Spot the Hockey Stick #9: Andrew Weaver

It’s been too long since our last round of Spot the Hockey Stick! but despite the impressive backpedalling of some that the Mann, Bradley and Hughes study is sooo old hat and soooo last millennium, it’s still being cited at breathtaking pace as the best thing in climate science since the thermometer.

Thus we come to Dr Andrew Weaver, of the School of Earth and Ocean Sciences at the University of Victoria in Canada. In his EOS460: Earth System Science course which you can find at this link.

Now this next bit will cause some reaction, so Steve if you’re reading this, put down the bottle so you don’t spit beer all over the keyboard.


Remember the Mann-Appell article only a few days ago, where on the subject of the Medieval Warm Period and the Little Ice Age, they were definite that the MWP and LIA were regional only events and not global, and that this was why the Hockey Stick did not have them?

For instance, skeptics often cite the Little Ice Age and Medieval Warming Period as pieces of evidence not reflected in the hockey stick, yet these extremes are examples of regional, not global, phenomena.

Well, here is Dr Andrew Weaver’s view in Lecture 1:

UPDATE April 9, 2005: Some of the language in this has been edited at the request of Andrew Weaver.


  1. Spence_UK
    Posted Mar 16, 2005 at 3:17 PM | Permalink

    No. This has got to be a joke.

    I wonder what the statistical skill of that little reconstruction is?

    Next year, tell his kids to get him something other than a magenta crayon for Christmas!!!

  2. Louis Hissink
    Posted Mar 16, 2005 at 6:48 PM | Permalink

    And its all within an envelope of +/- 0.2 deg Celsius – good grief! if my temperature went up that much I doubt AI would notice it. I would need a bit more than a cool refreshing beer to cope with this one.

  3. John A.
    Posted Mar 17, 2005 at 2:47 AM | Permalink

    Re: #2

    Yes, but don’t you see Louis, the difference between disastrous warming and catastrophic cooling is only 0.4C, that’s why we need to crash the world economy.

  4. Michael Mayson
    Posted Mar 17, 2005 at 3:43 AM | Permalink

    You too can get the above if you fit a 3rd order polynomial trend line ( in Excel) to Mann’s data.
    And what do you get with a 4th order? – well, a hockey stick of course.
    I think the 5th order should be for a beer.

  5. Posted Mar 17, 2005 at 4:16 AM | Permalink

    This proves that you can fit a 3rd degree polynomial to almost any data set.

    I have one additional web site where you can find the Hockey stick: The home page of the Swedish Environmental Protection Agency:
    The hockey stick is accessible only in a frame, so I can’t give you its exact address. An English version of the home page is available from the link Webbkartor (You have to choose English two times). If you choose the link Climate change you get a text. Scroll down and you will find a link called “greenhouse gases and climate change”. Clicking on this link will load a frame with texts and links. One of the links is A Warmer world, and if you scroll down in this frame you find it: The hockey stick, without error bars and with an interesting figure description.

  6. Jan Janssens
    Posted Mar 17, 2005 at 4:33 AM | Permalink

    I think Mr. Weaver’s presentation is excellent. Why excellent? Because it sticks to the facts. As a result, his briefing can be used by both proponents and sceptics of human-induced global warming to defend their respective points of view.
    Slide 14 clearly shows current temperature variations fit perfectly within the millennia-long temperature-boundaries. On the other hand, slides 39-41 are perfectly suited to defend the doomscenarios if nothing’s done to curb greenhousegas emissions. Both groups use current facts and figures, but the first uses data from the past to put the current trends in their proper perspective, whereas the latter applies models to simulate a potentially catastrophic future.
    This controversy will persevere as long as these 2 approaches are not united. Basically, this boils down to getting a COMPLETE understanding of ALL climatic and weather related processes, of ALL their interactions, and of ALL the data-gathering methods. At the moment, we need either a climatic Einstein or nature itself (time) to sort this out.

  7. Hans Erren
    Posted Mar 17, 2005 at 7:01 AM | Permalink

    re # 5

    A direct link to ‘A warmer world’

  8. Peter Hearnden
    Posted Mar 17, 2005 at 7:57 AM | Permalink

    I don’t know. In your efforts to find any way possible of villifying the ‘Hockey Stick’ you search around the net, rummage through someones on-line notes for something (anything?) to triumphantly post here (like some kind of self appointed climate truth policeman meeting his masters?), and ritually submit yet another scientist to CAtype ridicule. Just what *is* it with you and this place John? It’s worse than disrespect, it’s shameful.

    Who’s next on the list?

  9. Hans Erren
    Posted Mar 17, 2005 at 8:34 AM | Permalink

    The “spot the hockeystick” is to show that this graph has become synonymous with global warming to policymakers and press, virtually neglecting alternative reconstructions.

  10. David H
    Posted Mar 17, 2005 at 11:19 AM | Permalink

    Peter, this is what it says under the Swedish Hockey stick. Note, not a caveat or error bar in sight.

    “The mean temperature of the earth suddenly began to rise in the early 20th century, after many hundred years of fairly insignificant variations. At least the warming of the last few decades seems to have been caused mainly by anthropogenic emissions of greenhouse gases. — From Mann et al., 1999”

    John replies: That little plot is the subject of the next Spot the Hockey Stick! instalment. Stay tuned.

  11. Jos Verhulst
    Posted Mar 17, 2005 at 2:15 PM | Permalink

    Here is an older version of Mann’s hockey stick:
    Both versions seem to differ considerably

  12. N. Joseph Potts
    Posted Mar 24, 2005 at 5:54 PM | Permalink

    Peter, I think much of these highjinks would dry up if Mann, et al would come forward and admit to the public that they deliberately fudged their hockey stick. I admit this is quite unlikely, and fear in any case that it would spoil quite a lot of good, clean fun we’re having with this quack and those who (unfortunately for all of us) have fallen for his drivel.

    Not only does honest, penetrating, and valid criticism not move this propagandist to a recanting of his fraud, it moves him to CONCEAL the methods by which he produced it. He and his allies deserve every bit of ridicule we can heap on them. We owe it to all those who, in the future, may fall for the many expert lies they most certainly will be exposed to.

    The only proper way to deal with anything THIS SERIOUS is to make fun of it, just as Charlie Chaplin did with Hitler. Did Chaplin think Hitler funny? No. Did he think Hitler ridiculous? Positively.

  13. Erwin Noyes
    Posted Jan 10, 2007 at 6:44 AM | Permalink

    I wish to know how the temperatures were derived by Mann et al in developing the “Medieval Warm Period” chart for the Northern Hemisphere 1999.
    As only aboriginals were present for much of the time period in most of North America, as temperature recording devices with any reasonable degree of accuracy were not available until the early 19 hundreds, how on earth were the temperatures arrived at and particularly with such precision?
    I have heard rumor that one technique was through the measurement of some tree rings, if this is so I would like to know the corrclation used to determine temperatures from tree rings relative growth.

    Please enlighten me.
    Thank you in advance.

  14. MarkR
    Posted Jan 10, 2007 at 10:13 AM | Permalink

    A good starting read

  15. Willis Eschenbach
    Posted Jan 11, 2007 at 2:22 AM | Permalink

    Peter H., people keep saying “Why do you keep harping on about the Hockey Stick, don’t you know we’ve moved on?” … This is why. The message that the Hockey Stick is fatally flawed still hasn’t sunk in.


    To paraphrase H. L. Menken: “No one ever lost money underestimating the intelligence of the public.”

  16. DaleC
    Posted Jan 11, 2007 at 5:29 AM | Permalink

    The Hockey Stick is alive and well in my 15 year old son’s geography text book, first edition published 2006 for the 2007 academic year and beyond. In the chapter on climate it says

    “The 1990s were the warmest decade of the millennium, and 1998 the hottest year. In all, there was a temperature rise of close to 1C across the continents.”

    The first sentence is a paraphrase of the TAR, which says

    “New analyses of proxy data for the Northern Hemisphere indicate that the increase in temperature in the 20th century is likely to have been the largest of any century during the past 1,000 years. It is also likely that, in the Northern Hemisphere, the 1990s was the warmest decade and 1998 the warmest year (Figure 1b).”

    Figure 1b is of course the Hockey Stick. The abstract for MBH99 says

    “…our results suggest that the latter 20th century is anomalous in the context of at least the past millennium. The 1990s was the warmest decade, and 1998 the warmest year, at moderately high levels of confidence.”

    Note that where MBH have the qualifiers “suggest’ and “moderately high levels of confidence’, and the TAR has “likely’, and both have “warmest’, the geography text asserts as facts, and uses the much stronger and more emotive “hottest’.

    And I wonder where they got the “close to 1C’ from, since the TAR claims only 0.6. Surely not a gratuitous exaggeration?

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