Among the very best of the science-oriented blogs I try to read regularly is Tom Levenson’s Inverse Square Blog. Tom, who teaches science journalism at MIT, isn’t a climatologist, but whenever he writes about climate science or politics, it’s usually worth a look.

Apparently, the folks at Scientific American agree, and they recently invited Tom to contribute a guest post to the magazine’s blog site. It’s primarily about the recent kerfuffle over the possibility that neutrinos might be able to travel faster than light, and a bit on the lengthy side, but he does manage to work climate in there, so let’s skip to that bit and run with his central theme, which is:

understanding what we do know, and then engaging the challenge of a new result in that context.

One of the main problems with criticisms of the science behind anthropogenic climate change (second only to the fact that most criticisms are of the scientists, not the science), is that hardly any of that criticism posits an alternative that might accommodate what we do know about the Earth’s climate and how it responds to the forcings (ultimate causes) that bring about change.

Now, that’s not to say that all critics must offer an alternative explanation at every juncture. It is quite acceptable in science to simply point out errors, whether in the data collection process or the analysis of that data. Indeed, that constitutes the majority of the debate within any team of scientists. Finding such problems is what keeps science honest, and when scientists stop challenging each other’s work, you have to draw one of two conclusions. Either the scientists are no longer doing their jobs, or the theoretical underpinning of the subject at hand has stood up to repeated challenges for so long that the chances of it being essentially wrong are sufficiently low to allow the community to move on to more interesting questions.

So how do you know which conclusion to draw here? The public climate-change debates, are, it should be noted, largely between climatologists and non-climatologists, rather than within the climatology community itself. So that suggests the latter. But it is still possible that the entire climatology community has fallen down on the job. The only way to know with some degree of confidence which conclusion is correct is to examine the criticism closely, which, I think, is what Tom’s post is all about. It is what I’m interested in here, at any rate. And that brings us back to the need for some alternative explanation to the prevailing theory.

This is something the denial camp rarely, if ever, provides. If a group is going to argue that thousands of climatologists are wrong, and that the Earth isn’t warming at a historically rapid rate, and therefore there’s nothing to worry about, then it behooves that group to at least entertain some discussion of how that argument fits with the broader understanding of the science that has led so many scientists to accept the notion of dangerous anthropogenic climate change.

As Tom puts it:

Hence the (perhaps meta-)value of the faster-than-light neutrino story. This experiment will have to overcome the hurdles thrown up by special relativity’s ubiquitous influence, by the physics of high energy phenomena and so on. That’s how the process of discovery moves from tantalizing initial impressions to settled knowledge. Understanding that process illuminates the hurdles facing climate science denialists: to advance their case, they must reconcile their criticisms of mainstream climate research with the exceptionally well understood basic physics of radiative transfer and the thermal properties of different gases — as well as streams of evidence flowing from direct observations and from the ongoing inquiry into the correlation between evolving climate models and what we can see of the climate itself.

Not only do we know that increasing the amount of greenhouse gas in the atmosphere should lead to a warmer planet, but scientists have been predicting as much for more than a hundred years. And the basic chemistry and physics that led to those first predictions date back another half century.

That basic science doesn’t just explain what we’re seeing happen on Earth here and now. For one thing, it explains why the surface Venus is so much warmer than Mercury’s, despite being tens of millions of kilometers further from the Sun. For another, it gives us a good understanding of why sea levels seem to rise and fall in concert with the amount of carbon dioxide the air.

More to the point, the fact that global temperature records show a relatively steady increase over the last 150 years or so is exactly what we expect to see, given what we know about the way carbon atoms vibrate when subjected to radiation of a given wavelength. For a claim that the Earth isn’t warming — or that the warming is negligible — to hold water, then someone, somewhere, at some point, should be able to explain how that claim might square with all the undisputed chemistry and physics that suggests otherwise.

Again, data collection errors and illogical analysis are valid criticisms. But without some level of scientific explanation for the discrepancy between a hypothesis and established theoretical framework that governs a discipline, the validity of the criticism just doesn’t have a lot of staying power. Especially after repeated efforts to demonstrate errors fail. This is why the not-yet-peer-reviewed findings of the BEST team on the alleged urban heat island bias in the temperature records don’t really count for much. Real Climateer Erig Steig put it succinctly in his take on the BEST story:

As far as the basic science goes, the results could not have been less surprising if the press release had said “Man Finds Sun Rises At Dawn.”

Science tell us the Earth should be warming. We’ve been predicting that the Earth will warm, and it appears to be warming, pretty much line with our predictions. If you want to challenge that, then tell us where we went wrong. Oh, and it would really be helpful if you told us how we went wrong.

There are a few critics out there who do dare to challenge the basic science informing “alarmist” climate science. Take Matt Ridley, a once-respectable science writer whose work on genetics and evolution are widely regarded as top-notch. Somewhere along the way, he decided he didn’t trust the science coming out of the IPCC, and he took a closer look. Not close enough, though, because his criticisms are wildly misinformed. In a widely circulated transcript of a recent speech, Ridley tries to argue that one of the key pieces of the ACC pie, the sensitivity to climate forcings, has been grossly exaggerated by the vast majority of climatologists.

The central issue is “sensitivity”: the amount of warming that you can expect from a doubling of carbon dioxide levels. On this, there is something close to consensus – at first. It is 1.2 degrees centigrade. ….

But whereas there is good consensus about the 1.2 C, there is absolutely no consensus about the net positive feedback, as the IPCC also admits. Water vapour forms clouds and whether clouds in practice amplify or dampen any greenhouse warming remains in doubt.

So to say there is a consensus about some global warming is true; to say there is a consensus about dangerous global warming is false.

To someone unfamiliar with the massive amount of research that has gone into this central question of climate sensitivity, this might make some amount of sense. But of course, the climatologists haven’t missed something so fundamental. Ridley’s mistake (just on this issue; the rest of speech is riddled with comparable misrepresentations and outright falsehoods) is to ignore the fact that while the feedback effects from cloud cover remain uncertain, the effect of water vapor itself isn’t. And we know from basic science that water vapor is a powerful greenhouse gas, responsible for a serious amount of positive feedback. Ridley’s arguments only work if you ignore the critical relationship between the amount of water vapor in the air, and the heat capacity of the atmosphere.

Climatologists like James Hansen have applied paleoclimate data to our understanding of the role of water vapor feedback, and come up with a near-term climate sensitivity of about 3 degrees C and a long-term sensitivity of 6 degrees C. Why should we trust Hansen’s theory and not Ridley’s? The easy answer is Hansen is a climatologist who has devoted his professional (and much of his personal) life to the subject, while Ridley is a science writer with no relevant training. But a better answer is because Hansen’s description is consistent with those elements of science that have stood up to decades of challenges, while Ridley’s is not.

And this, my friends, is why I call critics like Ridley “pseudoskeptics.” They embrace the scientifically valuable but easy road of being skeptical, but refuse to do the hard work that it takes to actually understand what they’re skeptical about. And science is about the hard work of studying nature as well as skepticism of ideas that challenge what we think we know. Real skeptics embrace both.