RealClimate logo


Unsettled Science

Filed under: — gavin @ 3 December 2009

Unusually, I’m in complete agreement with a recent headline on the Wall Street Journal op-ed page:

“The Climate Science Isn’t Settled”

The article below is the same mix of innuendo and misrepresentation that its author normally writes, but the headline is correct. The WSJ seems to think that the headline is some terribly important pronouncement that in some way undercuts the scientific consensus on climate change but they are simply using an old rhetorical ‘trick’.

The phrase “the science is settled” is associated almost 100% with contrarian comments on climate and is usually a paraphrase of what ‘some scientists’ are supposed to have said. The reality is that it depends very much on what you are talking about and I have never heard any scientist say this in any general context – at a recent meeting I was at, someone claimed that this had been said by the participants and he was roundly shouted down by the assembled experts.

The reason why no scientist has said this is because they know full well that knowledge about science is not binary – science isn’t either settled or not settled. This is a false and misleading dichotomy. Instead, we know things with varying degrees of confidence – for instance, conservation of energy is pretty well accepted, as is the theory of gravity (despite continuing interest in what happens at very small scales or very high energies) , while the exact nature of dark matter is still unclear. The forced binary distinction implicit in the phrase is designed to misleadingly relegate anything about which there is still uncertainty to the category of completely unknown. i.e. that since we don’t know everything, we know nothing.

In the climate field, there are a number of issues which are no longer subject to fundamental debate in the community. The existence of the greenhouse effect, the increase in CO2 (and other GHGs) over the last hundred years and its human cause, and the fact the planet warmed significantly over the 20th Century are not much in doubt. IPCC described these factors as ‘virtually certain’ or ‘unequivocal’. The attribution of the warming over the last 50 years to human activity is also pretty well established – that is ‘highly likely’ and the anticipation that further warming will continue as CO2 levels continue to rise is a well supported conclusion. To the extent that anyone has said that the scientific debate is over, this is what they are referring to. In answer to colloquial questions like “Is anthropogenic warming real?”, the answer is yes with high confidence.

But no scientists would be scientists if they thought there was nothing left to find out. Think of the science as a large building, with foundations reaching back to the 19th Century and a whole edifice of knowledge built upon them. The community spends most of its time trying to add a brick here or a brick there and slowly adding to the construction. The idea that the ‘science is settled’ is equivalent to stating that the building is complete and that nothing further can be added. Obviously that is false – new bricks (and windows and decoration and interior designs) are being added and argued about all the time. However, while the science may not be settled, we can still tell what kind of building we have and what the overall picture looks like. Arguments over whether a single brick should be blue or yellow don’t change the building from a skyscraper to a mud hut.

The IPCC reports should be required reading for anyone who thinks that scientists think that the ‘science is settled’ – the vast array of uncertainties that are discussed and dissected puts that notion to bed immediately. But what we do have are reasons for concern. As Mike Hulme recently wrote:

[S]cience has clearly revealed that humans are influencing global climate and will continue to do so, but we don’t know the full scale of the risks involved, nor how rapidly they will evolve, nor indeed—with clear insight—the relative roles of all the forcing agents involved at different scales.

The central battlegrounds on which we need to fight out the policy implications of climate change concern matters of risk management, of valuation, and political ideology. We must move the locus of public argumentation here not because the science has somehow been “done” or “is settled”; science will never be either of these things, although it can offer powerful forms of knowledge not available in other ways. It is a false hope to expect science to dispel the fog of uncertainty so that it finally becomes clear exactly what the future holds and what role humans have in causing it.

Dealing with the future always involves dealing with uncertainty – and this is as true with climate as it is with the economy. Science has led to a great deal of well-supported concern that increasing emissions of CO2 (in particular) are posing a substantial risk to human society. Playing rhetorical games in the face of this, while momentarily satisfying for blog commenters, is no answer at all to the real issues we face.


567 Responses to “Unsettled Science”

  1. 551
    phil c says:

    David (550)
    I appreciate the reply.

  2. 552
    Silk says:

    Read #544

    “Seems like a pretty broad assumption to make that economic growth and or population growth automatically means more CO2 output; regardless of the the variant level these scenarios assume. If the reason why it’s assumed to be that way is cause it’s always been that way that’s a pretty specious justification.”

    Rubbish.

    The IEA know more about energy use that you or I. The IEA say increasing energy demand and use of the next 40 years will be huge.

    If you would care to show me how that energy demand can be met without generating a load of CO2, I’d be very keen to hear about it.

    If you ACTUALLY READ the SRES, you’d see that a massive body of research went into constructing these scenarios, and understanding the factors that drive emissions. Section 3.4 for example.

    Your attempt to characterise the SRES as “scientists just looked at what happened in the past, and used that to forecast the future” is NOT what happened.

    You say you read it. Read it again. More slowly. Particularly Chapter 3.

    “There are very serious endeavors underway to deal with this issue. Frankly, it’s insulting that these models seem to place SO little value in their efforts that they are not accounted for with the models.”

    This statement is beneath contempt. How many man-hours went into writing all the underlying literature that was used to build the SRES?

    Tell you what. YOU go away and work up an emissions scenario for the next 40 years. You’ll have to justify all your assumptions on emissions and underlying activity data of course.

    Then we’ll model your scenario and see what happens.

    “And I don’t agree with your assumption that without “significant policy intervention” this solution is solvable.”

    Well you are wrong. Completely and utterly wrong.

    “Carbon price setting will serve just to make the resource more scarce”

    Doh. If you don’t make the resource more scarce, you can’t solve the problem, can you? Either you put the CO2 in the atmosphere and deal with the consequences, or you don’t.

    “and good luck trying to get the Chinese government to go along with a price setting for carbon. It’s never going to happen.”

    They already have. It’s called the CDM.

    “This solution requires a technological solution, not a governmental one.”

    Who do you think has the greatest interest in Copenhagen succeeding? The negotiators? The politicians? WRONG.

    The single largest stakeholder in this process is the clean tech companies, and the investors that support them. If this process fails, the investment drains away, and we burn all the coal.

    Let me make this very, very simple for you. Coal is cheap. If we burn all the coal CO2 will go above 550ppm.

    Therefore we either need to

    a) Make the cost of burning coal so prohibitive, that we do something else (or do CCS)

    b) Make the cost of ‘something else’ cheaper than coal

    In the end, we use a sort of hybrid approach, increasing the CO2 price, while using regulation to drive private investment in low-carbon technology.

    Perhaps you’d like to tell me what your alternative policy approach to solving the problem “Humans emit 49GtCO2e GHG in to the atmosphere annually and if we do not halve emissions by 2050 then we face very serious climate problems” is?

  3. 553
    Silk says:

    #548

    “The main concern about the models is not that they are pointless but that they are presented to the public as if they are a true measure of what will happen.”

    Not true. The are presented as what might happen, within a range of uncertaincy.

    Can you find fault with the following, form the IPCC AR4?

    “For the next two decades a warming of about 0.2°C per decade is projected for a range of SRES emissions scenarios. Even if the concentrations of all GHGs and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected. Afterwards, temperature projections
    increasingly depend on specific emissions scenarios.”

    “Do the models take into account cosmic rays in the formation of clouds – they cant do this properly because no one really knows if really do effect clouds and if so to what extent.”

    And do they take into the impact of cans of coca cola produced a year?

    Demonstrate to me that there is a mechanism that could link GCR to climate, and that this impact would have a significant impact, and we can stick it in the model.

    (Models reproduce PAST and RECENT climate. Therefore there is ZERO evidence that adding a GCR model (or any other ‘missing’ forcing) would make the models significantly better)

    “Should if the experiments at CERN provide information that cosmic rays do seriously effect clouds that would show that the models must have been missing an important driving mechanism.”

    CERN won’t prove anything about cloud formation.

  4. 554
    Arie says:

    @540
    “There’s a very strong correlation between economic growth and CO2.”
    But there’s no correlation between CO2 and the recent global temperature changes. Just look at the last 8 or 10 years (rising CO2 levels, temperature stable or declining a little). So climate is far more complex than “more CO2 is more greenhouse-effect is higher temperature”, even the “climate scientists” simply don’t know yet.

    @550
    The point of the CERN experiment is that climate changes in the past have been much bigger than the changes we witness now, so before industrial activity played any role. That’s why the IPCC was so keen to hide the MWP, or said it only happened locally.

    CERN is investigating what the mechanism is for these huge natural(!) changes. Only when we understand that mechanism, we can say anything valid about human contribution to global warming right now. As a physicist I’m really shocked how politically influenced discussions on this “scientific” website are.

  5. 555
    Deech56 says:

    RE Hank Roberts

    By the way, did you click the link at the bottom of the page, where it says “Cited by” this paper?
    http://www.sciencemag.org/cgi/content/abstract/326/5957/1256

    John Cook posted a summary of Mann, et al. 2009 here, but with all the new visitors and the renewed (heightened?) interest in millennial temperature reconstructions, a post on this article would be timely. I think it would be instructive to also put the new findings into the context of the progression of the science, from the earlier reconstructions (Mann, Jones, Briffa in the 1990s) through Mann, et al. 2008 to the present.

    The availability of the data sets and analysis routines, as well as the public availability of the article itself, must also be noted. I would especially recommend the alternative analyses from the PNAS paper that Mike Mann has provided in his supplementary material. These analyses have provided tools for those of us who defend the science, and provide a way to disarm at least one meme (show the data!) from the critics. Like the records that Eric used in this post, the information is out there for anyone who wants to do their own analysis.

  6. 556
    Deech56 says:

    Oops – for “this post” I meant this post.

  7. 557
    Silk says:

    “But there’s no correlation between CO2 and the recent global temperature changes.”

    BZZZZT! Nice try. Thanks for playing!

    Next contestant please.

  8. 558
    Catherine Jameson says:

    Hi Gavin #521, Chris #523, and Silk #533 – thankyou for your comments. I have continued to look round this site and taken a look at some of Sherwood’s papers – I have insufficient maths to be able to understand a lot of what I’m looking at, which is frustrating. Hank #529 – sorry I tried to find the source again myself and couldn’t, I think it was somewhere on geocraft.com. It was a uni website. If it was clear to me 20 years ago that the various disciplines don’t talk enough to each other, it now seems that many discourses have diverged so much that they’ve become discontinuous with others which deal with overlapping fields – which is somewhat annoying to say the least! Having discovered the skeptical science website – thanks Silk – I think I will go look around there for a while until I understand the arguments a little better. Thanks once more, Catherine.

  9. 559
    JP says:

    “Copenhagen climate change conference: Fourteen days to seal history’s judgment on this generation”

    My gosh, doesn’t the Guardian realize that History has already rendered its judgement.

  10. 560
    phil c says:

    553
    And do they take into the impact of cans of coca cola produced a year?
    Demonstrate to me that there is a mechanism that could link GCR to climate, and that this impact would have a significant impact, and we can stick it in the model.

    Have you watched Jasper Kirkby’s presentation at CERN

    http://cdsweb.cern.ch/record/1181073

    GCR appear to influence cloud formation, cloud cover effects the climate. He may be wrong but that’s why they are doing the experiment. If the experiment shows the influence to be real then the models would be shown to be missing something significant.

  11. 561
    phil c says:

    553
    Not true. The are presented as what might happen, within a range of uncertaincy.
    Sorry but this is not how they are presented in the general media.

  12. 562
    Silk says:

    phil c – Can’t get streaming to work on my computer. But, given that the preamble suggests “Indeed recent satellite observations – although disputed – suggest that cosmic rays may affect clouds” then clearly the experiment is worth doing.

    (But you’d still need a climate model to work out what the net effect of this on climate was! Oh, the irony!)

    The models may be, indeed, missing this. Or rather, they may under-estimate the effect of changes in solar, because this ‘indirect’ effect is not included (the direct change in forcing is, of course)

    However, this doesn’t change the facts that

    a) There is no trend in GCR over the measurement period, and that Svensmark’s attempts to correlate GCR with temperature fail if you use the full data set.

    b) This doesn’t impact on the fact that climate sensivitiy to CO2 is 3 degrees, since the determination of this (from indepdent data sets) is not dependent on understanding the GCR effect, if one exists.

  13. 563
    modulles says:

    “The IEA know more about energy use that you or I. The IEA say increasing energy demand and use of the next 40 years will be huge.”

    Nope, don’t accept that reasoning. Why do you assume that because I am asking about this topic I don’t already know a great deal regarding it?

    Have you ever heard of this btw?
    http://en.wikipedia.org/wiki/Argument_from_authority

    I will however take a look at their data and see what it says.

    “If you would care to show me how that energy demand can be met without generating a load of CO2, I’d be very keen to hear about it.”

    I seriously doubt you would be willing to listen based upon your comments. BUT if you are willing to keep your mind open enough I will compile some of the information and send you via private email.

    “If you ACTUALLY READ the SRES, you’d see that a massive body of research went into constructing these scenarios, and understanding the factors that drive emissions. Section 3.4 for example.”

    Wrong again. Why are you assuming that just because someone disagrees with your viewpoint they must be uninformed. I have read the info, I have my doubts about the analysis. You want me to just follow blindly? Not going to happen.

    “Your attempt to characterise the SRES as “scientists just looked at what happened in the past, and used that to forecast the future” is NOT what happened.”

    [edit] Secondly, you misquoted me by saying

    ““scientists just looked at what happened in the past, and used that to forecast the future””

    So let me re-post my quote from before:

    “If the reason why it’s assumed to be that way is cause it’s always been that way that’s a pretty specious justification.”

    NOTE Keyword “If”. Or ‘In the event that’. Which by definition assumes the following to be true, however is conditional on further review of said following statement. This is before further review of the SRES so is no longer relevant since it’s clear how they come to their conclusions after actually reading it.

    “You say you read it. Read it again. More slowly. Particularly Chapter 3.”

    Dealt with above; read it. Question the conclusion and basis for their analysis. I’ll read it again for kicks though if that makes you happy. REALLY slowly even…

    “‘And I don’t agree with your assumption that without “significant policy intervention” this solution is solvable.”

    ‘Well you are wrong. Completely and utterly wrong.'”

    You want to expand on that a bit more and try to prove your case why government intervention is absolutely needed in order to solve the issue and without intervention it’s not possible?

    “Doh. If you don’t make the resource more scarce, you can’t solve the problem, can you? Either you put the CO2 in the atmosphere and deal with the consequences, or you don’t.”

    The question is about levels and degrees of change. If you make something scarce without being able to provide an alternate resource to supply energy you’re left with a serious energy issue. Cause while supplies go down prices will rise for carbon, if you’re trying to do that in order for investments to move toward alternatives then the market needs to be able to respond to it in a timely manner lest people go without.

    I disagree with your approach to FORCE it to happen through regulation. I don’t think the market will be able to respond quickly enough to it, so again it’s about what level of price constraint you place.

    “They already have. It’s called the CDM.”

    I have serious doubts about the enforcement mechanisms regarding this. I’ll believe it when I see it. China has monolithic focus on economic growth, if this limits that ability I would see them backing out of the agreement.

    Thought this was an interesting read on that:

    http://www.renewableenergyworld.com/rea/news/article/2009/12/credit-where-credit-is-due-understanding-the-clean-development-mechanism

    “Who do you think has the greatest interest in Copenhagen succeeding? The negotiators? The politicians? WRONG.”

    Asked and answered your own question…I never raised this issue. Sounds like you just like saying “WRONG”. Any relation?

    http://en.wikipedia.org/wiki/John_McLaughlin_%28host%29

    “Therefore we either need to

    a) Make the cost of burning coal so prohibitive, that we do something else (or do CCS)

    b) Make the cost of ’something else’ cheaper than coal”

    Yeah, option B.

  14. 564
    phil c says:

    553
    CERN won’t prove anything about cloud formation.

    why are CERN spending a lot of time and money on an experiment called CLOUD
    I ask again, have you actually watched Kirkby’s presentation?

    [Response: Because they aren’t going to form clouds in their chamber. They are trying to form aerosols. – gavin]

  15. 565
    phil c says:

    564
    taken from the CERN website
    http://public.web.cern.ch/public/en/Research/CLOUD-en.html

    Cosmic rays are charged particles that bombard the Earth’s atmosphere from outer space. Studies suggest they may have an influence on the amount of cloud cover through the formation of new aerosols (tiny particles suspended in the air that seed cloud droplets)

  16. 566
    phil c says:

    562
    phil c – Can’t get streaming to work on my computer.

    try this, it links to the same CERN presentation
    http://seekingalpha.com/article/175641-climategate-revolt-of-the-physicists

    (But you’d still need a climate model to work out what the net effect of this on climate was! Oh, the irony!)
    why the irony, I make a good living building computer models but I know the model must include all the appropriate factors. You can rule out coca cola cans (553) but I’m not so sure about cosmic rays.

    From what I’ve the seen the climate models only ever show temperatures going up because CO2 is rising. It wouldn’t be very scary if they didn’t. But cloud cover effects temperatures as much (if not a lot more) than CO2 , and if CERN shows that cosmic rays/aerosols effect cloud cover then the models could be shown to be missing a major factor.

    The results from the climate models could turn out to mean little more than, unless we reduce CO2 emissions or the temperature drops due to something other than CO2 it will continue to get hotter.

    It is quite possible that CLOUD will show there is no link but if that was a certainty why would CERN would waste any time and money on it?

  17. 567
    phil c says:

    I came to this site because I had watched the presentation by Jasper Kirkby and could see that the CLOUD experiment could make a major contribution to our understanding of the climate.

    Whether his experiment yields any significant information I would have expected more interest for the people who run this site , especially as CLOUD is being run by a team of physicists at CERN.

    I received the following comments

    Ed 315 As for Professor Kirby, I think the blog post you refer to actually sums up the state of that ‘theory’ rather nicely: “They haven’t completely worked out the mechanism yet…” Uh huh… And I’ve got some stock to sell you. I haven’t quite worked out how the guy we’re buying it from is investing it but… trust me.

    Call us back when you have worked out the mechansism, will ya?

    Either Ed (whoever he is) has never heard of CLOUD in which he’s not very interested in climate science
    or he’s is deliberately being sarcastic about a serious scientific experiment.
    Either way, I wont be taking “Ed” very seriously from now on

    Gavin comments

    [Response: Of course. Do you think I’m the pope or something? But you are still confused – there is no way that CLOUD is going to show anything about the radiative effect of CO2. Nothing. Nada. Zip. – gavin]
    or [Response: Because they aren’t going to form clouds in their chamber. They are trying to form aerosols. – gavin]
    Gavin deliberately evaded the point that CLOUD may show a link between cosmic rays/aerosols and cloud formation.

    This site is called RealClimate with the sub-title “Climate Science from Climate Scientists”. So, why not be like a proper honest scientist and say something like “we doubt that the CLOUD experiment will yield significant results but we recognise that if it does we may have to reconsider the role of CO2 within the context of atmospheric warming”

    The attitude on this site shows that you are too tied up with CO2 to be relied on for objectivity.

    [Response: No. You have an idea that somehow evidence for GCR initiation of aerosols implies a direct link to cloud variations over recent decades, a change in the sensitivity of climate to CO2 and the attribution of recent changes to CO2 and the other human forcings. The problem is, as we have been trying to demonstrate, that this idea is not true. I would be fascinated to learn more about aerosol-cloud interactions, and to get improved estimates of climate sensitivity. But neither of these things can possibly come from the CERN experiments. Instead, they will (hopefully) get a an estimate of how variations in the ion-induced aerosol formation gets transmitted to aerosol number and density. It will be interesting, but only a tiny step. This recognition is not because of some irrational attachment to CO2, but simply a recognition that the physics underlying our understanding of the greenhouse effect is much more solidly based. – gavin]


Switch to our mobile site