Global Temperature: the Post-1998 Surprise

I thought I would reblog this because it seems like a really clever illustration. In some sense, it’s another illustration of the escalator. Making a big deal of the “pause”/slowdown since 1998 essentially ignores that such a slowdown occurred immediately after a large jump in surface temperatures. Of course, if you start your analysis prior to 1998, the slowdown isn’t nearly as evident. I also liked the comment in the post that a lack of “statistically significant” warming is not the same as a lack of warming – something worth repeating.

Open Mind

Given how rapidly global temperature was rising prior to 1998, what’s the most surprising thing about global temperature since 1998?

Most who call themselves “skeptics” of global warming would probably say “No global warming since 1998!” Under the name “hiatus” or “pause,” it features prominently in public discussion and even in senate testimony (e.g. from Judith Curry). In truth, such a “pause” or “hiatus” is not that surprising, neither from a statistical point of view nor based on climate model output. But there is one thing about post-1998 temperatures, compared to the pre-1998 temperatures, that is quite a surprise.

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12 Responses to Global Temperature: the Post-1998 Surprise

  1. Mike McClory says:

    It is a remarkable post. Clearly shows there is no real hiatus. That is only evident by cherry picking the values to start and end. A more fair presentation is to look at how the trend line progresses, which is what Tamino has done. The records didn’t suddenly appear in 98, there was prior data and that has to be allowed for. Definitely going to bookmark that one.

  2. pbjamm says:

    Very nice analysis but I also would very much like to see the results if 1998 was included in the trend line (just to preempt the anti-science crowd). the I am no mathematician so I will leave it to the experts though if I have time after work I may take a stab at it.

  3. BBD says:

    I also liked the comment in the post that a lack of “statistically significant” warming is not the same as a lack of warming – something worth repeating.

    As indeed it has been. 😉

    But that is not to detract in any way from this latest iteration of a very informative look at the data.

  4. pbjamm, maybe, but I think that one can easily see that even if you included 1998, which would increase the trend slightly, and then started from the end of the trend line in 1998, it really wouldn’t make much difference. As far as I can tell, there’s little one can do to really preempt the anti-science crowd. They’ll just find something else 🙂

  5. pbjamm says:

    I did a quick look on woodfortrees and while it does move the trend line it does not signifiantly change the finding

    http://goo.gl/MAzhRF

  6. Very good, thanks. Yes, if you were to draw a zero-trend line from the end of your 1998 trend, most of the data since 1998 would still be above the line.

  7. KR says:

    And if you include 1998 in the initial trend line, the 1999-onward data has a steeper trend, 0.073 C/decade for HadCRUT4. You really have to include (cherry-pick) the start of 1998, including that 3-sigma El Nino, to make even the silliest of claims about a recent ‘pause’.

  8. It’s an interesting idea to substitute temperature in these graphs for a rise in unemployment figures. How would such long term data be viewed? Would there be any celebration or happiness that the problem was getting better?

  9. Gareth,
    I’m not sure what you’re getting at. I think that we’d all be happy of temperatures stopped rising and if we could be confident that that would be the case for the foreseeable future.

  10. What I am trying to say is that if the figures related to unemployment, we would be very concerned that the figures had remained stubbornly high with no sign of a reduction. The idea that the rise is much slower is not really any comfort unless they start to fall. Another view is that if the figures related to mortality from a particular condition, we would still be seriously concerned and be working on solutions. I just can’t see why the levelling of of a rise is any comfort to skeptics when there is no fall and we are pretty convinced that heat is going into the deep ocean.

  11. Gareth,
    Yes, I agree. In fact, it’s even more significant in that we’re now seeing La Niña years that are a warm as previous El Niño years.

  12. BBD says:

    Eg the Cowtan & Way tweak of HadCRUT4 which puts ENSO-neutral 2013 ahead of 1998, notable for its super-El Niño and concomitant warmth.

    The pause that isn’t a pause…

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