survive this?Thanks,KIPP

    [Response: From Wikipedia:

    The PETM is accompanied by a mass extinction of 35-50% of benthic foramanifera (especially in deeper waters) over the course of ~1000 years - the group suffering more than during the dinosaur-slaying K-T extinction. Contrarily, planktonic foramanifera diversified, and dinoflagellates bloomed. Success was also enjoyed by the mammals, who radiated profusely around this time.

    ...

    The increase in mammalian abundance is intriguing. There is no evidence of any increased extinction rate among the terrestrial biota. Increased CO2 levels may have promoted dwarfing[27] - which may (perhaps?) have encouraged speciation.

    ]

  • Hank Roberts // December 27, 2008 at 1:22 am

    Kipp, an absorbtion band means a bit of the molecule can wiggle, waggle, or sproing at that particular frequency.

    CH4 has a few more possible ways of moving than CO2.

    How that actually creates and absorbs photons is going to take advanced math. Can’t help ya.

    You’ll find a _lot_ of whacko stuff on the web about this. If you search for information, stick with academic and journal references. Don’t rely on some guy on a blog.

  • Phil. // December 27, 2008 at 1:31 am

    Chris’s point was that CH4 is behind CO2 molecule for molecule when they start from zero, however when starting from the present day concentrations CH4 is more effective. This is because the lines in the CO2 absorption bands are more saturated and increase absorption by broadening into the wings of the band, whereas CH4 is nearer to the linear range.

  • tamino // December 27, 2008 at 2:13 am

    Also from wikipedia:

    The event saw global temperatures rise by around 6 °C over 20,000 years…

    It’s not impossible that we’ll experience that much warming in just a few centuries.

  • Kipp Alpert // December 27, 2008 at 3:32 am

    Hank Roberts: Thanks.I’ve been bloggin for about a year and a half. over at accuweather fighting swarms of denialists. So in that time I learned everything I know about science because I didn’t listen to other people who have an Agenda.First the IPCC, then books on Climate Biology, a Little geology and less Physics. So I love the purity I find in science, and when it says warmer I salute. Don’t worry about me with those wing nuts,I can handle them no problem.After all, they never study science anyway. They have learned not to mess with me because there arguments are so fallacious, and dumb. Great,thanks KIPP

  • Richard Steckis // December 27, 2008 at 3:38 am

    Tamino. The PETM extinction event was almost entirely confined to the oceans. In fact there was an increase in the abundance of mammalian life during the PETM. In fact, it was during this time that primates evolved.

    Also you seem to argue that the increase in CH4 is entirely due to anthropogenic forces. However there is evidence of increased CH4 output from the oceans and from the Arctic tundra. I don’t think that it is unequivocally determined that these are anthropogenically forced.

  • Kipp Alpert // December 27, 2008 at 3:38 am

    Phil:I noticed when I compared bands of CO2 and CH4, that CO2 covered the length - breadth of the band and CH4 covered the middle mostly. Another question.Don’t the two molecules carry a certain amount of pressure as well and would that be relevant. Like,these GHG’s react more too the IR and tumble while water vapour,is a great absorber. Thanks’KIPP

  • Kipp Alpert // December 27, 2008 at 3:40 am

    Responder of wiki_Thanks for your time,KIPP

  • Kipp Alpert // December 27, 2008 at 3:50 am

    Hank Roberts:I used to rely on Gristmill at first, then learned enough on my own, to fight, then kept on reading.Science is so universal, and changing(especially climate)that you have to know some meteorology, and everything you need to get started with is in the IPCC.From there you can get into more specifics, about warming,theIR, feedback loops,pH,deforestation, ocean acidification, and basically everything about what we can do to save ourselves, no thanks to X presidents. Thanks again KIPP

  • Kipp Alpert // December 27, 2008 at 3:53 am

    Tamino:It is like an angel to my ear to hear anyone who is not addicted to the dark forces of natural variations, and understands Rapid Climate Change. KIPP

  • chriscolose // December 27, 2008 at 4:35 am

    Ray

    The RF for methane is pretty complicated (I’ve actually never seen a number cited for temperature increase per 2x CH4). Though, the IPCC TAR has a formula in their report much like they do for carbon dioxide (dF=5.35*ln[C(t)/C(1750)] ), so that part shouldn’t be hard to work out. It’s just a little algebraically “longer” and has an N2O dependence.

    But the forcing not only includes its direct absorption component, but also changes in the hydroxyl radical and tropospheric ozone due to oxidation. The lifetime of methane also becomes longer as the hydroxyl radical is lost in the atmosphere leading to an enhancement of the overall forcing. Oxidation of CH4 also leads to tropospheric ozone and stratospheric water vapor which have their own radiative effects

  • chriscolose // December 27, 2008 at 4:42 am

    Hey, I said that part about ozone twice!

    Kipp- take Hank’s advice. There’s lots of authoritative reports on this stuff (which don’t get very mathematical) which always makes for better reading than random factoids in comments. Personally, I hope I convey accurate information, but a lot of people don’t (willfully or mistakingly), and sorting out which “blogs” get the facts or the majortiy of the facts right is not easy.

  • dhogaza // December 27, 2008 at 5:05 am

    Tamino. The PETM extinction event was almost entirely confined to the oceans. In fact there was an increase in the abundance of mammalian life during the PETM. In fact, it was during this time that primates evolved.

    So, in your mind, the fact that this happened 20x slower than we might expect warming to happen due to anthropogenic CO2 means that … what …

    That we’ll just evolve 20x times faster, because the slow pace led to a huge increase in the rate of speciation in mammals back then?

    What evidence do you have that a 20x increase in the rate of warming over the PETM is harmless to people?

  • Kipp Alpert // December 27, 2008 at 5:10 am

    Thanks Chris:It’s starting to come together, and it’s exhilarating to say the least. will.If you get the time, could you explain to me something about bands and how they function, and why they are in certain parts of the atmosphere.From Photography I understand color and kelvin watts and spectral bands from that,but is hard for me to see why CO2 is in three bands and maybe CH4 in others, (in the atmosphere)and shouldn’t they mix as they tumble around. I am still waiting for you to write your first book, as you are good with words.Thanks,KIPP

  • Kipp Alpert // December 27, 2008 at 5:15 am

    Chris Colose:Have any sites or books I should buy.I’ll come and take your portrait for your first book. I did Akio Morita a while back. cool guy.F of Sony.
    KIPP

  • michel // December 27, 2008 at 8:13 am

    On another thread, I said that our way of life would have to change in order to reduce atmospheric CO2 to 300ppm, and the consensus seemed to be that no, this was wrong. That discussion focussed on electricity generation and transport, and the consensus seemed to be (incomprehensibly) that we could carry on as now, malls, suburbs and driving, just move to windmills to generate electricity and electric cars to drive. We did not cover agriculture to any extent.

    Methane is another issue that suggests our way of life will have to change. Where is the methane coming from? Livestock. Our current farming practices are also incredibly energy intensive. It has been suggested that something like 20% of UK energy consumption is from simply growing crops. That is before you take account of the energy involved in trucking produce from Scotland to London and back because of the energy intensive supermarket distribution system, and all the energy involved in packaging and driving to markets to shop for it. And throwing out all the waste.

    Add to that methane from livestock, take account of the total GG content of the atmosphere not just CO2, and lifestyles are going to have to change. Not only will we have to laregly stop driving, we’ll have to move to a much less fertilized, pesticided and mechanized agriculture. More manual, that means, more composting, more crop rotation, more mixed farming.

    Less steaks. More local shops and local vegetables. Less vegetable oils, soy and corn products, and more of the traditional oats, barley, root vegetables. More cooking and less factory produced foods. Less agricultural subsidies.

    You can argue about whether this is really necessary in itself - whether lowering GG concentrations is really necessary. What it seems impossible to argue is that to lower GGs, this really will be required, and that it will be huge.

  • Richard Steckis // December 27, 2008 at 8:17 am

    Dhogaza.

    As usual you are quick with the mouth and slow with the brain. You really lead with the chin old chum.

    Where did I say that evolution was any amount faster or slower?

    The PETM occurred at a time when the climate of the earth was at least 15 degrees C hotter than now. The PETM added another 8-10 degrees to that. It was an environment totally unlike ours today. So don’t think you can draw comparisons with today. The trigger for the PETM is still a matter or research but generally methane or co2 outgassing is not considered the cause but an effect that initiated positive feedbacks. Orbital forcing and seismic disruption of the methane calthrates are postulated as likely triggers.

    Dhogaza, you really are a bozo.

  • Ray Ladbury // December 27, 2008 at 2:40 pm

    Michel, I don’t think anyone is disputing that lifestyle changes help or that they will be necessary. Alternate energy sources will be essential, as well, though. It is a mistake to pre-judge the solution.

  • dhogaza // December 27, 2008 at 3:29 pm

    Speaking of bozos …

    Also you seem to argue that the increase in CH4 is entirely due to anthropogenic forces. However there is evidence of increased CH4 output from the oceans and from the Arctic tundra. I don’t think that it is unequivocally determined that these are anthropogenically forced.

    The evidence of increased CH4 output from the Arctic tundra is related to permafrost melting, due to anthropogenically forced warming.

    That’s the whole point …

  • EliRabett // December 27, 2008 at 3:36 pm

    To understand why a change in CH4 concentration currently has a greater effect than a change in CO2 concentration you have to understand some spectroscopy, kinetics and radiative stuff.

    A good place to start is David Archer’s implementation of MODTRAN, play around with it changing CO2 and CH4 concentrations.

    http://geosci.uchicago.edu/~archer/cgimodels/radiation.html

    1. Note what the emission of the ground is like (place your detector 0.001 km from the ground looking down)

    2. Now go to 70 km and look down, see where the different molecules absorb CO2, CH4, H2O, O3. Easiest way to do this is zero out all but one. This is not obvious for H2O, you have to set the Water Vapor Scale Factor to zero. Even that doesn’t get rid of everything, there are small residuals buried in the parameterization that Archer uses, but feel free to overwhelm each molecule in turn

    3. Note where methane absorbs and CO2 wrt the curve.

    4. Now go to “realistic values”, 375 ppm CO2, 1.7 ppm methane or you can just hit the reload on your browser. Run MODTRAN and write down the Iout (the IR flux emitted by the earth)

    6. Change the CO2 or CH4 concentration by some amount, and write down the new Iout. Note the amount of change for an equal change in concentration of each gas

    7. Systematically increase the concentration of methane and graph the difference between Iouts as you increase methane by equal amounts (say 5 ppm). Note the change in behavior from linear (same change per unit change) to logarithmic

    8. Buy your family dinner. They are pissed at you for not paying attention to them. Explain that this is better than World of Warcraft or Second life

  • Hank Roberts // December 27, 2008 at 4:59 pm

    You can’t trust some guy on a blog to give you accurate information. One check is to ask for citations. Trolls don’t footnote, generally. In some cases you can positively rely on the posting of a vehement denial unaccompanied by any source as a good hint there’s information there the person would prefer you not look up, though this can’t be considered a reliable clue.

    Scholar is almost always more helpful than ordinary Google.

    Search Scholar and you’ll find the PETM is being studied because it’s the closest analog we have in recent geological time to the changes we’re making (although we’re changing the world far faster than happened then).

    http://www.es.ucsc.edu/~jzachos/pubs/Bowen_etal_06.pdf

    “… During the PETM, carbon addition to the oceans and atmosphere was of a magnitude similar to that which is anticipated through the 21st century.This event initiated global warming,
    biotic extinction and migration, and fundamental changes in the carbon and hydrological cycles that transformed the early Paleogene world.
    The PETM demonstrates that extreme and rapid changes in Earth systems can be triggered by carbon cycle perturbation even in times of globally warm climate and in an ice-free world. As described here, an array of changes in the atmosphere, geosphere, hydrosphere, and biosphere have been documented during the PETM, and these studies have provided insight into the temporal patterns and coupling of changes in the Earth systems that accompany massive carbon release in a warm world….”

    http://badc.nerc.ac.uk/data/quest/PETM.html

    The DOI citation system is used a lot, e.g.

    http://dx.doi.org/10.1016/j.epsl.2007.06.033

    “… a warming of ~8 °C above background values of ~17 °C. …”

    The geologists have realized we are now living at one of those dramatic changes in stratigraphy that would, to some future geologist, be clear evidence of a major climate and extinction event and mark a new geological era, and named it: the Anthropocene.

    http://www.gsajournals.org/perlserv/?request=get-abstract&doi=10.1130%2FGSAT01802A.1

  • Kipp Alpert // December 27, 2008 at 8:41 pm

    DHOGAZA:
    No one said that evolution would accelerate faster. The variety of species could be enhanced, but not it’s speed.
    Twenty times warmer would mean another extinction event. If it was 20x warmer you would be dead. If you have ever taken a sauna, just turn it up to two thousand degrees, and your blood would boil. Never let you mouth be made a fool, by all your other senses. KIPP

  • dhogaza // December 27, 2008 at 9:35 pm

    No one said that evolution would accelerate faster. The variety of species could be enhanced, but not it’s speed.

    Underlying mutation rates, etc, wouldn’t change, but the mass extinction event would presumably lead to another round of fast (by evolutionary standards) radiation and speciation. Punk Eek all over again.

    So it kinda depends on how you want to define “rate of evolution”.

    But that wasn’t really the point of my snarky comment. The notion that a rate of climate change an order of magnitude greater than that seen in the PETM would *not* lead to a mass extinction event is hard to support. Especially given that we’re already in the midst of a human-caused mass extinction event due to the changes we’ve made to the planet’s ecosystems thus far.

    The notion that we need not worry about it is unsupportable. And that’s how I interpreted the comment. “Oh, the mass extinction was mostly marine, and BTW this was the period when primates arose” sounds like a “don’t worry, be happy” comment to me.

    We’re already seeing evidence that ecosystems can’t respond quickly enough to the rate of climate change we’re already seeing.

    And good old-fashioned habitat destruction has led to many credible evolutionary biologists strongly suggesting that we’ve already triggered a new mass extinction event …

    I just don’t buy the “don’t worry, be happy” argument - even if that makes me a bozo.

  • Kipp Alpert // December 28, 2008 at 2:13 am

    DHOGAZA: As a new blogger I didn’t know where you were coming from. Listen, why don’t you just come out and say what you feel rather than going around making a comment here, and a different one there.The problem with our future and the climate is that people don’t really know what will happen and when. I’ve been fighting deniers (accuweather)for a year and a half, and those are the ones who need to have their clock cleaned. No one here was giving an opinion but science fact and their analysis was as correct as your motive is for humanity to wake up. I had my ass handed to me by a professional bunch of deniers.OIL reps, anti government, scientifically challenged babies. The way that you could cut to the chase is to say what you think in the strongest terms, and let other people say what they think.No B.S. Just your own concern which you eventually made clear. All believers are more than concerned but they don’t always have to state that at every interval.If your an activist what are you waiting for, Greenpeace and other organizations need you now. Why not say we are beyond tipping points or we are already in a tipping point in the Arctic, because it has already begun a positive feedback loop. Be direct. Your good intentions shouldn’t fall on deaf ears,So shout it out.Just do it your way, and let other people accept it or not. I think now that since as Chris Colose said, if we stopped GHG’s tomorrow, there is still more in the pipeline which may take a millenia to return to the normal exchange of co2 in and co2 out, that humanity could be close to extinction.Dennis Hlinka thinks that we are getting there, and as a scientist told me,Kipp we just don’t know when that tipping points will come to fruition. When I say I cannot make that call,it is not my cumbia experience. It was the fact that I don’t know enough science to even give my opinion. I am an activist to, but I use strategy, and don’t weaken my own argument by clinging on to other points then critcize them. Make your own argument and kick some butt doing it. Don’t fight in your own camp. These people agree with you. What words could you use and how would you write them to have the most effect.That is the question. PeaceKIPP

  • Hank Roberts // December 28, 2008 at 2:47 am

    > don’t weaken my own argument by clinging on
    > to other points then critcize them. Make your
    > own argument

    He’s right you know. Repeating bogosity even to attack it merely makes it more memorable to the average reader. Remember this:

    “[CDC] recently issued a flier to combat myths about the flu vaccine. It recited various commonly held views and labeled them either “true” or “false.” … within 30 minutes, older people misremembered 28 percent of the false statements as true. Three days later, they remembered 40 percent of the myths as factual.

    Younger people did better at first, but three days later they made as many errors as older people did after 30 minutes. Most troubling was that people of all ages now felt that the source of their false beliefs was the respected CDC….”

    The psychological insights yielded by the research, which has been confirmed in a number of peer-reviewed laboratory experiments, have broad implications for public policy. The conventional response to myths and urban legends is to counter bad information with accurate information. But the new psychological studies show that denials and clarifications, for all their intuitive appeal, can paradoxically contribute to the resiliency of popular myths.”

    http://www.washingtonpost.com/wp-dyn/content/article/2007/09/03/AR2007090300933_pf.html

    Good intuition there KIPP. Science proves your approach works — and repeating myths to attack them makes the myths stronger.

  • dhogaza // December 28, 2008 at 5:46 am

    Sorry, Kipp, I didn’t mean to offend you.

    I know that you are not a science denialist (including evolution and atmospheric physics, i.e climate science).

    I hope you don’t think I believe that.

    The reality, though, is that depending on how you define “THE RATE OF EVOLUTION”, our current major extinction rate will, or won’t, accelerate it.

    I’m simply not certain how you, in your view, define it. “Mutation rate” is actually a useful metric. So is the rate of fixation of such mutations. One doesn’t expect mutation rate to increase due to climate change (AFAIK). But speciation due to vacated ecological niches? Different question.

  • dhogaza // December 28, 2008 at 5:56 am

    Why not say we are beyond tipping points or we are already in a tipping point in the Arctic, because it has already begun a positive feedback loop. Be direct. Your good intentions shouldn’t fall on deaf ears,So shout it out

    I’ll also say, that science isn’t really telling this, that I’m not going to “shout it out”.

    I know that science is getting closer to this position, and when it reaches it, I won’t be shy. But I’m waiting for the science, OK?

    Which is far different than REFUSING TO BELIVE the science.

    And I speak as dude who spent 15 years on the board of a fairly prominent, science-driven, regional NGO conservation organization, instrumental in old-growth protection efforts.

    In such a position, I always felt I should base my efforts on the most *defensible* position, possible. And, I’ll say, when my regional NGO entered a lawsuit … the other side (mostly the feds) … knew they’d lose.

    Now, the current situation … it’s clear we’re nearing tipping points, as you suggest. Are we there, or do we have a decade or two?

    I’d say science says we have some time. Not much. Not enough to satisfy the Luddites like DaveA, etc.

    But I think the basic political battle has been won. Whether the victory is strong enough to lead to positive action … I’m doubtful. Here in the US, the Senate is likely to bar significant progress, regardless of the 58 vs 42 votes or so the Repubs can garner.

    That’s our system. We still have to live with it …

  • Richard Steckis // December 28, 2008 at 9:01 am

    Dhogaza,

    I would have to support Kipp’s assessment of your methodology. Whilst I am not a supporter of AGW, Kipp makes a lot of sense.

    Your approach seems to be: make your own interpretation of a persons comment, make your own meaning from it, ascribe it as that persons own opinion and then attack them on it. E.g. you ascribing to me the “it will be all right” attitude. In effect you are attacking your own construct.

    I merely made the point about mammalian abundance so that people do not immediately assume that all environmental perturbation events will turn out the same way and to be careful about drawing conclusions about extinction events.

  • Nick Zervos // December 28, 2008 at 2:06 pm

    Probably a more relevant example of the earth’s negative feedback response is revealed in the Vostok ice core data. In every one of the previous interglacial periods shown in those ice cores the global temperature was 2-3 Deg. C higher than it is now. Obviously no runaway global warming was triggered by such temperatures.

    But that’s not necessarily good news.

    Indeed if a tipping point was crossed, it was the triggering of a new ice age. The fact that the temperature reached just about the same peak value in every one of the previous interglacial periods seems too much of a coincidence to be explained by only the solar forcings of the Milankovich cycles.

    So what we should be worried about is the initiation of a new ice age once the temperature reaches the observed threshhold value (whether or not the temperature rise is due to human contributions).

  • dhogaza // December 28, 2008 at 6:03 pm

    E.g. you ascribing to me the “it will be all right” attitude.

    OK, in black-and-white, then:

    Will expected warming be harmful, or not? Yes, or no?

    As far as my “misinterpretation” of your posts, you might take more care in what you write.

    For instance, you first came here masquerading as someone with a graduate degree in science.

    Whilst I am not a supporter of AGW

    What exactly does this mean? I’m not a supporter of AGW, however I do trust mainstream science to get stuff right, much more than I trust your opinion, for instance …

  • Hank Roberts // December 28, 2008 at 7:10 pm

    > PETM, evolution
    http://www.psgb.org/Meetings/Winter2005.html

    “… . One of the many questions that remain to be solved with regard to the earliest evolution of primates is the reason for their sudden and virtually simultaneous appearance in the fossil records of Asia, Europe and North America.”

    http://www.es.ucsc.edu/~jzachos/pubs/Kelly_etal_2005.pdf

    > tipping point, ice age

    Probably not; it’s been looked into.

    http://scholar.google.com/scholar?q=%2Bclimate+%2B%22next+ice+age%22

    http://www.sciencemag.org/cgi/content/summary/297/5585/1287

  • David B. Benson // December 28, 2008 at 8:09 pm

    Richard Steckis // December 27, 2008 at 3:38 am — No mammilian family from the Paleocene currecntly survives and most of the extinctions are associated with PETM.

    Nick Zervos // December 28, 2008 at 2:06 pm — Call the Holocene interglacial 1, the Eemian interglacial 2 and so on. Only interglacials 2 and 4 were definitely warmer at Vostok than interglacial 1. In particular integlacial 5, during MIS 11, appears to be most similar to the Holocene.

    Only for interglacial 2 is the evidence, AFAIK, good enough to state with some confidence than global temperatures were about 2 K warmer than during the Holocene. Lesson: tmeperatures in Antarctica may not well represent global temperatures.

  • Ray Ladbury // December 28, 2008 at 9:45 pm

    Nick Zervos, I don’t think you can draw a causal link between increased temperature and the onset of a new “Ice Age”. Forcings change (e.g. subtle changes in insolation associated with Milankovich cycles), and when they do the climate responds, perhaps somewhat cushioned by increased greenhouse warming until that, too decreases. An ice age is at present the least of our worries climatically speaking.

  • David B. Benson // December 28, 2008 at 10:08 pm

    Ray Ladbury // December 28, 2008 at 9:45 pm — Yes, but for the Eemian (interglacial 2), the Votok ice core record is clear: temperatures and CO2 concentrations track together, +- 50 years; no better resolution is possible in the proxy series.

  • David B. Benson // December 28, 2008 at 10:30 pm

    Here is a suggestion for anyone who would like to look at the Eemain data, all available from the NASA Paleoclimatology website.

    NGISP not only has excellant time/depth resolution to at least the early Eemian, but (presumably, GRIP2 does) also has CH4 records. These can then be used to re-time the Long Antarctica ice cores; these latter have CO2 measurements. So then dates and CO2 concentrations can be checked for the peak of the Eemian.

    My hypothesis is that within 50 years of the beginning of declining temperatures in Greenland, CH4 concentrations follow. Checking against Vostok and Dome C one will find that CH4 and CO2 concentrations go hand-in-hand, within the resolution available from those records, about 50–100 years.

    If confirmed, such would help to confirm orbital forcing (and that Antarctica temperatures followed Greenland temperatures after some decades of delay).

  • Richard Steckis // December 29, 2008 at 5:46 am

    David B. Benson:

    The PETM was 55 million yeas ago. I would not expect most of the mammalian families to have survived that amount of time. However, I am doubtful on your premise that none of them survived to the current time. I do not have the information to either refute or accept your premise.

    Monotremes are one example of an order of mammals that have survived over 100 million years. Our Australian marsupials are also very ancient mammals.

    But where you are really wrong is that there was NO mass extinction of mammals or other terrestrial fauna during the PETM. From what I have read so far, the PETM mass extinction was largely confined to benthic foraminifera.

  • Leif Svalgaard // December 29, 2008 at 5:48 am

    tamino // December 27, 2008 at 2:13 am
    “The event saw global temperatures rise by around 6 °C over 20,000 years…”
    It’s not impossible that we’ll experience that much warming in just a few centuries.

    Such rapid warmings [and coolings] have occurred many times in the past…

    [Response: Six deg.C in a few centuries for the global average? I don't think so. What's your evidence?]

  • Richard Steckis // December 29, 2008 at 5:49 am

    What I meant was that you were wrong in assuming there was a mass extinction of mammal during the PETM.

    The PETM was not the only event of it’s kind in the Paleocene-Eocene interface. There were actually three events with the PETM being the most prominent.

  • Richard Steckis // December 29, 2008 at 6:26 am

    Dhogaza:

    “Will expected warming be harmful, or not? Yes, or no?”

    Yes and no if it warms as expected. This is because, as in all environmental perturbations there will be winners (those that can adapt and flourish) and losers (those that can’t adapt). Humans are highly adaptable and will survive.

    [Response: I think it's just a meme to say that "in all environmental perturbations there will be winners and losers." The end-permian extinction seems to have had vastly more losers than winners.]

    “What exactly does this mean? I’m not a supporter of AGW, ….”

    Exactly that. I know that climate changes. It always has. It changes at different rates. However, I don’t anyone has really done the sums on the actual carbon budget of the planet with any degree of accuracy. If I am wrong on that please direct me to the literature (NOT Weart’s book please). Until a full carbon audit is done, I will remain skeptical of AGW.

    The PETM event released somewhere between 1000 and 4000 Gt of CO2 and methane into the ocean-atmosphere system on top of an already elevated CO2 production (atmospheric co2 was about 2000ppm). According to http://www.radix.net/~bobg/faqs/scq.CO2rise.html, The current natural production of carbon is about 60 GtC per year and the anthropogenic production is about 7.1 GtC where: 1 GtC corresponds to ~3.67 Gt CO2.

    The figures do not seem to add up, especially since less half of the anthropogenic co2 is stored in the atmosphere.

    Maybe I have missed something. Please enlighten me (without abuse please).

    [Response: Exactly what numbers don't add up?]

  • Ray Ladbury // December 29, 2008 at 2:50 pm

    Richard Steckis says, “Humans are highly adaptable and will survive.”

    You know, given that the term “survive” could encompass outcomes ranging from evacuating the planet for a moon base to a few isolated bands of hunter-gatherers with average life expectancy of 20 years, you’ll forgive me if I don’t find your reassurance comforting.

    As to your “carbon audit,” I think that the fact that the isotopic composition of carbon in the atmosphere is changing in the direction of fossil sources is sufficient to demonstrate that we are behind the current increase. Or do you know of another massive source of fossil carbon?

    What is more, I’d like to keep it that way. We can control our own emissions. However, if we warm things up enough where natural emissions dwarf our own, we might just repeat the PETM experiment again–this time in a world with 9 billion people. You are indeed missing something. Maybe you should read your own sources:

    “Fossil fuels contain practically no carbon 14 (14C) and less carbon 13 (13C) than air. CO2 coming from fossil fuels should show up in the trends of 13C and 14C. Indeed, the observed isotopic trends fit CO2 emissions from fossil fuels. The trends are not compatible with a dominant CO2 source in the terrestrial biosphere or in the ocean. If you shun details, please skip the next two paragraphs.

    * The unstable carbon isotope 14C or radiocarbon makes up for roughly 1 in 10**12 carbon atoms in earth’s atmosphere. 14C has a half-life of about 5700 years. The stock is replenished in the upper atmosphere by a nuclear reaction involving cosmic rays and 14N [Butcher, p 240-241]. Fossil fuels contain no 14C, as it decayed long ago. Burning fossil fuels should lower the atmospheric 14C fraction (the`Suess effect’). Indeed, atmospheric 14C, measured on tree rings, dropped by 2 to 2.5 % from about 1850 to 1954, when nuclear bomb tests started to inject 14C into the atmosphere [Butcher, p 256-257] [Schimel 95, p 82]. This 14C decline cannot be explained by a CO2 source in the terrestrial vegetation or soils.
    * The stable isotope 13C amounts to a bit over 1 % of earth’s carbon, almost 99 % is ordinary 12C [Butcher, p 240]. Fossil fuels contain less 13C than air, because plants, which once produced the precursors of the fossilized organic carbon compounds, prefer 12C over 13C in photosynthesis (rather, they prefer CO2 which contains a 12C atom) [Butcher, p 86]. Indeed, the 13C fractions in the atmosphere and ocean surface waters declined over the past decades [Butcher, p 257] [C.Keeling] [Quay] [Schimel 94, p 42]. This fits a fossil fuel CO2 source and argues against a dominant oceanic CO2 source. Oceanic carbon has a trifle more 13C than atmospheric carbon, but 13CO2 is heavier and less volatile than 12CO2, thus CO2 degassed from the ocean has a 13C fraction close to that of atmospheric CO2 [Butcher, p 86] [Heimann]. How then should an oceanic CO2 source cause a simultaneous drop of 13C in both the atmosphere and ocean ?

    Overall, a natural disturbance causing the recent CO2 rise is extremely unlikely.

  • drj11 // December 29, 2008 at 4:00 pm

    Where are you getting your 20 times worse figures from? (as in “CH4 is a more potent greenhouse gas on a per-molecule basis, about 20 times as much as CO2″).

    IPCC AR4 gives CH4 a GWP 25 times that of CO2 over 100 years (table 2.14). That figure is mass for mass. mole for mole it’s about 9 times. Looking at the 10 year timescale the GWP is 72 times that of CO2, but that seems needlessly short term.

    I think I prefer the mole for mole figures, because often one is thinking of some chemical process where you can choose to emit one molecule of CO2 or one molecule of CH4.

  • Leif Svalgaard // December 29, 2008 at 7:35 pm

    tamino:
    [Response: Six deg.C in a few centuries for the global average? I don't think so. What's your evidence?]

    What is your evidence that it did not? As usual, one can dismiss things like the MWP and the LIA by claiming they were not ‘global’ enough, but the end of the Younger Dryas was abrupt [decades], not only in the Northern Hemisphere but in the Southern as well, e.g. the Huelmo/Mascardi Cold Reversal.

    [Response: First you say "Such rapid warmings [and coolings] have occurred many times in the past.” When I ask for your evidence, the best you can do is “What is your evidence that it did not?”

    The MWP and LIA, global or not, are nowhere near 6 deg.C globally, maybe not even 0.6 deg.C. As for the end of the younger dryas, the warming rate indicated by the Vostok ice core is a mere 0.5 deg.C/century, a far cry from the 3 deg.C we’re likely to see this century. And that’s at Vostok; the global temperature change is likely to be half that.

    It’s painfully obvious that you just spouted off with no evidence whatever, and when called on it you’re too embarrassed to admit the truth. You should be far more embarrassed by this lame attempt to save face, than by your original gaffe.]

  • David B. Benson // December 29, 2008 at 7:39 pm

    Richard Steckis // December 29, 2008 at 5:46 am — My mistake. No large mamals survived PETM, with the known exception of a 40 kg (adult weight) species which pygmied down to about 4 kg during PETM and then afterwards re-acquired the larger size. The evidence is from Wyoming, is discussed in any decent book on paleontology and on many web sites devoted to that topic. But starters are

    http://en.wikipedia.org/wiki/Paleocene-Eocene_Thermal_Maximum
    http://paleocene-mammals.de/large_herbivores.htm

    The speciation of mammals following PETM was surely due to the opening of so many niches caused by the extinction of many lines, even whole orders. Very little is known, at least by me, about the corresponding extinction of plants, which surely also happened.

  • george // December 29, 2008 at 7:47 pm

    Chris Colose said:

    “The RF for methane is pretty complicated (I’ve actually never seen a number cited for temperature increase per 2x CH4). Though, the IPCC TAR has a formula in their report much like they do for carbon dioxide (dF=5.35*ln[C(t)/C(1750)] ), so that part shouldn’t be hard to work out. It’s just a little algebraically “longer” and has an N2O dependence.”

    From this PNAS table you can see that the part of the methane equation which contributes most to the forcing does not have a logarithmic dependence on methane concentration, which would explain why one does not see a “CH4 sensitivity” (degrees per doubling) quoted in the literature as one sees for CO2.

    Incidentally, the PNAS methane equation indicates that the methane radiative forcing change per ppbv methane concentration change is about 0.0004 W/m^2, which means a 10 nmol mol-1 (ie, 10 ppb) change (quoted above for 2007) would be expected to produce about 0.004 W/m^2 change in forcing, or about 0.003 deg C temp change (assuming 1 W/m^2 forcing change leads to 0.75 deg C change in temp).

    For comparison, by the equation for CO2 given in that same PNAS table, a 2 ppm increase in atmospheric CO2 (roughly the current yearly increase) should lead to about 0.02 deg C increase in temp.

    I agree that it is of concern if methane is on the rise again, but if methane is increasing at the value given in the paper Tamino quoted ( 10 nmol mol-1 per year), the effect on global temp would still be relatively small (about 15%) compared to that caused by the yearly CO2 increase.

  • Gareth // December 29, 2008 at 8:28 pm

    The concern is that it will rise far faster: Semiletov at the AGU suggested that 6ppm (not ppb) was possible from the East Siberian Shelf (no timescale given) - that’s enough for a lot of warming, and consequent feedback…

  • Leif Svalgaard // December 29, 2008 at 8:47 pm

    tamino:
    [Response: Six deg.C in a few centuries for the global average? I don't think so. What's your evidence?]

    It’s painfully obvious that you just spouted off with no evidence whatever

    Do I really have to show you a Wikipedia page: http://en.wikipedia.org/wiki/Younger_Dryas
    The temperature change was 12 degrees in a decade or so.

    [Response: Maybe you should read it before you link to it.

    A temperature change of 12 deg. is nowhere mentioned in that Wikipedia article. It does mention large temperature changes in very short time spans in Greenland and in other areas at high latitudes in the Northern hemisphere. It also mentions the considerable doubt that it was a worldwide synchronous event, with climate change in different geographical areas a thousand years apart. Then there's also the fact that the most likely cause was a change of ocean circulation, which is likely to cause a "see-saw" of thermal energy between hemispheres with little change in global average temperature, what Seidov and Maslin call "heat piracy."

    Get this: 6 deg.C global average temperature change is the total change from full glacial to interglacial conditions. The younger dryas was a "hiccup" in the last deglaciation; nobody in his right mind believes that the younger dryas showed the same global change as a full transition from glacial to interglacial.

    The only explanation for clinging to your indefensible statement is egotistical obstinacy.]

  • Leif Svalgaard // December 29, 2008 at 9:23 pm

    tamino:
    [Response: Six deg.C in a few centuries for the global average? I don't think so. What's your evidence?]

    The only explanation for clinging to your indefensible statement is egotistical obstinacy.

    It is always fun to yank your chain; here is some more stuff for you to bash:

    [edit]

    [Response: I guess your idea of "yanking my chain" is behaving like an idiotic child. I once took you seriously as a scientist; no longer.]

  • dhogaza // December 29, 2008 at 9:41 pm

    It is always fun to yank your chain

    Well, you’ve just done a lot to raise your credibility ’round here.

    NOT.

    Actually, Tamino, deleting the rest of the post might simply serve to somewhat preserve a reputation that perhaps doesn’t deserve preserving.

    And that’s a lot of “erves” in there :)

  • TCOisbanned? // December 29, 2008 at 10:17 pm

    Tammy, it appears that there is debate on the timing , global nature and/or rapidity of the Younger Dryas event (even within that wiki article).*

    I think Leif’s statement may have been too strong, but that some of your criticism is not perfectly stated either. For instance the comment about MWP “local or global” (seeming to discuss the futility of the MWP case even if we posit global being similar to the iconic NE Europe record), followed by a statement about global extent of MWP (seeming to differentiate it from local).

    The whole thing becomes confused with whose burden of proof it is. And also with the harsh words each of you is throwing at each other, I think it will be hard for you each to do the nescessary definition of terms to see where you agree and disagree.

    ————

    As an outsider, I get the impression that the Younger Dryas is suggestive but not conclusive about what kinds of radical events can occur. (I realize that leaves a lot of room…but the fact is we just don’t have a good record of global temp versus time.)

    [Response: The MWP, global or no, did not represent 6 deg.C of global average temperature change -- the total change between full glacial and interglacial, and nearly 8 times the global warming since 1900. Neither did the younger dryas.]

  • TCOisbanned? // December 29, 2008 at 10:18 pm

    * I guess we need to cite a “diff” to really make sure we are talking about the same article.

  • george // December 29, 2008 at 11:07 pm

    gareth said

    The concern is that it [methane] will rise far faster: Semiletov at the AGU suggested that 6ppm (not ppb) was possible from the East Siberian Shelf (no timescale given) - that’s enough for a lot of warming, and consequent feedback…

    I understand the concern about the quickening pace of emissions and possibly even tipping points, but I would simply be careful to conclude much (if anything) about where methane release may be headed (particularly based on very recent changes in the methane emission rate indicated by Rigby et al)

    USGS just released a report on “Abrupt Climate Change” in which they considered methane

    Methane is a potent greenhouse gas. Concern about future abrupt release in atmospheric methane stems largely from the possibility that the massive amounts of methane present
    in a solid form known as methane hydrate in ocean sediments and in permafrost may become unstable in the face of global warming. Warming or release of pressure can destabilize methane hydrate, forming free gas that may ultimately be released to the atmosphere.

    Although there are a number of suggestions in the literature about the possibility of a dramatic abrupt release of methane to the atmosphere, modeling and evidence from ancient ice cores do not indicate such a release to the atmosphere within the last 100,000 years or in the near future.

    While a catastrophic release of methane to the atmosphere in the next century appears very unlikely, it is very likely that climate change will accelerate the rate of persistent emissions from both hydrate sources and wetlands. Current models suggest that wetland emissions could double in the next century. Methane released from the hydrate reservoir will likely have a significant influence on global warming over the next 1,000 to 100,000 years”.

    I’m not arguing that methane is of no concern, but what happens over a period of just a few years is insufficient to say much about where methane emissions are headed even in the near future (just as with temperature).

    ** BTW, I realize that the PNAS equation given for methane forcing probably only applies approximately over a certain concentration range, but if you put in 6ppm for the final atmospheric concentration, it yields a change in temp of about 1.4 deg C (again assuming 1 W/m^2 forcing change yields 0.75C temp change) which, while certainly of concern, is still significantly less than what is expected from CO2 alone if CO2 emissions continue at the current pace.

    Personally, I’m most concerned about CO2 at this point and it seems to me that if tipping points involving methane are ever reached, that is most likely to come about as a direct result of warming due to CO2 increases, so reducing CO2 is where the primary focus should be.

    I doubt there is much (if anything) that can be done about methane once it starts coming out of melting permafrost, at any rate.

  • David B. Benson // December 29, 2008 at 11:21 pm

    The MWP was definitely not global. No indication of it in liminological studies in Patagonia. Antarctica underwent some indefinite ‘cold rerversal’.

    The is a recent book by an anthropologist about it. The review in TNYT(?) indicated that during MWP droughts occurred as far south as Peru.

  • Gareth // December 29, 2008 at 11:43 pm

    I doubt there is much (if anything) that can be done about methane once it starts coming out of melting permafrost, at any rate.

    And therein lies the rub…

    Methane emissions from the ESS alone have the potential to make any mitigation we might embark on redundant.

    Suppose we do hit a 450 ppm CO2 target, which yields an increase of 2C (very optimistic on both counts). Add in methane, and we are in deep “doo doo”. Especially because it’s a positive feedback.

  • David B. Benson // December 30, 2008 at 12:03 am

    george // December 29, 2008 at 11:07 pm — Agreed, but lowering CO2 still further will (within a few decades) lower temperatures enough to avoid further (significant) methane releases.

    The methane I am concerned about is that in peat bogs and northern marshes. Release of such methane is implicated for PETM at least.

  • Kipp Alpert // December 30, 2008 at 12:20 am

    Ray Ladsbury or Hank Roberts:An article just came out about predictions in the Artic and that the models didn’t compute the lubricating effect of water beneath the Ice. We also know that there is a lot of methane clathrates under perma frost, and not far from it’s surface. I think that the positive feedback cycle(LOOP) has indeed begun, but has been overlooked, as more warming is presently the focus. When any ice melts you have absorption of IR in dark water.Water warms, melting more ice, more absorption,less reflectivity and on and on.I think it is happening but isn’t apriori on the whats next to notice list.What
    are your thoughts. Thanks KIPP

  • Hank Roberts // December 30, 2008 at 2:05 am

    Find a cite, or a good secondary source naming the journal and/or author and maybe the month it was published, and we can probably find it.

    Check RealClimate, try the Search box at top of page. Last I recall, one of the real experts who actually works in this field said the water going down the moulins really is taken into account.

    A story read somewhere could be anything from any time in the past. Google doesn’t turn up anything using the words you wrote that seems novel. No time to look further right now.

  • Hank Roberts // December 30, 2008 at 3:54 am

    Kipp, while you’re looking for that source, you might read the thread around this. Mauri Pelto is a specialist in the area and was helping me understand something about how Arctic cap ice behaves. I don’t know if the article you remember is one of those discussed, but this is a good example of testing what you think, or was for me.

    Look back in the thread; by the time Mauri posted this he’d gotten a bit pestered by people sure they knew more than he did because they’d read something on blogs somewhere. That’s a mistake I make myself as an amateur reader. I’m trying to cure myself of it by listening to the people like Mauri:

    http://www.realclimate.org/index.php/archives/2008/10/what-links-the-retreat-of-jakobshavn-isbrae-wilkins-ice-shelf-and-the-petermann-glacier/#comment-100509

  • Richard Steckis // December 30, 2008 at 4:04 am

    Ray.

    I think you have your isotopes of carbon wrong. The isotope analyses you refer to are the ratio of the stable isotopes C12 and C13. It is those ratios that are used in the analysis of anthropogenic co2. Refer to IPCC FAR chapter 2 figure 2.3. Whilst the delta 13C seems to track atmospheric co2, the relationship is not very good post 2003.
    C14 is not used in stable isotope analysis for obvious reasons (it is not a stable isotope).

    I have a little bit of experience in stable istope analysis and understand the principles quite well. I have been involved in research on stable isotope analysis of fish otolith carbonate.

  • dhogaza // December 30, 2008 at 4:39 am

    Whilst the delta 13C seems to track atmospheric co2, the relationship is not very good post 2003.

    This bozo has to wonder if you’re mistaking a short-term fluctuation that might very well have a physical explanation with data that might actually refute an established statistical trend?

    But since I’m a bozo, I’m sure you’re right, that any recent blipping of the correlation must be significant …

  • Richard Steckis // December 30, 2008 at 5:01 am

    Tamino:

    “Response: I think it’s just a meme to say that “in all environmental perturbations there will be winners and losers.” The end-permian extinction seems to have had vastly more losers than winners.”

    No. You seem to think that it has to be some sort of even balance between winners and losers. That is rather simplistic thinking and evolution doesn’t work that way.

    The losers of the end Permian extinction in the marine environment were the sessile benthic organisms such as the benthic foraminifera, the bryozoans, and gorgonians. The winners were the more mobile animals such as snails, crabs and urchins.

    The Archosaurs and Therapsids (ancestors of the mammals) were among the big winners of the Permian extinction event. Would it be too long a bow to draw to say that we might not have evolved if the Permian extinction never happened? Probably.

    I never said that the winner/loser scenario would be an even thing.

    By the way, memetics is regarded as a waning philosophy: http://en.wikipedia.org/wiki/Meme

    [Response: Wikipedia says this about the end-permian extinction:

    It was the Earth's most severe extinction event, with up to 96 percent of all marine species[3] and 70 percent of terrestrial vertebrate species becoming extinct; it is the only known mass extinction of insects.[4][5] 57% of all families and 83% of all genera were killed off. Because so much biodiversity was lost, the recovery of life on earth took significantly longer than after other extinction events.[3] This event has been described as the “mother of all mass extinctions”.

    I think you’re the one doing the “simplistic” thinking. By your logic, the bubonic plague had both winners and losers — I’d call that a dreadful perspective.]

  • dhogaza // December 30, 2008 at 5:39 am

    By your logic, the bubonic plague had both winners and losers — I’d call that a dreadful perspective.

    Oh, geez, Tamino, you don’t get it …

    The human race survived the Black Plague.

    Obviously the death of 40% of Europeans and the consequent disruption of the social infrastructure was far, far less costly than the development of effective antibiotic measures last century.

    We wasted our time and money figuring out how to cure such diseases. Get with the program!

  • Richard Steckis // December 30, 2008 at 5:54 am

    Tamino:

    “Response: Exactly what numbers don’t add up?”

    I did a quick calculation of the amount of co2 required to raise the concentration of co2 in the atmosphere by 1 ppmv. My calculations are:

    Mass of the earth’s atmosphere: 5148000 Gt
    Mass of CO2 at (383 ppmv): 298057 Gt
    Mass of CO2 at (384 ppmv): 298835 Gt
    CO2 require for 1 ppmv change: 778 Gt

    The IPCC FAR Chapter 7 uses a figure of 2.12 GtC per year for a 1 ppm change (note b for Table 7.1).

    Is my mathematics wrong? Am I missing something? Am I being too simplistic and why?

    But at 2.12 GtC per year, it would take 367 years to reach a storage change of 778 Gt.

    [Response: You're off by a factor of about 100. Mass of atmosphere ~ 5 million Gt. Take 1 ppm of that, ~ 5 Gt. Compensate for molecular weight of CO2 compared to average for air, ~ 7.8 Gt, not 778.

    Then convert 2.12 GtC to 7.77 GtCO2.]

  • Richard Steckis // December 30, 2008 at 5:58 am

    Oh. In addition, 383 ppmv = 579 ppm by mass.

  • Phil. // December 30, 2008 at 6:12 am

    george // December 29, 2008 at 7:47 pm

    From this PNAS table you can see that the part of the methane equation which contributes most to the forcing does not have a logarithmic dependence on methane concentration, which would explain why one does not see a “CH4 sensitivity” (degrees per doubling) quoted in the literature as one sees for CO2.

    Methane shows a square root dependence which is what you’d expect from a strong absorber.

  • Richard Steckis // December 30, 2008 at 6:26 am

    Tamino:

    “I think you’re the one doing the “simplistic” thinking. By your logic, the bubonic plague had both winners and losers — I’d call that a dreadful perspective.”

    Nothing simplistic about it. Nature has no perspective. Perspective is a human construct. Evolution is built on the bodies of the dead. Natural selection is about survival of the fittest. That is nature.

    Don’t try to ascribe natures way to my own philosophy. That is what Dhogaza does so well.

  • Richard Steckis // December 30, 2008 at 6:46 am

    Tamino:

    “Response: Six deg.C in a few centuries for the global average? I don’t think so. What’s your evidence?”

    In decades actually.

    see: http://www.ncdc.noaa.gov/paleo/abrupt/index.html

    [Response: When the hell are you people gonna learn, 1: the big abrupt changes you refer to are local, not global, and 2: you'd know that if you bothered to read the goddamn references you supply yourself.]

  • Ray Ladbury // December 30, 2008 at 11:04 am

    Richard Steckis, do you even bother to read the posts here? Because I did not say anything about specific isotopes except for the quoted material from your own reference, which you also seem not to have read.
    Richard posits, “Whilst the delta 13C seems to track atmospheric co2, the relationship is not very good post 2003.”–cite?
    Good Lord, Man, so your logic is that because of a short-term glitch, we should ignore the long-term correlation? That, Sir, is astounding.

  • Hank Roberts // December 30, 2008 at 12:00 pm

    Tamino, Leif’s argumentative style reminds me of a cat — he makes a mistake, tries to land on his feet, and looks at you and says “I meant to do that” even when ‘that’ includes pissing you off.

    Dunno if you can pretend he doesn’t get to you, but I recommend it, I suspect he’ll straighten this out if he doesn’t find enough amusement in baiting you.

    Playground rules don’t quite work in ASCII, but I do watch Leif straighten out — or deftly ignore if needed — some of the weirder and more persistent peculiar-theory posters out at solarcycle24, so I know he can do both sides of the game. Why not not play instead, is my suggestion to him here.

    Some folks are older and tireder, or younger and more hypergolic, than others. “Hard argument” like you’d do at a science meeting blows up real fast in text form online without the voice tone and body language to moderate how it’s heard.

    Safest thing is always to assume 90 percent of the emotional content we read online is projection. Letting people get their fingers into what makes us mad is just to be avoided because this is a mask, a performance, not a purely intimate heartfelt exchange with people who always understand or give a damn personally.

    Can’t tell for sure.

    That’s why I try to pretend to be patient and caring and helpful. Not that I like it, I’d sooner
    http://s55905.gridserver.com/banner3.png
    But some day I may need to be a nice person for real, and I need the practice if I’m ever going to learn how in time..

    [Response: He crossed a serious "stupid threshold" with his latest gigantic mistake. But gloating about how much fun it is to yank my chain, shows that he's a real asshole, with the maturity level of a 2-year old. He's gone from this site forever.]

  • TCOisbanned? // December 30, 2008 at 1:43 pm

    If I read Tammy right, his points are that the the MWP, whether or not global, was insufficient to show magnitude Leif alleges. And that the Younger Dryas had sufficient rate locally, but not globally. This seems to be two different logics (for MPW and Younger Dryas). Also confusing things is it seems like there are some comments to effect that MWP was not global (in contrast to the “if” possited in first sentence.) What a muddle.

  • TCOisbanned? // December 30, 2008 at 1:45 pm

    It’s really a drag tying to have debate anyhow, with the delay for comments to be accepted and with debate with blog owner, means he has huge advantage (banning, snipping, etc.) It’s almost like everyone has to have their own blog to comment at each other.

  • dhogaza // December 30, 2008 at 2:17 pm

    CO2 require for 1 ppmv change: 778 Gt

    The IPCC FAR Chapter 7 uses a figure of 2.12 GtC per year for a 1 ppm change (note b for Table 7.1).

    This is what I love about the denialsphere. Steckis has the balls to think that somehow the world’s leading experts are going to be off on this most basic of figures by TWO ORDERS OF MAGNITUDE, and that his back-of-the-envelope calculation will set the world straight.

    Steckis, let me give you joy of your world-class ego. Too bad your knowledge doesn’t match it.

  • dhogaza // December 30, 2008 at 2:20 pm

    Nothing simplistic about it. Nature has no perspective. Perspective is a human construct. Evolution is built on the bodies of the dead. Natural selection is about survival of the fittest. That is nature.

    Everyone here - with the possible exception of your fellow denialists like DaveA - are well aware of this.

    Don’t try to ascribe natures way to my own philosophy. That is what Dhogaza does so well.

    Yet, it’s true that you are certain that there is nothing to worry about, and it’s true you keep dragging up “nature’s way” in the discussion.

  • Richard Steckis // December 30, 2008 at 2:24 pm

    Ray.

    You are the one who was rabbiting on about 14C. The FAR report Chapter 7 only mentions it once:

    “Carbon also has a rare radioactive isotope,
    carbon-14, which is present in atmospheric CO2 but absent in
    fossil fuels. Prior to atmospheric testing of nuclear weapons,
    decreases in the relative amount of carbon-14 showed that fossil
    fuel carbon was being added to the atmosphere.”

    That is on page 515. It merely mentions that co2 from fossil fuels was being added to the atmosphere. Gee. What a revelation.

    Ray. You don’t need a cite to see that delta 13C values do not absolutely track co2 emissions. You only have to eyeball it. But to make sure, I am going to download the data and analyse it.

    And Ray. The dataset for Delta 13C in the IPCC report is only about 20 years in length. And what I observe is not a glitch and even the long term correlation is doubtful. Peaks don’t match peaks and troughs don’t match troughs. Rate changes vary over time between the two.

  • dhogaza // December 30, 2008 at 2:28 pm

    This seems to be two different logics (for MPW and Younger Dryas).

    Separate events with separate causes and separate outcomes might be … different?

    Also confusing things is it seems like there are some comments to effect that MWP was not global (in contrast to the “if” possited in first sentence.)

    I’ll take “science” behind door number one, please.

    What a muddle.

    There’s muddling going on, for sure, but it’s not Tamino who’s muddled.

  • Richard Steckis // December 30, 2008 at 2:33 pm

    Dhohaza:

    “This is what I love about the denialsphere. Steckis has the balls to think that somehow the world’s leading experts are going to be off on this most basic of figures by TWO ORDERS OF MAGNITUDE, and that his back-of-the-envelope calculation will set the world straight.”

    Stop running off at the mouth and please show me where my mathematics is wrong. I really would like to know because I don’t actually believe the the WORLD’S LEADING EXPERTS are two orders of magnitude out.

    Show me where my calculation is in error. Please.

    [Response: You're off by a factor of about 100. Mass of atmosphere ~ 5 million Gt. Take 1 ppm of that, ~ 5 Gt. Compensate for molecular weight of CO2 compared to average for air, ~ 7.8 Gt, not 778.

    Then convert 2.12 GtC to 7.77 GtCO2.]

  • Hank Roberts // December 30, 2008 at 2:59 pm

    > gloating
    Can’t complain, as I don’t have a blog and don’t want one. I recall someone told FDR in the 1930s that there had been something like 300 banks in the US and he replied what a shame it was there hadn’t been that many bankers. I feel the same way about blogs. Lots of blogs. Few bloggers. I like the results you get.

    >Steckis
    Where is your work on otoliths published? Can’t find anything but minnows and audiovisual equipment associated with your name. Was it the fish collection paper?

  • Ray Ladbury // December 30, 2008 at 3:54 pm

    Richard Steckis, All the stuff about particular carbon isotopes was a direct quote from the resource YOU provided–and evidently did not read. Dude, if you don’t even read your own resources, why in the hell should we pay attention to what you say?
    And as to your contention about mismatches in C-13 and CO2, uh, Dude, it’s kind of a complicated system. I wouldn’t expect more than the trend to agree. It does–or do you have another suggetion for why CO2 AND C-13 are increasing.
    Richard, here’s a hint. You stopped passing the straight-face test a long time ago. Maybe you need to find another audience where you haven’t already shot your credibility.

  • Ray Ladbury // December 30, 2008 at 4:01 pm

    Richard Steckis takes the long view:
    “Nothing simplistic about it. Nature has no perspective. Perspective is a human construct. Evolution is built on the bodies of the dead. Natural selection is about survival of the fittest. That is nature. ”

    Actually, Richard, I’ll confess to a bias in favor of the continuation of human civilization. I just like people better than cockroaches and blue-green algae. Specist, I know, but what can I do. Not all of us can preserve the level of ignorance you have to remain 100% objective.

  • Ian Forrester // December 30, 2008 at 4:46 pm

    Steckis said: “I am going to download the data and analyse it.”

    Once you have “analyzed” the data will we have to apply a 100 times fudge factor to it as needed previously?

    And you call yourself a scientist.

  • luminous beauty // December 30, 2008 at 4:51 pm

    And what I observe is not a glitch and even the long term correlation is doubtful. Peaks don’t match peaks and troughs don’t match troughs. Rate changes vary over time between the two.

    And this can’t be explained by non-linearities in carbon sinks and sources? Why not?

  • dhogaza // December 30, 2008 at 7:00 pm

    Stop running off at the mouth and please show me where my mathematics is wrong.

    Tamino already told you: 5 million Gt over a million is 5 Gt, not 500 Gt. Tamino showed you the adjustments necessary to get a bit less than 8 Gt of CO2, which contains about 2.2 Gt carbon, just as the IPCC says.

    He didn’t specifically point out that the “m” in “ppm” stands for “parts per million”. He was probably unaware that it was necessary.

    This is called “arithmetic”, not “mathematics”.

    [Response: Bear in mind also that the original comment asked where he went wrong, rather than claiming that the experts were wrong.]

  • Dano // December 30, 2008 at 7:47 pm

    Evolution is built on the bodies of the dead. Natural selection is about survival of the fittest. That is nature. ”

    No.

    Natural selection is not about that at all.

    It is about random genetic mutations allowing individuals a higher likelihood of successful reproduction, thus being more likely for passing along the mutated gene (Mendelian genetics) to the next generation, who then must be more likely to successfully reproduce, etc.

    So survival of the fittest is an old concept, since rejected.

    Well, certain ideologies haven’t rejected it as it is convenient for their worldview, but science mostly doesn’t use it anymore.

    Best,

    D

  • dhogaza // December 30, 2008 at 8:16 pm

    So survival of the fittest is an old concept, since rejected.

    Well, Darwin himself understood it to be reproductive fitness … so I gave Steckis the benefit of the doubt.

    But reading your snippet … the “build on the bodies of the dead” bit makes me think that perhaps you’re right …

  • Dano // December 30, 2008 at 8:55 pm

    But reading your snippet … the “build on the bodies of the dead” bit makes me think that perhaps you’re right …

    I powered through many courses as an undergrad in genetics, pop. biology, botany, biology, ecology, ag., etc. I wasn’t going to graduate without having this stuff pounded into my skull 83 times. I was dumb enough to choose a term paper on Rhododendron reproduction - a spp. that has variable chromosomes, so by G– I’m going to use it!! ;o)

    Best,

    D

  • David B. Benson // December 30, 2008 at 10:05 pm

    Richard Steckis // December 30, 2008 at 5:54 am — It is easy to find the reference to check the following facts: In 2007 CE anthropogenic emmisions of CO2 were equivalent to 10 billion tonnes of carbon (37 billion tonnes of CO2). Of this about 1.5 million were due to deforestation and the remainder largely from fossil fuels. This caused the CO2 concentration in the atmosphere to increase 2.0–2.0 ppmv; the remainder went into the oceans with some removel on land.

  • Chris Colose // December 30, 2008 at 10:52 pm

    As usual, Tamino is correct in his correspondence with Leif on the global extent of warmings/coolings.

    Even during the YD regional changes may have been 6 C or even more, but globally there was probably not much change due to the see-saw effect. the abrupt climate changes during the last glacial are not of the same nature as the modern global warming. The IPCC AR4 has discussion of this. Leif Svalgaard’s claim otherwise is absurd.

    [Response: He so totally crossed the stupid threshold with that one.

    But it's a sign of the times; the denialosphere has raised their stupid level to astronomical heights. It only muddies the water -- which of course serves their purpose. Dissent and disagreement aren't just valuable, they're essential, but sheer idiocy is neither.]

  • Kipp Alpert // December 31, 2008 at 1:45 am

    Dano:The statement should apply to it’s time, then, what it could mean today. “Survival of the fittest” was meant the strongest and in the beginning of last century , lustiness meant strength. So perhaps there is good meaning in survival to the most horney, and make another kid, before lunch. KIPP
    And make sure he’s not a denier, or he gets to sleep with the other Donkeys.

  • Kipp Alpert // December 31, 2008 at 1:53 am

    Chris Colose,Hank Roberts,Tamino.
    Aren’t the temperature differences in the arctic show much more warming, when it warms,
    than say Connecticut, or is it a matter of relativity. Mean between excess/defect.KIPP
    Chris thanks for going over to accuweather and leaving some good stuff.

  • Kipp Alpert // December 31, 2008 at 2:16 am

    Hank Roberts:I’m about ready to get out of Accu-bull,bottom feedin.After one and a half years I have been trying to do the right thing.
    The latest deniers, the younger generation of anti government, black helicopter,Bush grown, conservative truth slayers, are starting to suggest as an aside, that the poor will suffer, but aren’t they just beneath our human pay grade, if you get my meaning.True scum she ariseth.KIPP

  • Kipp Alpert // December 31, 2008 at 2:43 am

    Hank Roberts:Was it you who noted the proliferation of the blogesphere.I think that there has been small prosperous start ups of denier sites,all rather shallow,I mean empty. This is a political Issue as much as Science seems to get in it’s way. I’m sure you know this. I wrote a poem about the French resistence for my French wife, and the ending is relevant
    There is a single teardrop.
    that scurries round the cheek,
    a teardrop lost,what could have been,
    and sadness before we weep,
    so all had felt,
    they lost their Jean Moulin,
    those are the tears that flow,
    beneath the city street.

    And is this what it will take to fight, the liars in our midst. KIPP

  • Richard Steckis // December 31, 2008 at 5:15 am

    Hank,

    My work was published in Journal of Fish Biology.

    Ref: • Edmonds, J.S., Steckis, R.A., Moran, M.J., Caputi, N. and Morita, M. (1999). Stock delineation of pink snapper Pagrus auratus and tailor Pomatomus saltatrix from Western Australia by analysis of stable isotope and strontium/calcium ratios in otolith carbonate. J. Fish Biol. 55(2): 243-259.

    I had to go second author even though all the research on tailor (bluefish) was my own.

    • Steckis, R.A., Newman, S.J., Bastow, T.P., Juanes, F. and Edmonds, J.S. (2007). Stable isotope ratio analysis of the sagittal otolith carbonate of bluefish Pomatomus saltatrix among three continents reveals distinct ontogenetic habitat partitioning: implications for stock identity studies. (In Prep).

    I am also a co author in the following ref:

    • Newman, S.J., Steckis, R.A., Edmonds, J.S. and Lloyd, J. (2000). Stock structure of the goldband snapper Pristipomoides multidens (Pisces: Lutjanidae) from the waters of northern and western Australia by stable isotope ratio analysis of sagittal otolith carbonate. Mar. Ecol. Prog. Ser. 198: 239-247.

  • Richard Steckis // December 31, 2008 at 5:16 am

    Tamino.

    Thanks. I knew i was wrong somewhere.

  • Richard Steckis // December 31, 2008 at 5:38 am

    Bloody spreadsheets.

  • Richard Steckis // December 31, 2008 at 5:56 am

    Luminous:

    “And this can’t be explained by non-linearities in carbon sinks and sources? Why not?”

    Perhaps. But then it can’t be used to quantify anthropogenic forcing. Because the theory is that a rate change in Anthropogenic co2 forcing will be matched (to within a certain error) with a rate change in delta 13C. If there is a significant divergence then other factors may in play and the usefulness of the technique for the intended purpose must then be re-examined.

  • Julian Flood // December 31, 2008 at 1:58 pm

    Re dhogaza // December 27, 2008 at 3:29 pm

    “Speaking of bozos …

    The evidence of increased CH4 output from the Arctic tundra is related to permafrost melting, due to anthropogenically forced warming.”

    Or perhaps not: see

    Controls on suppression of methane flux from a peat bog subjected to simulated acid rain sulfate deposition

    Vincent Gauci, Nancy Dise, David Fowler

    Acid rain controls are having an effect on methane suppression. Told you so.

    JF

  • luminous beauty // December 31, 2008 at 2:52 pm

    Steckis,

    Argumentum ad infinitum. Repeating nonsense over and over doesn’t make it true.

    We expect other factors to be in play. This is the real world, not a laboratory. Noise is the norm. There hasn’t been any divergence that cannot be accounted for. Except in your fantasies.

  • dhogaza // December 31, 2008 at 3:42 pm

    Acid rain controls are having an effect on methane suppression. Told you so.

    We’re working ourselves into a frenzy where all pollution control is bad, now? We should spew as much as possible of everything into the atmosphere?

  • dhogaza // December 31, 2008 at 3:48 pm

    Well, Julian Flood does provide us a bit of unintentional internet humor at his web site, where he outlines his [ocean] surface pollution hypothesis of global warming.

  • george // December 31, 2008 at 5:16 pm

    Richard Steckis:

    from wikipedia:

    Carbon dioxide in earth’s atmosphere is considered a trace gas currently occurring at an average concentration of about 385 parts per million by volume or 582 parts per million by mass.[16] The mass of the Earth atmosphere is 5.14×10^18 kg [17], so the total mass of atmospheric carbon dioxide is 3.0×10^15 kg (3,000 gigatonnes).

    ( 5.14 million Gt)x 0.000582 = 2.99 trillion metric ton (or 2,990 gigatonnes)

    That’s the total mass of CO2 in the atmosphere.

    Since the (volumetric) mixing ratio for CO2 is about 385 ppmv, we find

    that 1 ppmv (ie, by volume, not mass) is about
    2.99 trillion metric ton/ 385 = 7.77 billion metric tons (7.77 Gt) of CO2

    In carbon equivalents, that is 2.12 billion metric tons (ie, Gt) of Carbon (obtained by multiplying 7.77 by 12/44), the number quoted by IPCC

    David Bensen:

    first, wikipedia gives yearly emissions of CO2 as 27 billion metric tons (not the 37 you gave above)

    27 Gt CO2 is 7.36 Gt in carbon equivalents.

    Second, that can not simply be divided by the 2ppmv by which atmospheric CO2 currently goes up to yield an equivalent for 1ppm.

    in fact if one simply did that, one would incorrectly conclude that 1 ppm is about 3.68 Gt, which is almost twice the actual value of 2.12 Gt (for 1 ppm equivalent)

    The issue is that almost half the yearly human caused CO2 emissions are taken up by natural sinks so only roughly half of the total yearly emissions stay in the atmosphere and contribute to the 2 ppm boost in concentration.

  • David B. Benson // December 31, 2008 at 6:29 pm

    george // December 31, 2008 at 5:16 pm — Emissions are well estimated as 10 GtC for 2007 CE. including deforestation. (44/12)x10 Gt = 37 GtCO2, close enough.

  • george // December 31, 2008 at 7:54 pm

    David Bensen:

    You are correct about the emissions if one includes the land use changes (eg, deforestation).

    It seems the 27 Gt CO2 quoted by Wikipedia does not include land use changes like deforestation.

    IPCC AR4 lists emissions from fossil fuel burning and cement production as 7.8GtC/yr (which equates roughly to the number given by wiki)

    The IPCC also list emissions from land use changes (which includes deforestation) as 0.5 to 2.7 GtC /yr.

    If one assumed 2.7 GtC/yr, the total

    fossil fuel burning + land use change = 7.8 + 2.7 = 10.5 GtC/yr

    (roughly the same as your 10 GtC/yr number)

    However, my second point still stands: regardless of what the precise number is for current yearly emissions, one can not simply divide yearly emissions by the 2ppm yearly atmospheric increase to calculate the mass equivalent for a 1 ppm change.

    In other words, using your numbers, one can not simply divide 10 Gt by 2ppm to give 5 Gt per ppmv (implied by your comment to Richard Steckis above)

    If one is going to use emissions, one must also account for the precise fraction of yearly emissions that remain in the atmosphere (estimated by IPCC to be about 60%) as i indicate above.

  • David B. Benson // December 31, 2008 at 9:56 pm

    george // December 31, 2008 at 7:54 pm — Yes, probably 10.5 GtC is the more precise figure.

    I fail to see the implication. Such was not intended and I did mention the need to account for the fraction of emissions going into the ocean, etc.

  • Richard Steckis // January 1, 2009 at 3:17 am

    Luminous.

    I managed to get 10 years of Delta 13C data so far from Mauna Loa (1991-2001).

    Linear regression of co2 vs D13C reveals a highly significant relationship (p<0.001). Therefore variations in D13C can be explained by variations in co2 concentration. However.

    The R squared for the model is 0.66. This means that approx 66% of the variation in D13C can be accounted for by variation in co2. This means that a full 33% of the variation in D13C cannot be accounted for by variation in co2.

    What this means I do not know. However, there may be other factors in play. Transforming the data did not improve the model.

    As such an R squared of 0.66 if not resolved, and if it persists with an increased dataset, indicates to me that D13C has limited use as a proxy for anthropogenic co2 forcing.

    I am sure Tamino is going to lay into me on this one and tell me I am a statistical moron.

  • Richard Steckis // January 1, 2009 at 3:28 am

    George.

    I think I know where I miscalculated. My interpretation of a Gigatonne is 1 x 10^12 tonnes (as it is in Wikipedia and just about everywhere else). It seems that the figure you quote for Gigatonnes is equivalent to 1 x 10^15 tonnes.

    This arises because depending where one is in the world a billion is either 1 x 10^9 or 1 x 10^12.

    My Gigtonne was 1 x 10^9, therefore the 2 orders of magnitude difference.

  • Richard Steckis // January 1, 2009 at 3:30 am

    “I think I know where I miscalculated. My interpretation of a Gigatonne is 1 x 10^12 tonnes (as it is in Wikipedia and just about everywhere else).”

    correction 1 x 10^9 = 1 Gigatonne in my interpretation.

  • Richard Steckis // January 1, 2009 at 3:33 am

    Sorry. Second correction:

    “It seems that the figure you quote for Gigatonnes is equivalent to 1 x 10^15 tonnes.”

    That should be 1 x 10^12 tonnes.

  • Richard Steckis // January 1, 2009 at 3:39 am

    From: http://www.tiscali.co.uk/reference/dictionaries/english/data/d0081651.html

    BILLION

    In British English billion has traditionally meant a million million. The American meaning of billion (a thousand million) has become standard in technical and financial use, and it is now better to use it in all circumstances.

    It seems that the IPCC uses the English units instead of the more accepted (these days) American units.

  • Phil. // January 1, 2009 at 4:28 am

    Steckis the prefix Giga is a standard SI prefix which means 10^9.

    http://physics.nist.gov/cuu/Units/prefixes.html

  • Richard Steckis // January 1, 2009 at 5:15 am

    George.

    Forget everything I said today about my calculations for mass of co2 in the atmosphere.

    I know where I went wrong. I said that 386ppm was 0.0386% and then used the percentage in my calculations. I should have used the ppm value 0.000386 to convert to co2 mass. Therefore I was out by two orders of magnitude.

    There you go Dhogaza. See what happens. Everything improves if you use a slide rule instead of a spreadsheet.

  • Richard Steckis // January 1, 2009 at 5:16 am

    Phil. I know what the prefix Giga means.

  • Phil. // January 1, 2009 at 5:58 am

    Richard Steckis // January 1, 2009 at 5:16 am

    Phil. I know what the prefix Giga means.

    Your last several posts would seem to indicate otherwise.

  • Richard Steckis // January 1, 2009 at 7:55 am

    Phil.

    Gigatonne means one billion tonnes.

    Depending on your definition of billion that could mean either 1 x 10^12 or 1 x 10^09 tonnes.

    Of course the most accepted in science is 1 x 10^09.

  • Red Etin // January 1, 2009 at 10:45 am

    Richard Steckis

    BILLION

    The english language word milliard means a thousand million. (Also used in Dutch “miljard”). The recently invented word “billion” is unnecessary.

  • michel // January 2, 2009 at 8:11 am

    This is from today’s UK Independent. Now, if we could just get the proposal analyzed in Excel, then do a PowerPoint presentation, we could probably get everyone to buy in to it and get moving. Terrifying, they really do not seem to have heard of the law of unintended consequences….

    “The plan would involve highly controversial proposals to lower global temperatures artificially through daringly ambitious schemes that either reduce sunlight levels by man-made means or take CO2 out of the air. This “geoengineering” approach – including schemes such as fertilising the oceans with iron to stimulate algal blooms – would have been dismissed as a distraction a few years ago but is now being seen by the majority of scientists we surveyed as a viable emergency backup plan that could save the planet from the worst effects of climate change, at least until deep cuts are made in CO2 emissions.”

    http://www.independent.co.uk/environment/climate-change/climate-scientists-its-time-for-plan-b-1221092.html

  • Hank Roberts // January 2, 2009 at 4:26 pm

    Long time since I last heard the “short billion” vs. “long billion” argument.

    http://www.google.com/search?q=10e12+billion
    http://scholar.google.com/scholar?q=10e12+billion

    Tangentially, another useful conversion found with the latter search:
    “… speed of light. .. roughly 300,000 kilometers per second (3.6 * 10E12 teraangstrom per fortnight) …”
    http://www.rgoarchitects.com/Files/fallacies.pdf

  • Phil. // January 2, 2009 at 4:55 pm

    Richard Steckis // January 1, 2009 at 7:55 am

    Phil.

    Gigatonne means one billion tonnes.

    No it doesn’t it explicitly means 10^9 tonnes, the word ‘billion’ is not part of the definition!

    http://www.bipm.org/en/si/si_brochure/chapter3/prefixes.html

    Depending on your definition of billion that could mean either 1 x 10^12 or 1 x 10^09 tonnes.

    Of course only one accepted in science is 1 x 10^09.

    Hank, one of the most useful for the speed of light is 1 foot/nsec, very handy for approximating the delay between firing a laser and the arrival of the light at its destination.

  • Ian Forrester // January 2, 2009 at 5:09 pm

    Richard Steckis said: “I know what the prefix Giga means…… Gigatonne means one billion tonnes.”

    This proves that you do not know what giga means. Giga has been defined as 10^9 by the IUPAC (1947).

    If you really are a scientist (in the full meaning of the term) you would not be using sloppy scientific terms such as billion.

    Science is a very precise discipline and terms are defined rigorously because of that. To be sloppy is a sign of being a poor scientist which may carry over into other aspects of your scientific endeavors.

  • Hank Roberts // January 2, 2009 at 6:23 pm

    > 1 foot per nanosecond

    I recall reading that Admiral Hopper used to hand a foot of wire to people unclear on the concept, for example when some Congressman was asking why they couldn’t get rid of this annoying lag time when using a geosynchronous satellite to talk on the phone to someone on the other side of the world.

    I think that’s one in her hand:
    http://www.jamesshuggins.com/i/tek1/grace_hopper_grace4_full.jpg

    http://gracehopper.org/2007/about/grace-hopper/

  • Red Etin // January 3, 2009 at 4:30 pm

    Ian Forrester

    “If you really are a scientist (in the full meaning of the term) you would not be using sloppy scientific terms such as billion.”

    …thereby you slight many of the contributors to this thread, including the author of it.

  • Ray Ladbury // January 3, 2009 at 9:18 pm

    Red Etin, Context is everything. To use the term billion is not necessarily sloppy if all parties to the conversation share a common definition. To take the precisely defined prefix giga=1E9 and substitute “billion=1E12″ is flat careless. Want me to draw you a map?

  • Gus // January 5, 2009 at 9:18 pm

    There appears to be a solution to this. Replace cattle and sheep farming with kangaroo ranching. Kangaroos have long been known to emit much lower levels of methane than ruminants (http://www.newscientist.com/article/mg20026873.100-how-kangaroo-burgers-could-save-the-planet.html?DCMP=OTC-rss). Delicious too!

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