Archives for May 16, 2008

In the blue corner we have Roger Pielke Jr (Prometheus) and Lucia Liljegren (The Blackboard). In the red corner we have James Annan (James’ Empty Blog) and Gavin Schmidt (RealClimate).

Interestingly, all four of the contenders accept the the IPCC consensus view on climate change, but Pielke Jr/Liljegren show that IPCC projections are currently falsified by observations, whereas Annan/Schmidt have the opposite view. Read the various blog posts and make up your own minds.

Lucia Concludes:

The IPCC projections remain falsified. Comparison to data suggest they are biased. The statistical tests accounts for the actual weather noise in data on earth.

The argument that this falsification is somehow inapplicable because the earth data falls inside the full range of possibilities for models is flawed. We know why the full range of climate models is huge: It contains a large amount of “climate model noise” due to models that are individually biased relative to the system of interest: the earth.

It will continue to admit what I have always admitted: When applying hypothesis tests to a confidence limit of 5%, one does expect to be wrong 5% of the time. It is entirely possible that the current falsification fall in the category of 5% incorrect falsifications. If this is so, the “falsified” diagnosis will reverse, and not we won’t see another one anytime soon.

However, for now, the IPCC projections remain falsified, and will do so until the temperatures pick up. Given the current statistical state ( a period when large “type 2″ error is expected) it is quite likely we will soon see “fail to falsify” even if the current falsification is a true one. But if the falsification is a “true” falsification, as is most likely, we will see “falsifications” resume. In that case, the falsification will ultimately stick.

For now, all we can do is watch the temperature trends of the real earth.