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What we can learn from studying the last millennium (or so)

Filed under: — mike @ 15 May 2010 - (Español)

With all of the emphasis that is often placed on hemispheric or global mean temperature trends during the past millennium, and the context they provide for interpreting modern warming trends, one thing is often lost in the discussion: space matters as much as time. Indeed, it is likely that the regional patterns of past climate changes, rather than simple hemispheric or global mean temperature trends, will best inform our understanding of the dynamical mechanisms involved. Since much of the uncertainty in future projections relates to regional climate change impacts, it makes particular sense to focus on those changes in the past that involve regional changes and the underlying mechanisms behind them.

For instance, melting of the cryosphere (and consequent rises in sea level), subtle shifts in drought and rainfall patterns, and extreme events, are all regional effects that could be important threats to ecosystems and our environment. Such changes are often associated with phenomena like ENSO or the North Atlantic Oscillation. Yet there remain large uncertainties about how such mechanisms will respond to anthropogenic climate change.

There are a number of potential ways forward to improve our understanding. A first step is to look directly at the time-series of specific systems (like the ENSO index or the ocean temperatures in the North Atlantic) and try to extend them as far back as possible using proxy data. This gives more information on what the natural variations in these phenomena look like, and thus a better idea of how big a forced response would need to be before it could be reliably detected. Secondly, we can look to see if there is a relationship between various natural drivers of climate change (volcanic eruptions, solar variability or orbital forcing say) and any characteristics of these phenomena – amplitude, frequency or duration. Do volcanic eruptions appear to affect El Niño for instance?

For phenomena that need annual or decadal resolution data to be resolved, the last millennium or so is an obvious (and only) time period to be looking at for it is only for that period that there is sufficient paleo-data coverage of high enough temporal resolution. Other periods – such as the mid-Holocene 6000 years ago – are also useful, but the results are more long-term in nature (there is also a discussion of the value of different periods for reducing future projection uncertainty in this recent paper).

There are a number of different approaches to looking at reconstructions in recent centuries – some rely on high density regional networks (as seen in this recent paper by Guiot et al concerning European temperature trends for which they mostly used pollen data) and some rely on wider networks of more diverse proxies which aim to capture longer-range correlations to specific phenomena (such as the recent Mann et al (2009) paper).

When this is done, people usually find that while it was relatively cool in global mean temperatures from the 1400s to the 1800s known as the “Little Ice Age” and relatively mild in the 900s to 1300s interval ( sometimes termed the “Medieval Warm Period”). But the spatial reconstructions reveal, however, why such global terms can be quite misleading, and why alternative phrases such as the “Medieval Climate Anomaly” are being increasingly favored by the community. This latter terminology recognizes that while the interval displayed significant climate anomalies, they varied greatly, even in sign, from region to region. Many of the more profound climate anomalies, moreover, involve variables other than temperature, such as drought, rainfall, and atmospheric circulation. Though the medieval period is seen to be modestly warmer globally in comparison with the later centuries of the Little Ice Age (the peak global mean warmth is likely comparable to mid, but not late, 20th century warmth), some key regions appear to have in fact been colder, while other regions appear to have been warmer. Southern Greenland, for example, appears within uncertainties to have been as warm as today. However, much of the tropical Pacific was unusually cold, suggestive of the La Niña phase of the ENSO phenomenon (a similar conclusion was reached by Trouet et al (2009)). Thus even though some locations may have been as warm or warmer than today, the hemispheric mean appears not to have been.

Why does this matter? It matters because there are plenty of factors that can affect the overall mean temperature (solar variability, volcanoes, greenhouse gases, internal variability etc.) and so it is hard, given the uncertainties in the solar or volcanic reconstructions to precisely attribute the paleo changes in the global or hemispheric mean to these factors. But if we can look at more complex fingerprints of the changes, it might be possible to be more quantitative in those attributions since the spatial fingerprints of the different factors are easier to distinguish. Furthermore, if we can clearly tie the regional patterns to the different forcings, we might be able to use that information to inform regional projections under future conditions.

Thus we can basically say that the warmer conditions of the Medieval era were tied to higher solar output and few volcanic eruptions and the cooler conditions of the Little Ice Age resulted from lower solar output and more frequent volcanic eruptions. But these drivers appear to have had an equally important, though more subtle, influence on regional temperature patterns through their impact on climate phenomena such as ENSO and the North Atlantic Oscillation. The modest increase in solar output during Medieval times appears to have favored the tendency for the positive phase of the NAO, associated with a more northerly jet stream over the North Atlantic. This brought relatively greater warmth in winter to the North Atlantic and Eurasia. A tendency toward the opposite negative NAO phase helps to explain the enhanced winter cooling over a large part of Eurasia during the later Little Ice Age period.

There is some model support for these patterns (see also instance Shindell et al, 2001) when the models include interactive ozone photochemistry to produce this dynamical response to solar forcing, but it is not captured in a simulation of the NCAR CSM coupled model which lacks those processes. Neither model simulation reproduces the apparent La Niña pattern seen in the Medieval temperature reconstructions:

Figure 1: Spatial pattern of mean temperature difference between the MCA and LIA periods (defined at the intervals AD 950-1250 CE and 1400-1700 CE respectively) compared with simulations of two different climate models forced with estimated differences in natural (volcanic and solar) radiative forcing between the two periods (Mann et al, 2009).

Other model simulations, however, using a climate model that exhibits a particular tropical Pacific mechanism, do reproduce such a response. In such models, the tropical Pacific counter-intuitively tends to the cold La Niña phase during periods of increased heating, such as provided by the increase in solar output and low volcanism of the Medieval era. If this response holds for the future, something that is still vigorously debated, it could imply a more La Niña-like response in the future. Most of the state-of-the-art climate models, e.g. those used in the IPCC Fourth Assessment, by contrast, suggest the opposite–a more El Niño-like future climate. The credibility of the models with regard to this phenomenon is not high, however, and lots more work is going to be needed (both on paleo-reconstructions and model improvements) before we can be confident in the future projections of changes in ENSO-like dynamics and mean state.

690 Responses to “What we can learn from studying the last millennium (or so)”

  1. 401

    Rod 368,

    No, it’s the old pointing-out-that-crackpots-in-one-area-often-embrace-other-pseudosciences-as-well argument.

  2. 402

    Rod 373,

    Put in its grave through high-altitude spectral observations made during World War II. Please read:

    http://BartonPaulLevenson.com/Saturation.html

  3. 403
    Completely Fed Up says:

    “CFU (382), agreed, but that was left out of my maybe over simplification for clarity.”

    You mean you left the reason why your statement was wrong to make it clearer?

    Weird.

    So apart from the radiation of the layer below, there’s no radiation for the CO2 in the upper layer to trap is basically what you’re saying.

    Well apart from the food I’ve eaten, I’ve never ate a bite of food in my life. Ergo, I’ve just proved you don’t have to eat anything to live!

  4. 404
    Completely Fed Up says:

    “CFU (382), agreed, but that was left out of my maybe over simplification for clarity.”

    You mean you left the reason why your statement was wrong to make it clearer?

    Weird.

    So apart from the radiation of the layer below, there’s no radiation for the CO2 in the upper layer to trap is basically what you’re saying.

    Well apart from the food I’ve eaten, I’ve never ate a bite of food in my life. Ergo, I’ve just proved you don’t have to eat anything to live!

    Isn’t proof easy when you simplify by leaving stuff out!

    PS Why are you simplifying when you then state in 398 that the “problem” with CO2 saturation is about a DETAIL in calculation???

  5. 405
    Joe Cushley says:

    Hey Rod B,

    “Ray Ladbury (382), I concur with all of your statements. My assertions of the “less than irrefutable” are based on the degree or the differential of the functions.”

    Is this denier-ese for “Sorry, I was wrong” ???

  6. 406
    Ray Ladbury says:

    Rod, you might want to reserve the technobabble for some site where people don’t speak real technical language. I’m sorry, but your use of “degree” and “differential” isn’t meaningful here.

  7. 407
    CM says:

    CFU (belatedly — sorry),

    #336: I agree that the burden of proof today lies on those who deny we are warming the planet by emitting CO2. I don’t think the same applies to the attribution of a particular drought event even though global warming is pushing us towards more drought on the average.

    #337: “Is the 1999 temperature NOT affected upward by the excess of CO2 humans have placed in the atmosphere over the preceeding 12 decades?”

    Sure, it was. Put another way, the global mean temperature of 1999 was very unlikely to have been as high in the absence of human CO2 emissions. (A temperature that high doesn’t show up in the first 110 years of the GIStemp record, and yet by 1990s standards, 1999 wasn’t even particularly warm!) The global mean temperature is on an undisputable upward trend and formal attribution studies have shown human fingerprint. A regional event is a different matter.

    #338: “So show that AGW shifted rain into SE US and made drought there less.”

    I wasn’t claiming it did, I was arguing a general point; sorry if that wasn’t clear. “There is no clear evidence of hydroclimate change in the Southeast during the period of anthropogenic forcing of climate” (Seager et al.). As noted before, models project increased precipitation in the near term future but this is more than balanced by increased evaporation; the 2005/6 drought did not fit this pattern (ibid.).

    Your turn: do you think anthropogenic warming made made the 2005 drought in the Southeast US worse than it would have been around, say, 1901? (Yes, this is a trick question — see the left-hand map in AR4 fig. 3.9.)

  8. 408
    Ibrahim says:

    Barton Paul Levenson #361

    CFU#359

    Thank you for you answers.

    I know enough.

    Regards

  9. 409
    Rod B says:

    Hank (394) actually my simple hypothetical example does not require the low level CO2 to do anything with the absorbed energy. But (still keeping it (over?)simple) the energy would transfer to other gases through collision.

  10. 410
    Rod B says:

    CFU, I was simply trying to answer a basic question with a clear and simple answer. I wasn’t explaining radiation physics or the entire atmospheric processes re GHGs.

    The detail in calculation (your words) response was to a totally different post. Try to keep things straight.

  11. 411
    Rod B says:

    Ray Ladbury (406), if you don’t understand differentials and how they (it) relates to forcing ala AGW then I am blown away. Take any 1st year calculus on your way to PhD land? Though my point (which I mentioned just for the record; we’ve all been through it before and I didn’t intend to resurrect it just now) is simply that the forcing equation for CO2 as it goes from say 350ppm to 700ppm because of anthropogenic emissions has never been observed, even by proxy, nor tested nor irrefutably (totally is probably a better word) explained with physics. Which, BTW, is a differential.

  12. 412
    Completely Fed Up says:

    Rod B, that sort of technobabble only works on the pre-school readers.

    The mechanism was understood and calcualted in 1950’s.

    Oh and as to “the forcing equation for CO2 as it goes from say 350ppm to 700ppm because of anthropogenic emissions has never been observed”

    a) Equations have never been observed. Not even F=ma.

    b) We are observing the effect of the log dependence of CO2 to forcings

  13. 413
    Completely Fed Up says:

    “I don’t think the same applies to the attribution of a particular drought event even though global warming is pushing us towards more drought on the average.”

    CM, still you make this.

    WHO IS ATTRIBUTING something to a particular drought? *I* *am* *not*.

    I repeat

    I

    AM

    NOT

    So why do you continue to argue as if I am?

  14. 414
    Completely Fed Up says:

    “Your turn: do you think anthropogenic warming made made the 2005 drought in the Southeast US worse than it would have been around, say, 1901?”

    If we had had AGW at the same level of accululated effect, yes, it would.

    (note: your trick question is not a trick one because the 1901 event was a weather event that AGW would have added to, thereby making it worse).

  15. 415
    Hank Roberts says:

    > But (still keeping it (over?)simple) the energy would transfer
    > to other gases through collision.

    No photons emitted in all directions including up and down?
    One way transfer of energy away by collision, but not back?

    If you rule out the other known energy transfers to and from CO2, what remains is indistinguishable from magic.

  16. 416
    Completely Fed Up says:

    “400
    Jacob Mack says:
    23 May 2010 at 12:22 AM

    Not every drought is made worse, yes you know that”

    But you seem to consider it impossible to say that a drought is made worse by AGW.

    Now, come back and get to the FRIGGING POINT:

    SE US Drought.

    Was that made worse by AGW.

    ME: Yes.

    You?

  17. 417
    Completely Fed Up says:

    “I answered all of your questions as well. CFU, are you high or something?”

    Are you? Certainly seems like when you’ve asserted so strongly you’ve answered all my questions. Hallucinations are a common consequence of drug abuse:

    Post #239:

    OK, peeps. A poll.

    Indicate which ones you agree with by listing as

    YES: # # #

    and which you disagree with by listing as

    NO: # # #

    1) AGW (climate change) creates warmer weather.

    2) Warmer weather makes drought more severe.

    3) Droughts are made more severe if you increase temperatures.

    Which ones are agreed as correct and which ones as wrong?

    (merely one example amongst several)

    Then again you don’t listen, you merely pontificate Jacob, and assume a position to me that you can attack.

  18. 418
    Completely Fed Up says:

    Rod B you again try to rewrite history and hope that nobody checks (a quite Republican way of arguing: bald faced lies knowing that nobody is checking).

    Post 397: CFU (382), agreed, but that was left out of my maybe over simplification for clarity.

    But in post 410 you complain that that was about something else other than CO2 saturation.

    Well 398 was this: Theoretically, the CO2 at the higher altitudes would have the radiation from the saturated CO2 at the lower levels to absorb…

    Which was about CO2 and your assertion that this was saturated and unable to affect climate change.

    There was nothing there about another post.

    Did you think nobody would check???

  19. 419
    Completely Fed Up says:

    CM: “Put another way, the global mean temperature of 1999 was very unlikely to have been as high in the absence of human CO2 emissions… The global mean temperature is on an undisputable upward trend and formal attribution studies have shown human fingerprint. A regional event is a different matter.”

    No, a regional event is NOT a different matter.

    What do you think happened to all those CO2 molecules over, say, the central US?

    Do you think they went away somewhere? Maybe shuffled off to Canada and Greenland to increase the warming there?

    No. CO2 is well mixed.

    Maybe the photons that came up from the US Soil was not in the range that CO2 traps, therefore there was no effect from CO2’s greenhouse effect?

    No, it’s the same mud as everywhere else. Thermodynamic laws did not decide to take a vacation.

    If you have no change in the events, how can you change the sum of those events?

    You can’t.

    You’re wrong.

  20. 420
    Completely Fed Up says:

    “because of anthropogenic emissions has never been observed, even by proxy, nor tested nor irrefutably (totally is probably a better word) explained with physics. Which, BTW, is a differential.”

    No, it’s a blue.

    WTF?!?!?

    Seriously, did you verb your nouns just there SERIOUSLY???

    No, science is not a differential.

    No, observation is not a differential.

    Cue The Humpty-Dumpty Defence: differential means what I mean it to mean, no more and no less.

  21. 421
    Jacob Mack says:

    CM # 407 all well stated and accurate. Of course sometimes more precipitation due to evaporation has other effects at times as observed.

  22. 422

    Rod, is it possible you mean “a derivative?”

  23. 423
    John E. Pearson says:

    413: BPL I have no idea what he is talking about. It is pure gibberish.

  24. 424
    John Mashey says:

    re: 401 BPL
    “No, it’s the old pointing-out-that-crackpots-in-one-area-often-embrace-other-pseudosciences-as-well argument.”

    Actually, unlike, say Arthur Robinson, candidate for the US House in Oregon’s 4th district, and known to RC readers, I do not think Happer fits that. I think he is more in the Seitz/Jastrow/Nierenberg mold, in which a serious scientist holds intense political/ideological views that seem to cause them to abandon scientific thinking in any science whose results conflict with their other views. Then, they use their (legitimate) science credentials to claim expertise far beyond their own.

    One more time, Happer is Professor of Physics @ Princeton, and a NAS member, neither of which tend to be true of most lovers of pseudoscience.

    But since 2006, he has been Chairman of GMI, and a Board member for years before. About a page and a half of CCC Report is devoted to him, and Table A.6.2 (a) shows his long participation in various activities, including signing the OISM Petition.

    As of today, the 2nd item at GMI Home page says:

    “Institute Chairman Dr. Will Happer was a witness before the House Select Energy Independence and Global Warming Committee in a May 20 hearing titled “Climate Science in the Political Arena.” The video is available here.” (Although the video (at Markey’s site) isn’t actually there yet, but it will show up, I assume).

    Happer’s testimony only identifies him as:

    “William Happer Cyrus Fogg Brackett Professor of Physics
    Princeton University”

    It also says:

    “The views I express today are my own, and not official views of my
    main employer, Princeton University, nor of any other organization with which I am associated.”

    I certainly believe his views are not official views of Princeton … but if people peruse the GMI website, my CCC report, or the imminent Oreskes/Conway “Merchants of Doubt”, they can assess whether or not his views represent the Institute of which he is Chairman…and whose funding is interesting.

    (But sadly, none of this has anything to do with the interesting topic of the original post, which likely has a lot to do with resolving some differences amongst proxy-based temperature reconstructions and reducing uncertainty ranges.)

  25. 425
    Jacob Mack says:

    CFU when I have more time to look over data/papers, then maybe I will have an answer for that region, but it may still be speculation:)

  26. 426
    CM says:

    CFU,

    #413: You have not been attributing the severity of the drought to AGW? Sorry. Uhm, what are we discussing?

    #414: But if the map I pointed you to can be explained as you say by a fin-de-sièclespell of warm weather, maybe the 2005/6 drought could be just regional weather too, and as likely to happen in the absence of AGW?

    #417 (poll): In the global mean, yes. Most of the time, in most places.

    Hey, if we know nothing more about a drought event than that it happened somewhere in the 2000s, it seems reasonable to me, based on what we know in general, to start out assuming that AGW made a significant contribution to the probability of that event. It seems imprudent to press that claim in debate, though, at least until studies have confirmed a significant link between that event and AGW, and unreasonable to continue pressing it if they fail to do so.

    #419: Strawman. CO2 is well-mixed and radiative forcing works the same everywhere. That was never at issue. And yet, surface temperatures do not respond uniformly. Let alone rainfall patterns, etc.

  27. 427
    Completely Fed Up says:

    “#413: You have not been attributing the severity of the drought to AGW? Sorry. Uhm, what are we discussing?”

    *I* have been discussing that AGW has affected and worsened the SE US drought.

    I haven’t attributed that drought to AGW.

    “#414: But if the map I pointed you to can be explained as you say by a fin-de-sièclespell of warm weather, maybe the 2005/6 drought could be just regional weather too”

    No, that is only a non-AGW effect if the effects of AGW on that region was to introduce rainfall that otherwise would not have entered the system.

    Back again to the 1999 temperature.

    HYPOTHESIS:

    Weather made that temperature 0.2C cooler than normal. The effects of trapped heat by CO2 and other greenhouse gasses increased that by 0.5C. Net effect: ~0.3C warmer than normal, but 0.2C cooler than the times around it.

    If the AGW effect had NOT been evident, the temperatures in 1999 would have been around that of 1920.

    “#417 (poll): In the global mean, yes. Most of the time, in most places.”

    I’ve used this before, so here it is again:

    Get a Random Number generator.

    Collect 30 value pairs (x,y) such that x=0-29 and y=Rand(30)-15+x.

    Look at the numbers.

    Even though you see numbers in the latter half of the series that are within the 90% confidence limits of the first 10 numbers, thereby leading you, Jacob and Gilles to consider that those numbers were not affected by the monotonically increasing effect of x, you KNOW (because it’s in the equation), each and every value is affected and increased by an upward trend…

    The regional effect is only cancelled if the changes engendered by AGW makes entrainment of colder air into the region feasible AND that the warming that allowed that entrainment has not increased the temperature over the median climatological value of the region it has been moved into.

    “Hey, if we know nothing more about a drought event than that it happened somewhere in the 2000s, it seems reasonable to me, based on what we know in general, to start out assuming that AGW made a significant contribution to the probability of that event.”

    That’s certainly one option, where you wish to show that a NEW DROUGHT was caused by AGW.

    However, I’m not talking about CAUSING one. I’m talking about making one that would have existed ANYWAY worse.

    Take, as an example, the Sahel.

    Already bone dry.

    It won’t be made much more “droughty” by AGW. It’s already pretty maxed out on the drought thing.

    But it WILL get hotter because of AGW.

    The number of occurrences may be no more, but it will still be affected by AGW because the ones that are there are worse.

    NOTE: This is very much the reason that fella who disagreed with the IPCC on hurricane FREQUENCY would be unaffected, as opposed to the IPCC consensus report that said it would. His position was that the number of events would not change markedly, but the severity for any event that was going to happen anyway (even sans AGW) would be worse.

    “#419: Strawman. CO2 is well-mixed and radiative forcing works the same everywhere. That was never at issue. ”

    No, it wasn’t a strawman, it was an argument by illogical extreme.

    If more heat was retained in the central US (for example), then although the WEATHER may have a colder state for a short time (e.g. El Nino/La Nina), if AGW hadn’t been there, the WEATHER at that region and time would have been colder yet.

    Therefore AGW affected that region by warming it, even though the WEATHER variation added a cooling term that overwhelmed the smaller but persistent warming climate effect.

  28. 428
    Completely Fed Up says:

    PS This: “#413: You have not been attributing the severity of the drought to AGW? Sorry. Uhm, what are we discussing?”

    Is not what I responded to. I responded to #407: “I don’t think the same applies to the attribution of a particular drought event”

    Note: NOTHING about “attributing the severity” in that version.

  29. 429
    RichardC says:

    427 CFU. Single events are random within a single reality. If we had another reality, where AGW didn’t exist, then weather would be different from the beginning of where AGW didn’t start, and by now everything would be completely different.

  30. 430
    Rod B says:

    CFU (418), Oh, Paleeezze! I’m impressed. Turning two separate rather simple posts/comments into a convoluted integrated mess ain’t easy.

  31. 431
    Rod B says:

    BPL, here’s my dictionary.
    Noun: differential
    1) The result of mathematical differentiation; the instantaneous change of one quantity relative to another; df(x)/dx
    2) A quality that differentiates between similar things
    3) A bevel gear that permits rotation of two shafts at different speeds; used on the rear axle of automobiles to allow wheels to rotate at different speeds on curves
    Adjective: differential
    1) Relating to or showing a difference
    2) Involving or containing one or more derivatives

  32. 432
    Hank Roberts says:

    > it wasn’t a strawman, it was an argument by illogical extreme.

  33. 433
    John E. Pearson says:

    One more time, Happer is Professor of Physics @ Princeton, and a NAS member, neither of which tend to be true of most lovers of pseudoscience.

    I know lots of scientists who believe all sorts of crazy shit outside of their field.

    This is way OT so if you must delete, delete away, but it’s sort of interesting anyway.

    Shoot. I almost got converted to belief in water-witching a while back. I had to locate the main waterline between my house and the meter. The pipe was plastic so they couldn’t run a current through it and measure the field. The guy who came out bent a coat hanger and started wandering around. Every time he passed over the spot where I’d told him i thought the pipe must run the coat hanger deflected downwards, pointing towards the spot where I thought the pipe was. It was an astonishing site to behold. For several seconds I believed he had found the pipes by water witching. Then my rationalist self took back over and I told the guy “you found the pipe where i said it was. I want confirmation or I don’t pay.” Later on the plumbers came and dug up the pipe starting at the meter and working their to the driveway. It was ten feet up the concrete driveway from the spot where the water witcher had claimed it was. He was simply confirming my bias.

  34. 434
    Completely Fed Up says:

    Yes Hank. When a position is logical, it’s hard NOT to use an argument that shows the illogical extreme.

    And CM, you never used “attribution of severity” before until you pretended to quote me.

  35. 435
    Ray Ladbury says:

    Rod B., Physics is a differential? Do tell. You are talking out your ass and then denying it. You have thereby graduated to the level of “not even wrong”. We can do experiments in the lab that show that CO2 does not saturate. We know CO2 radiates as well as relaxing by collision. The fact is that Happer, in his testimony is full of a brown messy substance that is the product of normal metabolic processes. I find it hard to believe that he is not a good enough physicist to know he is wrong. You have a ways to go before you even rise to the level of wrong.

  36. 436
    Hank Roberts says:

    > When a position is logical, it’s hard NOT to use an argument
    > that shows the illogical extreme.

    It’s hard. Please try harder.

    “It is a good example of the ‘old’ way of doing science.
    http://web.sbu.edu/history/tschaeper/Hist101/101wwwfbacon.html

  37. 437
    Completely Fed Up says:

    OK, Hank. Here’s the facts:

    1) CO2 is well mixed.
    2) CO2 is a greenhouse gas.
    3) We produce lots of CO2.
    4) Conclusion: AGW means we’re retaining more energy therefore warming.

    Yup?

    Now, how can that NOT warm a region unless 1 is false and therefore that region is UNAFFECTED by CO2 therefore AGW hasn’t warmed that place?

    That is the ABSOLUTE conclusion of CM’s attempt to wave off my position with “The global mean temperature is on an undisputable upward trend and formal attribution studies have shown human fingerprint. A regional event is a different matter.”.

    The ONLY way that makes ANY sort of counter to my position is if it is promoting the fact that AGW doesn’t affect regions, only globes.

  38. 438
    Completely Fed Up says:

    Rod B, #430, I note that you fail to actually point to where your defense of your indefensible statement as “not to do with CO2 saturation” was “meant” to go.

    You’re busy waving your hands going “this is not the statement you read”.

    It should be FAR easier for the person who MADE the statement to show where the statements were “meant” to apply.

    Yet you haven’t managed yet.

    The smokescreen isn’t working.

  39. 439
    Completely Fed Up says:

    “Noun: differential”
    “1) The result of mathematical differentiation; the instantaneous change of one quantity relative to another; df(x)/dx”

    That’s not a science.

    “2) A quality that differentiates between similar things”

    That would be “differentiator”, not “differential”.

    I’ve just realised: this isn’t from a standard dictionary, is it, Rod.

    “3) A bevel gear that permits rotation of two shafts at different speeds; used on the rear axle of automobiles to allow wheels to rotate at different speeds on curves

    This isn’t science either.

    “Adjective: differential”

    If it’s an adjective, where’s the noun this is emphasizing? “a differential” is not grammatically correct.

    Guess your grammar is not standard either.

    “1) Relating to or showing a difference”

    This again would be “differentiator” or “difference” in more common parlance.

    “2) Involving or containing one or more derivatives”

    Maths. Again.

  40. 440
    Completely Fed Up says:

    “429
    RichardC says:
    24 May 2010 at 11:20 AM

    427 CFU. Single events are random within a single reality.”

    Good job I had my shades on there, I could have been blinded.

    _Yes_, I _know_.

    Now each single event is acted upon by one or more forces, yes?

    Why isn’t AGW one of them? Or does it not affect any single event, just the aggregate?

  41. 441
    John Mashey says:

    I realize it is awful to actually discuss the topic of the post, but it is actually interesting.
    Consider the various reconstructions that cover, say 1500AD-1700AD.
    They vary somewhat (although generally within the envelope from MBH99).
    There are at least several possible reasons:
    a) Different selections of proxies.
    b) Different calibrations of them.
    C) Different statistical techniques for combining them.

    Can people point at studies trying to sort out the reasons for the differences?

    (This is all related to a conjecture that there might be different regional fingerprints for different combinations of causes for the AD1600ish drops in CO2 and temperature.)

    [Response: This is basically the question investigated by Rutherford et al (2005) [Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R., Hughes, M.K., Jones, P.D., Proxy-based Northern Hemisphere Surface Temperature Reconstructions: Sensitivity to Methodology, Predictor Network, Target Season and Target Domain, Journal of Climate, 18, 2308-2329, 2005] available here. – mike]

  42. 442
    RichardC says:

    440 CFU said, “Now each single event is acted upon by one or more forces, yes? Why isn’t AGW one of them? Or does it not affect any single event, just the aggregate?”

    We have two timelines. One is AGW, the other is one where we avoided AGW. Each single event occurs in only one of the timelines. The AGW timeline will have worse droughts on average, but a single drought in AGW time might not even exist in no-AGW time, and vice versa.

  43. 443
    Hank Roberts says:

    CFU, you are asserting the overgeneralization this post tries to address:

    “one thing is often lost in the discussion: space matters as much as time. Indeed, it is likely that the regional patterns of past climate changes, rather than simple hemispheric or global mean temperature trends, will best inform our understanding of the dynamical mechanisms involved.”

  44. 444
    CTG says:

    Heads up: Easterbrook has responded to claims that he faked a graph in his recent Heartland talk… by faking another graph.

  45. 445
  46. 446
    Septic Matthew says:

    395, John Mashey, and other related posts: Back in #206, I posted a pointer to a nice presentation on kudzu by Toronto researchers. You don’t need to perform onerous research, like looking in Wikipedia or looking for research papers, that presentation ought to do it, and they actually have better maps. Hopefully, you will read that and return, saying “yes, that is convincing evidence from people who actually study it.”

    A remarkable number of populations have spread dramatically over the same time span:

    tick-borne Lyme disease;
    antibiotic resistant (and indeed MDR and XDR)disease-causing bacteria;
    HIV;
    Africanized honey bees;
    West Nile Virus;
    zebra mussels;
    water hyacinths;
    Dutch Elm disease;
    gypsy moths;
    ice plants;
    Moroccan mustard;
    fire ants;

    and many, many more. Spreading is what invasive species do. Trying to conclude that one in particular out of dozens, maybe thousands, moved an extra 10% of its range because of AGW requires great belief.

    Once you get beyond the fact that CO2 absorbs IR (and then either warms the adjacent atmosphere or re-radiates IR), the rest of AGW theory is flimsy and simple-minded. You have presented what I consider a “simple minded” argument: a particular invasive species has done what all invasive species do, and that is taken as evidence for AGW.

    This is not to deny that Ontario might be warming and that might permit a more rapid spread of kudzu; but kudzu has survived extremely cold winters before, and it will survive this last extremely cold winter.

  47. 447
    Completely Fed Up says:

    “Once you get beyond the fact that CO2 absorbs IR (and then either warms the adjacent atmosphere or re-radiates IR), the rest of AGW theory is flimsy and simple-minded.”

    Do you have anything that states WHY it must be flimsy and simple minded?

    Your assertion seems to be the only flimsy and simple-minded excuse here.

    “This is not to deny that Ontario might be warming”

    No *might* about it.

    It is warming.

    We have the thermometers.

  48. 448
    SecularAnimist says:

    Septic Matthew wrote: “Once you get beyond the fact that CO2 absorbs IR … the rest of AGW theory is flimsy and simple-minded.”

    You clearly enjoy making such insulting comments.

    You just as clearly don’t know what you are talking about.

  49. 449
    Completely Fed Up says:

    “CFU, you are asserting the overgeneralization this post tries to address:”

    It’s a generalisation, yes. But NOT an overgeneralsiation.

    If you cannot get the current climate without including AGW, then that shows that every single place is affected that you cannot get right without including anthropogenic CO2e.

    The overgeneralisation is where you are all saying “it only affects global averages, not regional areas”.

    You cannot get a change unless you change the individual events.

    And the promoter of that change is the Sun and the greenhouse gasses.

    The sun shines everywhere.

    The greenhouse gasses mix and appear all over the globe.

    And nothing in your quote addresses your point, nor refutes mine. It is a generalisation, and one that emerges from the requirement to prove the effect and its magnitude.

    I don’t have to prove the effect: the global trend does that.

    And I am not concerning myself with the magnitude.

    Therefore your quote is not germane.

  50. 450
    Completely Fed Up says:

    “We have two timelines. One is AGW, the other is one where we avoided AGW.”

    In our thought experiment, yes.

    “ach single event occurs in only one of the timelines.”

    No, only in reality and we only have the one reality, the one with AGW. Therefore we are not talking about reality but our thought experiment.

    And there’s no problem there in having each single event happening in BOTH timelines.

    “The AGW timeline will have worse droughts on average,”

    And this is done by increasing the severity of drought that was going to happen anyway and causing droughts that would not otherwise have happened.

    ” but a single drought in AGW time might not even exist in no-AGW time, and vice versa.”

    Nope, the single drought had several causes.

    In one timeline, the cause of energy retention by having a concentration of ~400ppm CO2 happened in only one timeline, but all other variables were the same.

    This sort of “what if something was different” thought experiment is done all the time. The proof of Lorentz time dilation and the argument for the constancy of the speed of light for all observers in any inertial frame, even very different ones are both made by changing only one thing.