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The Forum > Article Comments > Imagine a world without climate models > Comments

Imagine a world without climate models : Comments

By Rob Wilby, published 25/1/2011

What could have been achieved without climate models?

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predicting the future
of course we'll believe it
how silly not to
even better if we can waggle fingers at other people

let's all bet our future on current science and technology
what a safe bet
particularly since there is a consensus
what could go wrong?
Posted by rpg, Tuesday, 25 January 2011 9:13:22 AM
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Climate models were originally - 70s, 80s - designed simply to investigate the interaction of various aspects of climate. Someone got the bright idea to see what happened when the models were run decades into the future.

But they should have been ruled out as predictive models right from the start. For one thing they are far too complex to be reliable even over one or two years,let alone decades, for another they are sensitive to initial starting conditions. The confident lines you see on IPCC forecast graphs are, in fact, the result of multiple runs of the numerical model using different starting conditions. I'm fuzzy on exactly how it works but its something like the climate modeller then choosing the most stable of the results.

Further, they use a host of assumptions, particularly a crucial assumption concerning water vapour in the atmosphere.

Now you may still say everything is alright, and the assumptions are fine, but the strange part about all of this is that the public, the policy makers and even the vast majority of scientists who support global warming have no real idea of how the forecasts are derived or of the assumptions involved.

Nor has there been any proper review of any of this by a truely independent body. All we have is a form of "peer review" which is of no earthly use in checking forecasts.

The whole issue is completely wacked.
Posted by Curmudgeon, Tuesday, 25 January 2011 10:24:20 AM
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You just can't help it, can you curmudgeon?

One day this:
"the graphs have to be "adjusted" to make them say what the theory requires."

Next day this:
"the climate modeller then choosing the most stable of the results."

I agree, you are fuzzy - and you bang on about being professional?
Posted by bonmot, Tuesday, 25 January 2011 10:38:20 AM
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Thanks Rob

WHAT IF....?

Is there any other profession - except perhaps astrology, astrophysics, economics, social sciences, theology, etc, - where one could (i) assume “….equal-weighted averages as best-guess results…”; while (ii) noting there is “….little agreement on metrics to separate “good” and “bad” models…”; (iii) etc ad nauseum (see abstract below); and yet claim its "what if" “projections” reveal such "science-is-settled" certainties about the future that economies and societies must be transformed immediately into a zero-carbon Ecotopia to ensure our survival?

Knutti, Reto, Reinhard Furrer, Claudia Tebaldi, Jan Cermak, Gerald A. Meehl, 2010: Challenges in Combining Projections from Multiple Climate Models. J. Climate, 23, 2739–2758. doi: 10.1175/2009JCLI3361.1
http://journals.ametsoc.org/doi/abs/10.1175/2009JCLI3361.1?prevSearch=%5Ball%3A+%5Bkeyword%3A+%22Climate+prediction%22%5D%5D&searchHistoryKey=

"Recent coordinated efforts, in which numerous general circulation climate models have been run for a common set of experiments, have produced large datasets of projections of future climate for various scenarios.... It is thus unclear by how much the confidence in future projections should increase based on improvements in simulating present-day conditions, a reduction of intermodel spread, or a larger number of models....Last, there is little agreement on metrics to separate “good” and “bad” models, and there is concern that model development, evaluation, and posterior weighting or ranking are all using the same datasets. While the multimodel average appears to still be useful in some situations, these results show that more quantitative methods to evaluate model performance are critical to maximize the value of climate change projections from global models."

Alice (wondering in Warmerland)
Posted by Alice Thermopolis, Tuesday, 25 January 2011 12:33:13 PM
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Very Interesting; so how do the models (correctly "scenarios") of the IPCC compare with the empirical evidence. Very well it seems.
For anyone who wants to take the time to find out and not rely purely on the "denialist" mantra of "models are bad".

That Snowman is sure getting sooty.
http://www.realclimate.org/index.php/archives/2011/01/2010-updates-to-model-data-comparisons/
Posted by sillyfilly, Tuesday, 25 January 2011 1:53:22 PM
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Come on sillyfilly...you can't let the facts get in the way of a good story.
Posted by Phil Matimein, Tuesday, 25 January 2011 4:32:57 PM
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