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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. 251

    ralphieGM 233: If it took a billion years to accumulate fossil hydrocarbons how is it possible to release the CO2 in that mass in “a couple of dozen decades”?

    BPL: The coal is mined, then shipped to power and industrial plants where it is burned. The reaction is

    C + O2 => CO2

  2. 252

    ROFL, Doug.

    May I steal (with attribution) your line about subpoenaing Venera 9? It would make a great Tweet.

  3. 253
    Alan Millar says:

    #249 Barton Paul Levenson

    “Here’s your explanation: Continents moved, the albedo changed, the rise of vascular plants increased the rate of CO2 weathering, and the continued fall in mantle temperatures slowed the outgassing of CO2.”

    Barton

    Those factors may indeed have contributed to the billion year negative climate response.

    My point is that such or similar and combination of factors continue today.

    What evidence is there that todays combination of such factors leads to a positive climate response rather than the negative one we have seen for the last billion years?

    Alan

  4. 254
    Doug Bostrom says:

    Barton Paul Levenson says: 28 May 2010 at 7:19 PM

    May I steal (with attribution) your line…

    Be my guest and if there’s a space(!) problem forget the attribution.

    CEI’s Senior Fellow of Honeybucket Cleaning Chris Horner loves the limelight.

  5. 255
  6. 256
    Snapple says:

    I hope that the British find the hacker/s soon.

    Here is the latest about the investigation.

    http://legendofpineridge.blogspot.com/2010/04/norfolk-constabulary-continues-its.html

    “Climategate” made me read about global warming, and it was not hard to see that the denialists are very dishonest. They don’t argue with what the scientists really say. I always read what the scientists say, not just what the denialist claim they say. Once I realized that denialists deliberately lie, I stopped reading them to try to understand scientific arguments. Their articles are only useful as examples of propaganda and sophistry.

    Climategate brought me into the AGW camp, but it doesn’t seem to have had that effect on other people. I still hope a successful criminal investigation will change that.

    The British investigators described what the alleged hackers did as “criminal offences in relation to a data breach at the University of East Anglia.”

    According to the Financial Times:

    “There have been indications that the hackers could have been based in Russia, and some experts believe they may have been hired by sceptics based in the US.”—The Financial Times (4-15-10)

    I hate to think Americans did this to the British.

    I just delete denialists because they are crude arrogant bullies. They imagine that they are smarter than every scientific organization–NAS, NASA, etc. Really, I think they are not very successful or accomplished people if they think they can understand climate science from some e-mails.

  7. 257
    Rattus Norvegicus says:

    Doug, I developed a system to get my cat to take his prednisone: use a bit of butter, or even better anti-hairball creme, and bury the pill in that. Worked every time.

    [Response: I was going to say OT--but then the anti-hairball comment brought it right back in line--Jiim]

  8. 258

    #236/240 David B. Benson #237 Hank Roberts

    Thank you both. I tried and failed so far. It’s not in Siddall et al 2003 “Sea-level fluctuations during the last glacial cycle”. The Glickson image is pixelated.

    My problem is pixilation because I need to zoom in on the lower image where the break is. Usually in a PDF they insert the full resolution images which can be 2000 pixels wide or more, so zooming in does not pixilate as much.

    But you did give me an idea to search the sources.

    For example on page 1927 of rsta.royalsocietypublishing.org/content/365/1856/1925.full.pdf I see the ref. (c) palaeoclimate temperature change: calculated and observed temperature. Calculated temperature is the product of forcing (b) and climate sensitivity (3/48C (W mK2)K1). Observed temperature is Vostok temperature (figure 1) divided by 2.

    It’s good HiRes and can be enlarged, but it does not have the hook at the end. I will keep looking though the references to the original data or the PDF


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  9. 259
    Antiquated Tory says:

    I don’t think the goal is “understand science.” I think the goal is “delay any action so I can keep making money/not be inconvenienced for the duration of my lifetime.” Then humanity can go to Hell for all they care.

  10. 260
    Ray Ladbury says:

    Lichanos says, “Ah, beware the sword of the Dunning–Kruger effect, for it cuts both ways!”

    Well, given the way you fell on it, I believe it is safely sheathed inside you.

  11. 261
    ralphieGM says:

    “BPL: The coal is mined, then shipped to power and industrial plants where it is burned. The reaction is

    C + O2 => CO2″

    Sir: CO2=> C + O2 also.

    You are worried that ALL the ancient CO2 used to created fossil hydrocarbons are being released back to the atmosphere in a brief spurt of human productivity these past few decades. If we burn fossil hydrocarbons we will merely return the CO2 to the atmosphere where it will be dissolved in the oceans or used up by plants (see the reaction above). This worry about CO2 is premature. I think CO2 may be good for the globe and plant life – so not to worry.

    [Response: Think again--jim]

  12. 262

    #220 Lichanos the anonymous

    Re. your concern with the Dunning-Kruger effect. You said it cuts both ways? But there are a couple problems with your assessment. To paraphrase the words of a character from ‘The Princess Bride’ I don’t think that effect means what you think it means.

    In fact I think you have exemplified the effect while inferring it is I who do. Let me break it down for you. First, the description of the effect:

    http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect

    The Dunning–Kruger effect is a cognitive bias in which “people reach erroneous conclusions and make unfortunate choices but their incompetence robs them of the metacognitive ability to realize it.”[1] The unskilled therefore suffer from illusory superiority, rating their own ability as above average, much higher than in actuality; by contrast, the highly skilled underrate their abilities, suffering from illusory inferiority. This leads to a perverse result where less competent people will rate their own ability higher than more competent people. It also explains why actual competence may weaken self-confidence because competent individuals falsely assume that others have an equivalent understanding. “Thus, the miscalibration of the incompetent stems from an error about the self, whereas the miscalibration of the highly competent stems from an error about others.”

    Here’s the primary problem. You are exemplifying the following in your posts “The unskilled therefore suffer from illusory superiority, rating their own ability as above average, much higher than in actuality”

    All I do is say look at the well established science, and have on several occasions inferred that I can and do make mistakes. So I sort of fit the “by contrast, the highly skilled underrate their abilities, suffering from illusory inferiority”, description.

    Said another way, you have presented your claim to have superior logic as a proof, while I have only claimed that your opinion can’t overturn the well established science and the understanding that derives from that.


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  13. 263
  14. 264
    John E. Pearson says:

    255: Snapple said “denialists … are crude arrogant bullies. … I think they are not very successful or accomplished people if they think they can understand climate science from some e-mails.”

    Snapple: Blog “scientists” bear the same resemblance to scientists that pole cats do to mountain lions.

    http://itech.pjc.edu/sctag/marbled_polecat/pic4.jpg

    http://i28.photobucket.com/albums/c245/johnepearson/lion.png

    http://www.inquisitr.com/wp-content/rush-limbaugh.jpg

    http://europe.theoildrum.com/uploads/465/cv_hansen.jpg

    See?

  15. 265
    John E. Pearson says:

    ralphieGM says: “I think:

    You haven’t shown any evidence of that.

  16. 266
    Ron Taylor says:

    Alan Millar says #253: “What evidence is there that todays combination of such factors leads to a positive climate response rather than the negative one we have seen for the last billion years?”

    Not “for” but “over” the last billion years. There were indeed some very tough periods for today’s fragile humans during that billion years, such as the Cretaceous, for one example. What we are concerned about is the next few hundred years. What happens 20,000 years from now might be fine for the few people still around to enjoy it. But for the next few hundred years the evidence points to a very unfortunate positive response.

  17. 267
    Thomas says:

    Alan, 191. You could find this answer with some digging, but I’ll give you the gist of how homostasis on a geological timescale is thought to work. Essentially CO2 and some other greenhouse gases moderate temperature. Volcanic activity associated with plate tectonics recyles CO2 that had once been buried in the form of carbonates and subducted into the mantle. The weathering of silcate rocks absorbs CO2 forming carbonates. The rate of weathering increases with higher temperatures, so fortunately for the lifeforms on this planet there is a sort of thermostat that acts on a geological timescale. Of course these processes, volcanism, and weathering are not entirely constant (assuming no change in global temps to normalize the meaning of weathering suscepibility), and that means some geologic ages are hotter than present, and some are colder. There is evidence that the planet probably had snowball earth episodes (essentially total glaciations), and has been quite a bit hotter than present as well. But on the whole the carbonate/silicate weathering has tended to keep the planet mostly within a reasonable temperature range. If CO2 didn’t act as a greenhouse gas and allow this crude thermostat to work, advanced lifeforms would not have developed!

    Mark @170. There is some coupling of temperature and CO2 as well. Higher temperatures over centenial/millenial timescales do tend to increase atmospheric CO2 concentrations. Fortunately the strength of this effect isn’t very high, otherwise the climate of our planet would be highly unstable. The issue has been discussed here.

    Hank Roberts. Thanks. I think that is excellent advice. I know people get pretty frustrated, what with the same tired trollish attacks again and again. But we need to be reminded that allowing ourselves to get riled up is counterproductive. I hope people will ask themselves the question “I could post XXX, but is that wise? Will I regret it later on?”. Its easier for me (I think) because I am more of a part-timer here than many. Getting away from the sniping, and the trolls helps you to avoid getting overly frustrated.

  18. 268

    #261 ralphieGM

    I’ll make you a deal. Show me why there is no reason to worry, environmentally, economically and biologically, using actual science (peer reviewed and peer responded) in the context of the mean values of the consensus view pertaining to the effects of CO2, in the context of human existence, and I will send you a check for $1000.

    And just to make it more fun, if you are wrong, and there is something to worry about, you send me $1000.

    Cool with you?

    But first you have to post your real name. I don’t deal with fake people.


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  19. 269
    Jim Eager says:

    ralphie wrote @261: If we burn fossil hydrocarbons we will merely return the CO2 to the atmosphere where it will be dissolved in the oceans or used up by plants

    How’s that hypothesis working out for you so far, ralphie?

    Oh, look, the amount of CO2 has already increased in the atmosphere by 38% since we started burning fossil carbon on an industrial scale, and continues to increase by 2.2 to 2.9 ppmv each and every year.

    Reality is already telling you that you’re wrong. All you have to do is take your blinders off and take your fingers out of your ears.

    Come on, you can do it, ralphie.

  20. 270
    Jim Eager says:

    Alan Millar wrote @253: What evidence is there that todays combination of such factors leads to a positive climate response rather than the negative one we have seen for the last billion years?

    Oh, I don’t know, maybe the parts of the last billion years were temperature went not just up, but way, WAY up?

    Damn, but you’re obtuse.

  21. 271
    Jim Eager says:

    Barton, did you miss the post where the extended digit (Lichanos) came right out and admitted he was here to troll?

  22. 272
    Frank Giger says:

    Mind if I take a stab at this, since I’m the conservative in the crowd?

    First, the science isn’t claiming the climate – which is always changing – is primarily driven my man. This is the most common misperception and disconnect between activists of all stripes.

    What the science is showing is that the climate rate of change is, with more than ninety percent certainty, being affected by man-made emissions.

    Laid out on a long scale, we are past the “hump” of the inter-glacial pause, with the peak being the hot part, and starting down the cooling trend. However, we’re looking at a “double peak” bucking what is the expected curve.

    Like every investigator, the question is “what is different now from the past where this didn’t happen?” Some of it is tectonics, sure, but that’s a really slow grind. The factor that stands out is the greenhouse gasses we’re pouring into the atmosphere. Ice cores and other records bear this out, from the isotope variety of CO2 in the air to fossils.

    In many respects I’m disinterested in whether the present climate change track is caused by the early 1900′s or those dasterdly SUV’s because in large measure the die has already been cast and we’re going to have to adjust to it.

    That is different from saying we shouldn’t work to lower emissions of all types. If we’re nudging the current climate course by ten percent why wouldn’t we seek to mitigate this? It’s the old saw of when one finds one’s self in a hole the first course of action is to stop digging.

    This is also way different from agreement with the proposed political actions to mitigate our effect on the current climate trend. I can’t think of a single agenda item at the UN climate summits that makes any sense to me other than as a means to shake down the “developed” world for money with little actual progress – or as a feel good “greenwashing” effort to provide political cover to keep doing what we’re doing, as an example.

    I also try to ignore the fatalists. Activists always work with worse case scenarios in order to use fear to further their agenda. “We’ll all be dead in a mass extinction event in twenty years if cap and trade (or a carbon tax or some government market control measure) isn’t passed this Congressional Session!”

    Really?

    I’m not reading any of that in the IPCC reports.

  23. 273

    #263 Bob (Sphaerica)

    On page 20 of that paper is what looks like the same data set, but it does not have the break and elongated period for the last 150 years.

    It is the break and elongation of time period that makes it the right image for the video.

    I really appreciate your trying to help though. I’ve been trying to locate it for about a month and a half now.


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  24. 274
    Richard Steckis says:

    24
    John P. Reisman (OSS Foundation) says:
    26 May 2010 at 1:38 PM

    Minor grammar correction:

    “An quantifiable reduction in”

    should read:

    A quantifiable reduction in

    You yanks seem to put an in front of everything. “An” is generally reserved for words that start with vowels (e.g. a, e, i, o, and sometimes h as in hotel, u is the vowel with the exception to this rule).

  25. 275
    RalphieGM says:

    Jim Eager:”Oh, look, the amount of CO2 has already increased in the atmosphere by 38% since we started burning fossil carbon on an industrial scale, and continues to increase by 2.2 to 2.9 ppmv each and every year.

    Reality is already telling you that you’re wrong. All you have to do is take your blinders off and take your fingers out of your ears.”

    Come on, you can do it, ralphie.”

    I can. But increasing CO2 in the atmosphere is not necessarily a bad thing. Unless you think the extra CO2 will make the sky fall – which would be a bad thing. But it is also possible that increased solar radiation has raised ocean temperatures, thereby releasing a bit of that ancient CO2 into the atmosphere. My guess is as good as yours on this – I haven’t seen the higher CO2 levels you refer to linked to a single environmental problem.

    Ralph is my real name and I registered with my real email address. And I used my initials to save typing. Not trying to hide anything here.

  26. 276
    Tim Jones says:

    The Competitive Enterprise Institute lawsuit includes allegations regarding Gavin Schmidt and Real Climate. They’re attributing a lack of timeliness to NASA responses to provide climate and related data. I thought we were assured this was taken care of.

    CEI sues NASA for temperature data, ‘Climategate’ documents
    http://www.eenews.net/eenewspm/2010/05/27/9/
    (05/27/2010) subscription
    Robin Bravender, E&E reporter

    A free-market advocacy group sued NASA today to obtain documents relating to errors in temperature data and a scientist involved in the “Climategate” controversy.

    The Competitive Enterprise Institute’s lawsuit,filed in the U.S. District Court for the District of Columbia, asks the court to require NASA to produce records the group tried to obtain under the Freedom of Information Act.

    http://www.eenews.net/features/documents/2010/05/27/document_pm_01.pdf

    CEI is requesting documents relating to corrections that were made to NASA’s temperature records and the agency’s response to FOIA requests. CEI has also asked for documents relating to the content or propriety of e-mails by NASA climate scientist Gavin Schmidt.

    Schmidt was among scientists whose e-mails were hacked last year from the University of East Anglia’s Climatic Research Unit. The publication of the e-mails sparked suspicions that the scientists were trying to manipulate and suppress climate data. Scientists involved in the controversy have repeatedly denied any wrongdoing.

    CEI said its FOIA requests were filed in 2007 and 2008, but NASA has objected to producing the requested information.

    “This lawsuit calls NASA to account for a nearly three-year stonewalling of internal documents on the most important regulatory issue of our time,” said CEI senior fellow Christopher Horner.

    A NASA spokesman was not immediately available for comment.

  27. 277
    Snapple says:

    The UVA law professors are sticking up for Dr. Mann. Don’t let this all get to you Dr. Mann!

    http://legendofpineridge.blogspot.com/2010/05/university-of-virginia-defies-comrade.html

  28. 278
    Edward Greisch says:

    244 Doug Bostrom: “people who show up here to argue against reality -do- have the capacity to understand.”
    Don’t be so sure of that. Rethink.
    ******Self edited.

  29. 279
    Doug Bostrom says:

    Rattus Norvegicus says: 28 May 2010 at 8:07 PM

    …use a bit of butter, or even better anti-hairball creme, and bury the pill in that.

    There’s no butter sweet enough, no flavor sufficiently delicious to mask the bitter taste of being forced to admit one has been duped by a smooth-talking huckster selling home meteorological stations, or a living caricature of a bloviating aristocratic buffoon straight out of Punch, or a mercenary litigator mantled with the ridiculous title of “Senior Fellow.”

  30. 280
    GFW says:

    Now that we’re actually doing some citation, I realized this is the right place to see if anyone can help me find a paper I swear I saw …

    IIRC, there’s a paper from the early 1990s where the GCM the authors were using predicted increasing antarctic ice, which puzzled them, and they found it was the increased precipitation (lowering surface salinity) that was doing it (in the model). Now that increase is happening in reality and it’s really quite a coup to have both predicted it and to have attributed it to one of the mechanisms now believed to underlie the observed increase.

    Does anyone know what paper I saw? It’s driving me nuts.

  31. 281
    Completely Fed Up says:

    “214
    Rod B says:
    28 May 2010 at 1:07 PM

    CFU, against my better judgment: “your idea is dumb” is not an ad hominem as you say; “you are dumb” is; ‘you are dumb, neurotic, psychotic, NUTS’ really is.”

    No, “you are dumb” is an INSULT, you idiot.

    (see what I did there? I insulted you. However, I didn’t ad hom you because that idiocy claim is not being used to say your’re wrong).

  32. 282
    Completely Fed Up says:

    Alan, it only takes 15 minutes to kill a human. Why does a billion years matter?

    It takes less than 200 years to turn a town into a strange ruin oddity. Why does a billion years matter?

    It takes less than 1000 years to turn a town into geology and strange magnetic disturbances for The Time Team to investigate. Why does a billion years matter?

    If we ruin the ecosystem, it won’t take a billion years to kill all humans.

  33. 283

    Alan 253,

    Different time scales. The silicate-carbonate cycle takes millions of years to work.

  34. 284

    ralphie 261,

    Time scales, ralphie. Time scales. The CO2 is building up faster than the natural sinks can absorb it. That’s WHY it’s building up and not remaining level.

  35. 285
    Ray Ladbury says:

    RalphieGM, Ah yes, there is never any need to worry when one remains unconstrained by knowledge of the facts. Dude, you know, under normal circumstances, I might try to educate you, but somehow I think that would be fruitless. Or I might try to correct the howling misinformation in your post so it did not infect anyone else’s thinking, but your missive is so pathetic that I suspect you make the few quasi-intelligent denialists blush. No, better to let your post stand on its own–a towering monument to ignorance.

    “Never teach a pig to sing. It doesn’t work, and it annoys the pig.”–Mark Twain.

  36. 286
    CTG says:

    Re #230, Ken Coffman.

    Ah, so Easterbrook’s trained attack puppy Coffman shows up here to try and distract attention from the fact that its master lied about present day temperatures.

    Coffman would like us all to believe that Don just made an innocent little mistake, and that the world really has been warmer for the last 10,000 years.

    Oh, and yes, the MWP actually happened in the 4th century AD. That’s where Don labelled it, so that’s where it must have happened – and if not, it was just a mistake, honest.

  37. 287
    Leonard Evens says:

    According to RalphieGM,
    “But it is also possible that increased solar radiation has raised ocean temperatures, thereby releasing a bit of that ancient CO2 into the atmosphere. My guess is as good as yours on this”
    Your guess is not as good as the established science as indicated in peer review published papers. That the increased carbon comes from human activities is well established. Among other things, it can be identified by isotopic analysis.

  38. 288
    Leonard Evens says:

    RalphieGM says
    “But in terms of a mass balance – we are only returning to the atmosphere what was here before – regardless of the speed at which it is reflowed. It seems to me we are just re-distributing CO2 rather than creating it – and I can’t see cause for alarm.”

    Let me ask you some questions. What are the reservoirs of Carbon in th Earth? How much Carbon, approximately, is in each reservoir? Where can I see your model of how Carbon moves from one reservoir to another on different time scales?

    If you find the answers to these questions, you may discover that you model for the Carbon cycle is hopelessly naive and no basis for for understanding it.

  39. 289
    manacker says:

    Jim Eager wrote:

    Barton, did you miss the post where the extended digit (Lichanos) came right out and admitted he was here to troll?

    Sure. There are those who wholeheartedly support anything posted by RealClimate as “gospel truth” since it reinforces their own opinions and beliefs (i.e. the “AGW-faithful”) and then there are those who may be skeptical of some of the claims regarding potentially serious AGW.

    The first category is called (by itself) the “scientific consensus” or “mainstream” and the second group is called “deniers” or “trolls”

    The same two groups are called (by the second group) the “AGW-groupies” and the “rational skeptics of the dangerous AGW premise”.

    Pick a name – it doesn’t make much difference.

    If you shut out different opinions and viewpoints you end up with a pretty sterile thread, with everyone just patting each other on the back with “good work”, “yeah, man”, “jes’ fine”, etc. comments.

    You need a “troll” or two to keep the thread from becoming a “yawner”, right? You should thank Lichanos for bringing some life to this thread.

    Max

  40. 290
    Snapple says:

    I am really proud of the University of Virginia today. They aren’t going to knuckle under to the unscrupulous and demagogic Attorney General Ken Cuccinelli’s judicial persecution of the climate scientist Dr. Michael Mann, allegedly for defrauding Virginia’s taxpayers.

    I’m a Virginian who sent children to U.Va., and the only fraud I see is Attorney General Cuccinelli, a shameless lickspittle who wastes my taxdollars defending the unscientific canards of the fossil fuel interests and persecuting global warming scientists under the color of law.

    http://legendofpineridge.blogspot.com/2010/05/uva-refuses-to-roll-over-for-commissar.html

    That barbarian Cuccinelli could read Dr. Mann’s scientific papers, but he wants to twist the e-mails into some conspiracy theory just like the thieves who stole the CRU e-mails.

  41. 291
    Rod B says:

    Ken Coffman (230), Though the diagram you reference (from NASA) shows the correct net results, I think it is misleading. It shows the radiation emanating from the earth surface as net 21% of the base; not showing the actual gross radiation of 116% of the base skips over some important physics. IMHO.

  42. 292
    ralphieGM says:

    #282 Ray Ladbury said “I might try to educate you, but somehow I think that would be fruitless.”

    Ray I am highly educated already. But if you can point to a single environmental problem linked to the rise in CO2 over the past 50 years I may change my relaxed attitude towards the problem and I will worry along with you.

  43. 293
    Rod B says:

    trrll (234), as a skeptic I agree with the thrust and most of the specifics of your post. Calling models a “weakness” is silly. But I think you come close to taking one too many steps. While models are extremely helpful and supportive, especially in multi-parameter analyses as climate, they are still built by the scientists and contain no independent cognitive process separate from what they are given and told to do. While indicative, they are not a nail-in-the-coffin proof/validation of any process as you come near to implying.

  44. 294

    #274 RalphieGM

    Where are you getting your information? Which scientific source?

    ‘possible solar’ – Based on what?

    http://www.ossfoundation.us/projects/environment/global-warming/myths/its-the-sun
    http://www.ossfoundation.us/projects/environment/global-warming/solar

    “I haven’t seen the higher CO2 levels you refer to linked to a single environmental problem.”

    Increasing droughts due to latitudinal shift is not an environmental problem?
    During the FACE experiments some had the foresight to examine the effect of higher CO2 concentrations on food crops. Crops that do not fix nitrogen dropped proteins. That’s not something to worry about? You see, just because the plant stalk gets bigger, does not mean that we get more, or better food.

    How do you come to these notions?

    As to your real name. I’m asking what is your last name? And will you take me up on my $1000 challenge (#268)?


    A Climate Minute The Greenhouse EffectHistory of Climate ScienceArctic Ice Melt

    ‘Fee & Dividend’ Our best chance for a better future – climatelobby.com
    Learn the Issue & Sign the Petition

  45. 295
    jyyh says:

    #278 GFW can’t help you there but remember seeing something similar, likely had something about incorprating glacier modelling into GCMs.

  46. 296
    Completely Fed Up says:

    “show up here to argue against reality -do- have the capacity to understand.”
    Don’t be so sure of that. Rethink.”

    They have the capacity.

    What they lack is the will.

  47. 297
    Doug Bostrom says:

    GFW says: 29 May 2010 at 3:03 AM

    You might try beavering the cites in papers mentioned here, in the section “Antarctic Sea Ice is increasing”:

    Is Antarctica losing or gaining ice?

  48. 298
    Lichanos says:

    #241 Barton Paul Levenson says:

    [I posted a comment on this before, but it didn't show up. So here's another try...L]

    Here is the argument for AGW.

    1. Increasing the level of a greenhouse gas in a planet’s atmosphere, all else being equal, will raise that planet’s surface temperature.
    2. CO2 is a greenhouse gas (Tyndall 1859).
    3. CO2 is rising (Keeling et al. 1958, 1960, etc.).
    4. Therefore Earth should be warming.
    5. Earth is warming (NASA GISS, Hadley Centre CRU, UAH MSU, RSS TLT, borehole results, melting glaciers and ice caps, etc., etc., etc.).
    6. The warming is moving in close correlation with the carbon dioxide (r = 0.874 for ln CO2 and dT 1880-2008).
    7. The new CO2 is mainly from burning fossil fuels (Suess 1955, Revelle and Suess, 1958).
    8. Therefore the global warming currently occurring is anthropogenic.
    Q.E.D.
    Which of the above points do you dispute, and on what basis?

    1. I agree. “All else being equal” is a very important phrase here. Lindzen puts it just this way. The earth is not this type of a system -
    it is a dynamic system. More CO2 will tend, however, to raise temperature to a point.

    2. I agree totally.

    3. I agree completely.

    4. This is a reasonable deduction. In that sense, I agree. I agree that AGW is a plausible scientific hypothesis. I have never said otherwise.

    5. Very vague. Earth has warmed? Since when? Last 200 years? Since the Little Ice Age? Since Industrialization? How much has it warmed? If it has warmed, is the increase more than we have ever seen in the past? (I don’t think anyone says this, only that the RATE is greater than ever in the past.) Ice caps go up and down. Much of northern ice cap ice free in 18th century (historical literature) and north pole ice free in and early 1960s (see Navy photos of nuclear submarines at th pole). Questions of the validity of the temperature record are important – we are dealing with increases of relatively small magnitudes.

    6. If No. 5 is demonstrated, then No. 6 is true. They are linked. You must pass 5 before you get to assert 6.

    7. Completely agree. Seems indubitable.

    8. Non sequitur. I would say, “plausible that AGW is part of the warming observed, whatever magnitude we decide on in No. 5.” IPCC says highly likely that MOST of the warming in the last 150 years is AGW. They do not say ALL. And, again, this is only if No. 5 is demonstrated. Note, I only say plausible, because correlation does not prove causation at all. You are probably aware that the paleo record shows CO2 rise lagging temperature rise. I know there is an explanation offered for this, but it highlights that correlation does NOT prove causation. Plausible…valid hypothesis. But without the temperature record, you are nowhere. This
    is why I said the record is one of the two foundations of AGW.

    It is important to note what you have left out of your summary of the AGW view:

    9. The warming trend (alleged to be of significant magnitude) that is (plausibly) caused by human injections of CO2 to the atmosphere, will continue into the indefinite future, as long as the CO2 concentration continues to rise or remains at its higher level, and the rate of warming will accelerate the global mean temperature to beyond what it would be if “all things were kept equal.” That is, warmer earth, more vapor, more clouds, more H20 GHG effect – the most powerful one – more warming, etc.

    This is not a necessary conclusion following any of the above. Again, it’s a plausible hypothesis, but it’s support is weak, and I believe comes principally from GCM runs. Model runs, in turn, assume some of the points above are proven, and that the model properly treats the necessary system dynamics – a big assumption.

    That’s all there is to my point of view.

  49. 299
    Completely Fed Up says:

    “they are still built by the scientists and contain no independent cognitive process separate from what they are given and told to do.”

    Yeah, now unless you’re on Star Trek, you can’t say “Computer, please model a global warming climate caused by human CO2 production” and expect it to do so.

    It’s hard enough to get the model realistic, never mind make it lie.

    Humans on the other hand lie like billy-o.

    Don’t you.

  50. 300
    Doug Bostrom says:

    Edward Greisch says: 28 May 2010 at 11:46 PM

    244 Doug Bostrom: “people who show up here to argue against reality -do- have the capacity to understand.”
    Don’t be so sure of that. Rethink.

    I mean technically speaking, compared to a cat. Bigger neocortex; sort of like the difference between a four-function calculator and a reasonable laptop computer.

    But of course it’s the running code that really counts…


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