Imagine for a moment if Microsoft had 24 competitors around the world, each building their own version of Microsoft Word. Imagine further that every few years, they all agreed to run their software through the same set of very demanding tests of what a word processor ought to be able to do in a large variety of different conditions. And imagine that all these competing  companies agreed that all the results from these tests would be freely available on the web, for anyone to see. Then, people who want to use a word processor can explore the data and decide for themselves which one best serves their purpose. People who have concerns about the reliability of word processors can analyze the strengths and weaknesses of each company’s software. Then think about what such a process would do to the reliability of word processors. Wouldn’t that be a great world to live in?

Well, that’s what climate modellers do, through a series of model inter-comparison projects. There are around 25 major climate modelling labs around the world developing fully integrated global climate models, and hundreds of smaller labs building specialized models of specific components of the earth system. The fully integrated models are compared in detail every few years through the Coupled Model Intercomparison Projects. And there are many other model inter-comparison projects for various specialist communities within climate science.

Have a look at how this process works, via this short paper on the planning process for CMIP6.


  1. There is no doubt about it, climate science needs your help desperately.

    Their climate models have been shown to be… [SNIP]

    [I’ve disallowed your comment under my comment moderation policy. This blog is not a forum for repeating denialist talking points – there are plenty of other sites for that. Feel free to go and study a little more on what a climate model is, and is not, and then come back and say something intelligent. – Steve]

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  4. Steve,
    Thanx for this one. And for the 2 posts in february. Beautiful triplet!
    I’ll spread the word on Bart Verheggen’s Dutch blog ‘Klimaatverandering’
    Best wishes. Goff

  5. GJ: Many thanks. The three posts fit together in a way that will soon become apparent. 🙂

  6. Chris Anderson

    Hi Steve, I posted on the February entry. In the interest of full disclosure, I’m a climate scientist, and I do a lot of outreach on climate change and seasonal forecasts. I really appreciate this analogy, and I’m going to use it, if you don’t mind.

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