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On attribution

Filed under: — gavin @ 26 May 2010

How do we know what caused climate to change – or even if anything did?

This is a central question with respect to recent temperature trends, but of course it is much more general and applies to a whole range of climate changes over all time scales. Judging from comments we receive here and discussions elsewhere on the web, there is a fair amount of confusion about how this process works and what can (and cannot) be said with confidence. For instance, many people appear to (incorrectly) think that attribution is just based on a naive correlation of the global mean temperature, or that it is impossible to do unless a change is ‘unprecedented’ or that the answers are based on our lack of imagination about other causes.

In fact the process is more sophisticated than these misconceptions imply and I’ll go over the main issues below. But the executive summary is this:

  • You can’t do attribution based only on statistics
  • Attribution has nothing to do with something being “unprecedented”
  • You always need a model of some sort
  • The more distinct the fingerprint of a particular cause is, the easier it is to detect

Note that it helps enormously to think about attribution in contexts that don’t have anything to do with anthropogenic causes. For some reason that allows people to think a little bit more clearly about the problem.

First off, think about the difference between attribution in an observational science like climatology (or cosmology etc.) compared to a lab-based science (microbiology or materials science). In a laboratory, it’s relatively easy to demonstrate cause and effect: you set up the experiments – and if what you expect is a real phenomenon, you should be able to replicate it over and over again and get enough examples to demonstrate convincingly that a particular cause has a particular effect. Note that you can’t demonstrate that a particular effect can have only that cause, but should you see that effect in the real world and suspect that your cause is also present, then you can make a pretty good (though not 100%) case that a specific cause is to blame.

Why do you need a laboratory to do this? It is because the real world is always noisy – there is always something else going on that makes our (reductionist) theories less applicable than we’d like. Outside, we don’t get to perfectly stabilise the temperature and pressure, we don’t control the turbulence in the initial state, and we can’t shield the apparatus from cosmic rays etc. In the lab, we can do all of those things and ensure that (hopefully) we can boil the experiment down to its essentials. There is of course still ‘noise’ – imprecision in measuring instruments etc. and so you need to do it many times under slightly different conditions to be sure that your cause really does give the effect you are looking for.

The key to this kind of attribution is repetition, and this is where it should become obvious that for observational sciences, you are generally going to have to find a different way forward, since we don’t generally get to rerun the Holocene, or the Big Bang or the 20th Century (thankfully).

Repetition can be useful when you have repeating events in Nature – the ice age cycles, tides, volcanic eruptions, the seasons etc. These give you a chance to integrate over any unrelated confounding effects to get at the signal. For the impacts of volcanic eruptions in general, this has definitely been a useful technique (from Robock and Mao (1992) to Shindell et al (2004)). But many of the events that have occurred in geologic history are singular, or perhaps they’ve occurred more frequently but we only have good observations from one manifestation – the Paleocene-Eocene Thermal Maximum, the KT impact event, the 8.2 kyr event, the Little Ice Age etc. – and so another approach is required.

In the real world we attribute singular events all the time – in court cases for instance – and so we do have practical experience of this. If the evidence linking specific bank-robbers to a robbery is strong, prosecutors can get a conviction without the crimes needing to have been ‘unprecedented’, and without having to specifically prove that everyone else was innocent. What happens instead is that prosecutors (ideally) create a narrative for what they think happened (lets call that a ‘model’ for want of a better word), work out the consequences of that narrative (the suspect should have been seen by that camera at that moment, the DNA at the scene will match a suspect’s sample, the money will be found in the freezer etc.), and they then try and find those consequences in the evidence. It’s obviously important to make sure that the narrative isn’t simply a ‘just-so’ story, in which circumstances are strung together to suggest guilt, but which no further evidence is found to back up that particular story. Indeed these narratives are much more convincing when there is ‘out of sample’ confirmation.

We can generalise this: what is a required is a model of some sort that makes predictions for what should and should not have happened depending on some specific cause, combined with ‘out of sample’ validation of the model of events or phenomena that were not known about or used in the construction of the model.

Models come in many shapes and sizes. They can be statistical, empirical, physical, numerical or conceptual. Their utility is predicated on how specific they are, how clearly they distinguish their predictions from those of other models, and the avoidance of unnecessary complications (“Occam’s Razor”). If all else is equal, a more parsimonious explanation is generally preferred as a working hypothesis.

The overriding requirement however is that the model must be predictive. It can’t just be a fit to the observations. For instance, one can fit a Fourier series to a data set that is purely random, but however accurate the fit is, it won’t give good predictions. Similarly a linear or quadratic fit to a time series can be useful form of descriptive statistics, but without any reason to think that there is an underlying basis for such a trend, it has very little predictive value. In fact, any statistical fit to the data is necessarily trying to match observations using a mathematical constraint (ie. trying to minimise the mean square residual, or the gradient, using sinusoids, or wavelets, etc.) and since there is no physical reason to assume that any of these constraints apply to the real world, no purely statistical approach is going to be that useful in attribution (despite it being attempted all the time).

To be clear, defining any externally forced climate signal as simply the linear, quadratic, polynomial or spline fit to the data is not sufficient. The corollary which defines ‘internal climate variability’ as the residual from that fit doesn’t work either.

So what can you do? The first thing to do is to get away from the idea that you can only be using single-valued metrics like the global temperature. We have much more information than that – patterns of changes across the surface, through the vertical extent of the atmosphere, and in the oceans. Complex spatial fingerprints of change can do a much better job at discriminating between competing hypotheses than simple multiple linear regression with a single time-series. For instance, a big difference between solar forced changes compared to those driven by CO2 is that the stratosphere changes in tandem with the lower atmosphere for solar changes, but they are opposed for CO2-driven change. Aerosol changes often have specific regional patterns change that can be distinguished from changes from well-mixed greenhouse gases.

The expected patterns for any particular driver (the ‘fingerprints’) can be estimated from a climate model, or even a suite of climate models with the differences between them serving as an estimate of the structural uncertainty. If these patterns are robust, then one can have confidence that they are a good reflection of the underlying assumptions that went into building the models. Given these fingerprints for multiple hypothesised drivers (solar, aerosols, land-use/land cover change, greenhouse gases etc.), we can than examine the real world to see if the changes we see can be explained by a combination of them. One important point to note is that it is easy to account for some model imperfections – for instance, if the solar pattern is underestimated in strength we can test for whether a multiplicative factor would improve the match. We can also apply some independent tests on the models to try and make sure that only the ‘good’ ones are used, or at least demonstrate that the conclusions are not sensitive to those choices.

These techniques of course, make some assumptions. Firstly, that the spatio-temporal pattern associated with a particular forcing is reasonably accurate (though the magnitude of the pattern can be too large or small without causing a problem). To a large extent this is the case – the stratospheric cooling/tropospheric warming pattern associated with CO2 increases is well understood, as are the qualitative land vs ocean/Northern vs. southern/Arctic amplification features. The exact value of polar amplification though is quite uncertain, though this affects all the response patterns and so is not a crucial factor. More problematic are results that indicate that specific forcings might impact existing regional patterns of variability, like the Arctic Oscillation or El Niño. In those cases, clearly distinguishing internal natural variability from the forced change is more difficult.

In all of the above, estimates are required of the magnitude and patterns of internal variability. These can be derived from model simulations (for instance in their pre-industrial control runs with no forcings), or estimated from the observational record. The latter is problematic because there is no ‘clean’ period where there was only internal variability occurring – volcanoes, solar variability etc. have been affecting the record even prior to the 20th Century. Thus the most straightforward estimates come from the GCMs. Each model has a different expression of the internal variability – some have too much ENSO activity for instance while some have too little, or, the timescale for multi-decadal variability in the North Atlantic might vary from 20 to 60 years for instance. Conclusions about the magnitude of the forced changes need to be robust to these different estimates.

So how might this work in practice? Take the impact of the Pinatubo eruption in 1991. Examination of the temperature record over this period shows a slight cooling, peaking in 1992-1993, but these temperatures were certainly not ‘unprecedented’, nor did they exceed the bounds of observed variability, yet it is well accepted that the cooling was attributable to the eruption. Why? First off, there was a well-observed change in the atmospheric composition (a layer of sulphate aerosols in the lower stratosphere). Models ranging from 1-dimensional radiative transfer models to full GCMs all suggest that these aerosols were sufficient to alter the planetary energy balance and cause global cooling in the annual mean surface temperatures. They also suggest that there would be complex spatial patterns of response – local warming in the lower stratosphere, increases in reflected solar radiation, decreases in outgoing longwave radiation, dynamical changes in the northern hemisphere winter circulation, decreases in tropical precipitation etc. These changes were observed in the real world too, and with very similar magnitudes to those predicted. Indeed many of these changes were predicted by GCMs before they were observed.

I’ll leave it as an exercise for the reader to apply the same reasoning to the changes related to increasing greenhouse gases, but for those interested the relevant chapter in the IPCC report is well worth reading, as are a couple of recent papers by Santer and colleagues.

559 Responses to “On attribution”

  1. 501
    Ray Ladbury says:

    Jim Edwards, your post @495 is a perfect example of someone proposing a solution before they’ve bothered to study the problem–as well as a masterpiece of logical inconsistency.

    An example of the latter: First you say, “My views are immaterial;…” and in the very next sentence, “I think it’s best if everybody presents their views to the public in the most effective manner.”


    You say, “One thing I would note is that history has shown that seemingly intractable problems often become easier to solve the longer you wait [as technology improves].”

    Great! Shall we let that oil well spew for another 20 years because we’ll have better techology then? How about letting highway bridges crumble for another decade because we’ll have better technology?

    What you and Lomborg fail to consider is that

    1)waiting makes the situation considerably worse,

    2)we are dealing with a system that has tipping points that will wrest away what little control we have,

    3)another decade just makes the vested interests that oppose action richer and stronger,

    4)the problems of energy infrastructure need to be resolved in any case,

    5)technology doesn’t just “happen,” but requires a concerted long-term development effort and

    6)we have already delayed action by over 20 years past the point where climate change became a verified scientific fact and now need to buy time to find solutions.

    I would urge you to spend some effort to understand the problem before you try to dictate a solution.

  2. 502
    John Mashey says:

    re: #416 of
    Sorry, I guess I should have pointed back at one of the discussions, because a good implementation simply gives the moderator another option at approval/reject time, so need not take any more time, and clearly, if someone replies to a post placed in the shadow, it’s a hint that one may not have to read much of it to decide to leave it there.
    See this,
    for example.

    Hank & others: I’d throw some money in if that’s what it took.
    The features need to be designed by (RC moderators working with whoever implements this), i.e., the features have to be what the moderators would want&use, subject to implementation issues, and they have to be in the software that RC uses, not somewhere else), my opinions on desired features are irrelevant.

    Over the years, I have seen way too many once-useful newsgroups become useless from SNR decline….
    While bulletin boards have a long history, I do go back a ways 1982 USENET (or maybe earlier, I forget).

    re: a good candidate for shadows, as an example.
    I’m fond of the very nice Swiss glacier monitoring network website, as it presents well-illustrated summaries, nice charts, and carefully-collected data of their glaciers, starting ~1880.(The red-green-blue chart there is worth understanding.) The website lets you sort data and drill down for any details, so it’s a nice model. Of course, it’s stereotypical of the Swiss to be careful and meticulous – one Swiss ancestor of mine recorded every farm profit/expenditure to the penny for 50 years in a journal I still have.

    Anyone who lives in Switzerland can *see* the glaciers going up the mountains. Nevertheless, a few Swiss are unable to *see* any AGW problem and manage to ignore this obvious evidence, no matter how often it has been pointed out to them. Put another way, shadow(max).

  3. 503

    FG 498: Mr. Levenson, there are plenty of activists looking to completely upend the current financial and social system with AGW as their excuse.

    BPL: No doubt. Does that mean AGW isn’t happening?

  4. 504

    je 499: I’ve never met or heard a “denier”

    BPL: Really…? And yet they make up about half of Americans. Do you live on a small desert island? Who’s hotter, Ginger or Mary Ann?

  5. 505
    Frank Giger says:

    No, sir, it does not. But one must also be aware that the politics of AGW is full of overblown rhetoric and denial of the science.

    Over attribution of weather events, mass extinction just around the corner, and mass starvation in the USA within thirty years are the staples of the typical activist that denies the science and just makes up whatever suits their cause.

    Sadly, no amount of showing them the science will dissuade from this. They’re stuck in an ideological worldview that will not let facts in.

    It makes it very difficult to get anything meaningful done when one group simply wants to have a people’s revolution.

    (Mary Ann FTW)

  6. 506
    Jim Eager says:

    Frank Giger @498 invokes the “water mellon” argument. You know, green on the outside, pink on the inside.

    Nice piece of work, that Frank.

  7. 507
    Ray Ladbury says:

    Frank Giger,
    I agree that it is a mistake to oversell the science. Moreover, I think you will agree that I have at least tried to be scrupulous in that regard. That being said, the problem I have at this point is that I cannot bound with any confidence the damage arising from AGW in a BAU situation. There remains enough uncertainty in CO2 sensitivity on the high side and enough uncertainty about consequences of, say, 4 degrees or more temperature rise that I cannot rule out a possible collapse of civilization with any reasonable confidence.

    The extremes thus dominate the risk calculus, and the only appropriate strategy I know of in that case is risk avoidance while at the same time working to better refine bounding estimates of risk.

    Also, definitely a Mary Ann kinda guy, BTW.

  8. 508
    Frank Giger says:

    Sadly, it’s largely true.

    I remember when the folks that were most ardently for protecting the natural environment were hunters, farmers, and those that actually used the land. And they were’nt the least bit upset with Capitalism.

    Today they have largely been silenced.

  9. 509
    CM says:

    John Mashey #501, re: shadow threads,
    now I understand. Cool idea, hope some WordPress hacker will take it up (doesn’t look like it’s covered by existing plugins to move comments around, or style irrelevant ones “buried”).

  10. 510
    Tim Jones says:

    I just want to thank Dr. Jim Bouldin in public regarding his thoughtful off blog reply to the snafu I engendered regarding an off topic subject. I suspect RC mods and especially Gavin are sensitive and discouraged about a recent turn of events and I don’t want to aggravate the situation or act to turn useful conversation away from the designated topic. Such was my naive inquiry, though, and I apologize for the distraction.

    In future I’ll keep my remarks on point as many here have indicated is the way of these discussions.

  11. 511
    CM says:

    For the shadows, then:

    Frank Giger,
    get real. Mentioning “social justice” doesn’t make you a Marxist. And the IPCC doesn’t even mention it much. There’s some reference to social justice as an element of “sustainable development” in WG2 ch. 20. But the only sustained discussion is in WG3 ch. 2.6, “Distributional and equity aspects.” That section essentially notes three or four different approaches to what equity or social justice is, represented by thinkers like Rawls, Sen, and Nozick, and outlines possible implications for emission allocation rules. To the extent it concludes anything, it is that people disagree on this, and will probably have to find a practical compromise combining different criteria. Revolutionary it ain’t.

  12. 512
    Jim Eager says:

    Frank, the truth of the matter is that neither capitalism nor communism ever voluntarily did a single thing to protect the environment. Both have rapaciously exploit resources without regard to environmental impacts unless required to do so by legal mandate, and often not even then.

  13. 513
    jim edwards says:

    #504, Barton Paul Levenson

    1) “Denial” is a choice. It just means saying no. In the perjorative sense that it is used in the AGW debate,it is a dishonest act similar to apostasy. It implies a person is first practically convinced of the truth of the matter, then chooses to believe otherwise, in spite of the evidence. Denial in this sense requires the “denier” actually be made aware of the evidence – not just informed by a rock star that “AGW is real and coming your way”. [Alternatively, perjorative denial of a different sense may occur when a person refuses to even consider inconvenient facts / ideas. The classic ‘living in denial’]

    Most people have never considered the evidence pro or con. They’ve just been told, “the debate is over.” The people who don’t agree with you are not deniers in the perjorative sense. They’re unconvinced.

    If you actually read anything I wrote, you’d see I’m trying to help you convince them.

    2) Tina Louise was way more sexy than Dawn Wells, but Ginger was a high-maintenance manipulater. Mary Ann was a sweetheart and I love coconut cream pie. Advantage Mary Ann.

    #501, Ray Ladbury

    I apologize for being vague. I meant to say my views on AGW are immaterial but that I want the pro / anti / don’t-know sides to make their best cases to the electorate. Whether my ideas have merit shouldn’t depend on which “team” I belong to.

    For the rest, you appear to be willfully choosing to miscomprehend simple English.

    The modifier “OFTEN” in the middle of the sentence means it makes sense to wait to attempt to solve some problems, but not others.

    I don’t recall Bjorn or me advocating letting oil wells gush into the Gulf of Mexico…

    A better analogy would be a case where a 24 year-old woman has a 100% chance of developing fatal ovarian cancer by age 40. Should we give her an immediate ovectomy ? [depriving her of the chance to have children] Or should we wait ten years to see if a gene therapy is developed ? [hopefully, we let her decide this one, after informed consent]

    Please find a single sentence where I “dictated”, or even proposed, a solution to climate change.

    I merely proposed a method to help the pro-AGW side turn more of the unconvinced into convinced.

    Ranting six unsupported statements at me, and publicly calling me out for my supposed ignorance, is not a good way to get me to see the light. You really need to work on your people skills.

    As far as your claims go:

    #1 may be true, but it may be only moderately worse during the short wait and / or not irreversibly so

    #4 is correct, but it really begs the question. Africa needs more energy infrastructure – but what kind ? The US could happily rely on Canadian tar sands for a very long time – so long as our dollar is still accepted.

    #3 appears to be contrary to experience. Corporations are very good at getting on the subsidy gravy train. [see Richard Branson, BP and UK biofuel subsidies] Coal continues to have political legs, but the major energy players will probably figure out how to sacrifice coal to take larger market share at higher margins under a goverment control scheme.

    #6 is at least disingenuous, in that even the most recent IPCC report only claims a 90% probability that over half of the RECENT warming is due to man [only some from CO2, land-use also a culprit]. Assessment Reports one through three expressed far less certainty. I never heard an actual scientist in 1990 state that ANTHROPOGENIC global warming was a “verified scientific fact.” “Climate change” has been generally accepted as true for a lot longer than twenty years.

    #5 is part-right / mostly-wrong. Technological improvements DO just happen, in a free market system, because smart people are interested in solving problems – and others are looking for ways to profit. Some technological development occurs through long-term development. Many developments are serendipitous. 17 year-old Philo Farnsworth developed the idea for electronic television while ploughing a field in Idaho.

    #2 is a fear-mongering statement without evidence provided to back the claim. Most complex natural control systems involve negative feedbacks, not positive feedbacks with cascading tipping points.

  14. 514
    jim edwards says:

    #512, Jim Eagar,

    It sounds like you’ve never worked in manufacturing.

    Consider the three Rs: Reduce, Reuse, Recycle.

    I’m sure you know that the benefit to the environment diminishes drastically as one moves from reduction [large benefit] toward recycling [zero to moderate benefit].

    Not using resources in the first place is far superior to using them, shipping them, collecting them, re-shipping them, and re-processing them.

    California schools seem to obsess about recycling, which often has no real benefit – other than to make us feel better about ourselves.

    Margins are very thin in manufacturing. In manufacturing, bosses are obsessed with reducing costs, in order to maximize profits.

    They reduce defects / maximize yields, to REDUCE wasted materials.
    They find lighter packaging, to REDUCE shipping costs [fuel].
    They choose the location of distribution centers, and the size of vehicles, in order to maximize efficiency.

    When I worked in Silicon Valley, they retrained operators to work in the clean room without generating so many particles, thus REDUCING the required air flow through HEPA filters. All that filtered air must be warmed / cooled to 72 degrees; the retraining was designed to REDUCE energy costs.

    Note that capitalism supports recycling programs in gold, silver, copper, and even iron, without any direction from the government.

    Capitalism does NOT naturally support a recycling program for aluminum beverage containers, absent government intervention.

    Aluminum is a fairly common element with very high processing costs [electricity]. The majority of the resource savings has already been achieved by the capitalist beverage companies. [Do you remember how thick the Coke cans were thirty years ago ?]

    Is it really better to have an entire distribution system set up in reverse for a tremendous number of lightweight cans, rather than just floating a barge of bauxite to the refinery. Is all the trucking of crushed cans offset by the slight reduction in electricty savings ? If it made sense to do it that way, somebody would have been doing it for profit – like they do with iron.

  15. 515
    Ray Ladbury says:

    Jim Edwards,
    Again, it is clear you haven’t bothered to look at the evidence. Had you done so, you would realize that

    1)that the effects of CO2 persist for thousands of years and so, on any scale relevant to human civilization, are irreversible

    2)there are tipping points (e.g. when the Arctic becomes ice-free, when the oceans become a source rather than a sink of CO2, when the permafrost starts to outgas CH4 and CO2…), and that we don’t know how near we are to them. As to negative feedbacks–yes, the main negative feedback is increased thermal radiation as the planet heats up. We understand that. It doesn’t save our sorry butts.

    3)that Exx-Mob is hauling in about $30 Billion a year in profit. Massey Energy owns the W. VA Supreme Court. These guys won’t back down and they won’t play nice, and their interests only become more entrenched.

    4)And yes, tar sands and oil shale could last us a few decades, but then, we’d have new entrenched interests opposing needed changes, and we’d be no closer to where we really need to be–a sustainable economy. As to Africa and the developing world–they do not need a dirty 20th century energy infrastructure. I’ve lived there. I know.

    5)NO. Technology does NOT just happen. It requires research–basic research into the underlying science long before someone can stumble across the new invention. Where would Farnsworth have been without Maxwell and Faraday or Marconi. And dealing with climate change is going to demand developments in areas where we haven’t begun to do research yet.

    6)No. A 90% confidence does not equate to a 10% probability of being wrong. Don’t believe me? Tell you what. Let’s consider a little wager. Let’s say we have some opaque jars full of marbles. I tell you that all the marbles are either black or white. I then proceed to draw 22 marbles out and replace them. All 22 are white. Now, according to binomial statistics, which is the appropriate statistics here, I can conclude with 90% confidence that at least 90% of the marbles are white. I now offer you a bet: 10:1 odds–you win if the next ball is black. Do you take the bet?

    Confidence has to do with the level at which you have demonstrated a proposition, not the probability that it is true or not. It has to do with how much evidence you have so far.

    Now, Jim, I would suggest that if you would like to profit from this website, you would do well to take advantage of what it has to offer–namely the best resources for learning the science. You will find plenty of people here who have learned the material before you who would be happy to help you out with sincere queries (myself included). If all you want to do is “debate” or “vent” there are plenty of places on the intertubes where you can do that.

  16. 516
    ccpo says:

    Heard of Peak Oil, also heard of tar sands and methane hydrates [not that I’m saying we should, just that we could]

    If you think tar sands and/or methane hydrates are going to save the day, then you don’t understand peak oil. Since you claim to know what you’re talking about, can you please explain why I say this?

    Before lecturing me about how I need to read for 30 minutes, please take 3 minutes to read what I actually write with an open mind.

    Comment by jim edwards — 3 June 2010 @ 2:21 AM#

    I did. It’s way off. What should I do next?


  17. 517
    ccpo says:

    at heart, I’m an educator.

    I, actually being an educator, beg to differ. An educator does not accept false answers to questions. They will encourage discussion by facilitating a student’s discovery that what they offered was incorrect, but they will not say, “Yes, blue is yellow.”

    I think it’s best if everybody presents their views to the public in the most effective manner. Sunlight makes the best disinfectant, after all.

    Who cares about views? Their evidence is what is in question. But I note you are interested in opinions, not science. Basically, you are fully in favor of promoting false equivalencies.

    They’re hearing: earthquakes and everything bad is caused by AGW

    Why lie? I am on the computer far too much reading and researching, and what you are saying here is a huge distortion. You are taking, for example, that melting ice in Greenland leads to tremors, which is true, and twisting it into a lie that all tremors are. Why lie?

    the science is settled

    It is. Why not say so? (See multiple explanations on this site.)

    the world will end

    False. Civilization? Very possible. After all, many civilizations already have.

    polar bears will go extinc

    Mightn’t they? Can you say they won’t? The extinction rate today rivals that of the great extinctions in Earth’s past.

    and transitioning our economy will be painless

    Wow. A flat out lie.

    or even create immediate economic prosperity.

    Who is saying this? Cite your sources.

    Every time they find they’ve been oversold in one area, you run the risk of losing them, entirely.

    What is being oversold? If anything, the effects of climate change are being undersold. I’ve been called an alarmist more times than I can count, yet my views on Arctic Sea Ice and methane have been exceedingly accurate since 2006. After 2005 and the IPCC report, I stated unequivocally that the ice was melting faster than all but a tiny majority expected. I was right. Since then we have found that not only is Arctic Sea Ice melting, but so is Greenland and Antarctica. And the Arctic has set new records for extent (’07) and near-records for extent (’08, ’09) and set new record lows for total ice mass *every year.* This year is shaping up as a new record, and possibly much lower than the previous low. If we get a strong La Nina and the typical largely cloudless Arctic Ocean it typically brings, it’s a guarantee of new records for extent and mass, and a new record for mass, regardless of El Nino.

    I could explain this, but it would be pointless. I’m just overselling.

    I understand how the economy works. One thing I would note is that history has shown that seemingly intractable problems often become easier to solve the longer you wait [as technology improves].

    Then you don’t understand how the economy ultimately works. You are describing an economy pre-crest, pre-resource limits. From that point on, technology, a.k.a. greater complexity, typically leads to decreasing returns and ultimately helps usher in collapse.

    George W. Bush, who I did not vote for, probably saved more lives than anybody in the last fifty years by spending our tax dollars in Africa to combat AIDS.Comment by jim edwards — 2 June 2010 @ 7:53 PM

    Is that before or after counting the up to 1,000,000 who died in his wars? Also, if Bush wrote legislation to fund AIDS treatment, I’m a monkey’s uncle. Perhaps you mean he didn’t veto someone else’s good intentions?


  18. 518
    ccpo says:

    Most people have never considered the evidence pro or con. They’ve just been told, “the debate is over.” The people who don’t agree with you are not deniers in the perjorative sense. They’re unconvinced.

    False logic. If they aren’t trying to understand, but make a choice anyway, they are deniers, not unconvinced.

    I apologize for being vague. I meant to say my views on AGW are immaterial but that I want the pro / anti / don’t-know sides to make their best cases to the electorate. Whether my ideas have merit shouldn’t depend on which “team” I belong to.

    How does it not matter if you’re on a lying team, for example?

    #4 is correct, but it really begs the question. Africa needs more energy infrastructure – but what kind ? The US could happily rely on Canadian tar sands for a very long time – so long as our dollar is still accepted.

    Not at all. Tar sands will likely never meet US demand unless US demand falls to less than 4 or 5 mb/d.

    #2 is a fear-mongering statement without evidence provided to back the claim. Most complex natural control systems involve negative feedbacks, not positive feedbacks with cascading tipping points.

    Comment by jim edwards — 3 June 2010 @ 5:00 PM

    Cite, please.


  19. 519
    Completely Fed Up says:

    “#2 is a fear-mongering statement without evidence provided to back the claim.”

    And “what the IPCC is trying to get us to do will RUIN OUR ECONOMY!!!” is not??

  20. 520

    je 513: If you actually read anything I wrote, you’d see I’m trying to help you convince them.

    BPL: You won’t do it by minimizing the very real dangers, or saying that deniers of the science and defenders of the science are “equally” distorting the reality.

  21. 521
    Anonymous Coward says:

    Frank Giger (various posts),
    At the risk of stating the obvious, being an activist or an alarmist does not make one a communist. Similarly, being a communist does not make one an alarmist or an activist.
    If you find that people are making preposterous claims on RC or elsewhere, I would not recommend blaming it on a hidden political agenda. Not only is there a simpler, saner explanation but I would expect people who have an actual hidden agenda (besides trolling) to put some effort into their writing so as to make it less laughable.
    I would instead recommend turning down your imagination a few notches, reading actual communist publications and comparing what’s said therein to what’s said by the people you believe to be crypto-communists.
    Is it the Cochabamba summit that got you worked up so?

  22. 522
    Jim Eager says:

    jim edwards @514, actually, I have worked in manufacturing. I can assure you that in manufacturing, and in business in general, the purpose of reduce, reuse, recycle is to reduce costs, period — costs of raw materials and inputs, cost of waste handling and disposal, energy costs, costs of compliance with legal regulations, etc — not to protect the environment.

    Any environmental benefit is either collateral to the goal of reducing costs or is legally mandated. Any costs that can legally be externalized will be. Any legal regulation that can be gotten around will be.

    If you think not then you have not been paying attention: it hasn’t been just low wage labour and low cost transportation that has sucked manufacturing out of North America, and it has not just been the physical plants and jobs that were exported. The rapid growth in unregulated emissions in China and India are in large part our own previously regulated emissions.

    I stand by what I wrote: neither capitalism nor communism ever voluntarily did a single thing to protect the environment.

  23. 523
    Hank Roberts says:

    > Jim Eager
    > neither capitalism nor communism

    That’s one reason people promote democracy as a third alternative.

    You wrote:
    “costs of compliance with legal regulations, etc — not to protect the environment.”
    “”costs of compliance with legal regulations to protect the environment.”

    How do you get legal regulations to protect the environment? Elect someone like Richard Nixon and push for legal regulations to protect hte environment.

    There’s a famous observation from history that capitalist systems can be created starting from a democracy, but nobody has ever created a democracy starting from a capitalist system.

    China–going from soc ialism to capitalism without passing through democracy–is cautionary. They may have a chance to disprove history’s pattern if they can establish a democracy, and then environmental protections.

    Start a democracy and hang on to it if you want to protect the environment. It’s not a guarantee; it may be a precondition for success.
    Time will tell.

  24. 524

    #513 jim edwards

    Didn’t you say you were an attorney? Then you of all people should know that motive and bias establish premise, can of worms though that may be.

    I ask again, more specifically, what do you believe to be the cause of the change in radiative forcing?

    Do you believe Lomborg’s argument is sound?

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  25. 525
    Completely Fed Up says:

    “That’s one reason people promote democracy as a third alternative.”

    Democracy is not a third option.

    It’s an orthogonal option.

    Capitalism/Communism is how you apportion the wealth and power.

    Democracy is about how you attain a government.

    Not to mention, nobody’s ever done a democracy (the Greeks got closest, as long as you were male, Greek, adult and not insane).

  26. 526
    Jim Eager says:

    Hank @523: “That’s one reason people promote democracy as a third alternative.”

    Which is my point, Hank, although I don’t think democracy is an alternative, it’s a different concept entirely. Capitalism is an economic system, not a system of government. Capitalism is only capable of acting economically, it can not address noneconomic matters. It requires a government to act in the interest of society as a whole on noneconomic matters. Theoretically that government doesn’t have to be a democracy, although it has so far proven to be the least bad system of those tried. Communism, as it was constituted in the 20C, attempted to be both an economic system and a system of government, with disastrous results for both people living under it and for the environment.

    I entirely endorse your advice to start a democracy and hang on to it if you want to protect the environment.

  27. 527
  28. 528
    Mal Adapted says:

    No economic system can protect the environment if environmental impacts aren’t counted as costs in the production of goods and services. Otherwise, the tragedy of the commons ensues.

  29. 529
  30. 530
    Didactylos says:

    “Will 2007 still be considered an anomaly by September?”

    If the Arctic sea ice extent has shown us anything, it is that the trend is inexorable, but short range forecasting is hard.

    What does that remind me of?

  31. 531
    Didactylos says:

    I watched a film a while back about school debate teams in the US. What struck me in particular is that the winning strategy is basically the Gish Gallop. It is taught, expected, and routinely delivered. It encourages shallow thinking, and has no requirements for solid evidence.

    How many of these debate team members enter into politics? How many people are left with the impression that “winning” simply requires flooding your opponent with more arguments, true or not?

  32. 532
    Hank Roberts says:

    > seemingly intractable problems often become easier to solve
    > the longer you wait [as technology improves].

    Shifting baselines and forgetfulness ‘solved’ many such problems.

  33. 533
    ccpo says:

    “Speaking of climate change commitment . . .

    Will 2007 still be considered an anomaly by September?

    Comment by John P. Reisman (OSS Foundation) — 4 June 2010 @ 8:51 PM”

    Not much of one, particularly if a La Nina develops, and more so if a strong one, because – and I just learned this, and had been thinking the opposite – La Nina is associated with lower cloud cover in the Arctic.

    Seriously, though, did people not see this coming? We had the report last spring of the ocean voyage well into Arctic waters that revealed the ice to be more like Swiss Cheese than pack ice, even in areas the satellites were seeing as pack ice. Apparently they form of the ice, even if so weak and broken, was seen as the same as true pack ice.

    Then we had the shallow Siberian continental shelf out-gassing methane at a rate equal to the entire world ocean emissions. (As expected by those of us paying a bit of attention. I even had a conversation with a scientist, I think in Colorado, about two years ago who assured me this wouldn’t, couldn’t happen for a *very long time.* I told him to look at the reality, not the research. Al begins with observations, no?)

    Then we had the slow freeze in the Arctic. Warmer waters, anyone? And that fast, late growth of ice, but primarily in the area of Alaska, thus pretty much irrelevant.

    Then we get reports of the warmest 12 months, warmest Jan- April… etc.

    And how can we forget that greatest of all hits, “Did you know ice mass has been falling even more steadily than ice extent?” A.k.a, “The amount of total ice has fallen even in the years when extent was “rebounding.””

    And now for something really scary:

    June 4, 2007:

    June 4, 2010:


  34. 534
    Didactylos says:

    It’s dangerous to make predictions about ice extent. All we can really say today is that we are missing one million square kilometers – exactly like this time in 2008. That led to an almost unprecedented summer low, but conditions didn’t favour the dramatic late loss we saw in 2007.

    This year, maybe it will, maybe it won’t. May certainly saw a record rate of decline. If that continues through June, then we may see conditions very similar to 2007.

    It’s not worth getting excited about, sadly. It will just be another baseline for the denier to hang their lies from. “The ice has recovered since 2010. See, there’s thousands of square kilometers more than in 2010!”

    The stupid will just keep coming.

  35. 535

    #533, #534

    No way to tell since we really don’t have that level of understanding or resolution on natural variation just yet. I find it interesting that we are largely under the 2007 minimum though. Will be interesting to see what happens next and see if we improve predictability based on variation and conditions.

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  36. 536
    jyyh says:

    the aleutian low moved further than expected towards NA coast and doesn’t create the push on ice cross arctic, as a result ice movement has slowed everywhere but nares strait. all the seas around arctic basin are ahead of schedule. is this the beginning of the fast melt? already??

  37. 537
    Edward Greisch says:

    513 jim edwards: The climate is the one thing that has positive feedbacks. And they are large enough to really kill us. This is not a joke or a hype. The feedbacks we are already encountering are: Loss of Arctic ocean ice [albedo], melting Tundra peat bogs [CH4] and ocean bottom CH4 hydrate melting [CH4]. This is not fear mongering. I am afraid, and you should be too. Mother Nature has plenty of ways to make us humans extinct. There is no exception for humans. I have listed the kill mechanisms many times.

  38. 538

    #274 Richard Steckis

    I sometimes rewrite a sentence as my thoughts evolve. Since this is a blog rather than an article, I tend to not proofread as much as some might like. Call it a character flaw if you wish but it is not because I am a yank :) (though I believe I caught your drift).

    I do hope you are not inferring the British would never make a mistake? There is a Gulf of understanding to refute that at the moment.

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  39. 539

    #496 jim edwards

    My views are immaterial; at heart, I’m an educator. I think it’s best if everybody presents their views to the public in the most effective manner. Sunlight makes the best disinfectant, after all.

    Your analogy is weak. Try visiting a few of the places listed at this web page:

    and try spreading some of your sunlight at those places. I spoke with one creationist who said he did not really believe that the earth was only 6,000 years old, he thought they were wrong. From his perspective, the earth is 60,000 years old.

    This has nothing to do with ‘disinfectant’, it has to do with common sense and reasoning pertaining to understanding the validity of the scientific method of discovery. If I read your argument correctly, you think just show both sides?

    You may be an educator, but I hope not on AGW. You don’t have sufficient context to do this well. In other words, if you are educating on this subject by showing both sides in even context, you are a bad educator.

    Without context your are not educating, you are confusing. To pit opinions against well established scientific understanding as if both have validity is not educating. It would be like saying some people say 2+2=4, but other people say 2+2 is not 4, it could be something else. And then introduce quantum mechanics to them. Your premise has not foundation in reason as you have made clear. i.e. you have not made your case.

    I maintain, and you should know better, what you think reveals confirmation bias just as what I think. if what I think is based on the well established science, and what you think is based on giving even play to opinion, as well as the science, then you do not understand the contexts involved and absolutely should not be educating on the subject.

    I ask again, more specifically, what do you believe to be the cause of the change in radiative forcing?
    Do you believe Lomborg’s argument is sound?

    #513 jim edwards

    Context is key.

    – The debate is over on the well established science (unless you have some dramatic new evidence that shows that 2+2 is not 4?). Your idea that all it needs is sunlight is interesting in this context that the sun is already shining on the evidence and the understanding. Some choose to stay in their rooms and avoid the sunlight, preferring instead to read stuff on the intertubes that support their notion. More sunlight wont help until they are willing to step out into the light.

    – as far as I can tell you are still being ambiguous on too many things.

    – as far as I can tell, there is no significant evidence that you understand the ‘economy’. Your saying you understand the economy is not evidence of understanding. I am not saying you have no understanding of economic functions is specific contexts.

    To be fair, I would not claim I ‘fully’ understand the economy either though. I admit to being a generalist. It’s just that from what I am reading in your posts, I sense that you do not have sufficient grasp to understand what AGW means in that context. Maybe you could be more specific?

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  40. 540
    MapleLeaf says:

    Have people seen this from Spencer?


    This follows a post in which he estimates climate sensitivity (CS) to be about +1.7 C– marginally higher than the lower bound of the range of CS given by IPCC.

    Intriguing, in the one post he determines CS to be within the range given by the IPCC, and in the post following that he claims that almost all of the N. Hemisphere warming in the 20th century can be explained using internal climate variability (that assertion also seems to contradict the findings of Swanson et al. (2009, PNAS)). That is, the warming in the N. Hemisphere can allegedly be attributed to variations in SOI, AMO and PDO.

    Why the focus on N. Hemi. temps?

  41. 541

    #540 MapleLeaf

    Talk about grasping at straws! He seems to be picking at the periphery of understanding while ignoring the radiative forcing increase, and a multitude of other factors.

    For his idea to stand he will need to show that the dramatic increase in radiative forcing will not, should not, and in fact has not warmed the planet.

    I would love to see him get that through peer review and response!!!

    Oh, sorry, he’s not doing that? He’s just trying to support his notions (in opposition to the well established science) possibly/probably to boost his book sales.

    He did get one thing right though in context. “a minority of climate researchers” are arguing against the well established science.

    Spencer, Singer, Lindzen, Svensmark, Christy, Pielke. . .

    In that, one, or his minority, can state, based on a particularly myopic view, that natural variation ‘could’ explain the warming. Wonderfully ambiguous. “Could, “might”, “possibility”, “natural” (creative word crafting to the ambiguous). I don’t know if his cherry picking CRUTem3 and time periods is a factor, but based on the past, sometimes one can find a causal relationship in the current (I’m referring to his confirmation bias, not the data). I’m sure someone else can pick this apart better.

    Of course he brings up the canard of cloud cover (albedo).

    He ‘may’ be technically correct from an obtuse angle based on a limited view, but it seems reasonably obvious that he is contextually wrong. Cherry picking pieces to explain the whole is not good science. But is sure makes for a dandy red herring to wave around :)

    Context is key.

    As to why focus on NH temps? Hmmm. . . one ‘might’ wonder about that.

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  42. 542
    Completely Fed Up says:

    “Why the focus on N. Hemi. temps?”

    Because whilst the global average of climate reported by the IPCC is warmer than the gestalt peaks of the “MWP”, no such MWP exists to anything like the extent in the southern hemisphere.

    Therefore including the SH would mean that the MWP signal would be even LOWER.

    If denialists considered doing that, they would be creating the same Hockey Stick disappearance of the MWP as they accuse the IPCC of.

  43. 543

    About the melt: Didactylos is right, I’m afraid: 2010 will probably just be the new 1998.

    And he’s right about the variability and unpredictability. (Review the events of February-March in that regard!)

    A comparison: we’re currently (June 7) about three day’s melt ahead of 2006 (the previous low for this date.) That is, today’s extent is about the same as that of June 10, 2006. (Of course, 2006 did not see the then-record low minimum set in 2005 eclipsed–though 2006 did very effectively help set the table for the new record that arrived in 2007.)

  44. 544

    #543 Kevin McKinney

    Of course I don’t know, but the interesting behavior of the negative AO this year could be playing a role in the lower trend-line. Darn thing pushed back more negative again.

    I don’t have enough understanding to know the inter-dynamics, but I do think this year will add some good indicators to increasing predictability.

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  45. 545
    Doug Bostrom says:

    Somebody with some expertise might enjoy(?) looking at this latest work of Scafetta.

    Apparently a significant amount of recent warming is down to bad vibes:

    The planets, in particular Jupiter and Saturn, with their movement around the Sun give origin to large gravitational and magnetic oscillations that cause the solar system to vibrate. These vibrations have the same frequencies of the planetary orbits. The vibrations of the solar system can be directly or indirectly felt by the climate system and can cause it to oscillate with those same frequencies.

    More specific physical mechanisms involved in the process include gravitational tidal forces, spin orbit transfer phenomena and magnetic perturbations (the jovian planets have large magnetic fields that interact with the solar plasma and with the magnetic field of the Earth). These gravitational and magnetic forces act as external forcings of the solar dynamo, of the solar wind and of the Earth-Moon system and may modulate both solar dynamics and, directly or indirectly, through the Sun, the climate of the Earth.

    Got that? The vibrations of the solar system can be directly or indirectly felt by the climate system and can cause it to oscillate with those same frequencies And guess what? This means all the models are wrong, wrong, wrong:

    In conclusion, data analysis indicates that current general circulation climate models are missing fundamental mechanisms that have their physical origin and ultimate justification in astronomical phenomena, and in interplanetary and solar-planetary interaction physics.

    For myself, a mile wide and an inch deep, my credulity meter drops to “zero” when I bump into Scafetta’s claim that the IPCC flatly attributes 100% of warming since 1970 to anthropogenic causes. For me, everything Scafetta writes after that rhetorical fling turns into a gray blur of bemusement. But there’s much, much more to wonder about.

    This leaky balloon is going to take a while to deflate and meanwhile it is buoying the hopes of magical thinkers around the planet.

  46. 546

    The planets cause vibrations in WHAT??? The luminiferous aether??? What is vibrating?

  47. 547
    Completely Fed Up says:

    The aether was my call too. However the whole think is so silly (beyond Monty Python silly) that I couldn’t be arsed pointing out its stupidities.

    It’s like being given an all you can eat meal by dumper truck. It’s not even worth starting.

  48. 548
    Doug Bostrom says:

    Barton Paul Levenson says: 8 June 2010 at 11:44 AM

    The planets cause vibrations in WHAT??? The luminiferous aether??? What is vibrating?

    Well, there are early signs Scafetta’s latest is setting the chumposphere all aquiver, and no wonder because the paper is chock-a-block with such exciting and compelling evidence as this:

    Interestingly, the traditional Chinese calendar, whose origins can be traced as far back as the 14th century BCE, is arranged in 2 major 60-year cycles [Aslaksen, 1999]. Each year is assigned a name consisting of two components. The first component is one of the 10 Heavenly Stems (Jia, Yi, Bing, etc.), while the second component is one of the 12 Earthly Branches that features the names of 12 animals (Zi, Chou, Yin, etc.). Every 60 years the stem-branch cycle repeats. Perhaps, this sexagenary cyclical calendar was inspired by climatic and astronomical observations.

    It’s obvious, once you think of it. The traditional Chinese calendar was arranged in 60 year cycles, therefore today’s climate models are fundamentally wrong. Perfectly straightforward.

    Seriously(?) the paper is heavily dependent on identifying a 60 year cycle in the climate (where have we heard that before?) and thus it early establishes some caveats to bolster the case in spite of the otherwise distressingly phantasmagoric nature of these cycles:

    Errors in the data, other superimposed patterns (for example, volcano effects and longer and shorter cycles) and some chaotic pattern in the dynamics of these signals may sometimes mask the 60-year cycle.

    In other words, just because you can’t see it does not mean it’s not there.

    One very large plate of spaghetti, sliding down the wall.

  49. 549
    Witgren says:

    Doug Bostrom,

    Well, at least we know there’s employment for astrologers still in this day and age…all he needed to do was add some comments about “when Jupiter is in the House of Aries” or some such… BPL, I think Scafetta is vibrating, more than anything.

  50. 550
    waspbloke says:

    Could somebody at RC take a look at this and comment:

    I’m not sure I’ve read it right as the terminology is a little dense for my rudimentary understanding. It seems to be saying that GCMs overestimate albedo of clouds by some way? Did I read it right? Is this analysis valid and if so, what might such adjustments mean for model predictions?