The ‘correlation is not causation’ hockey stick

http://books.google.com/ngrams/graph?content=correlation+is+not+causation&year_start=1800&year_end=2008&corpus=0&smoothing=3

Mike Lorrey writes- PAY ATTENTION CLIMATE ALARMISTS:

“The phrase ‘correlation does not imply causation’ goes back to 1880 (according to Google Books). However, use of the phrase took off in the 1990s and 2000s, and is becoming a quick way to short-circuit certain kinds of arguments.

In the late 19th century, British statistician Karl Pearson introduced a powerful idea in math: that a relationship between two variables could be characterized according to its strength and expressed in numbers. An exciting concept, but it raised a new issue: how to interpret the data in a way that is helpful, rather than misleading. When we mistake correlation for causation, we find a cause that isn’t there, which is a problem. However, as science grows more powerful and government more technocratic, the stakes of correlation — of counterfeit relationships and bogus findings — grow larger.”

From Slashdot: The History of ‘Correlation Does Not Imply Causation’

==============================================================

From the Slate article referenced by Slashdot:

The graph below, again from Google Books, shows the shift in language that marked this change in spirit: Up until the early 1900s, causation showed up more often than correlation in the corpus; then the concepts flip. (I’ll let someone else explain why correlations have been trending downward since 1976.)

http://books.google.com/ngrams/graph?content=correlation%2C+causation&year_start=1800&year_end=2010&corpus=0&smoothing=3

 

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127 Responses to The ‘correlation is not causation’ hockey stick

  1. corio37 says:

    When I studied Psychology twenty years ago it was anxious to be regarded as a ‘real’ science, and so we got an excellent grounding in scientific method. Amongst other things we were told never to use the word ’causes’ in a scientific paper where ‘correlates with’ was correct. Unfortunately it looks like some Psychology faculties have forgotten that useful lesson.

  2. cbb says:

    An old professor said to us undergraduates, “Boiled lobsters are red. Not everything that is red is a boiled lobster”.

  3. anna v says:

    The graph only supports that the term “correlation” became popular . Causation seems pretty constant, it did not pick up the slack after 1976. It is probably fashions in scientific and semi language.

  4. anna v says:

    that is “semi-scientific” in the last line.

  5. Gunga Din says:

    Every day I that I go to work when I come home from work, my dog wants a treat.
    Therefore, if I never went to work, my dog would never want a treat.
    Or maybe if I never came home from work, my dog would never want a treat?
    More reasearch funds are needed.

  6. From Graph #1….”Correlation is not causation” is trending upward….

    From Graph #2….”Causation” peaked in 1885…oscillatted briefly….trended downward in 2000….
    “Correlation” overtook in 1900…peaked in 1976….rapid decline since….

    Conclusion: We are approaching the happy 1800 era when there was NO causation and NO correlation….Ignorance is Bliss….Orwell would be happy….

  7. Thomas T says:

    The better term would be, “correlation does not prove causation”, because correlation can damn well be a strong enough clue to be suggestive of causation. CO2 and global temperature is a case in point. Specifically, it was proposed over 100 years ago that the contribution of CO2 rise to temperature increase can be estimated. The subsequent observed correlation of CO2 and global temperature is thus suggestive, but not proof, of causation.

    What is important here is that at present no other parameter, such as solar or earth tilt, etc, correlates well with the observed rapid increase in global temperature.

    That is the kicker, and so, although correlation does not prove causation:

    If you hear hoofbeats, by all means keep looking for zebras, but smart money will be that you hear a horse.

  8. D Böehm says:

    Thomas T,

    Yes, correlation is not causation. But when you look at this, you are forced to admit that the only correlation between CO2 and temperature is that temperature changes cause CO2 changes; not vice-versa. There is no empirical scientific evidence showing that changes in CO2 cause changes in temperature. Draw your own conclusions.

  9. RoHa says:

    @ corio37
    “When I studied Psychology twenty years ago it was anxious to be regarded as a ‘real’ science, and so we got an excellent grounding in scientific method.”

    Same when I studied it 45 years ago. That grounding in scientific method added to the grounding that high school science had given me, and included a fair chunk of statistics. I learnt two very important things.

    1. Aspirations notwithstanding, psychology wasn’t a science.
    2. Get a professional statistician to do the stats for you.

  10. 0U812 says:

    Oh Dear. A ‘Mann’ made Éruption Volcanique thus looms large and when ignited will issue for many weeks to come.

    Tinfoil hat firmly attached, lead fused lab coat on, and now in the Level-B20 Lead-Lined bunker.

    [Via the Radio Dispatch] “I have shorted the locks. The doors are now sealed. I’ll remain here and keep recording the events for as long as possible.

    Later, you will eventually be able to retrieve all the tapes from the vault.

    For now I wish you, God Speed. Make Haste as you have little time.

    As you exit the research facility through the hills look to the east. A New Moon is about to be born and you will witness that event.

    As for me …. I did all that I could; History will show that. Signing Off.” [/Via the Radio Dispatch]

    XD

  11. David Ball says:

    It appears the time series selected is differing between graphs.

  12. Thomas T says:

    D. Boehm, consider feedback mechanisms before you force yourself to conclude. If you do so, then your pressure on yourself will evaporate.

  13. theduke says:

    Causation is much more difficult to prove. Everything is related. Similarities abound. Trends and characteristics overlap. Slopes can be equal. Correlation is everywhere. Lobsters are red and so are apples (unless they are green and then they correlate with grass.) Apples do not grow in the ocean, but to the untrained eye, they correlate with boiled lobsters. It’s arguable that they correlate because the similar color results from exposure to heat, but . . . .Oh, never mind.

    Repeat: Causation is much more difficult to prove.

    Forgive me, but the conclusion that increases in the trace gas CO2 are responsible for the slight increase in heat we’ve experienced over the past 100 years because establishment climate scientists refuse to vigorously explore (and disprove) other possible causes should be offensive to anyone who respects the scientific method.

  14. D Böehm says:

    Thomas T,

    Positive feedbacks have been falsified by Planet Earth; the ultimate Authority. Believe what you want, it isn’t reality. CO2=CAGW is a debunked fantasy.

  15. Mooloo says:

    What is important here is that at present no other parameter, such as solar or earth tilt, etc, correlates well with the observed rapid increase in global temperature.

    What temperature causes CO2 increases? The whole deck of cards comes tumbling down.

    Correlation should not even imply causation. Especially if your “proof” is the “I can’t think of anything else” type argument.

    At the best it is, as I tell my students, “consistent with”.

  16. kenskingdom says:

    Thomas T:
    So if Variable 1 and Variable 2 are correlated, and change in Variable 1 occurs before change in Variable 2, what can you conclude?
    (Hint: Variable 1 is NOT CO2 concentraion, Variable 2 is NOT Temperature.)

  17. theduke says:

    D. Boehm: but CO2=.10XAGW (or something like) is still a possibility.

  18. Gunga Din says:

    Thomas T says:
    October 2, 2012 at 8:53 pm
    The better term would be, “correlation does not prove causation”, because correlation can damn well be a strong enough clue to be suggestive of causation. CO2 and global temperature is a case in point. Specifically, it was proposed over 100 years ago that the contribution of CO2 rise to temperature increase can be estimated. The subsequent observed correlation of CO2 and global temperature is thus suggestive, but not proof, of causation.

    What is important here is that at present no other parameter, such as solar or earth tilt, etc, correlates well with the observed rapid increase in global temperature.

    That is the kicker, and so, although correlation does not prove causation:

    If you hear hoofbeats, by all means keep looking for zebras, but smart money will be that you hear a horse.
    ==============================================================
    Whether you probably hear a zebra or a horse or a bison depends on where you live or where you are in the zoo.
    “What is important here is that at present no other parameter, such as solar or earth tilt, etc, correlates well with the observed rapid increase in global temperature.”
    Really? “Rapid increase in global temperature”? Where were these measuring devices sited? Has anything happened since they were set that might bias there records? Has any bias entered in that has influenced what numbers have actually been enter and/or altered in the records? Temperatures don’t correlate with what the Sun has been up to? How about El Nino and La Nina? (Check out Tisdale’s work.)
    PS Please define just how “rapid” and just how much of an “increase” has occured and where it occured and over what period of time.
    PSPS Are you a member of the BBSB?

  19. Go Home says:

    “If the Washington Redskins win their last home game before the election, the incumbent party retains the White House. Otherwise, the out-of-power party wins.

    This pattern has failed only once since 1940, though which year it failed is something of a debate on Wikipedia, depending whether one honors a retroactive change to the rule to recognize the winner of the popular vote.”

    http://news.yahoo.com/your-nfl-team-can-predict-the-election.html
    Sounds like warmists arguing correlation implying causation…
    ++++++++++++++++
    If Denver rushes for more than 106 yards in its fifth game of the season, the incumbent party wins. Otherwise, the out-of-power party wins. This rule has held for every election since the Denver Broncos’ first season in 1960.

    Here is the Patriots Rule, true for 12 of the past 13 elections: If New England commits fewer turnovers than its opponent in the team’s first away game, the out-of-power party will win the White House. Otherwise, the incumbent party wins.

    {ONE FOR EACH TEAM)

    Saving the cardiac cards for last… the Cardinals Rule: If Arizona averages more than 18.2 yards per first down in its fifth-to-last game before the election, the out-of-power party wins. Otherwise, the incumbent party retains the White House. {17 out of 17)

    This Thursday: at St. Louis on Oct. 4

    GO CARDS or GO HOME

  20. pwl says:

    “One of the largest-ever studies of retractions has found that two-thirds of retracted life-sciences papers were stricken from the scientific record because of misconduct such as fraud or suspected fraud — and that journals sometimes soft-pedal the reason. The study contradicts the conventional view that most retractions of papers in scientific journals are triggered by unintentional errors. The survey examined all 2,047 articles in the PubMed database that had been marked as retracted by 3 May this year. But rather than taking journals’ retraction notices at face value, as previous analyses have done, the study used secondary sources to pin down the reasons for retraction if the notices were incomplete or vague. The analysis revealed that fraud or suspected fraud was responsible for 43% of the retractions. Other types of misconduct — duplicate publication and plagiarism — accounted for 14% and 10% of retractions, respectively. Only 21% of the papers were retracted because of error (abstract).”
    http://science.slashdot.org/story/12/10/02/180226/misconduct-not-error-is-the-main-cause-of-scientific-retractions

  21. theduke says:

    I wrote: D. Boehm: but CO2=.10XAGW (or something like) is still a possibility.

    Make that CO2=.10xGW

  22. Barry K says:

    Thomas T,

    Before humans became a factor, temperature variations an order of magnitude larger than what we’ve seen in the recent century occurred. Until scientists develop a model that can generate such changes without human influence (i.e. CO2), it’s clear that the models are neglecting some unknown effects….

  23. Thomas T says:

    establishment climate scientists refuse to vigorously explore (and disprove) other possible causes

    Name an establishment scientist that has refused to explore and disprove other possible causes. And once you name them, what is your evidence?

  24. davidmhoffer says:

    Oh gimme a break.

    Pick up a book that was written in the early 1800′s. You’ll find words in it that were common then and all but abandoned now. You’ll find common phrases that are no longer in use. You’ll find styles of expression that were the way regular folks talked that seem quaint or odd or stilted today. Anyone get to the saloon for a tipple lately? Anyone in 1820 mention renting a video and picking up some microwave popcorn?

    If “link” or “connection” or “association” or any number of other words were commonly used instead of “correlation” at various points in time, you’d esentially be getting a false negative because they were excluded from the search. Were they? I haven’t a clue.

    But language evolves over time and any study of terminology use that ignores that fact is just meaningless.

  25. Robin Melville says:

    I was warned about this fallacy by my Stats teacher who pointed out that when temporal and spatial measurements were taken into account it’s trivial to prove that, in England, churches cause pubs.

  26. Go Home says:

    Continuing with the “NFL predicts presidential election theme” above…

    So you put all team predictors into a climate model with each having excellent correlation factors (only 7 failures out of 32 predictors at approximately 10 samples per). This thing should be fail proof. But can it predict this years election?

    “Four rules were decided in the past week. The Bears Rule and the Titans Rule point to an Obama win, while the Bills Rule and the Buccaneers Rule point to a Romney win. The score is now 9-4 in Mitt Romney’s favor.”

    Already four to nine failures out of 13 predictions. When the last 65 years had a total of only 7 failures. Whats going wrong this year?

  27. For the umpteenth time, absent chance (coincidence), correlation is proof of causation. It’s just that correlation between A and B isn’t proof that A causes B, which is the fallacy.

    Wikipedia has a good summary,

    The cum hoc ergo propter hoc logical (correlation proves causation) fallacy can be expressed as follows:
    A occurs in correlation with B.
    Therefore, A causes B.
    In this type of logical fallacy, one makes a premature conclusion about causality after observing only a correlation between two or more factors. Generally, if one factor (A) is observed to only be correlated with another factor (B), it is sometimes taken for granted that A is causing B, even when no evidence supports it. This is a logical fallacy because there are at least five possibilities:
    A may be the cause of B.
    B may be the cause of A.
    some unknown third factor C may actually be the cause of both A and B.
    there may be a combination of the above three relationships. For example, B may be the cause of A at the same time as A is the cause of B (contradicting that the only relationship between A and B is that A causes B). This describes a self-reinforcing system.
    the “relationship” is a coincidence or so complex or indirect that it is more effectively called a coincidence (i.e. two events occurring at the same time that have no direct relationship to each other besides the fact that they are occurring at the same time). A larger sample size helps to reduce the chance of a coincidence, unless there is a systematic error in the experiment.

    http://en.wikipedia.org/wiki/Correlation_does_not_imply_causation

  28. Breaker says:

    So, is the point of the graph that the use of the word “correlation” has caused global warming and, with a five year or so lag, the cooling trend of the 2000′s? I guess Ronald Reagan’s saying, “Words have Consequences,” was more accurate than we thought.

  29. JJ says:

    Thomas T says:

    The better term would be, “correlation does not prove causation”, because correlation can damn well be a strong enough clue to be suggestive of causation.

    No. “Correlation does not prove causation” is a fine alternative wording, but the strength of a correlation does not have a damn thing to do with whether or not causation is also involved.

    What is important here is that at present no other parameter, such as solar or earth tilt, etc, correlates well with the observed rapid increase in global temperature.

    No. What is important here is that right under your “Correlation does not prove causation” sign, you need to pencil in “And ignorance doesn’t prove anything.”

    That is the kicker,…

    It is not a kicker. It is a logical fallacy. A variant of argumentum ad ignorantiam.

  30. AndyG55 says:

    @theduke “Correlation is everywhere. Lobsters are red and so are apples (unless they are green and then they correlate with grass.) Apples do not grow in the ocean, but to the untrained eye, they correlate with boiled lobsters”

    You really don’t understand the meaning of “correlation” do you. !!!

  31. AndyG55 says:

    @Phillip “( two events occurring at the same time that have no direct relationship to each other besides the fact that they are occurring at the same time)”

    And in the case of CO2 and global average (urban) land temperature, this ONLY happened for a period between 1976ish and 1998ish…

    which ALSO happened to coincide with massive urbanisation in many areas where land thermometers were located.

    Now that they are being more careful with land temp calcs (because they are being watched) and satellite temps are now accepted, the coincidence of CO2 and temperature increases has DISAPPEARED !!

  32. theduke says:

    Thomas T says:
    October 2, 2012 at 10:03 pm

    establishment climate scientists refuse to vigorously explore (and disprove) other possible causes

    Name an establishment scientist that has refused to explore and disprove other possible causes. And once you name them, what is your evidence?
    ——————————————————————-

    All of them. Cite a paper where someone associated with the IPCC has attempted to explore other possible causes for global warming than man-made CO2. Better yet, cite a paper that questions the orthodoxy that CO2 is the cause of AGW. Cite a paper that proves that causation and not correlation validates the theory of CO2 induced AGW.

    They decided a priori a long time ago that CO2 was the cause based on extrapolating a century-old theory. They haven’t bothered to prove it, because they’ve gotten away with relying on correlation.

    Junk science.

  33. theduke says:

    Thomas T wrote: “The better term would be, “correlation does not prove causation”, because correlation can damn well be a strong enough clue to be suggestive of causation.”

    So you want governments around the world to spend (or cause people to spend) trillions of dollars because you believe you have a “strong enough clue to be suggestive of causation?”

    That sounds “damn well” stupid to me.

  34. AndyG55 says:

    Robin Melville says:
    “I was warned about this fallacy by my Stats teacher who pointed out that when temporal and spatial measurements were taken into account it’s trivial to prove that, in England, churches cause pubs.”

    Robin, you have the causality wrong way around ;-)
    Churches are built, to cope with the evil of pubs……… or maybe…

    hmmmm this requires some more research.. …… funding please someone…

    I’ll do the pub part of the research.

  35. Doug UK says:

    Gunga Din says:
    October 2, 2012 at 8:49 pm
    Every day I that I go to work when I come home from work, my dog wants a treat.
    Therefore, if I never went to work, my dog would never want a treat.
    Or maybe if I never came home from work, my dog would never want a treat?
    More reasearch funds are needed.

    ………………

    And if you prefaced your research grant request with “The effect of Climate Change on Canine Pavlovian responses” – the money would be yours.

  36. DonK31 says:

    Simple logic tables:
    If A then B.
    If B…what about A?
    A may or may not be true.

  37. Michel says:

    Let’s remember Richard Feynman: http://www.youtube.com/watch?v=b240PGCMwV0

    Correlation is a statistical way to determine if experimental data fit with a theoretical model, and to compute a index of confidence for it.
    But a theoretical model canot be deducted from a correlation:
    – In the Northern Hemisphere chimneys are beginning to make more smoke in the Autumn.
    – At this same time leaves are falling from the trees.
    – There is a correlation between these two observations.
    – Therefore: is smoke causing the falling of leaves?

    Too many people make such mistakes because they don’t analyze all consequences implied by the theory that they expose.

  38. richardscourtney says:

    Philip Bradley:

    At October 2, 2012 at 10:29 pm you write

    For the umpteenth time, absent chance (coincidence), correlation is proof of causation. It’s just that correlation between A and B isn’t proof that A causes B, which is the fallacy.

    For the umpteenth time YOU ARE WRONG . Correlation proves nothing.

    Any two time-series will correlate for some periods of the time if they are long enough.

    Richard

  39. Urederra says:

    Lack or correlation proves lack of causation.

    That is what we should apply to CO2 and temperatures.

    I remind you people that Pearson was talking about quantified variables, or so I understood.

  40. Urederra says:

    Sorry, It should read. “Lack of correlation proves lack of causation”

  41. dave38 says:

    Robin Melville says:
    October 2, 2012 at 10:08 pm

    I was warned about this fallacy by my Stats teacher who pointed out that when temporal and spatial measurements were taken into account it’s trivial to prove that, in England, churches cause pubs.

    The reason is actually very simple.
    The Bible tells us to thirst after righteousness!

  42. peterk505 says:

    Plot a graph of ice-cream sales over a year.
    Plot a graph of swimming pool drownings over a year.
    Ah, we seem to have a correlation- they both peak around August!
    Now the burning question is- do ice-cream sales affect swimming pool drownings or vice-versa?
    Hmmm……

  43. As I’ve argued before, for the purposes of the scientific side of the climate debate, the “correlation does not necessarily imply causation” element of the fallacy is the most important one. Not only is there no empirical evidence to support the contention that anthropogenic GHG emissions control global temperatures; the graphs of the two phenomena don’t even line up. So I don’t understand why people are even looking for evidence (yes, that was a rhetorical statement; I understand why people are looking for evidence of a causal linkage between delta T and delta CO2 – but the reasons have nothing to do with science).

    However, from the policy side of the climate debate, the inverse argument is more important, i.e., that non-correlation demonstrates non-causation, or in other words, if there is no statistically significant correlation between two phenomena, it is impossible to posit a causal relationship between them. The IPCC itself admits this by arguing that “temperature response” should “scale linearly with forcings”, of which the most important (in their opinion) is human GHG emissions. The crux of the debate, therefore, should hinge on the fact that there is no statistically significant correlation between change in CO2 concentration and change in temperature over any time period for which reliable temperature records and/or proxies exist – with (again, as I’ve mentioned before) the sole example of Antarctic ice core samples, which seem to demonstrate a correlation, but with delta T preceding delta CO2, thus implying that the former causes the latter rather than the inverse.

    Moreover, and again from a policy perspective, if there is no statistically significant correlation between delta T and delta CO2, how can you design a policy to limit change in the former by constraining anthropogenic emissions of the latter? This basic question seems to keep getting lost in the manufactured (and totally irrelevant) furor over tenths of degrees.

  44. Dale says:

    I get older by 1 per year. CO2 goes up by 2 ppm per year.

    Therefore my age determines CO2 ppm.

    In 1974, CO2 was ~330 ppm. Thus, extrapolating out to when I’m 60 (2034), CO2 will be 450 ppm.

    Correlation == causation! It’s worse than we thought since CO2 – Temps is another “correlation == causation”, that means temps will be ~3.2C higher than pre-Industrial in 2034!

    BS!

  45. David S says:

    Philip Bradley
    Absent chance…or correlation the other way…or another causative agent, or any mixture of the three, ie absent everything else, so argumentum ad ignorantem in other words.

  46. AndyG55 says:

    “Any two time-series will correlate for some periods of the time if they are long enough.”

    And in the case of CO2 and temperature, a VERY SHORT 20 odd year period, with NO CORRELATION (negative in fact) between 1940-1970ish OR between 1998 and now.

    so over the time that there has been any significant human CO2 release, the correlation has only been for about 1/3 of the time…. and these MORONS try to attribute causation.. DOH !!!!

  47. AndyG55 says:

    sorry, I used “temperature”.. where I really meant “homogemnised NH Urban land temperature”

  48. H.R. says:

    Gunga Din says:
    October 2, 2012 at 8:49 pm
    “Every day I that I go to work when I come home from work, my dog wants a treat.
    Therefore, if I never went to work, my dog would never want a treat.
    Or maybe if I never came home from work, my dog would never want a treat?
    More reasearch funds are needed.”

    Fess up; your dog has you well-trained ;o)

  49. AndyG55 says:

    wrong again.. .. try..

    “rabid warmist activist manipulated urban land temperature”

  50. Otter says:

    tomt~ quick question in regards to your contention of rapid warming:

    How far did the Earth’s temp drop, from the height of the MWP, to the bottom of the LIA?

    How much of that has been regained since the bottom of the LIA?

    Thanks in advance.

  51. michael hart says:

    One accusation that could be levelled at the mentality of the hockeystickers, is that they are not very good at imagining alternative explanations to account for observations. Eliminating incorrect hypotheses is, in fact, the bedrock of the scientific method.

    A good scientist is distinguished from a mediocre one by their ability to imagine causal alternatives, and by their diligence in examining them.

    Other than that, I agree with David Hoffer’s comments above.
    Also, perhaps the nature of books has changed over time in terms of the technical/non-technical ratio. Does the search look for occurrences of the word or just the number of books that use it one or more times? Would this be affected by changes in book length? Perhaps Google hasn’t finished digitising books and is doing them by category, not chronological order. Perhaps they don’t have access to more recent technical publications for commercial reasons. Perhaps certain types of book are now translated into English more often.

    I dunno. But the list goes on, and the number of possible alternative hypotheses that could be tested is effectively infinite. The best scientists will break into a smile when they hear the phrase “One experiment too many!”

  52. richardscourtney says:
    October 3, 2012 at 1:26 am

    Any two time-series will correlate for some periods of the time if they are long enough.

    Which is chance. Note I said ‘absent chance’.

  53. DAV says:

    Philip Bradley says:
    October 2, 2012 at 10:29 pm

    For the umpteenth time, absent chance (coincidence), correlation is proof of causation. It’s just that correlation between A and B isn’t proof that A causes B, which is the fallacy.

    Possibly true but not when using only two variables. Not only is “correlation between A and B isn’t proof that A causes B” true but two correlated variable could have a common cause. The correlation between preachers’ salaries in New England and the price of rum have inflation as one of the drivers. Two correlated variables could also be mutual causes: chickens and eggs, so to speak.

  54. polistra says:

    Better slogan: DON’T USE STATISTICS.

    Stats remove the time dimension, which removes the one thing that can guide you toward finding a causation or connection. If you use graphs and waveforms, paying attention to regularities and PHASE, you’ll always be able to spot the leading and lagging variables… or determine quickly that there’s no connection at all between X and Y.

  55. Robin Melville says:

    You’ll note from above that temporally churches can be demonstrated to cause pubs to a high degree of confidence (I forget exactly the r^2 but it was 35 years ago). Post hoc ergo propter hoc, so to speak.

  56. richardscourtney says:

    Philip Bradley:

    At October 3, 2012 at 3:18 am in response to my rebuttal at October 3, 2012 at 1:26 am of
    your fallacious claim at October 2, 2012 at 10:29 pm saying

    For the umpteenth time, absent chance (coincidence), correlation is proof of causation.

    you quote from my rebuttal

    Any two time-series will correlate for some periods of the time if they are long enough.

    and reply

    Which is chance. Note I said ‘absent chance’.

    You cannot pretend that ‘chance’ may be “absent”, and that is why your assertion is plain wrong.

    Richard

  57. DAV says:

    polistra says:
    October 3, 2012 at 3:35 am

    Stats remove the time dimension

    I guess you never heard of autocorrelation of time series.

    If the time variable has been removed in an analysis, it was because it wasn’t considered or wasn’t deemed important. Statistics says nothing about whether time should or should not be a variable.

    … If you use graphs and waveforms, paying attention to regularities and PHASE, you’ll always be able to spot the leading and lagging variables

    Doesn’t work very well for chickens and eggs. The actual beginning is the only place where the first of two correlated cyclical events can be determined OR with an experiment which establishes a beginning.

  58. Alberta Slim says:

    I like Go Home’s correlatons. Great.
    ThomasT – Logic, does not seem to be your strong suit.
    As you head back to the safety of your Church of CAGW remember that those hoofbeats behind you are probably not from zebras, horses, or bison. The are from the sensible, scientific bloggers on WUWT.
    Open your mind please. The Alarmists have taken a short term correlation of global temperatures and rising levels of CO2, and extrapolated them with computer models that made forecasts/predictions that never came true.

  59. LazyTeenager says:

    theduke says

    experienced over the past 100 years because establishment climate scientists refuse to vigorously explore (and disprove) other possible causes should be offensive to anyone who respects the scientific method.
    ———-
    I’m pretty sure you have not vigorously explored the scientific literature to make this claim stick. And insisting on some arbitrarily high level of proof would be cheating.

  60. LazyTeenager says:

    D Boehm says
    D Böehm on October 2, 2012 at 9:23 pm
    Thomas T,

    Positive feedbacks have been falsified by Planet Earth; the ultimate Authority. Believe what you want, it isn’t reality. CO2=CAGW is a debunked fantasy.
    ————–
    Simply saying that positive feedbacks don’t exist isn’t good enough. Putting words in Natures mouth isnt a convincing argument either. It’s very likely you don’t understand positive feedbacks and how they apply to climate.

  61. Jit says:

    See what happens when you graph “global warming” and “anthropogenic climate change”. I’ve done it for Google Books and Google Scholar, the former stimulated by this post, the latter something I did back in February.

  62. richardscourtney says:
    October 3, 2012 at 3:45 am

    You cannot pretend that ‘chance’ may be “absent”, and that is why your assertion is plain wrong.

    Chance for the purposes of this discussion is a function of sampling. It is not a property of the real world.

    Chance is absent from the real world.

  63. MarkW says:

    Thomas T says:
    October 2, 2012 at 8:53 pm

    What is important here is that at present no other parameter, such as solar or earth tilt, etc, correlates well with the observed rapid increase in global temperature.

    That would be important, if it were true.
    The secondary factor that you are employing to improve your case is another phrase that I’m sure has also increased in recent decades. It’s called Cherry Picking. That is, pick the years where your hypothesis holds and discard all the others.

    In this case if you extend your timeline back a few centuries, and your forward to today, you find out that there is no correlation between CO2 levels and temperatures.

  64. Brian says:

    “(I’ll let someone else explain why correlations have been trending downward since 1976.)”

    The answer to this is fairly simple. With the information/computer/Internet revolution, we have seen an insane explosion in available information. Frankly, humans are not yet capable of dealing with the information overload. The reduced use of the word “correlation” reflects our inability to relate these large amount of diverse data. It is, in other words, an indicator of our psychological state of mind, in which uncertainty is growing and making sense of the world is increasingly challenging. This trend also explains why people have become increasingly ideological–they cling to simplifications (not guns and religion!) to make the world more manageable.

  65. MarkW says:

    Dale says:
    October 3, 2012 at 2:15 am

    I get older by 1 per year. CO2 goes up by 2 ppm per year.
    Therefore my age determines CO2 ppm.

    You have cause and effect reversed.
    Increasing CO2 is causing you to get older. If we could start lowering CO2 levels you would find yourself getting younger.

  66. MarkW says:

    Philip Bradley says:
    October 3, 2012 at 3:18 am

    Which is chance. Note I said ‘absent chance’.

    Which is of course the kicker.
    It is impossible to prove whether your correlation is real, or the result of chance.

  67. MarkW says:

    Philip Bradley says:
    October 3, 2012 at 5:37 am
    Chance is absent from the real world.

    This has got to be one of the stupidest things I have ever read.

  68. Thomas T says:

    Now the burning question is- do ice-cream sales affect swimming pool drownings or vice-versa?

    If eating ice cream were known to cause, say, stomach cramps that increased the likelihood of drowning, then correlation would be intuitive toward causation. But there is no intuitive link, and so your example is weak.

    Whereas, for over a century CO2 has been known to be a greenhouse gas.

  69. Dajake says:

    Could some one comment on something I read on another blog? (I have no science background other than high school)
    They claimed that co2 had an absorption rate of around 8% and a concentration of about 380ppm in the atmosphere. While H2o (water vapor) has an absorption rate of over 90% and a concentration of 30,000ppm. Is this true? So how could co2 be anything but completely negligible regarding climate change?

  70. andrew adams says:

    michael hart,

    One accusation that could be levelled at the mentality of the hockeystickers, is that they are not very good at imagining alternative explanations to account for observations. Eliminating incorrect hypotheses is, in fact, the bedrock of the scientific method.

    Sure, but suppose we have a hypothesis which is based on well understood physical mechanisms, which can’t be eliminated, is consistent with our observations and indeed predicted them in advance. Suppose the obvious alternative hypotheses have been examined and can’t account for observations. Suppose no one has so far put forward an alternative hypothesis which is actually supported by hard evidence. How much time, effort and resources are we supposed to devote to looking for alternative explanations which are unknown in nature, whose existence is entirely speculative, and which are certainly not required to exist? And if we at the point where we are looking for “unknown unknowns” then how will we ever know we have eliminated all possible alternatives? Surely there comes a point where we have to accept that we have an explanation which works well enough to be at least provisionally accepted?

    Now I’m not suggesting that we stop trying to improve our knowledge of the way our climate works, people are indeed still doing this and no doubt there are still gaps in our knowledge which will hopefully become smaller with time. But there is no particular reason to assume that this will lessen rather than increase the case for recent warming being caused by human GHG emissions.

  71. pochas says:

    The correlation coefficient between the series 1,2,3,….10 and 100.1, 100.2, 100.3,….101 is 1 (perfect correlation). The problem is that with two linear series, perfect correlation means absolutely nothing.

  72. Solomon Green says:

    The classic example of spurious correlation was provided by George Udny Yule, a Past President of the Royal Society and a colaborator of Karl Pearson in the development of statistics.

    A study of Church of England marriages betrween the years 1866 and 1911 showed a coefficient of correlation of +.95 with standard deviation of only .014 when measured against the standardised mortality of 1,000 in England and Wales. Thus providing clear evidence that marrying in church increased the risk of death.

    Actually, as Udny Yule pointed out, both series were reducing over the whole 45 year period and the only signifcant correlation was between each series and time.

    While there is evidence that human activity contributes to warming (e.g. UHI) and there is also evidence that human activity adds to CO2 levels, the correlation between any increase in CO2 levels and warming may well be spurious. (I am aware of 150-year old laboratory experiments but I am also aware that what works in a lab experiment more often than not does not translate well inot nature.)

    Both series (if measurable) are correlated directly to increasing numbers in the world population and to the increasing average wealth of that world population. Even if all energy were to be provided by “renewables” human activity would still contribute to warming so long as either or both the numbers and wealth of the world population continued to increase.

  73. D Böehm says:

    Alberta Slim says:
    October 3, 2012 at 4:05 am

    ThomasT – Logic, does not seem to be your strong suit.
    As you head back to the safety of your Church of CAGW remember that those hoofbeats behind you are probably not from zebras, horses, or bison. The are from the sensible, scientific bloggers on WUWT.
    Open your mind please. The Alarmists have taken a short term correlation of global temperatures and rising levels of CO2, and extrapolated them with computer models that made forecasts/predictions that never came true.

    Repeated for effect.

    * * *

    Andrew Adams,

    You have described the climate null hypothesis, which has never been falsified. Nothing observed today is unprecedented or unusual. It has all happened before, and to a greater degree, during times when CO2 was much lower.

    Therefore, the null hypothesis remains unfalsified, and the alternative hypothesis of CO2=AGW remains an unproven conjecture with no empirical evidence proving that it exists.

  74. MikeN says:

    Graph against temperatures please.

  75. andrew adams says:

    D Böehme,

    The case for current warming being caused by CO2 does not require that it is unprecedented or unusual, and stands on the physical properties of GHGs and their known existing effects on the earth’s climate. Your “null hypothesis” is illogical and unfalsifiable.

  76. andrew adams says:

    Apologies to D Böehm for misspelling his name.

  77. Gunga Din says:

    H.R. says:
    October 3, 2012 at 2:40 am
    Gunga Din says:
    October 2, 2012 at 8:49 pm
    “Every day I that I go to work when I come home from work, my dog wants a treat.
    Therefore, if I never went to work, my dog would never want a treat.
    Or maybe if I never came home from work, my dog would never want a treat?
    More reasearch funds are needed.”

    Fess up; your dog has you well-trained ;o)
    ===================================================================
    That is what my wife keeps telling me.
    Maybe if she stopped telling me that my dog would never want a treat?
    More research funds are needed.

  78. dcfl51 says:

    Andrew Adams,

    We know that the Earth experienced warming without any assistance from CO2 during the Medieval Warm Period, the Roman Warm Period, the Minoan Warm Period, the late Holocene Optimum and the Early Holocene Optimum. Therefore alternative explanations of warming ARE required to exist. The most likely cause of the current warming is some combination of the factors which caused the previous warmings and it would be a very good idea to research them. There is no shortage of candidate explanations, which don’t have to be mutually exclusive, the most prominent being ocean oscillations and cosmic rays.

    Your assertion that computer models based on the CO2 hypothesis match observations and, in fact, predicted them, is jaw-dropping. The models can only be made to match observations retrospectively by continually introducing post-hoc parameter adjustments and fudge factors such as aerosols. The models wildly exaggerate warming, principally because they get the magnitude and sign of water vapor feedbacks wrong. Hence the need for aerosols to dampen the warming from predicted to actual levels.

    We know that the warming effect of CO2 is logarithmic and that the IPCC says that a doubling of CO2 will produce a temperature rise of 3.3 degC (central estimate). Therefore, a rough and ready estimate of the effect of CO2 can be obtained as follows :-
    3.3 = X ln(2) therefore X = 4.76

    The atmospheric concentration of CO2 in the late 1800s is alleged to have been 278 ppm and it is now 398 ppm. So, since the late 1800s we should have seen a temperature rise of around
    4.76 x ln(398/278) = 1.7 degC

    from the effects of CO2 and associated feedbacks alone. To this should be added any warming from natural causes, urban heat island effect and dodgy data adjustments by climastrologists. Instead, we have only had warming of 0.8 degC including natural causes, UHI and dodgy adjustments. Doesn’t this make the models look a tad shaky ?

  79. D Böehm says:

    andrew adams,

    You are new here, otherwise you would be up to speed on the climate null hypothesis, which is easily falsifiable: simply show a current climate parameter that exceeds a past parameter during the Holocene. The curent climate is extremely benign by Holocene standards. Nothing unprecedented is happening. Temperatures, precipitation, storms, droughts and floods have all been more severe at times when CO2 was much lower.

    But don’t take my word for it. Arch alarmist Kevin Trenberth states that he wants the climate null hypothesis reversed, placing skeptics in the position of having to prove a negative. Trenberth understands what the null hypothesis means to his climate beliefs, and he doesn’t like it one bit. But by wanting to re-define the null to his liking, he is acknowledging its legitimacy as a corollary of the scientific method.

  80. Thomas T says:

    Nothing observed today is unprecedented or unusual.

    Nonsense. The rapidity is unprecedented. The role of human contributed CO2 is unprecedented.

    It has all happened before

    Not with this rapidity and human contribution.

    and to a greater degree

    Not in modern human history.

  81. Thomas T says:

    Temperatures, precipitation, storms, droughts and floods have all been more severe at times when CO2 was much lower.

    CO2 is not the sole driver of climate. The Milankovitch cycle, to name one, likely played a role in driving the Holocene climate.

    Moreover, a human global economy was not in place in the Holocene and, if it were, the climate change was gradual.

  82. dcfl51 says:

    Thomas T

    The rate of warming during the periods 1860-1880 and 1910-1940 was 0.16 degC per decade, the same as in the period 1970-2000. Phil Jones of the CRU has admitted that there was no statistically significant difference.

    Although there were not enough thermometer-based weather stations prior to the mid-1800s to allow a global mean temperature to be calculated, the Central England Temperature record is a thermometer-based record extending continuously back to 1659. This indicates that temperatures rose during the period 1695-1735 at more than 3 times the above rate.

    I’m afraid the claim that the recent rise in temperatures is unprecedented is bovine faeces.

  83. tadchem says:

    As an undergraduate student in chemistry, I felt a need to study statistics so I could make better sense of my own data. I obtained and studied cover-to-cover a copy of William Volk’s “Applied Statistics for Engineers” (1958, one volume of the marvelously useful McGraw-Hill Chemical Engineering Series).
    I learned that statistics is not for amateurs.
    When I see ‘scientists’ attempting to use anything more complex than a mean and variance, such as a regression, I think of three famous quotes: “Hey, Bubba! Watch this!” (Redneck Epitaph), “Do not try this at home!” (standard TV caveat preceding dangerous stunts), and “Nothing is more terrifying than ignorance in action” ( J.W. von Goethe, German writer).

  84. PeterB in Indianapolis says:

    Anyone claiming that a Null Hypothesis (not just climate-related, but ANY Null Hypothesis) is illogical and unfalsifiable has absolutely no understanding whatsoever of science or the scientific method.

    Of course, given the quality of schooling in much of the world these days, it doesn’t surprise me that many people don’t understand what a Null Hypothesis is and why it MUST be used as a baseline in any scientific discipline….

    Another thing that highly annoys me is the claim that “Anthropogenically Produced CO2″ is somehow NOT part of “natural variability”.

    When a beaver builds a dam, it isn’t somehow “unnatural”, now is it? When man builds a dam, this is not in any way “unnatural” either.

    As the great band Love & Rockets once sang,

    “You cannot go against nature, because when you do… go against nature, that’s a part of nature too!”

    Nothing that man does is “unnatural”. It is PHYSICALLY IMPOSSIBLE to do something “unnatural”. Everything that man does can be accounted for by physics, and anything “unnatural” would violate physics.

    As such, any CO2 we are adding to the atmosphere IS ACTUALLY part of “natural variability”. It is possible to ASSUME the the level of CO2 in the atmosphere would be different in the absence of natural human actions, but that just proves that natural human actions are a part of natural variability. However, it is also possible to hypothesize that the increase in atmospheric CO2 is the direct result of more CO2 being released from the oceans as they naturally warmed, and as the oceans again undergo their natural cooling cycles, they will begin to absorb more CO2, thus reducing the atmospheric concentration. If this does occur, then it will be increasingly difficult to quantify the human contribution. Sure, we can get a pretty good estimate of how much CO2 our activities RELEASE into the atmosphere, but what we release into the atmosphere through our activities doesn’t really seem to “hang around” in the atmosphere for very long, so it is very difficult to quantify what the “natural” level of CO2 in the atmosphere “should” be right now.

  85. PeterB in Indianapolis says:

    Thomas T.

    Your confusion lies with the idea that “Modern Human History” has no significance whatsoever when studying the climate of the Earth. The climate of the Earth can only be understood on geologic time-scales.

    To assign any significance whatsoever to the minute time-frame encompassed by “Modern Human History” is silly.

    Also, within “Modern Human History”, Greenland used to be, well, GREEN. Vikings settled there, and grew bountiful crops. Greenland isn’t particularly green anymore, because currently it is too damn cold there to grow much of anything. As such, it is quite trivially easy to prove that even within the timescale that you call “Modern Human History”, Greenland HAD TO HAVE BEEN WARMER in the PAST than it CURRENTLY IS NOW. If it had not been warmer in the past, I doubt very much that the Vikings would have bothered settling there, because I doubt that they would have been able to get any crops to grow. And yet we know, from archaeological evidence that the Vikings did indeed inhabit Greenland, and they did indeed grow crops there.

    So, according to your hypothesis, were the Vikings in possession of some magic which allowed them to grow bountiful crops in permafrost?

  86. Chad Wozniak says:

    djake – you have it right.
    The relative effect of water vapor = 33,000 ppm * 90 percent = 29,700
    The relative effect of CO2 = 380 ppm * 8 percent ~ 31 – or about 1/970 that of H2O, which establishes beyond any doubt that CO2 effect on climate is infinitesimal.
    And that’s before we consider the ratioo of man’s activities to CO2 activity (probably less than 1/1,000 of total CO2 activity – also infinitesimal.
    So in total you have 1/(970*1,000) as the effect of human activity on climate i.e., about a million to one odds against it. An infinitesimal of an infinitesimal.

  87. John Whitman says:

    PeterB in Indianapolis says:
    October 3, 2012 at 9:52 am

    - – - – - – -

    PeterB in Indianapolis

    I think you are on the trail of the fundamental false premise of the ideological environmental movement. I think their false premise is they merely posit that anything that man does to impact the universe for his own benefit, achieved from his uniquely rational cognitive processes, somehow makes man a malevolent entity. They think mankind is a disease when using his mind to impact the universe. I conclude that the ideological environmental movement is fundamentally anti-mind.

    Absurdly, the ideological environmentalists try to use their minds to convince us by intellectual argument that being anti-mind is better. They self-contradict.

    John

  88. David Ball says:

    Thomas T has been shown to be wrong over and over and over on multiple threads. He refuses to acknowledge any of it, and continues to spew his nonsense. We are supposed to accept him at his word when he says things like “Nonsense, the rapidity is unprecedented”? Who is the d-nire here?

  89. JPeden says:

    Philip Bradley says:
    October 2, 2012 at 10:29 pm

    For the umpteenth time, absent chance (coincidence), correlation is proof of causation.

    What MarkW said above.
    You’ve also “begged the question” by simply defining everything else possible as a cause in the real world of real science as “chance [coincidence]“. Therefore, while what you’ve said is “true” by definition, it does not itself relate to the real world of real science. But as to the current topic here of statistical correlation vs real causes, if words don’t relate to the real world, who cares? Answer, people for whom the repetition of some of the PNAS’s CO2CAGW “tenets” as empirically untethered dogma [mere verbiage] is just o’ so soooothing:

    “Thomas T says:
    October 3, 2012 at 9:11 am”

  90. John Whitman says:

    Someone correct me if I am wrong, but do not see any rabid rapid responders on this thread belonging to Cook’s Crusher Crew from Paranoiaville (CCCP***). If there is anyone commenting on this thread from CCCP then would you kindly self-identify in the name of the intellectual integrity of the Cook blog venue?

    ***any correlation to the acronym of the former Soviet Union is amusingly just coincidental and not intended. : )

    John

  91. Legatus says:

    “What is important here is that at present no other parameter, such as solar or earth tilt, etc, correlates well with the observed rapid increase in global temperature.”

    This is the old argument:
    Excluded Middle (False Dichotomy, Faulty Dilemma, Bifurcation):
    assuming there are only two alternatives when in fact there are more. For example, assuming Atheism is the only alternative to Fundamentalism, or being a traitor is the only alternative to being a loud patriot.

    It excludes such things as the Urban Heat Island Effect (probably the major “contributor” to “warming”, other land use effects, the death of the thermometers (many less measuring sites than ther used to be), “adjustments” made to the temperature record (always making it seem colder in the past and warmer now), changes in measuring methods (newer paints over screens replacing tho old whitewash, different methods and instruments, gridding, bad siting), the warmup from both the Little Ice Age and the 70′s ice age scare (the question here is not what made it warm up, but what made it get colder to warm up from in the first place), the medieval Warm period (just as warm as now, no SUV’s), and many others. Thus the phrase “at present no other parameter” is a false statement, many other parameters can also correlate.

    There is also no “observed rapid increase in global temperature”, rapid, where is this rapid? Careful measurements show no increase in over 100 years, no unprecedented rise seen compared to the history of the Holocene, the only place a “rapid” increase is seen is in the now discredited “hockey stick”, which was a flat out, bald faced lie, and in models, which are fiction.

    Thus the above statement is false in every way.
    You need to get out more.

  92. Gunga Din says:

    David Ball says:
    October 3, 2012 at 11:11 am
    Thomas T has been shown to be wrong over and over and over on multiple threads. He refuses to acknowledge any of it, and continues to spew his nonsense. We are supposed to accept him at his word when he says things like “Nonsense, the rapidity is unprecedented”? Who is the d-nire here?
    ==========================================================================
    That’s why I asked if he was a member of the BBSB, the “Baffle them them with Bulls**t Brigade”.
    (Though I think on the SkS Super-Secret thread they prefered to be called “Komment Krushers” or something like that.)

  93. David Ball says:

    Gunga Din says:
    October 3, 2012 at 11:53 am
    BBSB covers it nicely. I am not sure if anyone has already suggested Anthropogenic Science Squad, ……8^D

  94. D Böehm says:

    Thomas T reveals his ignorance of the subject once more:

    “The rapidity is unprecedented.”

    Wrong.

    The fact that CO2 has been rising steadily without any acceleration in natural global warming indicates that any effect from CO2 is so small that it cannot be measured. And if it cannot be measured, AGW is only a conjecture.

  95. Thomas T says:

    It excludes such things as the Urban Heat Island Effect (probably the major “contributor” to “warming”

    Yet, posters here did not question:

    Central England Temperature record is a thermometer-based record extending continuously back to 1659. This indicates that temperatures rose during the period 1695-1735 at more than 3 times the above rate.

    You do know that the Central England Temperature record during that time period 1695-1735 included indoor temperature measurements? Skepticism is selective on this website, if the data is useful, it is not audited.

    The curent climate is extremely benign by Holocene standards. Nothing unprecedented is happening. Temperatures, precipitation, storms, droughts and floods have all been more severe at times when CO2 was much lower.

    You do realize that our knowledge of Holocene climate, and your statement, relies heavily on decades of research, curiosity and scientific method of many, many climatologists? On this thread climatologists are both universally damned as being frauds…yet relied upon heavily for understanding.

  96. andrew adams says:

    dcfl51,

    My remark about not requiring alternative explanations related to modern warming, not past warm periods. For those clearly alternative explanations are needed and no one denies there are known factors other than GHGs which can cause warming, they just don’t explain the warming in recent decades. I’m not sure why you think that highly speculative and unproven theories about ocean oscillations and cosmic rays are a more plausible explanation that GHGs.

    I said nothing about climate models or how they compare to observations – you certainly don’t need a model to predict that increasing GHG levels will cause warming, you don’t neccessarily need them to make a rough estimate of how much warming to expect. Still, your claims about models overestimating the warming do not allow for the difference between transient and equilibrium sensitivity, you overestimate IMHO the effect of UHI and remarks about dodgy data adjustments are just cheap shots. Also, you say we have to allow for “natural warming”, but how do you know the net effect of natural factors has not been negative rather than positive? Having said all that, let’s accept for argument’s sake that the observed warming is a bit lower than expectations – why does that logically mean that the warming we have seen is not due to GHGs? Surely it would be more of a problem if there had been more warming than expected?

  97. Dale says:

    Thomas T:

    Let’s assume you’re right, and humans are cooking the planet with CO2. Okay? Now tell me, here in Melbourne, daily temps can vary by 25-30C, and yearly temps can vary by around 45C.

    So we raise the temp 2C. Scary, isn’t it? That’s less than the temp change between 6am and 6:30am. With rapid unprecedented warming occurring each morning, shouldn’t you alarmists be trying to stop the sun rising?

  98. richardscourtney says:

    Philip Bradley:

    At October 3, 2012 at 5:37 am you say to me

    Chance for the purposes of this discussion is a function of sampling. It is not a property of the real world.

    Chance is absent from the real world.

    I have sampled a bridge you may want to buy.

    Richard

  99. Jeremy says:

    Someone please explain to the current administration that

    1) wacky offensive reprehensible youtube videos do not cause the deaths of ambassadors.
    2) a lack of security detail and adequate protection may, however, place them in grave danger.

    Correlation is not causation.

    Controlling youtube is not the answer…oh wait a minute, of course, controlling youtube is exactly the kind of solution a powerful administration would seek – control the media and you control the people. While at it, why not seek to also control the means of production (all industry) by taxing energy (CO2). Oops, been there done that, aw shucks this administration seems to be way ahead of the sheeple, they are out thinking everyone.

  100. Dr K.A. Rodgers says:

    I have always liked the the correlation that those who drink water die. Kinda says it all.

  101. JJ says:

    andrew adams says:

    The case for current warming being caused by CO2 does not require that it is unprecedented or unusual,…

    Nonsense. Absent the assertion that current warming is both unusual and unprecedented, there is not even any need for a “case for current warming caused by CO2″. If what is happening now has happened before and is usual, there is nothing to explain, let alone support for any particular explanation.

    Hence, the extremes to which the Team has gone to defend the Hokey Stick – the only purpose of which is to prove ‘unprecedented’. And hence the current focus on weather events – the only purpose of which is to demonstrate ‘unusual’ and thus force attribution to CO2.

    … and stands on the physical properties of GHGs and their known existing effects on the earth’s climate.

    No, it doesn’t. The net effect of GHGs on the earth’s climate is unproven conjecture, not known. This is well demonstrated by the WIDE range of magnitudes attributed to the alleged effects, all by people claiming to ‘know’ what they are. Climate sensitivity to CO2 is held to be 0C to around 8C. Known. Hah.

  102. andrew adams says:

    D Böehm,

    I may not visit WUWT much but I am certainly familiar with the “null hypothesis” argument – I just don’t buy it.

    For a start there are different ways of investigating scientific questions, you don’t necessarily need a null hypothesis. But even if we want one it’s silly to say there is such thing as “THE climate null hypothesis” – scientists can choose a particular null hypothesis to suit the question they want to ask. You may prefer your particlur null hypothesis, the rest of us are not obliged to accept it.

    But my biggest objection is the one I stated in my previous comment – your chose null hypotheses is illogical, unfalsifiable and can’t answer the question being posed. Firstly it is based on a false premise, that if recent warming is due to GHGs it must necessarily be outside the range of that previously caused by natural factors. That simply isn’t true. Even if current conditions are not outside those seen previously in the Holocene (it is plausible that temperatures are actually higher but we don’t have good enough records to say for sure) that tells us nothing about which particular physical processes caused the recent warming – it could still be due to GHGs but your null hypothesis wouldn’t be falsified so what use is it?

    I would also make the point that the distinction between “natural” processes and warming due to GHGs is not as clear as you suggest in any case. The presence of GHG gases in the atmosphere has been an influence on the earth’s climate for millions of years, billions even. It’s an entirely “natural” phenomenon. Yet somehow because we have an increase in GHG levels due to “non-natural” cause there is this virtually unsurmountable burden of proof required to demonstrate it has had an effect.

  103. D Böehm says:

    andrew adams,

    You have it backward. The Principle of Parsimony warns against introducing an extraneous variable, when the Null Hypothesis provides a perfectly adequate explanation. The extraneous variable is CO2, which is not necessary to explain the current climate.

    There is no scientific evidence proving that any of the warming since the LIA is caused by rising CO2. None. It may contribute a negligible amount of warming. Or not. But the evidence is missing. Thus, AGW is merely a conjecture — a conjecture that the planet is clearly ignoring.

    This is the internet’s “Best Science” site; it is not a religious blog. So provide evidence to support your conjectures, or admit that your comments are based on evidence-free belief.

    Also, there are other explanations that do not require the CO2 variable. Prof Richard Lindzen writes:

    The notion of a static, unchanging climate is foreign to the history of the earth or any other planet with a fluid envelope. The fact that the developed world went into hysterics over changes in global mean temperature anomaly of a few tenths of a degree will astound future generations. Such hysteria simply represents the scientific illiteracy of much of the public, the susceptibility of the public to the substitution of repetition for truth, and the exploitation of these weaknesses by politicians, environmental promoters, and, after 20 years of media drum beating, many others as well.

    Climate is always changing. We have had ice ages and warmer periods when alligators were found in Spitzbergen. Ice ages have occurred in a hundred thousand year cycle for the last 700 thousand years, and there have been previous periods that appear to have been warmer than the present despite CO2 levels being lower than they are now. More recently, we have had the Medieval Warm Period and the Little Ice Age. During the latter, alpine glaciers advanced to the chagrin of overrun villages. Since the beginning of the 19th Century these glaciers have been retreating. Frankly, we don’t fully understand either the advance or the retreat….

    For small changes in climate associated with tenths of a degree, there is no need for any external cause. The earth is never exactly in equilibrium. The motions of the massive oceans where heat is moved between deep layers and the surface provides variability on time scales from years to centuries. Recent work suggests that this variability is enough to account for all climate change since the 19th Century.

    Finally, your personal belief can reject the Null Hypothesis. But the Null Hypothesis is part of the scientific method, a hypothesis which even climate alarmist Kevin Trenberth accepts. If you want to stick your fingers in your ears whenever the scientific method falsifies your beliefs, well, you have some company. See below.

    ° ° °

    Thomas T, no one here claims that all climatologists are “universally damned”. Name one commentator who has said that. Name just one.

    Internationally esteemed climatologists such as Prof Richard Lindzen, Dr John Christy, Dr Ferenc Miskolczi, Dr Tim Ball, and many others are routinely cited here. Only those climate charlatans who refuse to engage in fair public debates, and who refuse to share their data, methods, metadata and methodologies, are rightly castigated. Most alarmist scientists fall into that category. Why do they refuse to abide by the scientific method, with its transparency requirement? What are they hiding?

  104. richardscourtney says:

    andrew adams:

    At October 3, 2012 at 8:48 am you say to D Böehm,

    The case for current warming being caused by CO2 does not require that it is unprecedented or unusual, and stands on the physical properties of GHGs and their known existing effects on the earth’s climate. Your “null hypothesis” is illogical and unfalsifiable.

    I really, really wish warmists would learn some science instead of spouting their superstitious beliefs.

    The Null Hypothesis says it must be assumed a system has not experienced a change unless there is evidence of a change.

    The Null Hypothesis is a fundamental scientific principle and forms the basis of all scientific understanding, investigation and interpretation. Indeed, it is the basic principle of experimental procedure where an input to a system is altered to discern a change: if the system is not observed to respond to the alteration then it has to be assumed the system did not respond to the alteration.

    In the case of climate science there is a hypothesis that increased greenhouse gases (GHGs, notably CO2) in the air will increase global temperature. There are good reasons to suppose this hypothesis may be true, but the Null Hypothesis says it must be assumed the GHG changes have no effect unless and until increased GHGs are observed to increase global temperature. That is what the scientific method decrees. It does not matter how certain some people may be that the hypothesis is right because observation of reality (i.e. empiricism) trumps all opinions.

    Please note that the Null Hypothesis is a hypothesis which exists to be refuted by empirical observation. It is a rejection of the scientific method to assert that one can “choose” any subjective Null Hypothesis one likes. There is only one Null Hypothesis: i.e. it has to be assumed a system has not changed unless it is observed that the system has changed. Hence, you are plain wrong when you say to D Böehm

    Your “null hypothesis” is illogical and unfalsifiable.

    The Null Hypothesis is defined by the scientific method and NOT by D Böehm. It is completely logical and if it cannot be falsified then that provides a scientific indication.

    In the case of global climate no unprecedented climate behaviours are observed so the Null Hypothesis decrees that the climate system has not changed.

    Importantly, an effect may be real but not overcome the Null Hypothesis because it is too trivial for the effect to be observable. Human activities have some effect on global temperature for several reasons. An example of an anthropogenic effect on global temperature is the urban heat island (UHI). Cities are warmer than the land around them, so cities cause some warming. But the temperature rise from cities is too small to be detected when averaged over the entire surface of the planet, although this global warming from cities can be estimated by measuring the warming of all cities and their areas.

    Clearly, the Null Hypothesis decrees that UHI is not affecting global temperature although there are good reasons to think UHI has some effect. Similarly, it is very probable that AGW from GHG emissions are too trivial to have observable effects.

    The feedbacks in the climate system are negative and, therefore, any effect of increased CO2 will be probably too small to discern. This concurs with the empirically determined values of low climate sensitivity empirically obtained by Idso, by Lindzen&Choi, etc..
    http://www.warwickhughes.com/papers/Idso_CR_1998.pdf
    http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf
    Therefore, the man-made global warming from man’s emissions of greenhouse gases (GHG) could be much smaller than natural fluctuations in global temperature so it would be physically impossible to detect the man-made global warming.

    Indeed, because climate sensitivity is measured to be less than 1 deg.C for a doubling of CO2 equivalent, it is physically impossible for the man-made global warming to be large enough to be detected (just as the global warming from UHI is too small to be detected). If something exists but is too small to be detected then it only has an abstract existence; it does not have a discernible existence that has effects (observation of the effects would be its detection).

    To date there are no discernible effects of AGW. Hence, the Null Hypothesis decrees that AGW does not affect global climate to a discernible degree. That is the ONLY scientific conclusion possible at present.

    Richard

  105. andrew adams says:

    JJ,

    Absent the assertion that current warming is both unusual and unprecedented, there is not even any need for a “case for current warming caused by CO2″. If what is happening now has happened before and is usual, there is nothing to explain, let alone support for any particular explanation.

    I would say that the current warming is unusual, even if “unprecedented” would be too strong a claim (of course that entirely depends on what timescale – there is a precedent for pretty much anything if you go far back enough).

    There has cetainly been a strong warming trend over recent decases and the claim that there is “nothing to explain” is a bit odd given that many are people are arguing over exactly what the explanation is. There are good reasons to believe it is due to our GHG emissions and there are good reason for wanting to know if that is the case. So what if climate changed for different reason in the past, no-one said it can only change for one reason.

    The net effect of GHGs on the earth’s climate is unproven conjecture, not known. This is well demonstrated by the WIDE range of magnitudes attributed to the alleged effects, all by people claiming to ‘know’ what they are. Climate sensitivity to CO2 is held to be 0C to around 8C.

    Well we know the greenhouse effect increases the surface temperature by about 33C for a start so that is proof that GHGs play a significant role in the earth’s climate. There are no credible estimates of climate sensitivity anywhere near either 0C or 8C.

  106. dcfl51 says:

    Andrew Adams

    I owe you an apology. I conflated your post with another and attributed to you things which you did not say. I apologise.

    That will teach me not to flip between blogsites without keeping track of where I am.

  107. Bob Ryan says:

    Thomas T: the problem we have here is that there appears to be no correlation between changes in co2 concentration and changes in temperature. Indeed since 1959, when the first reliable estimates of co2 were obtained from Mauna Loa, changes in co2 lag behind and not ahead of changes in temperature. However, the more fundamental problem is that the temperature series and the co2 time series are fundamentally different in nature, the first has one unit root and the second two. What that means is that no meaningful correlation can be established between the two. This has led to a number of attempts through optimal fingerprinting studies to determine some relationship but they have failed to fully establish a link because, as Hasselmann (1979) noted the results only have significance if all the forcing are known. Have a look in IPCC(2007) appendix 9 for a brief summary of the fingerprinting method but go back to the original literature on the technique to understand how shaky the results actually are.
    If there was a clear statistical link then many of the arguments would have long disappeared and, indeed, the feedback problem would be relatively easily solved. Imagiine how easy it would be if (say) a lagged regression demonstrated that there was an unambiguous correlation between change in temperature and change in co2 the previous year (say) with an r2 of 0.5. This would demonstrate that 50% of the variance in temperature was attributable to changes in co2. Given the physics that would be pretty convincing. But there is no such relationship and it is very easy for anyone with a modicum of statistical skill to check it out.
    It is this lack of empirical association which has forced climate science into the arms of the modellers and they have really done a poor job of retrodicting temperature changes and time series with any reliability. So without correlation the case for any causation is weak and when the casual models are, in their turn, so weak, one does begin to wonder if the core paradigm in climate science is as cut and dried as so many would like to claim.

  108. D Böehm says:

    andrew adams says:

    “There has cetainly been a strong warming trend over recent decases…”

    No stronger than prior warming episodes, when CO2 was much lower.

    And:

    “There are no credible estimates of climate sensitivity anywhere near either 0C…”

    Wrong again. Dr Ferenc Miskolczi, who knows more than you or me about the subject, states that the effect of 2xCO2 is 0.0ºC. Planet Earth appears to agree with him.

  109. richardscourtney says:

    andrew adams:

    At October 3, 2012 at 1:40 pm you assert to JJ:

    There are no credible estimates of climate sensitivity anywhere near either 0C or 8C.

    I gave you links to independent empirical studies obtained by Idso using 8 different methods and by Lindzen & Choi from ERBE satelite data
    http://www.warwickhughes.com/papers/Idso_CR_1998.pdf
    http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf
    Those very credible studies each determine climate sensitivity of ~0.4 deg.C for a doubling of climate sensitivity.

    However, as you say, there are no credible higher values for climate sensitivity although the climate models each use a different value that is much too large to be credible. Kiehl assessed this
    (ref. Kiehl JT,Twentieth century climate model response and climate sensitivity. GRL vol.. 34, L22710, doi:10.1029/2007GL031383, 2007)
    and his Figure 2 showing the range of climate sensitivity and how it is compensated (i.e. fudged) by assumed aerosol forcing can be seen at
    http://img36.imageshack.us/img36/8167/kiehl2007figure2.png ]

    Richard

  110. andrew adams says:

    richardscourtnety,

    Hypotheses don’t magically come into existence of their own accord – scientists have to formulate them. And when formulating a null hypothesis the scientist has to decide on a proposition which is both falsifiable and, if falsified, provide an answer to the particular question the scientist wants to address.

    Now you say first of all –

    Null Hypothesis says it must be assumed the GHG changes have no effect unless and until increased GHGs are observed to increase global temperature.

    Well OK, that doesn’t seem unreasonable, but we not only have both increased GHGs and increased temperatures, we also have the proven existence of the greenhouse effect, so therefore ISTM that the notion that adding GHGs to the atmosphere will not increase temperatures has been falsified, even it doesn’t in itself tell us if all of the recent observed warming has been due to GHGs, or how much warming we might expect in future.

    But you claim otherwise. You say

    In the case of global climate no unprecedented climate behaviours are observed so the Null Hypothesis decrees that the climate system has not changed.

    But hang on, where did the word “unprecented” come from? That wasn’t in your hypothesis. You said “no effect”, not “no unprecedented effect”. Why does the effect have to be unprecedented? Where in the hypothesis that adding GHGs to the atmosphere will cause warming does it say that it must cause warming which is without precendent? That’s silly – as I said above nothing is uprecedented if you look back far enough and we know that there are factors other than GHGs which can cause warming.

    Your argument about climate sensitivity would have much more weight, if it were actually true that “the feedbacks in the climate system are negative” and that CS had actually been measured to be less than 1C. But it’s not and it hasn’t, and Lindzen and Choi certainly doesn’t demonstrate that. I mean come on, even Lindzen admitted that paper was flawed.

  111. Urederra says:

    Here is a weird correlation:
    Everytime Aaron Ramsey scores for Arsenal, someone very famous dies the following day. (or in less than 24 hours)

    Ramsey scores v Utd, Bin Laden dies. Ramsey v Spurs, Steve Jobs dies. Ramsey v Marseille, Gaddafi dies. Ramsey v Sunderland, Whitney Houston dies.

    http://uk.answers.yahoo.com/question/index?qid=20120212003800AAVAGq6
    http://www.dailymail.co.uk/news/article-2101478/When-Arsenal-player-Aaron-Ramsey-scores-famous-dies.html
    Do you want something weirder? Ramsey just scored less than an hour before. Will somebody very famous die tomorrow?

  112. andrew adams says:

    D Böhme,

    No stronger than prior warming episodes, when CO2 was much lower.

    Which doesn’t contradict my point since I never said that temperatures couldn’t increase for reasons other than CO2.

    Wrong again. Dr Ferenc Miskolczi, who knows more than you or me about the subject, states that the effect of 2xCO2 is 0.0ºC. Planet Earth appears to agree with him.

    I would say planet earth very much disagrees with him. If it were true it would mean that either CO2 is not a greenhouse gas (falsified by observations) or that changes in radiative forcing could never result in changes in climate (falsified by observations).

  113. richardscourtney says:

    andrew adams:

    I have been thinking about your post at October 3, 2012 at 1:40 pm and I think I may have discerned your difficulty. You say

    Well we know the greenhouse effect increases the surface temperature by about 33C for a start so that is proof that GHGs play a significant role in the earth’s climate.

    Absolutely right. However, the effect of atmospheric CO2 as a GHG is not linear. Each doubling of CO2 in the air has the same effect as the previous doubling. Therefore, the effect of increasing atmospheric CO2 from present levels has little effect.

    The GHG occurs from absorbtion of radiation (i.e. IR) in the atmosphere. A sheet of paper covering the window of a room also absorbs radiation (i.e. visible) so darkens the room. An additional sheet of paper absorbs more radiation so darkens the room some more. The addition of a tenth sheet makes little difference from the darkening of nine sheets. Similarly, adding more CO2 to the existing atmosphere makes little difference to the GHG.

    Also, the existing climate system responds to increased GHG to oppose effects of that increase; i.e. the feedbacks are negative.

    Richard

  114. D Böehm says:

    andrew adams,

    Among other things, it is clear that you still do not understand the Null Hypothesis.

    The Null Hypothesis is the statistical hypothesis that states that there are no differences between observed and expected data. Wake me when you get your head around that definition.

    Here you can see that the long term warming trend is decelerating [the green line]. There is no recent acceleration of global temperatures. This is based on empirical data.

    Give up on the alarmist blogs you have been reading. This is the internet’s “Best Science” site. After a few months here, the scales might fall from your eyes. Not likely. But possible.

  115. John Whitman says:

    andrew adams says:
    October 3, 2012 at 1:25 pm

    @D Böehm,

    [ , , , ]

    But my biggest objection is the one I stated in my previous comment – your chose null hypotheses is illogical, unfalsifiable and can’t answer the question being posed. Firstly it is based on a false premise, that if recent warming is due to GHGs it must necessarily be outside the range of that previously caused by natural factors. [emphasis by JW] That simply isn’t true. Even if current conditions are not outside those seen previously in the Holocene (it is plausible that temperatures are actually higher but we don’t have good enough records to say for sure) that tells us nothing about which particular physical processes caused the recent warming – it could still be due to GHGs but your null hypothesis wouldn’t be falsified so what use is it?

    [ . . . ]

    - – - – - -

    andrew adams,

    There is a false premise in your above argument. Your false and hidden premise is that there is an established ‘a priori’ environmental concern about some posited alarming problem caused by the mere existence of anthropogenic CO2 in the earth-atmosphere system even if the problem is not discernible in the null hypothesis case based on natural variability. In other words you falsely introduce a hidden premise that there is some mythical environmental ‘a priori’ problem for the earth-atmosphere system even though it is behaving like a historical earth-atmosphere system with only non-anthropogenic CO2.

    Your approach is somewhat irrelevant to the scientific discourse per se.

    NOTE: Your false and hidden premise is the fundamental pre-condition for the initial UN justification for the establishment of the IPCC . . . . so you are not alone. : ) You have a lot of environmentally emotional support, but little actual objective scientific support, within the IPCC.

    John

  116. AndyG55 says:

    andrew adams says:
    “There has cetainly been a strong warming trend over recent decases…”

    The warming trend was ONLY during a period from 1970ish-1998 which was part of the NATURAL cycle. (And mostly due to urban land tempertures and data adjustments)

    The coincidence of tempertaure and CO2 trend during that SHORT period is ONLY coincidence , (assuming you discount deliberate data tampering), NOT correlation and certainly NOT causation.

    If CO2 drove warming, it would have warmed between 1940-1970 and from 1998 until now.. BUT IT DIDN’T. So the hypothesis that CO2 forces warming is demonstrably FALSIFIED !

  117. RoHa says:

    @ Robin Melville

    I learned that in many cases churches did cause pubs. It used to take a long time and a lot of men to build a church. While it was being built, some smart operator would set up a pub nearby to provide liquid sustenance to the workers.

    After the church was built, the same establishment would provide relief for the victims of the long, tedious, sermons.

  118. If there was a clear statistical link then many of the arguments would have long disappeared and, indeed, the feedback problem would be relatively easily solved. Imagiine how easy it would be if (say) a lagged regression demonstrated that there was an unambiguous correlation between change in temperature and change in co2 the previous year (say) with an r2 of 0.5. This would demonstrate that 50% of the variance in temperature was attributable to changes in co2. Given the physics that would be pretty convincing. But there is no such relationship and it is very easy for anyone with a modicum of statistical skill to check it out.

    Well said.

    I have yet to see any correlation between CO2 change over some period and temperature change over some period, and where CO2 leads temperature that is more than trivial.

    And at the risk of reigniting rcourtney, the absence of correlation is proof of the absence of causation, bar chance and one other exception (one or more other causative factors operating in the other direction to CO2), which is the main argument (using fiddled aerosol forcings) used by AGW advocates as to why we don’t see a correlation.

  119. JJ says:

    andrew adams says:

    I would say that the current warming is unusual, …

    Yeah, but you’re the guy who just got done saying that ‘unusual’ wasn’t necessary to your case. You say lots of things. Talk is cheap.

    There has cetainly been a strong warming trend over recent decases …

    And recent centuries, and recent millennia – though we don’t appear to be above the peaks of similar timeframes. Yawn.

    … and the claim that there is “nothing to explain” is a bit odd given that many are people are arguing over exactly what the explanation is.

    Many people are arguing, often quite violently, over the will of Allah. This does not demonstrate the existance of that deity. You seem to have difficulty discerning belief from reality.

    There are good reasons to believe it is due to our GHG emissions transgressions against the flying spaghetti monster and there are good reason for wanting to know if that is the case

    Funny how that still works.

    So what if climate changed for different reason in the past, no-one said it can only change for one reason.

    Crops may fail for more than one reason, therefore THIS one is surely due to witches!

    Well we know the greenhouse effect increases the surface temperature by about 33C for a start …

    By what means do you think we ‘know’ that?

    … so that is proof that GHGs play a significant role in the earth’s climate.

    That is not the question before us. Whether GHGs play a specific, unproven conjectured role is. You are handwaving.

    There are no credible estimates of climate sensitivity anywhere near either 0C or 8C.

    Says you. You say a lot of things. Saying things is easy:

    There are no credible estimates of climate sensitivity near 4C

    See.

  120. richardscourtney says:

    andrew adams:

    At October 3, 2012 at 1:32 pm I took the trouble to explain the Null Hypothesis to you. That explanation included these statements:

    The Null Hypothesis says it must be assumed a system has not experienced a change unless there is evidence of a change.

    The Null Hypothesis is a fundamental scientific principle and forms the basis of all scientific understanding, investigation and interpretation. Indeed, it is the basic principle of experimental procedure where an input to a system is altered to discern a change: if the system is not observed to respond to the alteration then it has to be assumed the system did not respond to the alteration.

    and

    Please note that the Null Hypothesis is a hypothesis which exists to be refuted by empirical observation. It is a rejection of the scientific method to assert that one can “choose” any subjective Null Hypothesis one likes. There is only one Null Hypothesis: i.e. it has to be assumed a system has not changed unless it is observed that the system has changed. Hence, you are plain wrong when you say to D Böehm

    Your “null hypothesis” is illogical and unfalsifiable.

    The Null Hypothesis is defined by the scientific method and NOT by D Böehm. It is completely logical and if it cannot be falsified then that provides a scientific indication.

    At October 3, 2012 at 2:15 pm you reply to that saying:

    Hypotheses don’t magically come into existence of their own accord – scientists have to formulate them. And when formulating a null hypothesis the scientist has to decide on a proposition which is both falsifiable and, if falsified, provide an answer to the particular question the scientist wants to address.

    That is a complete non sequitur.
    As I explained to you SCIENTISTS DO NOT FORMULATE A NULL HYPOTHESIS : they assess how to determine if and how the null hypothesis is falsified by a change.

    If you persist in ignoring answers provided to you and parroting errors that have been refuted then it would seem your purpose is disruption of – and not involvement in – dialogue.

    Richard

  121. richardscourtney says:

    Philip Bradley:

    At October 3, 2012 at 8:26 pm you write

    And at the risk of reigniting rcourtney, the absence of correlation is proof of the absence of causation, bar chance and one other exception (one or more other causative factors operating in the other direction to CO2), which is the main argument (using fiddled aerosol forcings) used by AGW advocates as to why we don’t see a correlation.

    No need to “reignite” me. I am still waiting your offer for the bridge. I remind that at October 3, 2012 at 1:11 pm quoted you having said to me at
    October 3, 2012 at 5:37 am you say to me

    Chance for the purposes of this discussion is a function of sampling. It is not a property of the real world.
    Chance is absent from the real world.

    And I replied

    I have sampled a bridge you may want to buy.

    My sampling is good because it is a random selection from bridges in the real world which cross the Thames, so – as you assert – there is no chance involved in accepting my offer.

    It is a very good bridge and I am willing to accept a very cheap price.

    Richard

  122. Bart says:

    AndyG55 says:
    October 3, 2012 at 2:32 am

    Bob Ryan says:
    October 3, 2012 at 2:01 pm

    In fact, the correlation is evident across the entire modern CO2 record.

  123. Bob Ryan says:

    Hi Bart: I am not sure what your point is but coincidence on a graph is not correlation. Before establishing correlation we need to ensure that the two time series are stationary. Correlation without stationarity is quite meaningless. Stationarity is simply the property that the mean and variance are constant and any perturbations in the trend are mean reverting. Without stationarity in the data any correlation is likely to be spurious. Have a look at http://www.duke.edu/~rnau/411diff.htm for a straightforward explanation.

    The proper way to deal with this is to transform the two time series to attempt to induce stationarity before testing for correlation. Working with various data sets including this one I have hit the same problem that statisticians and time series modellers have discovered – determining correlation has proved very difficult. Hence the the attempts to resolve the problem through more sophisticated multivariate techniques as reported in AR4 s12.

    To be clear, I have little doubt that co2 is a forcing in climate change to some degree. However, tracking down its significance and the extent to which it is attenuated or magnified by other factors is where the real issues lie. I also have no doubt that the absence of correlation does not necessarily mean absence of causation – the former is a statistical concept, the latter is a physical one. Strong correlation is a strong clue that causality between variables is present but given the number of independent variables in play in the climate system the absence of correlation says nothing about causality one way or the other.

  124. Bart says:

    Bob Ryan says:
    October 5, 2012 at 2:41 am

    Bob, what we see in this chart is not that CO2 is forcing climate, but that climate is forcing CO2. The relationship, which holds true since 1958, when the era of modern, accurate measurements began, is approximately

    dCO2/dt = k*(T – To)

    where “k” and “To” are parameters to be determined. This is a local relationship. How it holds outside the bounds of the observational interval is unknown. But, it is enough to assign the lion’s share of the observed increase in atmospheric CO2 over that interval to natural forcing.

    When you integrate the relationship, you find that temperature is responsible for the change in CO2 we saw in the last half century, not humankind. Humans cannot have been responsible, because the rate of change of emissions is affine over the time period, and there is no room to insert an affine function in the relationship above. The conclusion which necessarily follows is that human inputs are rapidly sequestered, and natural processes dominate.

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