But even if the IPCC’s iconic statement were correct, it still would not be cause for alarm….The potential (and only the potential) for alarm enters with the issue of climate sensitivity—which refers to the change that a doubling of CO2 will produce in [global mean temperatures]. –Richard Lindzen, Wall Street Journal, November 30, 2009

Defenders of the IPCC position on climate science have adopted different strategies in dealing with the scandal of the CRU emails and computer code. Some authoritative voices, notably Judy Curry, have engaged in dialog with skeptics and have reassured PhD students that the “tribalism” revealed in the CRU emails has no place in science.

On the other hand, another very common reaction has been to mock the “deniers” for taking certain phrases out of context. This circle-the-wagons strategy tries to convince the public that the CRU episode has absolutely no bearing on the actual science, and that at worst it reveals petty personality flaws. This spin is epitomized in sarcastic pieces which take on the voice of the “deniers” and claim that the laws of physics are all a socialist hoax too.

These defenses are self-evidently absurd to anyone who has read the actual CRU emails in question. The public’s faith in the sacrosanct “peer-review process” will be understandably shaken when they read just how this “consensus” was enforced. Furthermore, the real debate was not between ultra-skeptics who say “global warming is a hoax” versus professional climate scientists who say “anthropogenic climate change is real.”

No, the true debate has been among practicing climatologists, with some arguing that the global climate’s sensitivity to a doubling of greenhouse gas concentrations may be well below the IPCC AR4’s reported range of 2C – 4.5C. If these “skeptics”–such as Richard Lindzen, Pat Michaels, and Roy Spencer–are right, then the case for large-scale government intervention to penalize carbon emissions is considerably weakened.

In this context, the evidence brought to light by “Climategate” may be very significant, because it reaffirms the chinks in the IPCC armor that the educated skeptics have been pointing out for years. It’s true, an email from Phil Jones by itself doesn’t make Richard Lindzen right or wrong, but when policymakers need to decide which scientific experts they can trust, then the CRU emails are very relevant.

Trying to Lump All Skeptics With Rush Limbaugh.

It is definitely true that some opponents of cap-and-trade have used the episode to make over-the-top declarations. For example, Rush Limbaugh has repeatedly said that global warming is a hoax, and a Fox News interviewer asked Kevin Trenberth if some of the CRU emails “don’t necessarily support the consensus view that global warming is real…Would you agree?”

Now if an actual scientist connected with the IPCC wants to debate such points, he or she will be shooting fish in a barrel. For one thing, there’s the sloppy terminology. “Global warming” is certainly not a hoax–we can be very confident that the earth is warmer now than it was in the year 1850.

Of course, what Limbaugh and the Fox interviewer meant was, “The theory that says governments around the world need to heavily intervene in their energy sectors right away, or else our grandchildren will face climate catastrophes, cannot be justified by careful scientific research.” Yet by using sloppy language, some of the loudest critics of Al Gore et al. end up justifying the caricatures of their opponents.

For example, by flatly denouncing “global warming” per se, the critics allow someone like George Monbiot to ridicule their paranoia by imagining a worldwide campaign to first infiltrate the ranks of the physicists and invent the heat-trapping ability of carbon dioxide, and then to falsify thermometer readings.

Lindzen, Michaels, Spencer, et al. Know the Laws of Physics.

Although they might be amusing to some, the physics analogies offered in the wake of Climategate miss the point. For example a group post at RealClimate tried to contain the PR damage by saying:

It’s obvious that the noise-generating components of the blogosphere will generate a lot of noise about this. but it’s important to remember that science doesn’t work because people are polite at all times. Gravity isn’t a useful theory because Newton was a nice person. QED isn’t powerful because Feynman was respectful of other people around him.

Such glib responses make it sound as if the support for the IPCC consensus is as rock-solid as the existence of gravity, but of course that’s not true. First of all, Newton’s theory of gravity turned out to be wrong; it was superseded by Einstein’s more general explanation. In the context of CRU and the skeptics, the issue isn’t, “Is ‘climate’ a useful theory to explain thermometer readings?” No, the real debate concerns very specific and quantitative disagreements. The reason QED (quantum electrodynamics) is powerful is that it allowed physicists to make very precise predictions that were experimentally verified.

The True Signficance of Climategate.

We finally come to the true revelations of the CRU emails, at least from my vantage point as an economist who has not formally studied climate science. I think it is fair to summarize the broad disputes by saying that experts such as Lindzen, Michaels, and Spencer have raised serious critiques of the global climate models used by the IPCC, or at least of the conclusions that the IPCC has drawn from such simulations. In response, the IPCC’s standard bearers (such as the crew of RealClimate) have confidently stated that the consensus is in, the debate is over, there is no serious doubt about what the models are telling us, etc.

Now as an outsider with no formal training, I personally can’t truly judge these disputes. I can think of analogies in economics where the position of Phil Jones et al. is understandable. For example, a few years ago many critics of outsourcing were arguing that the standard economic case for free trade was based on flawed assumptions. Most economists–including me–dismissed these “dissenters” as making minor technical objections that didn’t really affect the final policy decisions, and worse they were feeding into the hands of politicians who cared nothing about economic models but wanted to pass pro-union protectionist legislation. So I thought it was certainly possible that the mainstream climate modelers were telling the truth when they said they had no doubt about the reliability of their models. Perhaps their critics–who may have been perfectly sincere–really were making mountains out of molehills, and worse yet were being used by politicians who didn’t really care about the truth of the science.

The revelations from Climategate have made me much more willing to believe the critics who claim that the global climate models cannot bear the weight that so many are putting on them. To me, the silly CRU emails about beating up Pat Michaels, or being glad that a skeptic had died, were irrelevant and have no bearing on what we should think of the IPCC projections.

True Jaw-Dropper: The Wigley and Trenberth Exchange.

In contrast to these harmless remarks, this email exchange between Tom Wigley and Kevin Trenberth stunned me. Most coverage of the CRU emails has mentioned Trenberth’s statement, “The fact is that we can’t account for the lack of warming at the moment and it is a travesty that we can’t.” But the folks at RealClimate have argued (seemingly plausibly) that Trenberth was just being a good scientist, wanting to dot his i‘s and cross his t‘s. According to the damage control coming from RealClimate, the public shouldn’t buy into the lies of the deniers and think that Trenberth was doubting the basic idea that human activity is responsible for 20th century warming.

But hold on just a second. Trenberth’s follow-up email was even more interesting than the one receiving the bulk of the press coverage. Tom Wigley quoted Trenberth’s statement and said, “I do not agree with this.” In other words, Wigley was saying that he thought he and his colleagues could explain the lack of warming, and so there was no travesty. To this Trenberth replied (bold has been added):

Hi Tom

How come you do not agree with a statement that says we are no where close to knowing where energy is going or whether clouds are changing to make the planet brighter. We are not close to balancing the energy budget. The fact that we can not account for what is happening in the climate system makes any consideration of geoengineering quite hopeless as we will never be able to tell if it is successful or not! It is a travesty!

Kevin

At the risk of being melodramatic, I do declare that the above email is simply jaw-dropping. If the climate scientists cannot tell if a particular remedy is working, it means that they aren’t exactly sure how the climate would have evolved in the absence of such a remedy. In other words, Trenberth at least is admitting that he is not at all confident in the precise, quantitative predictions that the alarmists are citing as proof of the need for immediate government intervention. And this expression of doubt wasn’t from the distant past: Trenberth sent the above email in October of this year!

Gavin Schmidt: “All the Rest Is Economics.”

In a totally different context, Gavin Schmidt (perhaps unwittingly) gave away the game when he emailed this quote to journalist Andy Revkin:

If you ask a scientist how much more CO2 do you think we should add to the atmosphere, the answer is going to be none. All the rest is economics.

Since that is Schmidt’s view, it’s not surprising that he thinks Climategate is much ado about nothing. Whether the climate sensitivity is 1.9C, 2.8C, or 5.2C, what’s the difference? We’re already pushing into the zone of climate damages, and so further emissions are just going to dig us into a deeper hole, right?

But as Schmidt acknowledged, that’s just looking at the theoretical benefits of limiting further greenhouse gas emissions. (Let’s neglect the studies arguing that modest warming actually confers net benefits on the world.) The costs of limiting emissions also need to be considered. By forcing people to use more expensive energy sources, government constraints on emissions necessarily reduce material output. There is a tradeoff between avoiding future climate damages, and reducing traditional economic output.

Conclusion.

The scholarly skeptics do not doubt that the earth is warmer now than it was in 1850, and they don’t doubt that higher global temperatures would have noticeable effects on migratory patterns, ice sheets, and so forth. The real debate has been and continues to be: What fraction of this warming can be attributed to human activities? And then extrapolating, what will be the likely impacts on the climate if economic activity continues on its present trajectory?

When it comes to nuanced questions such as these–as opposed to loud mouths declaring, “Global warming is a hoax!”–the CRU emails and computer code are very revealing. Those of us who are not experts on climate models now have proof that the official line that “the science is settled” was a bluff. Of course it’s still possible that the IPCC projections may turn out to be accurate when all is said and done, but the confidence we should right now place in their modeling is much lower than what their biggest enthusiasts have been assuring us for years.