CO2 Warming Looks Real

Many have bent my ear over the last few months about global warming skepticism.   So I’ve just done some moderate digging, and conclude:

  1. In the last half billion years, CO2 has at times been 15 times denser, but not more than 10C warmer.  So that is about as bad as warming could get.
  2. In the last million years, CO2 usually rises after warming; clearly warming often causes CO2 increases.
  3. CO2 is clearly way up (~30%) over 150 years, and rising fast, mainly due to human emissions.  CO2 is denser than its been for a half million years.
  4. The direct warming effect of CO2 on warming is mild and saturating; the effects of concern are indirect, e.g., water vapor and clouds, but the magnitude and sign of these indirect effects are far from clear.
  5. Climate model builders make indirect effect assumptions, but most observers are skeptical they’ve got them right.
  6. This uncertainty alone justifies substantial CO2 mitigation (emission cuts or geoengineering), if we are risk-averse enough and if mitigation risks are weaker.
  7. Standard warming records show a real and accelerating rise, roughly matching the CO2 rise.
  8. Such warming episodes seem common in recent history.
  9. The match between recent warming and CO2 rise details is surprisingly close, substantially raising confidence that CO2 is the main cause of recent warming.  (See this great analysis by Pablo Verdes.)  This adds support for mitigation.
  10. Among the few bets on global warming, the consensus is for more warming.
  11. Geoengineering looks far more likely to be feasible and acceptable mitigation than emissions cuts.
  12. Some doubt standard warming records, saying they are biased by urban measuring sites and arbitrary satellite record corrections.   Temperature proxies like tree rings diverge from standard records in the last fifty years. I don’t have time to dig into these disputes, so for now I defer to the usual authorities.

It was mostly skeptics bending my ear, and skeptical arguments are easier to find on the web.  But for now, the other side has convinced me.

Added: The Verdes papers is also here.  Here is his key figure:

verdesmodelThe reconstructed forcing is made without any reference to the actual forcing, and with almost no free parameters, and yet matches it very well!

Added 1June: Verdes tells me he’s now in industry and hasn’t done any followup work, nor knows of any.  The data and method are public; seems a great topic for some grad student.

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  • Raphfrk

    “Among the few bets on global warming, the consensus is for more warming.”

    Surely for those to be indicative, they should be conditional on CO2 levels?

    Alternatively, it could be assumed that CO2 levels are going to increase anyway, and they are the only drivers of warming.

  • William Newman

    I couldn’t get the Verdes paper: “The requested URL /~redes/ps/PhysRevLett_99_048501.pdf was not found on this server.”

    • http://timtyler.org/ Tim Tyler

      It seems like a paywall to me.

  • http://www.geoffreyfalk.com/blog/blog.asp Geoffrey Falk

    The libertarian-conservative and real skeptic (not of AGW) Steven Dutch has a number of good, concise, readable papers posted on this subject, at Science, Pseudoscience, and Irrationalism (scroll down to the “Global Warming: A Swim in the Skeptic Tank” heading). The Science and Pseudoscience of Global Warming is a good place to start.

    To summarize his conclusions:

    There are lots of legitimate and serious questions about climate change that all researchers in the field readily admit. What convinces me of the reality of climate change, despite the uncertainties, is that the comments put out by climate change denialists are absolute, unmitigated garbage. We find distortion and misuse of credentials, publication of counterfeit papers, and scientific illiteracy of all sorts. This junk is on a par with the creationism of Michael Behe and Darwin’s Black Box….

    “Conservatism” and “conserve” come from the same root. You don’t unnecessarily squander limited resources you may need later. In fact you don’t unnecessarily squander anything—period. You keep your debt limited to the minimum necessary. You pay your bills. If you get an unexpected windfall, you manage it carefully to stretch it out. You treat things in your care like they’re your own.

    So completely apart from global warming, fossil fuels are finite and will have a finite lifetime, and we have no practical substitute
    ready to replace them
    . Therefore we need to manage them carefully to maximize their lifetime. First we need to extend the lifetime of the resources themselves, and second, we need to buy time to develop alternatives and bring them on line. Doing so will reduce greenhouse gas emissions as a side result.

    It’s a painfully amusing irony that most of the people who are lambasting Republicans for abandoning their traditional fiscal restraint, simultaneously pretend that finite resources are not a problem. We would have neither an energy crisis nor a global warming problem if conservatives treated fossil fuels the way they claim money should be treated. (For that matter, we wouldn’t be reeling from the collapse of the sub-prime lending market if conservatives had treated money the way they claim money should be treated.)

    You plan for the worst case. You don’t necessarily assume the worst case, but you have a plan if it happens. So even conservatives who regard the war in Iraq as a fiasco nevertheless tend to advocate gritting our teeth and slugging it out, because the worst case scenarios from losing or retreating are much worse than the present mess.

    Likewise, the libertarian skeptics Penn and Teller have researched the AGW issue competently, and come to the conclusion that they just don’t know whether AGW is real. (Teller is actually a
    fellow of the Cato Institute.) That’s the most that any scientifically literate and competent person can reasonably say against AGW. The ones who say more than that are almost invariably either scientifically illiterate, or letting their politics and/or religion dictate their science.

    • http://www.daviddfriedman.com David Friedman

      Your quote from Steve Dutch got me interested enough to go to his site and read some of it. He may, for all I know, be correct in his views in his field. But despite his stated intention to limit himself to his areas of technical competence, he is making arguments that depend on economics as well–in particular the bit you quoted about how conservatives should treat fossil fuels. Judging by that–and my subsequent correspondence with him–he had never heard of Harold Hotelling’s classic analysis of the economics of depletable resources, done seventy years ago. When pointed at an explanation of it he reacted with scorn and incomprehension.

      The incomprehension was signaled by his lumping together the peak oil controversy, which is relevant to the issue of depletable resources and the economics thereof, with the global warming controversy, which (from the economic point of view) depends on a public good problem that has nothing to do with depletable resources. Earlier he seemed to think that the extinction of the passenger pigeons–a standard tragedy of the commons–somehow invalidated Hotelling’s analysis.

      One of the ways in which I judge sources of expert information is by finding some area that overlaps with things I know something about and seeing whether they get that right. Judged by that standard, I wouldn’t rely very heavily on Dutch’s analysis. He not only doesn’t understand the relevant economics, which isn’t that surprising, he is also confident that he does.

  • William Newman

    The Wikipedia bets page gives the impression that the pros and antis might be talking past each other. The most common anti-IPCC position at this point seems to be that the CO2 impact is approximately equal to the mild direct warming effect of your point #4, that the fluctuations in climate from causes other than CO2 are much larger than IPCC holds, and that the general match between CO2 and global temperatures over 200 years involves some causality (from the direct warming effect) but also much more coincidence than the IPCC holds. Holding those beliefs, it might be natural for skeptics to bet that large excursions from the IPCC projections (in either direction, though especially below) are considerably more likely than the IPCC says. (Vaguely like financial quants making a bet on volatility instead of a particular expected future value.)

    Unfortunately, IPCC supporters’ predictions about overall temperature ranges seem to be hard to bet against in any reasonable timeframe. See the figures in http://www.realclimate.org/index.php/archives/2009/05/moncktons-deliberate-manipulation/ for how wide one prominent group of IPCC supporters consider the informally specified confidence interval to be, and I don’t get the sense that any of them are willing to formalize those confidence intervals for betting purposes as 95% or higher, more like one standard deviation.

    (Perhaps there is at least one IPCC climate model which has sufficiently solid microfoundations that some IPCC fans think some aspects of its predictions over the short term are more significant than random noise. If so, it’d be nifty if its supporters could use it to construct informationally-theoretically significant short-term predictions, in such a way that the result would reliably differ from the direct-warming-only-large-variance model above over a reasonably short time frame. The prediction wouldn’t need to be anything simple enough to be blurbed in a pop science article, it could be some weird highly correlated statistic involving zillions of weather stations and cloud cover satellite observations and whatnot. As long as I’m wishing, it’d be particularly lovely if the prediction were expressed not in terms of heavily massaged averages, but in terms of simple observations like surface temperature or wind speed at given stations, or perhaps cloud or ice cover in given regions. Perhaps only Bayesian Overcoming Bias ultrageeks would care, but hey, this is the twenty-first century, what better time to market IPCC settled science to the long tail?:-)

    (I am not just trying to be annoyingly archly sarcastic when I write “Perhaps…more significant than random noise” above. I just read the exchange at http://fortcollinsteaparty.com/index.php/home/bill-gray-and-kevin-trenberth-debate/ a few days ago, where a knowledgeable IPCCite responds to criticism about lack of short-term predictions with an appeal to the demonstrated success of the models in successfully hindcasting low-frequency trends. That’s not a direct statement that there are absolutely no reliable high-frequency predictions from IPCC’s preferred models… but it’s hard to see why a knowledgeable supporter would choose to answer a challenge about forecasting by appealing to hindcasting if the models had demonstrated clear ability at forecasting over the last ten years or so.)

  • http://hanson.gmu.edu Robin Hanson

    I know that this is a hot button issue, but the last two comments were 500 words each, and the post itself is only 350 words. You can post a link to a longer comment elsewhere, so please keep your comments, and especially your quotations, concise.

    William, keep trying; it’s there.

  • William Newman

    Robin Hanson wrote “the last two comments were 500 words each, and the post itself is only 350 words.”

    Hmm, sorry, if I had known you prefer precis+externallink for anything long, I’d’ve done it. And, incidentally, I suggest you post that as policy somewhere. It is a sensible policy, but for me, at least, the policy isn’t self-evident. In fact, since comments of that form are uncommon on the blogs I read, I wonder if I’m violating some norm by making them. E.g., perhaps linking to my own website might be interpreted as some sort of weird ego thing, or cynically misusing someone else’s site to advertise for myself.

  • loqi

    Geoffrey, I notice you bolded the following passage:
    “What convinces me of the reality of climate change, despite the uncertainties, is that the comments put out by climate change denialists are absolute, unmitigated garbage.”

    If this emphasis is meant to support Dutch’s argument, you may find this post illuminating.

    • Jonnan

      I’m not entirely sure I agree with the link. To the extent that it says “You should debate the *strongest* argument/opponent”, sure.

      But what about the case (As in climate denial) where there *are* no strong arguments/opponents. The fact is, that yes, the combination of a large quantity of opponents, but no opponents of quality, *does* indicate a substantial weakness in the position they’re defending.

      Jonnan

  • http://entitledtoanopinion.wordpress.com TGGP

    I came to believe in AGW for some similar reasons, and also because people who had been skeptical (and were politically motivated to be so) came around with more evidence but the reverse did not happen. It’s not really a big issue for me. I will say though that what I’ve seen of the Climate Audit site (which caused a big stink when it came close to winning a science blog award) is as levelheaded as Bjorn Lomborg on beta-blockers. I don’t know if they’ve come out and denied AGW rather than just critiquing some science though.

  • http://www.mccaughan.org.uk/g/ g

    William and Robin: I too get a 404 for the Verdes paper, and also for (e.g.) Verdes’s home page and publications page at IFIR. Google claims to have seen the latter two, at least, in a crawl a couple of weeks ago, and they are in its cache.

    Aha: the following seems to work, though it only gets you the HTML version in which equations and plots are scrobbled: http://google.com/search?q=cache:www.ifir.edu.ar/~redes/ps/PhysRevLett_99_048501.pdf.

  • Stan

    Another geoengineering solution for the longer-term is lower-tech, with greater side-benefits: biochar. Sequestering carbon while attempting to remedy global soil degradation seems like a solid strategy to add to the mix, with few built-in surprises or risks. You can even get a bit of energy out of the deal.

  • Jerry

    I have a couple of points I keep on my mind about this topic.

    1. While i haven’t seen any studies, I can be fairly certain that a good fraction of climatologist lean left..Its pretty ironic that an anti-bias group of people wouldn’t find this the first point of order to unravel.

    2. People have no problem projecting a highly chaotic system like weather out 50 years, but fail to do so to technology that would solve or fix the problem – such as moderate level nanotechnology – even when the progression of the technology has been following standard and predictable curves so far.

    3. Even if there IS global warming, and I am not denying there isn’t, It hasn’t been shown that the net effect would actually make our situation worse. Maybe this might result in more farmable land. Once again, I haven’t seen any information that didn’t come from what I suspect is a highly biased group of scientists. How does one determine if the intervention outweighs the consequences of not intervening? How do you remove the political biases involved, such as the socialists and communists that would love to use this topic as a bludgeon to beat down the evil capitalism – rather if it was true or not?

    All that said, I think there are some reasonable and cheap items that might be able to be addressed to slow down carbon release into the atmosphere and an unbiased reasoned look could be done, but my most likely prediction is that these discussions will be handled by the most biased as well as most vocal and radical elements inside the political machinery in both Washington and the UN.

  • http://macroethics.blogspot.com nazgulnarsil

    warming is irrelevant next to energy concerns.

  • http://blogjack.net Glen Raphael

    Regarding betting: There was a time when AGW alarmists liked to claim they were 98% certain – or more – that the temperature was going to increase a lot. This is why Lindzen wanted 50-1 odds. The fact that Annan wasn’t willing to accept 50-1 odds indicates the 98% certainty claim was rhetorical bluster, not a probability estimate. The actual odds offered by AGWers tend to indicate they have *some* confidence in some degree of future warming, but really not very much, and no confidence at all in the extreme disaster scenarios that keep getting floated. The odds they are willing to float on well-defined claims are not enough to make their bets tempting unless you have some reason to be confident it’s going to cool – as those Russian solar scientists did. Merely thinking the AGW case is overstated isn’t sufficient. (At least it wasn’t for me – I tried to negotiate a bet with Brian Schmidt for a while but eventually gave up.)

  • Kevin Dick

    Robin,

    I’d be happy to make a bet of up to $1000 against AGW (specifically against more than 1 deg C rise in AST from a doubling of CO2 concentration). If you’re willing to make such a bet in the abstract, I would be happy to try and work towards a mutually agreeable specification.

    BTW, I agree with you up to (5). I just think that that the overall feedback is pretty clearly neutral to negative and that natural variation of things like solar cycles and current oscillations have a much greater effect on temperature. This argues against mitigation because it means temperatures could just as easily go dramatically down as up. So we should allocate our resources to adaptation, whether up or down.

  • http://blogjack.net Glen Raphael

    correction: Lindzen was addressing the claims of 99 percent certainty with his offer at a 50-1 bet. (so there was lots of net expected value for Annan; it wasn’t a wash). Such as the claim here:

    “Continued global warming is virtually certain (or more than 99 percent likely to occur) at this point.”

  • Hal Finney

    But is this how we are supposed to resolve these sorts of questions? Surely it is impractical for the average person to perform this sort of analysis on complex technical issues.

  • Constant

    To simplify: there are two groups of global warmists: the cautious group, and the alarmists. Each group operates with its own hypothesis of global warming. The cautious group argues for the cautious version of the global warming hypothesis. After they have made their claims sufficiently cautious to be defensible, then the headlines announce, “global warming is real.” Then the alarmists interpret this announcement as if it referred to the alarmist global warming hypothesis. A lot of the skepticism is mainly motivated by and aimed at the alarmist hypothesis, but warmists interpret the skepticism as if it were aimed at the cautious hypothesis, and (for the duration of the attack on skepticism) pretend that the there is no alarmist hypothesis.

    This is, of course, a simplification of the situation, but the actual situation is even worse (e.g. warmists love to conflate skepticism with denial), and the simplification gives the flavor of it. Who knows what the global warmists are claiming today? They keep revising down the predictions to keep them from being falsified by the accumulating evidence, so unless someone has his finger on the pulse of global warmism, he doesn’t even know what it is that they claim this year.

  • http://critticall.com Thomas

    ITER doesn’t work. CERN LHC has problems. AGW is man made illusion.

    What could be worse?

    That the overcomingbias.com site is biased (toward so called Big Science). Much worse, even.

  • http://www.negotiations.com Calum Coburn

    Seriously surprised you’ve not mentioned a whisper on sun spots and solar radiation as the prime cause for recent temperature rises. Some in depth research exists to back this up: http://www.nationalpost.com/news/story.html?id=c6a32614-f906-4597-993d-f181196a6d71

  • http://hanson.gmu.edu Robin Hanson

    On comment policy, read the About page.

    On betting, with moderate funding I could make markets with much more informative estimates, elaborating full probability distributions.

    Stan, that seems prohibitively expensive.

    Jerry, yes moderate warming may not be especially threatening.

    Kevin, CO2 doubling seems unlikely before 2100, making this a very long term bet. Is it really plausible that our descendants would track each other down then, to get paid, for just $1000 payout?

    Hal, yes we can’t have each person dig, but the more amateurs who do, the more sources an average person could have. I would of course prefer betting markets.

    Calum, I cited my source for believing CO2 is the main warming cause; that source considers solar radiation.

  • Kenny Evitt

    “Warming”? I think it’s called “climate change” now – and probably for a good reason.

  • Yvain

    I agree with your conclusions. All of them, in fact, including the geoengineering one.

    For anyone interested in confidence levels and probability: Less Wrong surveyed its readership, who are a lot of the same people who read OB, and included this question. Of about 150 people who responded, people were on average about 70% confident AGW was real.

  • Constant

    On Verdes – For such a supposedly knock-down argument, I see surprisingly little further discussion – in fact, judging by hits, the paper seems surprisingly forgotten at this point. I don’t really know what the graph is of without paying $25 to read the article, at which point I may or may not be enlightened. Is the data used public? Where is the replication? Where are the independent statistical studies of the same data confirming Verdes’s result? There is always the possibility in this sort of situation that the researcher kept throwing different math at the data until he got something positive, which increases the possibility of a spurious positive result (similar to the data mining problem – a math mining problem; similar also to publication bias).

  • Constant

    To explain “in fact, judging by hits, the paper seems surprisingly forgotten at this point.”

    Here is a google search over the past year. The terms are the author’s name and words from the title (minus palo and verde to get rid of spurious results which I was seeing). There are 21 hits (number in the upper right hand corner) and most of them are still spurious.

  • Constant

    Second try on google search link. If this doesn’t work you’re on your own. Too bad there isn’t a preview.

  • http://ssmag.wordpress.com Science in Society

    http://ssmag.wordpress.com/2009/03/02/climate-change-and-scientific-objectivity/

    The climate change debate is unusual in that scientists are understood as being almost monolithically on one side of the debate; in the public eye it is common to view it as The Scientists vs. The Politicians.

    part of this phenomenon is structural: even under ideal cases, the debate about costs and benefits are split across disciplines. One technocratic approach to evaluating climate change would be as follows:

    1. Climate scientists estimate the extent of anthropogenic climate change, creating a graph of emitted greenhouse gases vs oC change in temperature, with nice error bars.

    2. Economists calculate the costs of any arbitrary temperature change, along with the costs of an adjustment to any arbitrary CO2 emission level. They find the point at which marginal cost equals marginal benefit.

    3. Political scientists refine this estimate by calculating the probable public-choice inefficiencies of government policies. They formulate the optimal policy, which will probably reduce emissions slightly less than the economists’ model proposes.

    Even in this model, when everyone stays inside their disciplinary lines, scientists will be in the position of pointing out the costs of our current choices. It is up to the social scientists to say yes, this is true, but the adjustment to lower emissions levels is not costless.

    Given these roles, and given that scientists, politicians, and journalists all have their own axes to grind, it is not surprising that scientists are often presented as being monolithically on the interventionist side on the climate change debate. The only way for their research not to be simplified into “Needs Action Now!” is if it claimed that either climate is static or that climate cannot be changed by man, both of which are almost certainly false.

  • http://hanson.gmu.edu Robin Hanson

    Constant, yes it is interesting that the Verdes paper got such little followup. Does anyone know of a better single transparent study on an empirical test of if CO2 causes recent warming?

    Kenny, and do you know that reason?

    Science, please do not post comments that just quote a 300 word page from somewhere else; a link is fine.

  • Kevin Dick

    Robin,

    The doubling is just a metric. I was referring to the standard climate sensitivity metric of doubling from a “pre-industrial” CO2 concentration (~280ppm to 560ppm). There’s a reasonably well accepted response curve we could use to time the bet. I’d be happy to use a 5, 10, 15, or 20 year time frame. No descendants necessary.

    Also, we’d make T3 part of the bet as well as AST because the models seem to agree that rises in T3 are the most unique signature for warming driven by GHG emissions.

    Was time frame your only objection in principle?

  • http://hanson.gmu.edu Robin Hanson

    Kevin, I expressed an opinion about warming, not Tropical Tropospheric Temperature, and said most observers don’t trust the models. I’d bet at 50-50 odds that average global temperatures will be higher in 20 years.

  • Julian Morrison

    It’s actually really trivial to bet against sea level rise – invest in coastal land. I suppose you could counter-bet by shorting the same land.

    This is assuming global warming => sea level rise.

  • http://timtyler.org/ Tim Tyler

    Re: This uncertainty alone justifies substantial CO2 mitigation (emission cuts or geoengineering), if we are risk-averse enough and if mitigation risks are weaker.

    By using the term “mitigation”, you appear to be assuming that global warming is undesirable. Since we are in an ice age, I find that premise to be questionable. What is the basis of it? Don’t we need a warmer planet, to get rid of the inhospitable icy wastelands, and turn the planet back into the tropical paradise it usually is, when not locked into a horifying glaciation cycle?

  • http://blogjack.net Glen Raphael

    Robin: somebody who thinks world temperature movement is entirely chaotic with no persistent warming component might offer 50-50 odds on temperatures being higher over any arbitrary timeframe but if you think “co2 warming looks real” you should be willing to offer better than 50-50 odds. Or to offer 50-50 odds on a specific minimum amount of positive increase. Otherwise the signal your bet offer sends is that you don’t strongly believe warming will occur. You just think it’s ever-so-slightly more likely than not, perhaps a 51% chance. Is that the message you want to send, or could you go higher? :-)

  • http://hanson.gmu.edu Robin Hanson

    Tim, I was careful to say “if”. The far tails of the distribution of outcomes are the most likely to be undesirable, and if one is risk-averse enough those tails weigh heavily.

    Glen, when haggling over a price, it is traditional to alternate making offers.

    • http://timtyler.org/ Tim Tyler

      Right – but why would one think that the warming risks weigh more heavily than the risk of reglaciation – which seems to be both obviously an enormous catastrophe – and *highly* likely – unless we actively warm the planet up.

  • ES

    I’m confused why there’s so much debate about whether global warming is human-caused. Surely if global warming is undesirable, it’s undesirable whether caused by human activity, sunspots, or anything else. Do some people really think that any harms caused by global warming are acceptable as long as they are “not our fault”?

    • http://timtyler.org/ Tim Tyler

      Because of the human desire to attribute blame and administer punishment. It makes a better story for the environmental activists if industrial humans are evil sinners, and they can charge in on a white knight and SAVE THE WORLD from the evil industrialist forces.

  • http://entitledtoanopinion.wordpress.com TGGP

    ES, David Friedman made the same point here.

  • http://blogjack.net Glen Raphael

    Okay: The IPCC claims further warming is 99% certain but I think it’s less than 95% certain, so I would be willing to bet global temperatures are lower in 20 years than today given 20-1 odds.

  • Kevin Dick

    Robin,

    Actually, in your point 9 you expressed the opinion that CO2 was responsible for warming. The T3 signature for CO2 seems to be one of the few points of agreement of the models that might give us some indication of causality. If you think consensus among experts is important, you should think there is some sort of signal here (as you often argue in the general case).

    But I’m not married to a T3 component. We can just do AST if you want (using one of the satellite series to address your point 12). T3 was mainly offering you a hedge against other natural variation. Many of the alarmists seem to complain these days about natural variation “masking” AGW. I can certainly construct appropriate odds without it.

    However, as Glen pointed out, 50-50 odds is a signal that you don’t really believe in your assertion. To your point about the social norms of negotiations, when you open with a complete non-commitment, it shows that you are not really serious. I’m happy to have the final word here be that you have a made an assertion in which you have measurably zero confidence.

    Now, if you simply want to observe some haggling norm… I can’t believe you would make such an insulting offer. How am I supposed to feed my family on that? Now, I could perhaps give you 9:1 odds against an AST increase 20 years out. That’s an order of magnitude better than Annan asserted. So I’m giving you a real deal here. It’s costing me and I’m going to look really bad if any of the other guys find out, but for you, I’ll do it. You’re turn, right?

  • http://blogjack.net Glen Raphael

    Kevin, you fool! You’re giving away the store! 10-1 would have been my next offer, but 9? So generous! Robin, you should jump on that before he regains his sanity!

  • kevin

    The relevant calculation for policy, of course, is opportunity cost. The thing is, I never see this mentioned by the political groups most concerned with climate change. Instead, they seem to think “If AGW exists then we must do everything possible to stop it.”

    Of course this doesn’t logically follow. Of course the libertarians and conservatives who are against this interference in the market don’t make the case from opportunity costs, or political rent-seeking. Instead they fall into the trap and say “AGW IS A LIE! JUNK SCIENCE! SUNSPOTS!”

  • http://hanson.gmu.edu Robin Hanson

    Kevin D, the graphs here show a 0.3C warming over 60 years, so I was going to offer to bet at 50-50 odds that this trend would continue, so at least a 0.05C rise in this number over 20 years. But you want a satellite time series. Is there such a series with a long past record that we have good reason to expect will continue for 20 years more?

  • Kevin Dick

    Oh, I must have misunderstood your original post. If your true belief is that we can expect temperatures in 2100 to be only .46C warmer (.05C/decade) than they are today, we absolutely agree! I believe I stipulated a mild first order forcing.

    Of course, that’s less than the latest estimates from the IPCC assuming no additional CO2 concentration increase from 2000 levels!:

    http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf
    (See Table SPM.3)

    So I think this implies you either you believe that we will actually stop emitting substantial amounts of CO2 tomorrow or you don’t believe CO2 will effect temperature that much.

  • Mike

    I had been under the impression that global cooling had occurred from 1940 to 1970. Is there an explanation for this cooling that is consistent with the story you tell?

  • Pingback: Interessantes woanders (2009.06.01) › Immersion I/O

  • http://naturalspiritofgoodcompany.blogspot.com/ William Newman

    I have looked at the Verdes paper, and my guess is that the fit is probably significantly worse after the time interval in the FIG. 2 reproduced in Robin Hanson’s post. Quite possibly it is also significantly worse before the plotted time interval, though that runs into increasingly uncertain data, and I can’t be sure without doing the actual model calculation instead of merely eyeballing it. Also, I don’t think there is enough information in the fit to really justify the strength of the claim in the abstract.

    (more here)

  • magfrump

    to loqi who cited that reversed stupidity is not intelligence, recall also this post:
    http://lesswrong.com/lw/ih/absence_of_evidence_is_evidence_of_absence/

    If there were legitimate technical arguments against global warming, we would very likely expect at least one intellectual conservative to have dug them up and presented them, instead of providing an argument that is pure bunk.

    Tied into this core concept is the idea that there are no intellectual conservatives (see: http://www.becker-posner-blog.com/archives/2009/05/is_the_conserva.html ).

    There are a few possible theories to explain this (science has been overtaken by liberals, conservative results are squished by “big science,” studying science somehow brainwashes you) the most popular one seems to me the least far fetched: the truth tends to match up with more progressive beliefs, therefore people who care more about the truth tend to be more progressive.

    Now I know the discourse on this has been quite technical, but it is hard for me to believe that any possibility is more likely than the last few intellectual conservatives assigning extra importance to an issue for political reasons so they don’t have to give up on their original beliefs.

  • http://entitledtoanopinion.wordpress.com TGGP

    Mike, one explanation I’ve heard is “global dimming”. As we reduced the kinds of pollutants that blocked sunlight the earth began heating up.

  • http://hanson.gmu.edu Robin Hanson

    William, the data and method of the Verdes paper are public. I encourage anyone interested to try to replicate his work, to check for robustness to the time interval used, and to see what the fitted model predicts for future temperature given expected future CO2 increases.

  • Kevin Dick

    @magfrump

    I think you misunderstand what I call the “well-informed skeptic’s position.” You are not alone, but it this doesn’t make the characterization correct. This position does not deny that CO2 is a first order forcing. Rather, it denies higher order effects.

    You will find plenty of “legitimate technical arguments” against higher order effects. In fact, I think you would be hard pressed to find published forecasts based on higher order effects that possess any skill. It’s the alarmists who have failed to provide any confirmatory data.

    As I’ve already explored with Robin, the first order effects, while real, aren’t worth getting excited about in light of other places we could spending our money.

  • Jayson Virissimo

    In my judgment, the AGW theory looks pretty solid. On the other hand, I think the models used to predict the magnitude and effects of global climate change are about as useful as analogous econometric forecasting models. In other words, I don’t trust them to be accurate that far into the future. The error bars are almost dishonestly narrow.

    What I really want to know is: What is the optimal temperature of the Earth (for long-term human happiness)? Are we currently above or below this point?

  • http://backseatdriving.blogspot.com Brian Schmidt
  • Ryan Glinski

    First, if you’re going to be a denialist, don’t slap and swat, make a fist and go for the throat:

    http://www.warwickhughes.com/icecore/

    Second, if we’re going to be extra super cautious and try to mitigate a problem even though we don’t necessarily trust the climate models that identify it, we’re going to need some method for deciding how to mitigate that doesn’t rely on the climate models for answers. How then do we decide what level of emission cuts are needed to prevent X degrees of change or inches of seal level rise? How do we decide what level of warming is dangerous and what is benign?

    In essence, say we don’t really buy into religion but we do buy Pascal’s wager, how do we figure out how to avoid hell without consulting the bible? I think the answer is you can’t and it’s all part of the illogical game of the wager/warming argument.

  • dj superflat

    said elsewhere, too, but isn’t the real question whether it’s worth trying to do anything about warming? the whole “is-it-warming-and-why” debate is just a side-show, because if the effects are likely to be easily handled when they arise, who cares? and the cost/benefit analysis obviously has to take into account how likely our efforts are to succeed (e.g., you can’t just ignore that india and china for the most part don’t want to play). whether it’s warming, that’s just reading a thermometer. whether it’s attributable to man, who really care (if warming will be bad enough, we should fight it even if we’re not the culprit, though it might influence our assessment of whether we can do much about it). similarly, if we’ve already put ourselves on a path to warming that can’t be reversed by anything we do in the near or nearish term, who cares about the causes, we just need to work on mitigation measures.

    almost all of the analysis of GW issues seems to me to largely ignore the real question that people like lomborg and others have answered in the negative (should we care/try to do anything about warming).

  • dj superflat

    forgot to mention: i love how the debate has been perverted so that skepticism regarding whether it’s worth trying to do anything about any warming that may be going on has been conflated with skepticism about whether there’s warming going on (or whether it’s AGW), all very, very different things.

  • Anthony

    The really important question with respect to global warming is not whether it is occurring, or even whether it is significantly human-caused, but “what is to be done”. That question does depend on the answers to the first two questions, but also on other factors. The green-left consensus proposals can be easily shown to be bad ideas while still assuming that AGW exists and will likely continue. (See, for example, Bjorn Lomborg’s “Cool It”, in which he supports the claims for GW being A, but disagrees with pretty much every one of the green-left policy proposals.)

    ES asks whether it matters whether GW is A, and the answer is “yes”, because if the cause is certain human actions, it may be possible to change or reverse those human actions. If, on the other hand, GW is entirely caused by solar variability, no amount of CO2 emission reduction will help. (Actually, it matters more than that, as reduction of CO2 emission is effectively the *only* policy proposal to address GW.)

  • Anthony

    Global warming skepticism is a trap which the Right predictably fell into. Predictable, because the Left has done this over and over; most damagingly over evolution and eugenics. Back in the early 20th century, the Left claimed that the truth of Darwinian evolutionary theory morally required eugenic policies. The Right, appalled by the immorality of eugenics, fought back not by challenging the Left’s derivation of “ought from is”, but by denying the “is”. This worked well enough, given the politics of the day, until Hitler made eugenics a dirty word and the Left abandoned it as a policy. (The vestigial creationism on the Right is focused mainly on the perception that Darwinism justifies what they see as sexual immorality, even though the left doesn’t actually push that line anymore, either.)

    There are still some uncertainties in the science of global warming, and there are a lot of people pushing certain policy proposals by exaggerating what the science actually does say, but the case against a carbon tax does not depend on disproving any aspect of currently-accepted climate science. The sooner the Right realizes that, the better.

  • ryanglinski

    Heyas. I posted a comment a few hours ago and I guess it violated some rule of moderation. Anyone have a link to the rules so I can avoid problems with moderation in the future?

  • http://hanson.gmu.edu Robin Hanson

    I just added to the post.

  • ryanglinski

    *wipes egg off face*

    I’m sorta embarrassed.

  • loqi

    magfrump:

    to loqi who cited that reversed stupidity is not intelligence, recall also this post:
    http://lesswrong.com/lw/ih/absence_of_evidence_is_evidence_of_absence/

    Please re-read the paragraph containing the bolded passage I was responding to, and note that it was not phrased in terms of missing good arguments. Rather, it was a generalization of the quality of the “comments put out”, and a litany of complaints about specific arguments. To open a statement with “What convinces me of the reality of climate change, despite the uncertainties” and conclude with the above is indefensible.

    If there were legitimate technical arguments against global warming, we would very likely expect at least one intellectual conservative to have dug them up and presented them, instead of providing an argument that is pure bunk.

    I agree that someone would have presented them, otherwise they’re not really arguments, are they? As you claim there’s no such thing as an intellectual conservative, they won’t present them, the scientists will. Back in reality, I agree more completely. Please provide me with convincing evidence that this hasn’t happened. Note that my personal lack of exposure to such arguments counts as roughly zero evidence to me, because I haven’t looked particularly hard for them. How confident are you in the thoroughness of your search?

    Tied into this core concept is the idea that there are no intellectual conservatives

    So, I really hope by “intellectual” you mean some specific culture of academics, and not “a genuinely intelligent person who shares valuable insights with the public”. Because if you mean something like the latter, you seem to be claiming that there is no such thing as an intelligent human being with conservative values.

    There are a few possible theories to explain this (science has been overtaken by liberals, conservative results are squished by “big science,” studying science somehow brainwashes you) the most popular one seems to me the least far fetched: the truth tends to match up with more progressive beliefs, therefore people who care more about the truth tend to be more progressive.

    As someone with values that could easily be described as “progressive”, I’d like to emphasize that there is no such thing as progressive or conservative beliefs. If you label your state of belief about the world as “progressive”, just because it correlates with the states of belief of other people you also label “progressive”, you run the risk of catastrophic stupidity.

    Now I know the discourse on this has been quite technical, but it is hard for me to believe that any possibility is more likely than the last few intellectual conservatives assigning extra importance to an issue for political reasons so they don’t have to give up on their original beliefs.

    With this, you are rendered incoherent. There are no intellectual conservatives, but the last few are responsible for the best technical rebuttals of AGW? Even if you’re right, what will that actually tell you about the arguments at hand?

  • Patrick

    What’s your opinion on ocean acidification?

  • Daublin

    As several posters have written, most “skeptics” agree with what you write in this article, and only disagree with the political choices that follow from it. In essence, you buried one of the most important parts of the debate:

    “This uncertainty alone justifies substantial CO2 mitigation (emission cuts or geoengineering), if we are risk-averse enough and if mitigation risks are weaker.”

    The second if is huge, but you listed it as an if within an if within a random bullet in the middle of the list. The Kyoto protocol has huge costs but minimal effect on CO2, and therefore minimal effect on CO2-based global warming. Even if CO2 is really harmful, how is this a helpful response?

  • Pingback: Will The Real AGW Skeptic Please Stand Up? « The Emergent Fool

  • http://randomspaniard.blogspot.com bsanchez

    I am also relatively sceptical, but less so now that I have plotted a simple chart of temperature and atmospheric co2 in my blog. I was quite surprised by the fit.

  • http://timtyler.org/ Tim Tyler

    The graph just shows that people have used more aerosols since the 1960s. Without comparing that to other factors involved in the climate, that really means *very* little for the case in favour of AGW.