Before I plunge into grading more papers discussing the potential recognition of sharia law in the United States and exploring what the concept of conscience in Judaism might tell us about conscience exemptions to otherwise applicable law, I need to warm up.
So let's review the bidding. My point on Climategate has been two fold. The first is that certain aspects of climate science are what Jim Manzi calls "grey area" science. Paleoclimatalogy is one of these. You can't run controlled experiments to test hypotheses. When it comes to temperature (which is what we are trying to reconstruct and model), we have direct data for only a fraction of the period in which we are interested.
We do have proxy data which are more or less closely correlated with temperature - thinks like tree rings, air bubbles trapped in ice cores, sediment deposits - but these things are also correlated with a variety of other confounding variables including, possibly, temperature itself (i.e., the relationship between these things and temperature may change as temperature changes and because we have little direct temperature data, this further confounds things.)
In short, reconstructing temperature over the past 2000 years is a bit like the tale of the blind monks examining an elephant. They must describe a very big thing with very little information.
Now, certainly climate scientists working in this area - or at least, I assume, most of them - do their best. But the process is inherently speculative and fraught with uncertainty. There is ample opportunity for research and confirmation bias.
What the Climategate e-mails document is the presence of that bias and attempts to put on a public face claiming more certainty and fewer complications than paleoclimatology can, in fact, deliver. The attempt to hide the decline in the Biffra tree reconstruction is on example of that.
And there is no doubt that they tried to hide it in documents that would be used by policy makers. Nothing that my local interlocutors Tom Foley and Seth Zlotocha have said contradicts that.
But they have gone a step further and said that it really doesn't matter. The "decline" was explained away in the scientific literature and so it is irrelevant. There are other reconstructions that either do not use or are less dependent on the tree ring data.
To say that the decline has been explained away because some studies "point to" anthropogenic causes is a bit too facile. It is possible that the "decline" is a result of anthropogenic causes which may or may not be related to carbon emissions or related phenomena. But,as this recent review of the literature concludes, it is still uncertain.
But, beyond that, any divergence shows that the relationship is not robust from external influences and since we don't have detailed data about the climate and atmosphere (and, in fact, fewer sources of data) from 1000 years ago, it is is hard to know that the relationship we observe for 100+ years (because that it the period for which we must calibrate the data)also characterized the preceding 1900.
This is where Seth and Tom would say that the other proxies come in. If they all move the same way in relationship to each other, then perhaps we can infer that they all move the same way in relationship to temperature. In other words, if the six blind monks all say the same thing about the elephant, we have a different fable.
But can we say that? Again, this is where the Climategate emails are instructive. In this case, our scientist monks (and it really is a very small group of interconnected people who do this work) were not "blind" in the sense that they seem to have been very concerned with homogenizing their work and actively hostile to outsiders who asked questions. Folks like Keith Biffra who seems to have wanted to acknowledge the limited nature of claims that could be made with confidence (he seems to have believed that it is quite possible that temperatures were as warm 1000 years ago as they are today, although this recent paper takes a more somewhat more aggressive view) got tremendous pushback from people like Michael Mann who were strongly committed to the idea of a hockey stick and the claim that 1998 was the warmest in 1300 years.
In the past three years, it has been my privilege to participate in academic discourse. I work in rather contentious areas of public law. In my experience, one does not threaten to beat up persons that one disagrees with. One does not boycott journals who publish work that one does not like. One does not discuss hiding or destroying data. One does not fight, tooth and nail, like Mann did, to withhold data from critics. One does not talk about presenting a "tidy picture" when the picture is, in fact, not that tidy.
But Tom and Seth would ask who cares if Michael Mann is a jerk as long as he is right? But it is not clear that, on the most important point, he is. Mann, of course, is the author of the hockey stick which he has repeatedly undertaken to illustrate using multiple proxies (not just the tree rings). In 2003, two AGW skeptics published a paper - in a peer reviewed journal - that essentially argued that the "hockey stick" was the result of improper statistical techniques. Mann took great umbrage, arguing that the critics, McIntyre and McKittrick, were the ones who had got it wrong.
Two investigations followed. A congressional report requested by AGW skeptic Congressmen Joe Burton was largely a statistical review of the hockey stick reconstruction lead by a professor of statistic named Edward Wegman. That report concluded:
It is important to note the isolation of the paleoclimate community; even though they rely heavily on statistical methods they do not seem to be interacting with the statistical community. Additionally, we judge that the sharing of research materials, data and results was haphazardly and grudgingly done. In this case we judge that there was too much reliance on peer review, which was not necessarily independent. Moreover, the work has been sufficiently politicized that this community can hardly reassess their public positions without losing credibility.
Overall, our committee believes that Dr. Mann’s assessments that the decade of the 1990s was the hottest decade of the millennium and that 1998 was the hottest year of the millennium cannot be supported by his analysis.'
Our committee believes that the assessments that the decade of the 1990s was the hottest decade in a millennium and that 1998 was the hottest year in a millennium cannot be supported by the MBH98/99 analysis. As mentioned earlier in our background section, tree ring proxies are typically calibrated to remove low frequency variations. The cycle of Medieval Warm Period and Little Ice Age that was widely recognized in 1990 has disappeared from the MBH98/99 analyses, thus making possible the hottest decade/hottest year claim. However, the methodology of MBH98/99 suppresses this low frequency information. The paucity of data in the more remote past makes the hottest-in-a-millennium claims essentially unverifiable. (Emphasis added.)
Another review was conducted by the National Academy of Sciences. It's report is often claimed to have validated Mann and the hockey stick but that seems to be an overstatement. This is what the NAS report concluded as summarized in a press release accompanying the report:
There is sufficient evidence from tree rings, boreholes, retreating glaciers, and other "proxies" of past surface temperatures to say with a high level of confidence that the last few decades of the 20th century were warmer than any comparable period in the last 400 years, according to a new report from the National Research Council. Less confidence can be placed in proxy-based reconstructions of surface temperatures for A.D. 900 to 1600, said the committee that wrote the report, although the available proxy evidence does indicate that many locations were warmer during the past 25 years than during any other 25-year period since 900. Very little confidence can be placed in statements about average global surface temperatures prior to A.D. 900 because the proxy data for that time frame are sparse, the committee added.
In the report itself, the NAS committee claimed that it was "plausible" that temperatures are the highest in the last 1000 years. But that's not saying much. Everyone seems to agree (well, not Mann, but many others) that there was a Medieval Warm Period (MWP), a Little Ice Age (LIA) and warming over the past 400 years coming out of the LIA. If it was as warm during the MWP as it is today, it calls into question the idea that we have unique anthropogenic warming. It doesn't mean that AGW does not exist, but throws a wrench into the idea that we have unique warming that can only be explained by anthropogenic causes.
To be sure, I can't see that it disproves the hypothesis of AGW. We could have a nonanthropogenic cause of the MWP (must have - unless there were a lot of smokestacks or urban heat islands in the lost civilization of Atlantis)and an anthropogenic cause of current warming out of the LIA. The latter may be less likely to reach equilibrium.
But recognizing the limited nature of these climate reconstructions ought to give us some perspective. It should remind us that the climate can change rather significantly for natural reasons. On a highly complex question, it would seem to lower our confidence in - at least - the more alarmist views of AGW.
Now, of course, all of this is accompanied by more complexity and inside baseball than I can relate here or that I can - to be honest - fully understand no matter how many "primary resources" I read. There are, apparently, issues surrounding the extent of local variations. Some folks want to say that the reconstructions are supported by observable phenomena (like the artic ice shelf) while others want to say that there is anectodal evidence that supports a strong MWP. There have been additional reconstructions. But we have to try to understand the scientific debate as best we can. My point, up to now, is that what paleoclimatology can tell us seems to be limited and uncertain. That uncertainty is exacerbated by the evident biases of some of the key researchers.
So I think we have to move on. Now I can read about the ethics of embryonic stem cell records and justifications for same sex marriage. More to come after I get tired of that.