15
votes

Seth Roberts claims that the field of climate modelling hasn't produced models that have effectively predicted future climate events. According to him the models are only validated on past data.

Is this charge valid or did climate models make important predictions about the temperature on earth a decade ago that came true? If so, what were the greatest successes of the models?

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  • 2
    climate != weather – Borror0 Mar 24 '11 at 0:31
  • AFAIK, the observation of climate change is a young one, and the techniques and models are evolving rapidly. Even if there was a good prediction model today, to tell how the climate is in 10-20 years from now, we then will have very different models, techniques and theories. – user unknown Mar 24 '11 at 2:21
  • 3
    The Kyoto Protocol got signed more than a decade ago on the claim that climate change exists. A decade might be enough time to make some substantial predictions about the future to validate a model empirically. – Christian Mar 24 '11 at 12:19
  • 2
    @Borror0 - While it may be true that climate != weather, if the climate models don't predict anything verifiable, they are not very useful. – Russell Steen Mar 24 '11 at 14:58
  • That climate change exists can be found afterwards, think of glaciers, historic weather logs, rings of age in trees and so on. But I don't quiet understand what the decade is used for: To make a prediction, or to validate it? If I make a prediction for 2100 I obviously can't validate it 2010. If I need 10 years to develop a prediction, I can't validate it 2011. Maybe 10 years are enough to validate a prediction, and maybe the first one were ready in 2000. – user unknown Mar 24 '11 at 15:57
16
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Firstly, 'climate events' is something of a contradiction in terms, since climate is a statistical average of weather this Seth Roberts has probably confused weather events with climate events.

Secondly, climate is clearly far more predictable than the weather, because everyone who books a ski or sun holiday, and manages to find the snow or the sun as expected when they arrive there, successfully predicts the climate. This happens often enough that people build businesses around the concept.

In addition, Global Climate Models have successfully predicted:

  1. That the globe would warm, and about how fast, and about how much.
  2. That the troposphere would warm and the stratosphere would cool.
  3. That nighttime temperatures would increase more than daytime temperatures.
  4. That winter temperatures would increase more than summer temperatures.
  5. Polar amplification (greater temperature increase - compared to former local averages - as you move toward the poles).
  6. That the Arctic would warm faster than the Antarctic.
  7. The magnitude (0.3 K) and duration (two years) of the cooling from the Mt. Pinatubo eruption.
  8. They made a retrodiction for Last Glacial Maximum sea surface temperatures which was inconsistent with the paleo evidence, and better paleo evidence showed the models were right.
  9. They predicted a trend significantly different and differently signed from UAH satellite temperatures, and then a bug was found in the satellite data, i.e. the models were right.
  10. The amount of water vapor feedback due to ENSO.
  11. The response of southern ocean winds to the ozone hole.
  12. The expansion of the Hadley cells.
  13. The poleward movement of storm tracks.
  14. The rising of the tropopause and the effective radiating altitude.
  15. The clear sky super greenhouse effect from increased water vapor in the tropics.
  16. The near constancy of relative humidity on global average.
  17. That coastal upwelling of ocean water would increase.

Source: http://bartonpaullevenson.com/ModelsReliable.html

  • Also, not so sure that "people build businesses around the concept" is a very good measure of an idea being actually correct :-) – Oddthinking May 1 '11 at 14:47
  • 1
    haha not in general no (else quack medicine and various other frauds would be valid). the point is only that some examples of the predictability of climate are very obvious, and give the lie to the claims that it is beyond the wit of man to predict climate. not many ski resorts in the sahara. – frankodwyer May 1 '11 at 16:13
3
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I am going to try to minimize block quotes in this answer.

Your question is problematic for two reasons. First, I think this really depends on how you define "long term." Also, no matter what anybody says there will always be somebody who predicts the opposite, and can claim to have been correct. I will try to address what was the consensus at the given time.

If we are talking about 40-50 years ago, there have been few real successes. In fact, in the 1970s people believed in "global cooling," that we would soon see massive glaciation across the entire world. This culminated with the plan to cover much of the world's deserts with oil, to soak up heat and prevent the global cooling. Fortunately, this plan was never enacted.

On the other hand, if you consider acid rain to be a climate issue, we have been remarkably successful in our predictions of this, although we did overestimate how bad the issue was. Acid rain never was as harmful as many believed. I guess that our almost-elimination of acid rain could be considered a triumph of long term climate predicution.

Another long-term climate prediction was the depletion of the ozone layer. Our predictions on this front have been pretty bad. In the 1980s we predicted a decrease in ozone of 7% over a 60 year period. Today this has been decreased to 4%. We also missed dramatically in our belief that ozone holes would pop up all over the globe. To date there are only two such holes.

I couldn't really think of anything else to investigate. But, there you go.

  • 7
    the global cooling claim is bogus. there was no scientific consensus about global cooling in the 70s. – frankodwyer May 1 '11 at 11:27
  • 1
    I would suggest that a few people believed in global cooling, but few (if any) climate scientists did. I would also like to see a reference for the "over the deserts in oil" plan. – Oddthinking May 1 '11 at 14:38
  • 2
    I would also like a reference for the prediction of a 7% decrease in ozone over 60 years. Was this before or after considering the effect of the Montreal Protocol that was enacted in the late 80s? – Oddthinking May 1 '11 at 14:40
  • What has the ozone hole to do with climate? – matt_black Feb 14 '12 at 23:19

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