Sane Skepticism, part 2
A new paper from the Journal des Sciences Hydrologiques is making its way around the more technical blogs dealing with AGW. The paper, titled On the Credibility of Climate Predictions, is authored primarily by Demetris Koutsoyiannis – a civil engineer and professor of hydrology – and alleges something that “skeptics” love to assert – that climate models are intrinsically flawed. I’m preparing for a trip to Chicago, so I don’t have time to go into the depth of the paper here, but I do think the paper is important, and therefore I’d like to illustrate the proper objective, skeptical attitude that is beneficial when analyzing a paper that is at odds with an established belief (in this case, my belief that GCM’s are a reliable, useful tool in projecting generalized climate change).
The abstract is obviously the first place to start when looking at a paper. The abstract is sort of a brief overview of what was done, what was found, and what the main conclusion is (or, at least, that’s what I was taught to do when I participated in the duPont Manual High School Regional Science Fair, an official ISEF regional fair). In full, here is the abstract from Dr. Koutsoyiannis’ paper:
Geographically distributed predictions of future climate, obtained through climate models, are widely used in hydrology and many other disciplines, typically without assessing their reliability. Here we compare the output of various models to temperature and precipitation observations from eight stations with long (over 100 years) records from around the globe. The results show that models perform poorly, even at a climatic (30-year) scale. Thus local model projections cannot be credible, whereas a common argument that models can perform better at larger spatial scales is unsupported.
In an even more succint summary, here is what was done: A bunch of models were run and their outputs were compared to what really happened; turns out they didn’t do so well on a point location basis. Now, we’re reaching an important juncture – a juncture where one’s attitude can change to denial or skepticism, but where only one is warranted. Let’s be very clear: skepticism does not mean “embrace any work which disagrees with an established point of science.” Skepticism is an attitude where everything is treated objectively. This is often where climate change skeptics make a key mistake; it’s not enough to be skeptical of the mainstream conclusions – one has to also be skeptical (in fact, even more so) of the conclusions that disagree with it.
A skeptic will ask a few questions just from this abstract. Is the assertion that unchecked and unverified models are often used in hydrology true? Why are the researchers only looking at eight stations if we’re talking about global circulation models? What does the author mean by “performed poorly?” Why is the notion that models are inaccurate at larger spatial scales unsupported by this data? Note that these questions have nothing directly to do with global warming or climate change. They are very general questions which are reasonably expected to be addressed in the paper.
Now, I wish I had time to share my two cents about the paper, but I’m just too busy. I’d encourage everyone to go through the paper, though – but with a skeptical attitude. Many folks commenting in the blogosphere are interpreting the paper has the death knell for climate modeling, but I don’t think that that specific interpretation is warranted here; this paper is not the “smoking gun” that climate models are fundamentally incorrect. I am dismayed that people are so worried about disproving global warming that they’d take a single statistical study on the accuracy of some very specific modeling projections and use it to throw the entire theory – which is supported by far more lines of evidence than model data alone – out the window.
To really be a skeptic , one must always be objective. This is because there is always uncertainty in a study, and every good study will open more questions to be answered than close existing ones. Take that attitude and read through the paper; over the weekend, I’m sure Gavin Schmidt from RealClimate and others will analyze it, and I’ll post links and comments to their analyses. If I have time, I’ll share my own analysis and thoughts on it over the weekend.