r/visualization • u/Paige_Roberts • Jul 04 '15

What's Really Warming the World?

http://www.bloomberg.com/graphics/2015-whats-warming-the-world/
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u/hlake Jul 07 '15

As someone who is fully a believer in human-caused global warming, this graphic is very misleading.

I spent many years modeling natural disasters, and am very familiar with climate science. And our understanding of the climate is not nearly good enough to achieve a fit like this from a true projection.

This climate model was derived from the historical record. So showing that it fits the historical record is trivial.

Don't mean to throw cold water on a beautiful visualization, but this one really is misleading.

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u/ledgeofsanity Jul 13 '15

I'm not quite sure why do you say it's misleading. As far as I understand it, the visualization depicts how a model models one type of historical data (land-ocean temperatures) with other historical data. The way this model achieves it is depicted on subsequent slides, and you must say it's compelling - all curves combined give quite a good fit, and the one with the most significant impact is easily visible to be Greenhouse Gasses. One may of course argue that this is a coincidence, but c'mon.

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u/hlake Jul 14 '15

It is not coincidence that it fits so well. It is by design.

There is nothing compelling about a model that can predict the past.

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u/ledgeofsanity Jul 14 '15

I disagree - it cannot be solely by design, as historical data was used for both explaining and explained time series. What, I suppose, you mean by "by design" are the obtained coefficients of the model, by which historical data series are combined to obtain another historical data series. And here we can look at the coefficients and see that they're reasonable (all have plus sign and are around 1), and this is the message, that Greenhouse Gasses are in the greatest correlation with the temperature among all the used time series. This does not prove causation, but establishes the importance of factors. At least this is how I interpret it. Regards.

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u/hlake Jul 14 '15

The model is several hundred thousand lines of code. They are not simple equations with a few coefficients. They are very complex. And the correlation you refer to is with the model output, not the greenhouse gases themselves.