We recently watched an episode of NOVA on PBS from 2010 about diving in Caribbean blue holes — very deep caves that look blue because of their depth.

Among other things, they have stalactites formed thousands of years ago during dry periods. Because the mineral formations are built drop by drop over a very long time, they are a time capsule of sorts. Like polar ice cores, but more relevant because of their location.

The big news was that the climate record showed five abrupt climate changes — abrupt meaning they took a mere 50 years to complete — over a period going back 71,000 years.

Note: there were no fossil fuel burning humans at any of these intervals to cause climate change.

This bring us to writer Jerry Pournelle

…I still have no answer to questions I asked forty years ago regarding the global warming controversy.

I said then that what we knew was well known: that in historical times the Earth has been both warmer and colder than it is now. It was warmer in Viking times until about 1300 after which the Earth began to cool. Since 1800 the Earth’s temperature has risen about a degree a century. About 1900 Arrhenius did some back of the envelope predictions of what would happen if CO2 levels doubled. Since 1900 the Earth’s temperature seems to have risen at about the rate that it had previously been rising: that is, there is warming, but there has been warming from 1800 when the Hudson and Thames froze solid enough to walk across, and the rate of warming doesn’t seem to have greatly increased so far as we can measure given the accuracy of the data. Some of the warming may well be due to CO2 but there doesn’t seem to be cause for alarm. We do need to continue to study this and develop better measurement tools.

A Bayesian analysis would conclude that it is better to invest in ways to reduce uncertainty than to spend resources on the predictions of the models; there is just too much uncertainty.

I also concluded long ago that cooling was still a possible threat: that the return of the glaciers requires energy to transport the water vapor to the cold areas where it can fall as snow, and this can have a runaway effect. That needs to be watched.

Regarding science and cherry picking: I would have thought that the experimentum crucis was the essence of science, and that’s certainly cherry picking. As I said long ago in my essay on the Voodoo Sciences, novelist need plausibility, lawyers need evidence, but scientists need data and hypotheses that explain all the data: one contrary result (cherry picking) is important. Look at the controversy over whether or not they have found faster than light neutrinos. No one supposes that if we are certain of FTL particles this will not force a revolutionary change in our standard models in physics. It won’t be dismissed as cherry picking.

As to Lindzen not having changed his conclusions over the years, I think I could easily say the same thing about many of the AGW believers. What I find alarming is that Lindzen asks questions about the models and their predictions, and concludes that there is not enough evidence to justify panic: that the best evidence is that the increasing CO2 is not a justification for alarm, and particularly not enough quality evidence to justify spending $Trillions on revising the entire industrial economy. What I get is a sociological discussion about the quality of the debate, and a discussion of Lindzen. I would not think that is a rational scientific discussion.