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A prediction that came true

11 Dec 2019 | Science Notes

In 1994 American meteorologists John Christy and Richard McNider took the 15 years of satellite data then available and measured the rate of warming in the lower “troposphere”, the region of the atmosphere between the Earth’s surface and about 10 km up. Climate models say the troposphere should be warming there faster than the surface if greenhouse gases are to blame. But Christy and McNider found the troposphere was only warming 0.09 degrees C per decade, less than 1˚ C per century and much less than models were predicting. Choosing empirical evidence over conjecture, they said it would probably continue to warm at that rate in the future. So nearly a quarter century later, in 2017, they repeated the measurement, with more than twice as much data to work with, and found the warming trend essentially unchanged at 0.096 degrees C per decade, about half what the average IPCC climate model estimates.

If Christy and McNider are correct, the troposphere will warm about 1.1 degrees C in response to a doubling of CO2 levels. This number matches the calculations of York University physicist William van Wijngaarden, as we showed in our video on the (so-called) simple physics slogan. But it's only half as much warming as the average climate model predicts.

So when they sneer "don't you believe the science?" the right answer is, depends on what you mean by science. You can believe the models or you can believe the data, but don't say you believe both because they don't agree with each other.

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