RealClimate logo


CO2 is not the only greenhouse gas, and greenhouse effects are not the only CO2 problem

Filed under: — gavin @ 7 July 2008 - (Español)

The title here should strike a familiar theme for most readers. Climate forcings do not just include CO2 (other greenhouse gases, aerosols, land use, the sun, the orbit and volcanoes all contribute), and the impact of human emissions often has non-climatic effects on biology and ecosystems.

First up last week was a call from Michael Prather and colleagues that the production of a previously neglected greenhouse gas (NF3) was increasing and could become a significant radiative forcing. This paper was basically an update of calculations done for the IPCC combined with new information about the production of this non-Kyoto gas.

Most of the media stories that picked this up focused on the use of this gas in a particular manufacturing process – flat screen TVs. Thus the headlines almost all read something like “Flat-screen TVs cause global warming”! (see here, here, here etc.). Unfortunately, very few of the headline writers read the small print.

NF3 is indeed a more powerful greenhouse gas than CO2 (as are methane, CFCs and SF6 etc.), but because it is much less prevalent, the net radiative forcing (as with other Kyoto gases) is much smaller. Unfortunately, no-one has any measures of the concentration of NF3 in the atmosphere. This is likely to be increasing, since production has stepped up rapidly in recent years, but the amount of gas that escapes to the air is unknown. Manufacturers claim that it is only a very small percentage – but historically such claims have not always been very reliable. However, it is almost certain that NF3 has not caused a significant amount of global warming (yet).

The one issue that many stories did get wrong was in the comparison with coal. Prather’s paper compared the effect of the entire global production of NF3 being released into the atmosphere with the CO2 impact of one coal-fired power station. Since that is the maximum estimate of the current effect, and only matches a single power-station, the subtlety of the comparison got a little lost on the way to “Flat screen TVs ‘worse than coal’” story….

Needless to say, no-one should be throwing away their flat screen TVs because of this (it’s not in the use of the TV that causes a problem), but manufacturers will likely need to step up monitoring of NF3 leakage or switch to an alternative process which some have already done.

The second story getting some attention, is the ocean acidification issue. As we’ve discussed previously, the increased take up in the oceans of human-released CO2 is rapidly increasing the acidity (lowering the pH) of the oceans, making it more difficult for many carbonate-producing organisms to produce calcite or aragonite. These organisms include corals, coccolithophores, foraminfera, shell fish etc.

Both of these issues are relevant to the ongoing climate change discussion and it’s good to see the media picking up (albeit imperfectly) on these ancillary discussions. But as with the “North Pole” lightning rod discussed last week, there always needs to be a hook before something gets wide press (the ‘tyranny of the news peg’ as ably described by Andy Revkin). In the first case, there was a link to a popular consumer item and in the second, there has been a concerted effort to get the ocean acidification issue higher up the agenda.

The fact of the matter is that most of what goes on in the sciences is completely (and usually correctly) well below the radar of the public at large. But when there are discoveries and issues that do have public policy ramifications, getting the public to pay attention often requires finding just these kinds of resonances. Now if there was only a way to make sure the story underneath was accurate….


232 Responses to “CO2 is not the only greenhouse gas, and greenhouse effects are not the only CO2 problem”

  1. 1
    S. Molnar says:

    Speaking of getting the details right, you say plasma TVs, but the articles you cite say LCD if they specify at all. Which is correct?

    [Response: Not sure – this press release simply says ‘flat panel displays’, as does the Prather article. NF3 is used in plasma etching, but I have no idea if that is connected specifically to plasma TVs. To be on the safe side, I deleted the ‘plasma’ reference above. If anyone has more information, please let us know. – gavin]

  2. 2
    Chris Colose says:

    The bad thing is that it has a radiative forcing of 0.21 W/m^2 per ppb and we do not have atmospheric measurements, the good thing is that its release is being looked at in terms of picomoles per mole. I’m curious as to where this gas cuts off outgoing radiation (definitely must be in the atmospheric window), but I can’t find anything on HITRAN.

  3. 3

    Only slightly off topic… but how extensive this kind of rhetorical attack is…

    HERE

    The time you take from your real work is appreciated more than you can possibly know.

    Thank you, for what you do, and for keeping us informed.

  4. 4
    John Mashey says:

    A third one, which as far as I know, has gotten little attention, since it’s more local, is that of the negative health effects of higher CO2 concentrations in already-polluted areas, i.e., like some cities here in California.

    Stanford Prof. Mark Z. Jacobson has a bunch of interesting papers, but in particular, it’s worth reading:

    Testimony to House April 2008.

  5. 5

    Exactly.
    “IGNORANT AMERICA: JUST HOW STUPID ARE WE?
    By Rick Shenkman, Tomdispatch.com
    Millions of Americans are embarrassingly ill-informed and
    they do not care that they are.
    http://www.alternet.org/democracy/90161/

    [edit – please stay on topic and off politics.]

  6. 6
    Mark J. Fiore says:

    I sometimes post to DeSmog.blog, or RealClimate.I’m going to review whar I’ve said before.The oceans have absorbed so much co2 that they have masked the true extent of the climate crisis.We had plenty of warning as much as 10 years ago about the increasing acidification of the oceans. I’m glad it is getting some press, but for those of us who have followed the news closely it is old news.Also, as I’ve said, most people seriously underestimate the danger of the methal(frozen methane) hydrates at the bottom of the worlds oceans melting.Along with massive expulsion of methane and co2 from melting peat and tundra in the Arctic, but especially in Siberia, the methal hydrates meling will indeed seal our fate.The Greenland ice sheets and Arctic ice, as well as the Antarctic major ice shelves, are all in real, real, danger of melting completely. The floods in the Midwest are jut a start.Desertification is increasing on a logarithmic scale upward, and the oceans have begun serious upwelling current changes, especially in the salinity levels off Greenland, a key downward force on the North Atlantic current.My research indicates that the North Atlantic current has already begun to change.
    And yet, at the current G8 summit, the US continues to obfuscate, minimize, and dimiss the severity of the problem.Now,finally, there is a call for an 80% reduction in manmade co2 by 2020. Finally. If you look at my posts, I said an 80% reduction must occur right now, for there to be any chance at all of averting real catastrophe for the planet.Finally, some are saying 80%, by 2020.
    I want the entire internet community to understand the way I feel.

    [edit – this is not the place for partisan politics, no matter how heartfelt]

    Mark J. Fiore
    markfiore50@hotmail.com
    Boston College Law School,1987 and Harvard University, 1982

  7. 7
    Eachran says:

    Mr Schmidt, I have read the links and understand the principal points. Thanks for the always interesting comments on this site.

    There has been an agreement to agree, at G8 today, to reduce emissions by 50% by 2050. Assuming all agree to reduce by 50% and achieve it (an heroic assumption), what affect will that have on ocean acidification. I tried to find out for myself the answer to this question by reading the original paper but it is a pay website. But perhaps the original paper doesnt contain enough information anyway.

  8. 8
    Nick Riley says:

    Indeed. For many years in dealing with policymakers I have pointed out that the lowering of seawater pH alone, via atmospheric CO2, justifies significant emission reductions.

  9. 9
    David Wilson says:

    a very interesting line of thought, pegging (with only minimal condescension :-) the issues to both the media and to the public consciousness (or unconsciousness as the case may be) – there is another thought, that homo sapiens has split into two species, one moral and one immoral, you come across the notion now and then

    anyway, I appreciate your digression, thought provoking, well done, thanks.

  10. 10
    Pete Best says:

    Probably explains why it is best to just stick with global warming and CO2 with some reference to rain forest destruction and land use changes. after all Al Gore and others have done enough work in this arena to get the momentum going and even the G8 have committed to 50% CO2 cut by 2050.

    Is this enough of a cut to stop AGW from being the disaster it is reported it is goign to be with BAU scenarios?

  11. 11
    Slioch says:

    I note that the Press Association report states, “Scientists have calculated that it [NF3] has a half-life in the atmosphere of 550 years.”

    I assume this half life may relate to the reaction of NF3 with, presumably, oxygen and/or water to form more stable end products that are either not GHGs or are rapidly washed out of the atmosphere, such as N2 and HF respectively. Maybe NF3 also slowly spontaneously decomposes. Its iodine analogue, the solid NI3, easily prepared by adding conc. ammonia solution to iodine crystals, does so: it explodes with a loud bang and a puff of violet smoke if sprinkled on the floor and trodden on. It was beloved of miscreant sixth-formers in the days before health and safety took the pleasure out of chemistry lessons.

    I have often wondered why the duration of CO2 (and other GHGs) in the atmosphere is not generally expressed in terms of half lives. Rather, it is usually stated that ‘CO2 lasts for a century or more in the atmosphere.’

    Can anyone shed some light on this question of half lives?

    [Response: For NF3 the half-life is dominated by photolysis (presumably in the stratosphere) and the reaction with the O(1D) radical. Since these reactions depend on the concentration of NF3, an exponential decay process with a well-defined half-life is a good fit. For CH4 or CO2, the chemistry is more complicated (much more so for CO2) and half-lives less useful a concept. For CH4, 12 years for the perturbative half-life (longer than the ~8 year residence time) is reasonable, while for CO2 the best approximation is a combination of 5 different exponential processes with half lives that range from 3 to 100,000 years. Thus there is a component of CO2 emissions (roughly 15%) that is effectively in the atmosphere forever. – gavin]

  12. 12
    Lennart says:

    “Needless to say, no-one should be throwing away their flat screen TVs because of this (it’s not in the use of the TV that causes a problem)…”

    Isn’t the higher energy use of plasma screens the biggest problem here? Or is that mainly because the newly bought screens are usually much larger than the old ones? See for example:

    http://www.guardian.co.uk/environment/2006/aug/13/energy.nuclearindustry

  13. 13
    Fair and Balanced says:

    “Now if there was only a way to make sure the story underneath was accurate….”

    Well. For a start, it could help if the IPCC and the real climate scientists made a commitment to tell the truth. One example: http://www.onlineopinion.com.au/view.asp?article=7553

    And in your response, please don’t just ad hom me. How about a reasoned response showing why this reference is actually incorrect.

    [Response: Well since you seem convinced that we are dishonest already, what is the point? However, a moment’s thought should tell you that the whole article is based on false premise: When reviewing an article, do you comment on the 90% of the paper you think is ok, or on the 10% you think is wrong? Thus parts of the IPCC text that people agreed with were generally not commented on – for instance, I read the SPM and did not comment – because I was in agreement. Hundreds of scientists read the various drafts of the SPM, and only a few raised relatively minor issues. If it was one of my papers, I’d have been pretty happy. But even if you don’t think the IPCC reviewing is rigorous (even though it is, and it is certainly a lot more rigorous than anything peddled by Harris and company has undergone), how about all the reviews by the National Academies, and professional societies and special committees? The number of scientists who have explicitly endorsed the central IPCC conclusions is legion – as anyone who has ever gone to the AGU or EGU meeting will see and as anyone who reads the literature will see. It’s a valid argument to say that consensus does not guarantee correctness, but it’s complete nonsense to argue there is no consensus. – gavin]

  14. 14
    pat n says:

    The fault for climate change having been “well below the radar of the public at large” for decades has been with NOAA National Weather Service (NWS) headquarters, NWS weather and NWS river forecast offices – not with the media and others not “finding just these kind of resonances”.

  15. 15

    Mark,

    I don’t think it’s a good idea to attack Republicans per se. I know the GOP has become significantly far-right in recent decades and that almost all the loony public attacks on AGW theory have come from GOP apologists like Rush Limbaugh and Ann Coulter, not to mention the egregious James Inhofe. Nonetheless, there are Republicans, even Republican office-holders, who recognize the problem and want to do something about it. In addition, half the audience is Republican, and we don’t want them to think this is a Republican/Democratic issue. That way lies endless gridlock. The issue must be non-partisan or it will not get solved.

  16. 16
    The Carrot says:

    A quick question from a relative layman: if we reduce the concentration of CO2 in the atmosphere will the oceans then start releasing CO2? Or is the absorbed CO2 in the oceans basically there to stay until it’s used by some biological process (reef building, shell formation, etc)?

    If it’s the latter it’s tough for me to see how a (much needed!) reduction in atmospheric CO2 mitigates the oceanic PH level.

  17. 17
    Abbe Mac says:

    Now if there was only a way to make sure the story underneath was accurate….

    The story does not need to be accurate. It only needs to be true!

    If there is a there is a theat to humanity from NF3 then whether the current production is equivalent to one, one thousand, or one million coal power stations is irrelevant. The public only need, or want, to know that something should be done about it.

    Meanwhile, the scientific truth is being severely compromised by scare stories about ocean acidifcation. How can those species be under threat when they have survived much higher levels of CO2 in geological past? Levels of atmospheric CO2 far higher than even those predicted for the next century? That sort of story does much more to sap the faith of the intelligent layman in scientists, than any confusion by journalists about numbers of power stations.

    HTH,

    Cheers, Alastair.

  18. 18
    dhogaza says:

    In addition, half the audience is Republican, and we don’t want them to think this is a Republican/Democratic issue. That way lies endless gridlock.

    Or, perhaps they’ll stop voting Republican, as I did when Reagan hit the national scene and it became clear that the socially responsible, science literate, and fiscally conservative bits of the party I grew up with was doomed to irrelevance.

    Now, I didn’t vote for Nixon because of character issues and his bullshit “secret plan to end the war” which was transparent baloney meant to win votes of those uncomfortable with the notion of withdrawing from Vietnam while at the same time being tired of it. (brings to mind John McCain’s recent claim to have a plan to end the conflict in Iraq, harumph).

    But his administration was great measured by its environmental and conservation accomplishments.

    He’d be tarred and feathered by today’s party. And my own state’s Tom McCall was, in essence, tarred and feathered by the Reagan-era rabid right who’d taken over the Oregon Republican party when he attempted to make a comeback and regain the governor’s office.

    [Response: No more partisan politics – gavin]

  19. 19
    Eachran says:

    OK, I sent an e-mail to one of the authors of the pH paper suggesting that they might like to go a bit further with the general and interested and worried public : worried because the timelines keep getting truncated.

    How about posting something on realclimate, I suggested.

    I am particularly interested in the relationship of muck in the atmosphere to acidity in the oceans.

    I dont much like 1 degree temperature rise (goodness gracious all that energy) in 100 years let alone 2 degrees but the oceans in 40 years?

    Any smart scientists out there to help Joe Public and me?

  20. 20
    B Buckner says:

    Gavin,

    You state that the increased take up in the oceans of human-released CO2 is rapidly increasing the acidity (lowering the pH) of the oceans. I understand the pH of the ocean had dropped 0.1 units in the period between 1750 and 1994, and that the current pH of the ocean varies from about 7.9 to 8.4. What data support your contention that the oceans are acidifying rapidly?

    [Response: Direct measurements of ‘rapid’ (this is on a geological timescale) acidification, and a sufficient understanding of ocean seawater carbonate chemistry to know why, plus the almost certain continuing increase in atmospheric concentrations of CO2. See the wikipedia article for references. – gavin]

  21. 21
    Goedel says:

    How can those species be under threat when they have survived much higher levels of CO2 in geological past? Levels of atmospheric CO2 far higher than even those predicted for the next century?

    I’m not sure whether this was sarcasm or not, but just in case… Current ocean species have spent hundreds of thousands of years evolving under a certain range of ocean pH. If that pH suddenly plunges, there will absolutely be a shakeup of the various ocean ecosystems, as different species have different responses to increased acidity.

  22. 22
    Rod B says:

    Just a quick (and probably irrelevant) clarification: I was using a common figure of speech and meant no denigration of real Softball. The fastest and best pitcher of any kind of ball, Eddie Feiner, threw softballs

  23. 23
    Milan says:

    It seems that one important response to shoddy science reporting is to contribute letters to the editor. They might set a portion of readers straight, as well as demonstrate to the newspaper staff that there are people paying attention to the accuracy of their science stories.

  24. 24
    George Tobin says:

    For purposes of legislative action, dire rhetoric is not usually all that effective because everybody cites worse case scenarios for every issue and legislators get used to dismissing it. Environmentalists have cried wolf more than most and that has given opponents a lot of ammo and leverage.

    To quickly get rid of an apparently dangerous product like NF3, it is necessary to show the practical alternative. The car companies got a reprieve for several years on taking asbestos out of brakes because they claimed that the alternatives were unsafe (they weren’t, but it took time and effort to show that). VOCs from auto paint shops were a demonstrable health and environmental harm on many levels but lawmakers had to actually see that water-based paints and drying sheds were a viable alternative before they pulled the trigger.

    I know from conversation with lobbyists, hill staffers and members over the years that consumer and environmental advocates are often ineffective because of compulsive self-righteousness and a strange pride in economic ignorance. Taking the position that everyone who disagrees is both immoral and stupid is rarely a winning tactic in any social setting.

    I am not a chemical engineer but I assume there is probably an alternative to NF3 or a way to create closed process for vapor collection that could be mandated, probably even with express industry cooperation in formulating the details. When the choices are concrete, the costs known and the rhetoric deflated, things can get bi-partisan in a hurry.

  25. 25
    Hank Roberts says:

    Lordy lord lord, a great initial post and most every response is either tangential, a digression, or from another planet. Focus, people.

    Gavin, you asked for a reference, here’s one — NF3 was a trivial chemical a few years ago, it’s becoming widely used very quickly.
    Here’s why:
    http://www.icis.com/Articles/2008/03/24/9109896/strong-photovoltaic-and-electronics-sectors-support-nitrogen-trifluoride-silane-and-ammonia-demand.html

  26. 26
    Rod B says:

    Wasn’t the recent G8 result a “loose” goal, not a commitment? Wouldn’t such agreements mean more if they include China and India?

  27. 27
    Rod B says:

    A sandbox 101 question: What is it that makes methane and others “much more powerful” greenhouse gases? Is it because their internal makeup allows considerably more IR absorption, molecule for molecule? Or is it because they absorb in bands like the window that are “virgin territories”? For example if we had no GHG in the atmosphere, then added say 50ppm of both CO2 and CH4, which gas would contribute more toward warming? Or is it related to the relative lifetime of the various gases? Or some combination?

    [Response: All of the above. Different bands are differently absorbed depending on what the resonance is (vibrational, stretching etc.) and that depends somewhat on the strength of the bonds (which is obviously molecule specific). Concentration matters a lot – absorption is linear at very low concentrations and flattens out to logarithmic at higher values. And overlap is really important. If a molecule absorbs in the atmospheric window region, it is much more important than one that overlaps with water vapour. – gavin]

  28. 28

    And an even more holistic approach would include (aside from all the effects from GW and GHG releases), the various other harms from doing the things that entail GHG releases; for example:

    1. the other, more local pollutants from driving I.C.E. cars & their harms;
    2. the money lost from not being energy/resource efficient/conservative, which at the macrolevel weakens our economy (never mind threats to the economy & livelihood from GW harms)
    3. the health benefits lost from driving rather than cycling & walking.
    4. increased crime because people drive rather than walk or cycle (there was a study that neighborhoods with heavier pedestrian and cycling traffic experienced less burglaries).
    5. the physical/psychological stress of commuting long distances, bec one chose to live far from work, when closer comparable houses were avaiable, plus the lost family time, leading to various family dysfunctions….
    6. War and conflict to secure our resources
    7. Destruction of rainforests to get the bauxite for aluminum coke cans, bec we didn’t recycle our cans (which saves 95% energy & reduces GHGs).

    And so on.

    Of course, to be fair, we must balance harms against benefits to some extent (as long as it’s not a case of “I beneift, others are harmed”).

    But in cases of desired benefits that entail harms, we should be looking for harmless or less/least harmful alternatives. This has not been done enough, since the industry-gov-media-military complex, focused and dependent on oil/coal profits, sort of makes it difficult for us to perceive problems they don’t want us to perceive, like GW and its many, many ramifications, and difficult to work on solutions (I’m still waiting for my plug-in-hybrid).

  29. 29
    catman306 says:

    Pat N. at #14:
    ‘The fault for climate change having been “well below the radar of the public at large” for decades has been with NOAA National Weather Service (NWS) headquarters, NWS weather and NWS river forecast offices – not with the media and others not “finding just these kind of resonances”.’

    It would appear that politics has played a part in what you report. But politics (and big money) has probably also played a part in how science is reported through the media and in the very selection of those who write for and appear in the media stories about climate change.

    To borrow a phrase, this is the politics of minds suffering from ‘Nature Deficit Disorder’. Education can help stamp out this ubiquitous disease.

  30. 30
    Hank Roberts says:

    > How can those species be under threat when they have survived
    Many did not, as you’d know if you looked it up. Rates of change….

  31. 31
    Matthew Newman says:

    In relation to the article, the Plasma TV’s have NF3. What do we know of NF3 and in technical matters what other choices do consumers have? In a greener ethical matter, don’t all companies find this as a concern? If these are being sold in the market at a higher demand rate, do we even have to think about the greatest number of the greatest good of everyone trying to buy into the companies products of plasma TV’s? I think so. This happens to be a main focus and a larger issue that should be discussed to the manufacturers. I believe that the research that has been brought up to this matter should be open for the public to learn and understand the information given.

  32. 32
    Chris says:

    re #17 Abbe Mac

    You have to go back an awful long way to get atmospheric CO2 levels that are that much higher than current ones. Around 20 million years. That’s a very long time even on evolutionary time scales (humankind has only been around for around 200,000 years and the tree-dwelling apes from which the h-ominid line descended were around about 10 million years ago).

    It’s the rates of change that are important. The current set of sea-dwelling creatures, and specifically calcite/aragonite-fixing species, have evolved under conditions of relatively constant or extremely slowly changing ocean pH, and so have a relatively limited som-atic adaptability to changes in ocean pH. Ocean pH just doesn’t change much on the many 1000’s of years time scale (barring catastrophic events). So these creatures are rather sensitive to what seem to be relatively small changes in pH of only a few tenths of a pH unit (remember the pH scale is a logarithmic one). This is easily demonstrated in the laboratory.

    So the answer to your question “How can those species be under threat when they have survived much higher levels of CO2 in geological past?”….is that they haven’t survived much higher levels of CO2 in the geological past. Either their evolutionary predecessors were adapted to higher CO2 levels in the past, or (as happened during some of the major extinction events) they didn’t survive the insults (raised global temperatures/ocean acidification etc.) of greatly enhanced atmospheric CO2 concentrations..

    ..that’s the concern…

  33. 33
    llewelly says:

    There has been an agreement to agree, at G8 today, to reduce emissions by 50% by 2050.

    I think this goal implicitly assumes that (a) methane clathrates will not be problem, (b) CO2 & methane release from melting permafrost will not be a problem, and (c) a melting of 50% or more of the Greenland Ice Sheet is something we can adapt to. While it’s still possible that these three assumptions will turn out to be true, the impact of one or two of them being wrong could be awfully high ….
    As for ocean acidification, this goal seems likely to cut the rate of acidification by about half. Ocean acidification is like global warming in that zero CO2-emissions are a prerequisite to a turn-around.

  34. 34
    Hank Roberts says:

    The industrial use explained (see also the link I posted earlier which leads to much on industrial volume and production):

    “… forming an amorphous silicon nitride (a-SiN) deposited film … N-supplying raw material gas … examples are nitrogen (N2), ammonia (NH3), hydrazine (H2 NNH2), hydrogen azide (HN3) and ammonium azide (NH4 N3). Besides these, nitrogen halide compounds such as nitrogen trifluoride (F3 N) and nitrogen tetrafluoride (F4 N2) can be used. …”

    http://www.patentstorm.us/patents/6712019/description.html

    Forewarned:

    “… if the chemical industry had developed organobromine compounds instead of the CFCs … then without any preparedness, we would have been faced with a catastrophic ozone hole everywhere and at all seasons during the 1970s, probably before the atmospheric chemists had developed the necessary knowledge to identify the problem and the appropriate techniques for the necessary critical measurements. Noting that nobody had given any thought to the atmospheric consequences of the release of Cl or Br before 1974, I can only conclude that mankind has been extremely lucky, that Cl activation can only occur under very special circumstances. This shows that we should always be on our guard for the potential consequences of the release of new products into the environment.”

    Time to accept the precautionary principle?
    http://nobelprize.org/nobel_prizes/chemistry/laureates/1995/crutzen-lecture.pdf

  35. 35
    Chris Colose says:

    Rod B,

    I’m going to quote a couple exerpts from raypierre’s climate book, and this is partially in line with what gavin said (particularly the fact that methane is stronger on a molecule-by-molecule basis because of lower background concentrations), but I’m not so sure it is in 100% agreement:

    …………………….

    //”There is, however, a widespread misconception that methane is in some sense an intrinsically better greenhouse gas than CO2. A few simple calculations will serve to clarify the true state of affairs….

    The common statement that methane is, molecule for molecule, a better greenhouse gas than CO2 is true only for situations like the present where methane is present in far lower concentrations
    than CO2. In this situation, the greater power of a molecule of CH4 to reduce the OLR results simply from the fact that the greenhouse effect of both CH4 and CO2 are approximately logarithmic in concentration. Reading from Fig. 4.35, we see that for methane concentrations of around 1ppmv, each doubling of methane reduces OLR by about 2W/m2. On the other hand, for CO2 concentrations near 300 ppmv, each doubling of CO2 reduces the OLR by about 6 W/m2. Hence,
    to achieve the same OLR reduction as a doubling of CO2 one needs three doublings of methane, but since methane starts from a concentration of only 1ppmv, this only takes the concentration to
    8ppmv, and requires only 7/300 as many molecules to bring about as was needed to achieve the same reduction using a doubling of CO2. Equivalently, we can say that adding 1ppmv of methane yields as much reduction of OLR as adding 75ppmv of CO2…..

    If methane were the most abundant long-lived greenhouse gas in
    our atmosphere, and CO2 were present only in very small concentrations, we would say instead that CO2 is, molecule for molecule, the better greenhouse gas. “//

    ………………..

    Hope that helps.

  36. 36

    And there are other ramifications from our GHG emissions. (I’ve just been reading Mark Bowen’s CENSORING SCIENCE: Inside the Political Attack on Dr. James Hansen and the Truth of Global Warming.)

    I also think we should reduce our GHGs, bec:
    They cause GW, which leads to scientists finding out, which causes lots of politicos to lie, cheat, deceive, and do other dastardly deeds in their attempts to cover up, censor, and distort the science, which may cause them to end up in a much hotter place than a globally warmed world. At the very least it increases cynisim toward government (and toward industries which fund the gov and media, and hire the politicos after/before their gov jobs), which feeds into increasing societal demoralization. Not to mention, helps thwart action to address GW — both bec the public isn’t getting the truth and bec they’ve been demoralized by such cover-ups and distortions.

  37. 37
    cce says:

    The article linked in #13 is paroting the nonsense from Vincent Gray, who worked in the coal industry (and thus must not have a “vested interest” according to the article) and has never published anything about climate change, and basically knows nothing about climate change in general. He is one of those people who uses the title “expert reviewer of the IPCC” to claim some kind of qualifications, when, of course, anyone can be an expert reviewer.

    The Canadian Free Press article is talking about the second order draft of chapter 9, not the first draft, and it doesn’t take much thought to realize that the first draft is going to have more comments than the second. The reason why 60% of the reviewer comments were rejected is because 50% came from one person, Gray. And the reason why they were dismissive is because his comments were incompetent. He has around 70 comments asking not to use the word “anthropogenic” and similar word changes. Other comments were basically wild declarations with no supporting evidence.

    Anyone who doubts this can read the comments for themselves and search for Gray’s name:
    http://ipcc-wg1.ucar.edu/wg1/Comments/wg1-commentAgree.html

  38. 38
    Chuck Booth says:

    Re # 17 Abbe Mac:
    ‘the scientific truth is being severely compromised by scare stories about ocean acidifcation. How can those species be under threat when they have survived much higher levels of CO2 in geological past?’
    Why don’t you read the scientific literature on ocean acidification and find out for yourself? Then, please come back and tell us who is compromising the scientific truth. The following will get you started:

    Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers (NSF, USGS, NOAA) http://www.ucar.edu/news/releases/2006/report.shtml

    Ocean acidification due to increasing atmospheric carbon dioxide (Royal Society, UK)
    http://royalsociety.org/document.asp?id=3249

    Evidence for Upwelling of Corrosive “Acidified” Water onto the Continental Shelf
    Richard A. Feely, Christopher L. Sabine, J. Martin Hernandez-Ayon, Debby Ianson, Burke Hales
    Science 13 June 2008: Vol. 320. no. 5882, pp. 1490 – 1492 DOI: 10.1126/science.1155676
    http://www.sciencemag.org/cgi/content/short/sci;320/5882/1490

    You might also check out NOAA’s Pacific Marine Environmental Laboratory Carbon Dioxide Program Ocean Acidification website: http://www.pmel.noaa.gov/co2/OA/

    For more general discussions of this topic, check the Wikipedia reference Gavin provided in # 20, or, this article by a couple of the leading scientists studying ocean acidfication:
    Carbon Dioxide and Our Ocean Legacy, by Richard A. Feely, Christopher L. Sabine, and Victoria J. Fabry http://www.pmel.noaa.gov/pubs/PDF/feel2899/feel2899.pdf

  39. 39
    David B. Benson says:

    The Carrot (16) — Suppose we found some means to rapidly remove excess CO2 for the air. Then the shallow ocean would degas to follow along, lowering pH. The CO2 already committed to the deep ocean will be there still, for a long, long time.

    That’s my amateur take on it.

  40. 40
    Sherry Orton says:

    As an emissions market analyst, I spend endless hours scanning every article that pops up on Google when you search for the words “greenhouse gas.” For all of the occasional slightly off-topic digressions, it was truely refreshing to read a genuinely intellectual, scientifically literate discussion on the topic. I will definitely come back to this site when I need to feed my brain something healtier than the rubbish that passes for journalism these days.

  41. 41
    Jamie says:

    RE: Greenhouse gases other than CO2

    Is there any discussion of a regulatory framework to control the use of volatiles that have “bad” IR absorption spectra? In other words, it seems that industrial chemicals could be quantitatively ranked based on how well their IR absorption spectra overlap with that of H2O. This could be coupled with the lifetime of the gas in the atmosphere. The worse this coupled ranking, the more tightly the chemical would be regulated. That would effectively price poor “greenhouse gas” performers out of the marketplace.

    Given the vast number of volatile chemicals in use in the world, such an approach would at least provide a general means for judging the use of these chemicals in industry.

  42. 42
    Sean says:

    Thanks Gavin for trying to keep politics to a minimum.

  43. 43
    pete best says:

    Re #38, its the speed at which it is hapenning I believe is a major factor, 30x previous events.

  44. 44
    Sean says:

    Previous response:
    “How can those species be under threat when they have survived? Many did not, as you’d know if you looked it up. Rates of change…”

    Those that did survive still have the genes left over from more acidic times. The phenomenally fast reproduction rate of most of these organisms ensures that they can adapt to changes.

    Nature is pretty impressive. Don’t trust me though I believe in life on Mars.

  45. 45
    Chris says:

    Re #39

    Did you mean “Then the shallow ocean would degas to follow along, raising pH”?

    When CO2 dissolves in water it equilibrates with a hydrated form (H2CO3) which dissociates into bicarbonate and carbonate according to the pH:

    CO2(air) {- – – – } CO2(aq) (+H2O) {- – – -} H2CO3 {- – – -} HCO3- + H+ {- – – -} CO3- – + H+

    where {- – – -} represent reversible arrows (equilibria)

    Knowing the total hydrated CO2 concentration, the concentrations of carbonic acid (H2CO3), bicarbonate (HCO3-) and carbonate (CO3- -) are easily calculated since the pKa’s defining the various equilibria are known.

    So the pKa’s (the pKa is the pH at which there is 50% of each species on either side of any of the individual equilibria are):

    H2CO3 {- – – – } HCO3- + H+ (pKa = 6.4)

    HCO3- {- – – – } CO3- – + H+ (pKa = 10.3)

    one can see that at pH 7.5 (sea water-ish) there is very little carbonate and most of the hydrated CO2 is in the form of bicarbonate

    [the actual proportions of the species can be calculated from the Henderson-Hasselbalch equation:

    pH = pKa + log ([base]/[acid])

    so for the carbonate (base)/bicarbonate{acid) equilibrium:

    [carbonate]/[bicarbonate] = 10^(pH-pKa)

    and at pH 7.5 [carbonate]/[bicarbonate} = 10^(-2.8)

    which is about 0.016]

    I believe that this is the problem for ocean species that use carbonate to build their skeletons/shells. There is already a limited amount of carbonate in the oceans due to the high pKa of the bicarbonate-carbonate equilibrium, and as the pH drops the equilibrium is shifted even further away from the already very small dissociation of bicarbonate to carbonate.

    Note that if CO2 were to “out-gas” from the oceans the equilibrium would be pulled in the direction of de-acidification (since bicarbonate needs to be protonated before it can dissociate into CO2 and H2O).

    Interestingly this identical CO2-carbonic acid-bicarbonate-carbonate equilibrium maintains the homeostatic pH in our blood (pH 7.4)…a relic of our evolutionary deep oceanic past.

  46. 46
    Phil. Felton says:

    Re #20
    You state that the increased take up in the oceans of human-released CO2 is rapidly increasing the acidity (lowering the pH) of the oceans. I understand the pH of the ocean had dropped 0.1 units in the period between 1750 and 1994, and that the current pH of the ocean varies from about 7.9 to 8.4. What data support your contention that the oceans are acidifying rapidly?

    I hope you realize that the pH scale is logarithmic?
    A change from 8.1 to 8.0 is a rise in hydrogen ion concentration of ~21%.

    Re #44
    Why do you assume that the acid resistance genes remain, particularly in an organism with a fast reproduction rate?

  47. 47
    Eachran says:

    So this is what I sent to Mr Zeebe this morning (CET).

    “Dear Mr Zeebe

    I read ScienceDaily’s report on your work following up from a link on realclimate.org.

    I understand the implications of ocean acidification but it is the first time that I have seen easily understandable numbers.

    What interests me are your forecasts for pH changes by 2050 on the usual global warming scenarios. It wasnt clear from Science Daily’s report what the basis for your upper range forecast of 0,35 is.

    I have posted a question to Mr Schmidt on the realclimate site but I wondered if it would help if you or one of your colleagues could yourselves post further explanatory information.

    Best regards and dont weaken

    Eachran”

    Now, I am not a professional scientist but I am thinking about it even at my advanced age, but I would like to know what the number is and why.

    This is the same issue as sea level rise or sea-ice extent or temperature rise, or the recent discussion about probability density functions.

    It all boils down to the same thing : what is the number.

    I posted on ice sheet mass balance and sea level rise on this very point and eventually two posters offered something.

    My background is science, social sciences, and law and when I used to do law I worked with some pretty smart people in the profession. My instructions to them were, I am never going to sue you because if a decision is made it is my decision.

    So all you scientists out there, there’s a challenge, no more ifs and buts or maybes or perhaps. I wont sue you.

    What’s the number on pH by 2050 and why, and what are its implications?

    I would add that I am impressed by Messrs Annan and Connelly for putting their money where their mouths are on climate issues.

  48. 48
    Chris says:

    #44 Sean:

    [“Those that did survive still have the genes left over from more acidic times. The phenomenally fast reproduction rate of most of these organisms ensures that they can adapt to changes.”]

    Not really. I don’t think that’s a supportable assertion without some evidence in its support! It’s more likely that the absence of selection pressure (more acidic oceans) will have resulted in the loss of the acid-adaptated genotype. Unless organisms have som-atic physiological adaptability (of the sort that lets us humans adapt to variations of altitude through the adjustment of the oxygen affinity of haemoglobin, for example) it’s unlikely that evolutionary adaptation could occur sufficiently quickly to allow adaptation to rapidly acidifying oceans..

    …so it’s a question of time scales again. If atmospheric CO2 concentrations were to carry on increasing at current rates for another 100 years or more it’s rather likely that a large number of oceanic species would succumb, however “phenomenally fast” the little critters tried to reproduce. One/two hundred years is likely to be far too short a period for adaptive evolutionary responses, and the situation would be more akin to the previous extinction events in Earth’s history, many of which are associated with raised greenhouse gas levels/warming/ocean acidification/anoxia etc.

  49. 49
    Aaron says:

    From an expert’s point of view, was the earth in a thermal equilibrium with the incident flux of sunlight before the industrial revolution?

  50. 50
    John Lang says:

    What was the PH of the oceans at the time the carbonate-based life forms of Trilobites and Ammonites totally dominated the oceans and CO2 levels were 4,000 to 7,000 ppm?


Switch to our mobile site