Oh my goodness, Judith Curry is the ultimate climate heretic — she’s absolutely notorious for…
Jere Krischel

Well, the criteria I set for the list was believing that humans don’t cause global warming after all, or that it’s not serious enough to worry about, or that it’s a hoax. I don’t think she thinks it’s a hoax, and I’m not sure if she thinks humans don’t cause it, but if she has made a statement somewhere that says “I think humans are responsible for less than half of warming,” I guess that would count.

However, if her position is simply that “we don’t know as much as we think, so it’s possible that the climate will respond differently than predicted,” then she isn’t saying that the IPCC projections are incorrect — or even that the actual temperature response couldn’t be above the high range of projections.

(To anyone reading the following digression, note that Jere and I have been debating climate science for awhile now…)

If you’e ever read an IPCC report, you should know that they put quite large error bars all over the place, and often those error bars are only 90% confidence intervals. Since they are constantly stating confidence intervals, the idea that no one has done “a sustained and systematic enquiry of how to understand and reason about uncertainty in climate science has not been undertaken by either climate researchers or philosophers”, as Judith Curry says, would be very surprising, at least if we expand our thinking to include mathematicians/statisticians and general studies on quantifying and reasoning about uncertainty.

My own readings about uncertainty have come from the catastrophic risk analyst Nassim Nicholas Taleb and his book “The Black Swan” and chapters of “Antifragile” posted on Medium. His opinion on global warming is simple. I recommend reading his article about the Precautionary Principle, although it is not about global warming. I think Taleb would tell you, the most concerning possibility is not that the “low” side of the uncertainty ranges could be wrong.

I do have reason to suspect that most individual scientists are not adequately trained in estimating uncertainty, but what gives me confidence in the science is not the size of each error bar and whether they are individually correct. What gives me confidence is the sheer number of approaches and angles that the issue has been examined. There are about ten thousand climate scientists all over the world, from different cultures, many of them drawing from work outside climatology — physics, chemistry, geology, biology/ecology, oceanography, etc. A lot of focus has been on “climate models” meaning computer simulations, but there are also many non-simulation models and analyses showing similar results.

On scientific topics I often prefer to read metastudies. Why? Because an individual study may be wrong, but a big collection of studies by different people, using different methodologies, that all say the same thing are highly unlikely to be wrong.

Finally there’s the fact that it’s been 38 years since the AGW consensus originally developed, and in all that time contrarians have not coalesced around any alternative hypothesis.

More than one answer was allowed. On average, those disagreeing with the IPCC gave 2.45 reasons why, yet not one of these answers broke the 50% mark, i.e. there is no consensus among contrarians. And while “natural variability” was the most common answer, it is also pretty vague; many factors go into “natural variability”. Climatologists will tell you that “natural variability” goes up and down — not just up. Source: PBL NEAA. Question 3c (Figure 6) in the original Verheggen study also suggests that contrarians do not agree on what, if not CO2, causes global warming.
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