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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. 101
    dlharman says:

    Dr. Schmidt,
    Very nice piece. Don’t be dismayed, I think you show exceptional patience and tolerance in the way you respond to comments. As a conservative and a believer in the science behind AGW, I appreciate the work you and others have done to uncover what has been happening regarding the climate. I’m astonished at the lack of rationality in the contrary arguments posted here and wonder why anyone put spew out a statement before checking their sources or even doing any basic research. It’s like watching a bunch of addicts react to the idea that their source of crack is about to dry up except the drug is actually a hydrocarbon.
    Thanks again.

  2. 102
    Willie Guerra says:


    Thanks for another great post. I was wondering if you could comment about the ‘settled-ness’ of the science in a different way. I but have never actually seen reported the percentage of climate change researchers that are actually climate contrarians (like Richard Lindzen, etc). Obviously this would not change the overall conclusions, but I’d be very interested to know how many skeptics are out there. Despite being pretty well read on the topic (I’m a graduate student doing paleoclimatology research) the closest I can seem to find is the level of certainty from the IPCC reports that humans are causing climate change – which is a slightly different story.

  3. 103
    Walter Manny says:

    11:06 AM

    To: “If you agree that there are many areas where the science is not settled, do you also agree that is unfair and unreasonable to label Richard Lindzen a ‘denier’?”

    I would argue that this business of calling people “deniers” is unfair and unreasonable to ANYONE. The term is clearly used in reference to the Holocaust to imply that skepticism regarding AGW theory is tantamount to Ahmadinejad’s rantings. At the very least, it is a tactical error on the part of AGW theory proponents to label those with whom they disagree using this noxious term. Those of us who in good faith have come to disagree with the mainstream point of view (as though that were in and of itself a sin) become suspicious of motives when slapped with the epithet “denier”. You hear arguments that to use the word is simply to apply the dictionary, but since it is certain not be received as such, why not find another word?

    In the past on RC, I have not been able to publish this complaint, the response being it was boring and off-topic. Fair enough, I suppose, but in light of the damage being wrought by the careless emails, perhaps now is the time to stop using such careless speech as lay folks try to work through the uncertainties Schmidt and Lindzen are analyzing differently.

  4. 104
    Doug Bostrom says:


    “If the science was settled, then we would stop asking for all those massive big research grants to do more research. Has anyone ever seen a published paper that didn’t say “more research is needed”?”

    Well, when you’re stuffed into the ass-end of the pantomime horse of climate science contrarian belief there’s a lot you cannot see. From the less suffocating outside perspective you can for instance see that on the one hand there is an enormous industrial sector with literally trillions of dollars in future profits at stake, versus a disorganized rabble of researchers turning out scientific findings that will be discovered and published regardless of consequences and quite without any particular goal in mind other than puzzle solving.

    Who has the greater incentive here to organize their efforts around getting money? People with trillions of dollars at stake, or people who are going to follow their curiosity even if it means permanently adopting an existence that is positively monkish in its selective choice of relative poverty versus optimum income?

    Hopefully the tiny but richly financed front half of the pantomime horse deeply appreciates the sacrifice of dignity and comfort the enormous rear end is making on its behalf.

  5. 105

    Let me allow some break in the serious discussion:
    “Massive Asian Carp Found Near Lake Michigan”
    So, the fish traveled _north_ the Mississippi system, don’t you see the pattern there?

  6. 106
    ADR says:


    Does increases in CO2 cause temperatures to rise? Or, does increases in temperature cause CO2 concentrations to rise?

    [Response: Both. – gavin]

    How does the Medieval Warm Period fit into human-induced global warming?

    [Response: It doesn’t. – gavin]

  7. 107
    Sloop says:

    Excellent tiny essay Dr. Schmidt on the philosophy and practice of science.

    I think there is a decent chance that the global response to the UEA CRU email hacking incident will provide a positive push to crafting national and international agreements, even if post-Copenhagen, that will begin to transform humanity’s fossil-fuel based economies and societies.

    To a certain degree, the denialist ideologues and the doubt creation orchestration that’s taking place are aiming at the wrong targets–the climatologists. That’s because they may not realize how deeply the executive agencies of governments around the world alrady appreciate the science and the future risk spectrum being delineated. (Or they do and thus realize it is unlikely they can directly take on and diffuse the momentum and partnering building up in relevant public authorities in US and elsewhere.)

    They also may realize that this incident may energize executive authorities to respond more energetically and effectively to the public disinformation efforts and hence are targeting political authorities as a last ditch effort. Of course we need political leadership and new legal frameworks; but there are politicians working on climate change responses who get it and much can be done within existing legal and management institutions for energy and environment, and, to repeat a point I made a while back and A. Lovins made more elegantly this week here, there are other good reasons to reduce substantially and eventually eliminate fossil fuel-based sources of energy. Eg., save the oil for plastics instead of powering motor vehicles with it.

    I speculate that executive authorities in particular have held back and allowed climatologists and their research outputs to be hammered brutally (going back to the beginning of the M&M-inspired hockey stick fiasco) in order to have the management doubt campaign run its course, figure out how to respond to it strategically, and set the table for prudent policy making and long-term implementation. Hence, as uncomfortable, frustrating, and tortuous as it is to argue endlessly with folks who cannot or will not seek to understand and ponder the science, the discussions surrounding this incident, both informed and not, are likely educating many people who genuinely wish to understand, and thus will help policy makers and implementers establish robust social, political, and management consensus for action.

    Finally, as alarmed as I am by the latest climatological, ecological, oceanographic findings regarding the progression and multiple impacts of atmospheric/ocean/climate change (it is in a physical, ecological, and economic crisis), I also appreciate Dr. Hulme’s provocative theses about the diverse social, political, and cultural responses to the climate change phenomenon as delineated in the WSJ column you cite today and in his 2009 book, “Why We Disagree About Climate Change”.

    (But currently I’m skeptical of the theory Hulme and Curry have recently advanced that we have a problem with “tribalism” in the discipline of climatology. Such a theory (which I’ve yet to find fully delineated by them) seems naïve and smacks of hurt feelings. As someone who must assess and utilize the science, and not engage in research, I could care less about whether good scientists are bossy or thin-skinned, or about rivalries and nastiness within the scientific community. I’ve little doubt may talented, dedicated scientists, such as yourself, can argue and act like arrogant bullies, especially when dealing with ignorance or ideology. But such behaviors are not relevant to my own responsibility to understand the science and act prudently in response in order to protect and uphold public interests and values,present and future. In fact, within reason, the more of a blood sport it is the more useful the debates are for management. On the other hand, there is little value in listening to professional scientists destroy the arguments of non-scientists.)

    Back to Hulme’s theses: Humanity will have to adapt a great deal to climate change; it will suffer a lot; and the planet and humanity together will probably fall over a couple of ‘tipping points’. Who we are and how we live is too dependent on and intertwined with oil and other fossil fuels for us as a planet to adapt quickly enough to avoid breaking through the 2 degree ‘guard rail’. And a number of climatological, ecological, and socio-economic surprises are possible and even likely.

    That’s tragic beyond words, but honesty about what we face is a pre-requisite to begin adapting to our most likely futures as best as we are able to by taking action now.

  8. 108
    Ron says:

    Ed Miliband, the UK Climate Minister was quoted in the Times Online today as saying “The science is clear and settled. ” Al Gore has been quoted as making similar remarks.

    Can anyone point me to a quote from climate scientist disowning or reprimanding such policicians?

    [Response: It depends on what the context is. If they are talking about hurricanes and climate change, then there are plenty. If they are talking about attribution of recent warming to human activity they are fine. The only error is when people either pro or con overextend such statements to encompass the whole scientific enterprise. – gavin]

  9. 109
    Gail Honeyman says:

    Could you recommend any specific resources, books, or other blogs on this topic?

  10. 110
    Mesa says:

    I keep coming back to the intrinsic variability argument, and we seem well within the one standard deviation band of that over the past century. The only thing that might modify that is if the thermometer record from 1910-1940 significantly overstated warming. However we have plenty of evidence of arctic melting then, as now. [and if the thermometer record form that period is inaccurate, i think we need to scrub the whole thng down again]. So, I think that’s the real problem modelers have to address:

    1. How do you account for the 1910-1940 warming without CO2.

    2. How do you account for the lack of warming over past 10 yrs.

    3. If the answers are some combination of inaccurate temperature record and/or natural variability (which they seem to be, as CO2 is the only large positive forcing in the GISS database), then it’s understandable why there are a lot of questions about the sensitivity estimates.

  11. 111
    Michael D. says:

    It’s snowing on December 4, 2009 in HOUSTON TX. ‘Nuff Said. Start looking for grant money to study the new thing (old I guess if you look at the 70s) Global Cooling.

    Wow.. The climate changes… Somehow I am not surprised. It’s been changing for millions of years and will continue to do so.. With or Without the influence of man. One Volcano alone can change the global climate. This has been proven scientifically without cherry picked and massaged data.

  12. 112
    Jim Torson says:

    Gavin’s commentary is a good discussion of science, but it misses the point. The CRU email affair should serve as a wake-up call to the scientific community, but unfortunately there is little evidence that it is having that effect. This shows that the scientific community has failed to understand the true nature of the manufactured doubt industry that has been so nicely described by Jeff Masters:

    The Manufactured Doubt Industry and the hacked email controversy

    As a result of this failure to understand the problem, the scientific community has also failed to come up with an appropriate and effective response to the manufactured doubt industry.

    The contrarians know they can’t “win” the scientific debate, but they don’t have to. All they need to do is to create doubt. This is very easy to do because most politicians and members of the public lack the time, inclination, and/or ability to discriminate between good science and bad science. The misrepresentations and outright lies of the contrarians present a real dilemma for scientists and others in the reality-based community. If there is no response, then incorrect information is left unchallenged. However, if it is challenged, then politicians and the public will just roll their eyes and think, “The scientists are still arguing about it. If they ever figure it out and stop squabbling, maybe then I will worry about it.”

    This problem was illustrated by the “debate” on global warming that Gavin participated in a couple years ago:

    Adventures on the East Side

    I’m sure Gavin did a fine job of presenting the science, but apparently he “lost” the debate to Lindzen and Michael Crichton. At the end, fewer people thought that global warming is a problem they need to worry about. Recent polls indicate that people continue to incorrectly think there is still a legitimate scientific debate about whether or not climate change is a problem:

    Americans Skeptical of Science Behind Global Warming

    There was a start on discussing these issues in your post on the role of flawed science:

    Something Is X in the State of Denmark

    George Ortega proposed consideration of a Climate Change Misinformation Act (CCMA) as a way to respond to the manufactured doubt industry. However, most people quickly rejected this in favor of “quite persuasion and presentation of the evidence.” The scientists favor this because it is what they have always done, and the contrarians favor it because it perpetuates the myth that there is a legitimate scientific debate about whether or not climate change is a problem.

    Scientists have been quietly presenting the evidence for decades (since at least Hansen’s 1988 testimony to congress), and the response of society to the climate change problem has been almost negligible. I’m not sure if I would fully support the CCMA proposal, but continuing to do nothing other than quietly presenting the evidence would be appropriate only if climate scientists are only interested in allowing events to prove that they were right about the science. Some other response to the manufactured doubt industry is needed if climate change is a problem that requires a response from society.

    Steve Easterbrook has written a good perspective on the CRU email affair:

    Open Climate Science or Denial of Service attacks?

    A recent WSJ editorial discusses the problems now faced by science:

    Climategate: Science Is Dying

    Although I do not agree with everything he says about science, many people will probably agree. But perhaps his conclusion is worth considering: “Everyone working in science, no matter their politics, has an (sic) stake in cleaning up the mess revealed by the East Anglia emails. Science is on the credibility bubble. If it pops, centuries of what we understand to be the role of science go with it.”

    It is time for the scientific community to devise an appropriate and effective response to the manufactured doubt industry.

  13. 113
    Susann says:

    So, hypotehetically, the top NEO researchers around the world conclude that there is a 90% chance that a new asteroid of significant size and potential for global damage will strke Earth in 2034… The people who frequent “contrarian” blogs are heard to respond “But, like, doesn’t that mean that there’s uncertainty in the science? You’re a fearmonger! An alarmist! Why should we trust these NEO researchers? They’re a small group of like-minded pals who read each other’s papers and want grant money! Why should we create a NEO diverting mission costing millions and millions of dollars if there’s uncertainty?”


    *grabs bottle of scotch*

  14. 114
    Krog says:

    #83 With respect to the anecdotal evidence of glaciers melting. It seems from casual reading that this melting is occuring at a faster rate than would be expected from the actual temperature increases over the past 50 years. Does anyone know why this is?

  15. 115
    Inge-Bert Täljedal says:

    #24, re: gavin’s reply. Not good enough. Firstly, anyone taking comfort in Smith must defeat Kramm et al. ( Has hardly been done, has it? Secondly, calling people names will neither settle scientific issues nor win public-oriented battles of rhetoric.

    [Response: Not really. There is a law of diminishing returns in dealing with cranks – they can keep on going for ever. You don’t need to believe me, but the neither G&T nor Kramm et al will convince anyone with an ounce of knowledge in this field. – gavin]

  16. 116
    Ike Solem says:

    Physics is a matter of probability and approximation – and any theory used to make predictions is going to be probabilistic. This is fundamental feature of all science – ask Richard Feynman:

    Are we therefore reduced to this horror, that physics is reduced to, not these wonderful predictions, but to probability? Yes we have – that’s the situation today – in spite of the fact that philosophers have said, “It is a necessary requirement for science that setting up an experiment exactly similar will produce results that are exactly the same the second time” – not at all.

    The main thing that differentiates math and physics is the role of approximations in physics. For example, consider the classic physics example, throwing a ball at a given angle and a given force and calculating where the ball lands. The simplest approach neglects any effect of wind speed and even frictional resistance from the air, and it assumes the ground is perfectly flat as well – so does that mean the equation is “wrong”?

    No, it’s just the first level of approximation – you can build more and more complicated models that improve the approximation. Physics, however, is always a matter of approximations.

    Take the issue of the accumulation and distribution of fossil carbon in the active Earth system – where does it all end up after we dig it up and burn it?

    Carbon, you know, is an element – like mercury. If you dig up mercury-laden coal and burn it, you have injected both carbon and mercury into the actively recirculating system, which means the atmosphere, the water bodies, the soil and the biosphere. The only way to remove carbon and mercury from this system is to bury it in sedimentary accumulation zones – which is a very very slow process.

    For example, mercury is enters the atmosphere during coal combustion, and often comes down in the rain, and that rain drains into rivers and lakes, where algae bind some of the mercury. Insects eat the algae, but the mercury bioaccumulates, and so insect mercury concentrations are higher – and fish that eat those insects also accumulate the mercury, and hence on to humans. If a human with a high mercury body load dies and is incinerated, the mercury returns to the atmosphere and the cycle begins again. Carbon behaves the same way.

    Is that science settled? Yes, it is called mass balance – even the medieval alchemists knew about it.

    If we can estimate the future concentration of infrared-absorbing gases in the atmosphere, we can then calculate what the global surface temperature range will be – as an approximation. Take the best estimate of global warming ten years from now – what unknown factors might alter that forecast? The obvious one is a large volcanic eruption that dumps aerosols into the stratosphere. However, our physical approximation of the lifetime of those aerosols in the atmosphere, vs. our approximation of the lifetime of carbon dioxide in the atmosphere, tells us that when the aerosols fall out, the CO2 will still be there.

    The greatest myths about physics are that it is an exact, deterministic science – a 19th century perspective that denies the existence of radioactivity or of quantum mechanics – but that appears to be the level of understanding on the denialist side.

    The deceptionist side is even worse, because this group doesn’t represent crackpots, but rather established researchers at various government institutions – these are the people who claim that you can burn coal in zero-emission gigawatt-scale plants and capture everything that comes out.

    Can we get an approximate idea of the physics of this process? Consider a hot combustion stream from a major power plant that burns 10 million tons of coal a year.

    A conventional 1 Gigawatt pulverized coal plant (same power as a medium nuclear plant for today’s standards) burns 416 metric tons of coal per hour and generates more than 127 metric tons per hour of solid and liquid wastes (see the MIT report The Future of Coal , Appendix 3.B).

    The difference there is about 300 tons per hour – but it’s not pure CO2 coming out the mix, there’s a lot of air and sulfur and smaller amounts of mercury and arsenic.

    So, what would it take to process a hot combustion waste stream delivering 300 tons of CO2 per hour? It should be obvious that the effort is doomed to failure, because the amount of energy needed to separate the CO2 from everything else is massive – even the simple IGCC cycle, aimed only at maximizing conversion to CO2 (like your car’s EGR valve), sucks up an addition 10% of the power plant’s output.

    Nevertheless, you see some climate scientists running around promoting coal carbon sequestration, and you see the Department of Energy boosting it to the tune of $2 billion in direct subsidies, and you see the coal and tar sands industries claiming it will solve all problems…

    So why hasn’t realclimate ever delved into the lack of substance here? Is it “outside your field of expertise” or something? Or are you just unwilling to criticize your scientific colleagues who rely on those coal-carbon DOE grants to stay in business?

  17. 117
    Dan says:

    [Response @ 72: Why would I write something I don’t agree with? I think that there is plenty of evidence that justifies reductions in emissions to reduce risks associated with further climate change. – gavin]

    I see. So the science is settled as far as you’re concerned? Must be, since you’re now ready to commit to pretty significant changes in the world economies…

    [Response: What is it with people refusing to stop playing semantic games? – gavin]

  18. 118
    Mike M says:


    “Every time someone like Monckton makes his ‘chaos’ argument (all very scientific sounding), this sort of low-hanging fruit should be picked
    and thrown at them. I’m hoping, as I carry on learning, that I’ll find analogies to ’seasonal forcing’ that can allow myself and others get a better intuitive grasp of where boundaries are, and where chaos might poke a nose in, so we have more fruit-based projectiles to throw at this growing ‘uncertainty’ meme. Any pointers gratefully received.”

    Yes this is a major foundational problem for agw prediction, and hence why Gavin and other climate modellers ignore the chaotic properties of the climate system. You’ll notice the overall agenda from them is to sort of say “we dont know if the climate is chaotic”. Then their models take a pass on the usual natural limits faced by trying to make long-range predictions about the climate.

    fact is it is chaotic and weather is it’s subset, making it chaotic because of the non-linear interactions between a probably infinite amount of factors but obvious ones like the atmosphere, oceans, land etc, a fraction of which we are aware. Then there’s the problem of the accuracy in measuring and setting all those initial conditions so they are not just some simplistic idealisation of the real world.

    It goes on and on.

    And dont let them fool you into the idea that they can make reasonably accurate predictions over a short period of time, because thats rubbish too. Any system as comlex as the climate will diverge from their model after the first few seconds on the clock.

    Thats the nature of the system they attempt to model, and they dare not speak its name; chaos.

  19. 119
    Jeffrey Davis says:


    I made the mistake of referring to another post by number. So, please cancel my posting of 12/4/2009 12:00PM.


  20. 120
    Bill says:

    Yes, thank you.

    The various feedback effects and sinks (I recently went to a SOI talk where they’d discovered a completely new CO2 interaction in coastal wetlands) are NOT settled science, and I’m glad that admits that.

    There’s a lot of climate skeptics that are simply rebelling against the Science-is-Settled/Al Gore crowd, because we know better.

    I think a good analogy for global warming is nutrition. People say losing weight is easy: calories in minus calories out get made up by the body. Likewise, watts in minus watts out determine the temperature of the planet. However, it’s not as simple as either of those camps want you to believe, simply because there’s very complicated feedback loops (both positive and negative) into the terms of the equation.

    At some point, sure, eating a lot more will make you weigh more, and dumping a lot of CO2 into the air will tend to make the planet warm, but the actual amounts are tough to calculate with accuracy.

  21. 121
    SecularAnimist says:

    Please show me the scientists — not industry-funded frauds and cranks, but real climate scientists — who are telling us that “the science is not settled” with regard to the need to rapidly phase out anthropogenic GHG emissions.

    Please show me the climate scientists who are saying that the science on that question is so unsettled, that we should continue burning fossil fuels at our current, business-as-usual, ever-increasing rate for as many more decades as economically recoverable supplies can be extracted, because there is no “settled science” that gives us any reason to do anything different.

    The fact is that the science has been settled on the need to phase out anthropogenic GHG emissions for a long time — that’s what Al Gore was talking about, and he was and is 100 percent correct. And the most current and best science is quite settled that emissions reductions need to start soon, and proceed rapidly, if we are to have any hope of avoiding far worse effects than those that are already, very visibly, and very shockingly, under way all over the planet.

    When the fossil fuel industry-funded deniers and obstructors prattle about what is “settled” and what is not “settled”, that is what they are lying about. They are pretending that no one knows or can say for sure whether the world should stop buying their products, so it is best to just carry on with business as usual.

    Look, folks: what is at stake here is not “science”. What is at stake is the survival of human civilization, very likely the survival of the human species, and quite possibly the survival of anything resembling the rich, diverse, resilient, thriving biosphere in which the human species has evolved.

    The deniers and obstructors don’t care about “science”. They are driven by greed. Period. The only thing they care about is keeping those hundreds of billions of dollars in profit rolling in, for as long as they can.

    That’s what is behind the phony-baloney pseudo-skeptics, from Fred Singer to every random Ditto-Head who regurgitates Rush Limbaugh’s vomit on a blog. The actual climate scientists need to realize this is not a debate between scientists, within the scientific community, over legitimate questions of science. This is an all-out assault on the future of the human race being waged, ultimately, by a very small number of very wealthy, very powerful, and unimaginably greedy people. I don’t doubt for a moment that if they thought they could get away with luring all the world’s climate scientists into one spot and then dropping a bomb on them to assassinate them all at once, they would do it. That’s what you are up against — that’s what all of humanity is up against.

  22. 122
    John S says:

    IPCC ar4:

    “Most of the observed increase in global average temperatures
    since the mid-20th century is very likely due to the
    observed increase in anthropogenic GHG concentrations.”

    With “very likely” defined by the IPCC as >90%.

    So then the science is isn’t settled, it’s just “very likely” settled?

    [Response: Whatever. – gavin]

    Quite the distinction, Gavin.

  23. 123


    You haven’t helped as much as you think.

    Those ‘partly’ in the know, are bothered by 90% or 95% confidence intervals associated with various individual observed climatic trends. They ‘know’ that that means there’s a 10% or 5% chance that a ‘real’ trend may be outside the projected envelopes. What they generally don’t understand is that climate savvy scientists, as ‘experts’, take the ‘congruence’ of many different, but related, trends into consideration when they make statements about AGW ‘as if’ the science were settled. Unfortunately, there are no ‘legitimate’ procedures for calculating effective ‘combined confidence intervals’ for very disparate data. And until the public becomes more nearly ‘as educated’ as the experts, they’ll have to take the experts’ judgment, somewhat ‘on faith’;-) That will always provide the deniers with an unfair advantage.

  24. 124
    CM says:

    I don’t know what each and every environmental group has said in response to “skeptic” science, but I know what mine did back in the 1990s when I was a full-time activist. We said the science was good enough to warrant a policy of huge cuts in carbon emissions. We said that the public debate needed to move on to getting the policy right, not to discuss the science. The science, we said, was best left to the scientists. The public should not listen to us on the science, and it should not look to individual scientists — whether “skeptics”, or scientists working for “our” side. The public and the policy-makers should listen to the IPCC because the IPCC process aggregated all the individual work, filtered out the noise and provided the best overview of the *current* state of scientific knowledge. What to do with that knowledge was a political question and the proper subject of public debate.

    I don’t think we ever said the science was settled.

    It was a good position then. Even better now.

  25. 125
    RichardC says:

    Your problem is that you’re focusing on the wrong word. The science IS settled, with settled being the operative word. “Settled” means “settled to the point of making the particular decision at hand.” By pretending that “settled” means to the end of an asymptote, you’re simply destroying the meaning of the word. The ANSWER is to ask, “Settled to what degree? … Oh, that, well, YES the science IS settled.”

  26. 126
    Russ says:

    Bruce Tabor wrote earlier, “I thought the IPCC put a >90% likelihood on human action being behind climate change in AR4. Are you saying this has since moved to an “almost certain” level?”

    I have frequently heard that line of thinking trumpeted by groups who don’t think policy changes are justified unless there is 100% certainty, which this article explains does not exist in science. I find it interesting that some people claim a >90% likelihood is not sufficient to make massive policy changes. If someone told you there was a >90% likelihood that you would be struck by a bus if you continued on your course and crossed the street, would you cross the street? I would imagine that most people would change their course and not cross that street. Clearly, >90% likelihood is enough certainty to impact the decision making process.

  27. 127
    WAG says:

    Great post. What I think is interesting is how deniers focus on the uncertainties of climate models, even though their own predictions of economic doom rest on even more uncertain ECONOMIC models. I posted this comment on Andy Revkin’s blog the other day, wondering, why not focus on those economic uncertainties as well? After all, economists are notoriously bad at predicting the future, given that their models rely on the most unpredictable of variables: human behavior. Why should we trust uncertain economic models over uncertain climate models?

    For starters, economic models hardly agree on the costs of cap-and-trade. The CBO estimates that with cap-and-trade, US GDP will grow about 0.03%-0.09% per year more slowly. On the more alarmist end of the spectrum, the National Association of Manufacturers’ worst-case estimate is 0.15% slower growth. We must also consider that like past cost analyses of environmental regulations (most of which have overestimated costs), neither of these models include the effects of technological change – breakthroughs spurred by higher carbon prices that allow us to produce the same level of output with less energy (e.g. efficient manufacturing processes, cheaper solar panels, etc.).

    In other words, economic models don’t agree on the exact costs of cap-and-trade, but they do agree that such costs will be relatively modest. And the dimensions of uncertainty – namely, how technology will respond to higher carbon prices – give us reason to believe that the costs will be smaller than predicted.

    The costs of global warming are also uncertain. However, there’s much more variation in these estimates. They range from modest (e.g. money spent building sea walls) to catastrophic (e.g. massive water shortages and famine in India), and are distributed unevenly around the world. And unlike economic costs, these catastrophic costs can’t be reversed or solved by spending money. Higher fuel prices may make growing crops more expensive for farmers, but 10 degree warming and long-term drought prevents crops from growing altogether – and you can’t negotiate a better price with the rain. Inventing cheaper solar power seems a much lower cost solution than inventing a way to make rain fall during a drought.

    Further, it’s harder to estimate the non-monetary aspects costs of climate change. How many flat screens is the extinction of polar bears worth? And unlike economic costs, which are well understood and fall within a defined scope (higher input costs, short-term job losses), our inability to predict with certainty how the natural world responds to human activity means there are many costs we may not have even imagined yet. If economists get it wrong, we may lose more jobs than we thought. But what happens if ocean acidification kills coral reefs and causes ocean food chains to collapse? If, as critics point out, humans lack the foresight to predict how interventions in the market affect national wealth, why would anyone trust our ability to engineer the workings of Nature to our likings?

    I’m not making a claim about the scientific validity of these musings, but rather using them to illustrate the point that while the costs of climate legislation are modest and fall within well-understood bounds, the costs of climate change range from moderate to worse-than-expected to literally unimaginable. The economic crisis has taught us to ignore these long-tail probabilities at our own risk.

  28. 128
    John Farley says:

    For the last couple of decades, it’s been getting more and more difficult to believe that anthropogenic global warming isn’t happening AT ALL. The evidence keeps mounting: temperature, rising sea levels, melting ice in Greenland and Antarctica, retreating glaciers. Are there unanswered questions about modern anthropogenic global warming? Of course, about the details. Including important details. But not: is it happening AT ALL?

    If current trends continue, the skeptics will end up like creationists. Is the science of evolutionary biology “settled”? Of course not. Are there unanswered questions about evolution? Of course, but they are about the details (including important details). The basic question of whether evolution is happening or not happening has been settled over a century ago, at least in the minds of scientists. Among nonscientists, it’s a different story. There are some people who for religious reasons cannot accept evolution.

  29. 129
    Steve Smith says:

    This is what happens when scientists stop merely giving advice and start actively lobbying government for particular legislation. This is what happens when climatologists try to educate laymen about trends without also giving a geological perspective. This is what happens when “scientists” look for data to support a particular hypothesis instead of testing it. Surely the current models are not perfect even if they are mostly correct. Where are the problems with them? This site is like a car salesman’s ad instead of a scholarly work. Take the title: “RealClimate.” That is like using the adjective “fair.” Its meaningless. When AGW’er (whatever that means – I only know what it means in context of its usage above) start admitting the warts of the climate models in something other than private and hidden emails, I’ll open my mind to their arguments and conclusions. Until then credibility is at issue. And no, I’m not a republican or employed by Exxon.

  30. 130
    Geno Canto del Halcon says:

    To label denialists “skeptics” is a complete misuse of the term. Good scientists are “skeptics” – that is really the point made in this post. Denialists are NOT “skeptics” because they have made a firm conclusion. We should not honor these folks with an honorable term.

  31. 131
    SecularAnimist says:

    Gavin, I have a question for you. You wrote:

    I’m in complete agreement with a recent headline on the Wall Street Journal op-ed page:
    “The Climate Science Isn’t Settled”

    Here’s my question:

    Are you in complete agreement that climate science gives us no reason at all to believe there is any need, let alone an urgent need, to reduce anthropogenic GHG emissions?

    Because when the Wall Street Journal op-ed page says “the climate science isn’t settled”, that’s exactly what they mean.

    [Response: Of course not. And I am very aware of why the WSJ uses that headline. – gavin]

  32. 132
    Terry Comeau says:

    At the fifty second mark of that video:

    “The science is agreed upon…”
    Gavin Schmidt

  33. 133
    Steve Smith says:

    “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.”

    The “real issue we face” is what “emissions of CO2 (in particular) are posing a SUBSTANTIAL risk to human society.” Give us a number that will assure that the risk becomes an INSIGNIFICANT one. Give us a number so that it becomes NO risk at all. Give us a number that would be the “natural” number for humans to emit. If this is the end of the world as we know it, we need the dire prognosis of how much carbon we actually need to sequester, not some abstract goal or best practice that we should strive for. In short, what is the optimum level of atmospheric carbon? The world needs to know.

  34. 134
    Michael says:

    What exactly is a “denialist”? I can’t find that in the dictionary.

  35. 135
    richard says:

    I just need to get in a comment that with all the revelations and now the shame coming up for a few scientists – we should not back down. I just read another infuriating article about CRU links to Shell Oil and I am crushed. These are the people we are trying to defeat! When will this end and the bad apples resign so we can get back to cleaning the air??

  36. 136
    Muscleguy says:

    I have always imagined the scientific enterprise as a swamp, extending out into the sea of ignorance. Scientists add firmness to the swamp, they link isolated clumps and consolidate the land. Further back in the mists the technologists are farming the really firm land but out at the frontier where somewhere firm to stand is hard to find building up some firmness of knowledge is a slow and patient business. Occasionally some useful idiots will attempt to build a marquee with balloons and stuff and parade around in their bit of the swamp pretending that it is both new and really firm ground, but sooner or later they either sink or someone points out they’re wearing waders or flippers on their feet. Even more occasionally than that someone disturbs something and a whole unsuspected island rises up before us and has the effect of stabilising much land around it. They are called Kuhn islands.

  37. 137
    Leighton says:

    This article seems helpful and constructive. The re-affirmation that “science,” as such, doesn’t dictate policy, because there are issues to be addressed that are external to the science, is important. But since this has long been conceded, and since we can also now agree that there are unsettled questions beyond the mere existence of AGW, the justification for continued shouts of “Denier!” (not to mention even more heated language) is hard to understand. And, honestly, the justification for the petty gamesmanship that exists plainly on the surface of the newly revealed correspondence and other files, can’t be found at all. But on the positive side, there is reason to carry the even-handed tone of this piece forward into future discussions, and for scientists to redouble efforts in the direction of fairness and transparency.

  38. 138
    Brian says:

    I believe in changing our ways, to reduce our impact on the earth. I work hard at this–harder than most. This is in part due to the awareness that has been brought about by global warming.

    But, I believe that the scientists releasing papers which prove dire predictions for the earth are charlatans. Perhaps these scientists want to help the earth, and this is their way to do it–to manipulate results. They can go to sleep at night, knowing they are doing the wrong thing for the right reason. Or, they are simply chasing grant money, proving what they know they need to prove to make the granter happy, either consciously or unconsciously. Or, they want to fit in with their peers and not rock the boat. Or, I figure they must be incompetent.

    As an engineer with no knowledge of climate science, it is clear to me that the science is not remotely settled. When someone tells the world that the science is settled, on something that is as complex and dynamic as the earth’s weather, warning bells go off. No, the science isn’t settled. The models in the latest scandle don’t even appear to represent science at all. Global warming is a carefully orchestrated plot to get the world to wake up to the impact it is having on the earth. It is doing the wrong thing for the right reason–to save the earth.

    [Response: There are no models implicated in the emails. Where do you get that idea? – gavin]

  39. 139
    Tony says:

    Nice strawman arguement. I believe the headline refers to both Al Gore’s comments on how climate change is “settled science” AND the recent comments from the White House muppet Robert Gibbs on how the climate change is “settled science”.

  40. 140
    rickster says:

    I am afraid that the “narrative” that Global Warming is all a hoax based on corrupted data as become fixed among the center-right media “commanding heights,” also called “The Village” based on browsing various blogss at the Atlantic, Politico, Washington Post, and N.Y. Times. I think this whole thing is one big non sequiter, but lay people who believe in science and that human caused global warming is going to affect have some pretty sever effects on the environment in which human civilization arose and where whe have to support 9 billion people are going to have step forward and vigourously defend climate scienctists because they are about to be ACORNED.

  41. 141
    Joseph says:

    Jeff Kiehl notes in a 2007 article from the National Center for Atmospheric Research, the models use another quantity that the IPCC lists as poorly known (namely aerosols) to arbitrarily cancel as much greenhouse warming as needed to match the data, with each model choosing a different degree of cancellation according to the sensitivity of that model.

    Is that even accurate? Models don’t normally work like that. It’s a multivariate analysis. The analysis will give you variable coefficients that produce the best fit possible. If negative aerosol forcing is a better fit for the model, that’s what you’ll get. If it’s a poor fit, you won’t get that. The quote above makes it sound like the coefficients are tweaked by hand to get what the modelers want.

  42. 142
    bcoppola says:

    I think this is my first time posting on RealClimate. Just a layperson here.

    Somewhat tangental to the central point here but: With all the conservative/business opposition to cap and trade, does no one remember that, in the US, cap and trade was first proposed and implemented by Republicans during the Bush I administration in the early 90s (and opposed by most of the left and environmentalists who saw it as a sop to business) as a “market based” solution to SO2 emissions/acid rain? Back then, we heard the same Chicken Little cries from the right wing and business that it would Ruin The Economy. Yet, it (a) worked and (b) affected the economy not at all. An article in a recent Smithsonian brought that all back for me.

    Granted, the current cap and trade plans are so watered down to let coal burning power plants off the hook that one wonders if they will do anything for CO2 emissions at all – yet neither that nor the history above keeps the usual suspects on the Right from braying that cap and trade will be the ruin of us all. And to be fair, some on the left and enviros seem just as blind.

  43. 143
  44. 144
    Errico says:

    This is all such déja vu common sense that many are getting bored with the settled and the unsettled. Time to start calling by the real name: all media bullshit.

  45. 145
    Dan says:

    re: 76. “There has been a clear infiltration of political advocacy into the public statements and casual private discussions of certain members of community”

    Proof of “political advocacy”? Documentation to support that absurd statement? Sorry, but your politically-driven, non-science opinion does not count as proof at all or have any validity. Furthermore, the “debate” you refer to has occurred over and over again through peer-reviewed journals and scientific conferences. You know, how science is actually done. And always has been done.

  46. 146
    David B. Benson says:

    donald moore (59) & John E. (77) — One way is to look at what the climate and all were like in the remote past when it was warmer. Mark Lynas did th3e library research and presents the results of that year in the Oxford libraries in his book, “Six Degrees”. Here is a link to a review:

    Max Anacker — Here is a link to yet another page which refultes your falsehood about recent global temperatures:

  47. 147
    Jonathan Fischoff says:

    Yep, science is never settled, and yet we have to make decisions. However, the question is should scientists be involved with advocating policy? You seem to conclude that scientists should be promoting policy. This is slippery slope that can easily lead to bias. Combine that with group think, and well there goes objective science. If you explain the science clearly, others will push the policy.

    For instance many times you link to papers to prove a point. I would instead take the time to very clearly show step by step the science and mathematics behind a paper. I would not worry so much about persuading people. Just educate.

  48. 148
    Eyal Morag says:

    Maybe some post on emissions target should we calculate methane for 100 year potential or less?
    Some frightening post on tipping points? Some people don’t know nothing on methane permafrost PETM…. another source can help maybe
    Or only I look at CO2 records from the past 800 kyr* see that the scale and at 300 ppm and start to feel some Unsettled feeling? The unsettled bits of climate science only make me feel more unsettled.
    It can be useful this days. Especially this 14 days.

    PS any one know on reasonable accomdetion in Copenhagen

    *High-resolution carbon dioxide concentration record 650,000–800,000 years before present
    Vol45315May2008 | doi:10.1038/nature06949

  49. 149
    Stephen Gloor (Ender) says:

    ccpo – “I’m hoping this whole e-mail thing has awakened the Average Scientist to one simple reality: You’re going to have to come out from behind your desks and engage the public actively, and critics strongly, if you (collectively) wish to help avoid the 6C scenarios.”

    Who then does the research. I am sure that this foolishness has cost climate researchers much time and on his job.

    This is not about the science. Gavin can come out from his desk as much as he likes however now, due the brilliant and utterly ruthless climate opposition, we now have two sound bites to deny warming. First it was “the hockey stick is broken therefore AGW is wrong. Now we have added an even more potent meme of “the CRU emails prove all AGW research is faked therefore AGW is wrong”

    I am not sure anybody realised what we were up against when the whole AGW thing first started impinging on rich people making lots of money. Those people are utterly without morals and using stolen private emails simply shows what lengths they will go to to continue to get rich or help their friends get rich. If this does not do the trick, to coin a phrase, they will simply hack something else that does.

    I think that this indicates that nothing will be done until the people calling the shots are sufficiently compromised by climate change to make such things impossible. What this means to the rest of the planet they do not care as they will be rich and/or dead.

  50. 150
    Jim Hanson (a different one) says:

    I have now spent about forty hours perusing this site–and specifically the current discussions (i.e., since the CRU scandal broke). I’m a reasonably literate person, with two college degrees, but in no way competent to judge hard-science literature, much less a ‘new science’ philosophy that has evolved since I last studied hard science.

    One skill I do have is in assessing–for lack of a better phrase–social commentary. Clearly, many of the (Climate) scientists posting on this site prefer to ignore their fundamental advocacy for their outcomes, nor for the cultural differences between scientists of different nations / societies.

    In sum, Bryan S in post 77 gets it about right. The mere fact that Al Gore became the popular mouthpiece for AGW created significant obstructions to a better understanding of the impact of political advocacy for AGW. Add to that the Nobel Prize for him–and you have the makings of political advocacy all over this subject.

    It would be good, I think, for some of the hard scientists posting here to understand that.

    Jim H.