1) A comment by Phil Jones, the director of East Anglia’s Climate Reach Unit (whose decision to step down temporarily has drawn fairly wide coverage), that he had used a “trick” to hide a decline in temperatures. This has probably been the most cited and best-explained point of criticism in the media. Basically, in a reconstruction of twentieth-century temperatures Jones grafted instrumental temperature records onto proxy temperature records based on tree rings, because at a certain point in time, those records became unreliable. Why the later tree-ring data are faulty isn’t understood, but a key point here for journalists is that there are many other lines of evidence that support a rise in temperatures during the latter half of the twentieth century. [Update: Please see the comments section for a more thorough explanation of Jones’s “trick” and the data behind it.]
This “trick”—perhaps better described as a “solution”—was explained in the scientific literature at the time, and there seems to be nothing nefarious about it. Many reporters explained the story in more detail than I have here. Those that didn’t misled their readers. The New York Times’s John Tierney explained the “trick” well enough, but still argued that when the final temperature graph was presented, policymakers and journalists “wouldn’t have realized” how it had been constructed. That may have been the case, but hopefully it wasn’t. Few reporters if any seem to have covered the “trick” (or “divergence problem,” as it is known to scientists) at the time, but one can hardly have expected them to if they understood and accepted the scientists’ rationale. But Tierney is right—journalists should always learn exactly how such graphs were constructed before reporting.
2) A comment in which Kevin Trenberth, the head of the Climate Analysis Section at the National Center for Atmospheric Research, called scientists’ inability to account for a lack of recent warming as a “travesty.” This is perhaps the second most cited criticism in the science category, though it has not been as well or as consistently explained as the “trick.” Basically, Trenberth was expressing frustration with researchers’ poor ability (pdf) to track short-term natural variability within the climate system. As we explained in a recent column, natural variability (e.g., cool weather) drowns out the signal from human-caused climate change, which becomes clear on longer timescales. The fact that scientists don’t have a handle on the former doesn’t mean they don’t on the latter. Journalists haven’t done a great job explaining this in the wake of the hacked e-mails, but a few have done better in recent years while addressing ongoing claims that “global warming stopped in 1998.”
3) A comment by Michael Mann, a professor at Penn State’s Department of Meteorology, that “it would be nice to contain” the Medieval Warm Period in a millennial temperature reconstruction. George Will latched onto this on ABC News’s This Week, where he had the scientist saying it would be nice to “hide” the warm period (which some scientists think had higher temperatures than we are experiencing now, but without the presence of human-generated greenhouse gases). The Morning Call in Allentown, Pennsylvania was one of the very few outlets to ask the scientist who the made the comment what he meant. Mann said that the word “contain” reflected his desire to identify exactly when the warm period began, rather than to deny its existence. This seems to be a reasonable explanation, but it would be nice to see more reporters fleshing it out and seeking other input about the statement’s significance.
4) The log of Ian (Harry) Harris, a computer expert at East Anglia’s Climate Research Unit, expressing frustrations with attempts to reconcile disparate climate data from around the globe. This one has come up only briefly in the mainstream press. NASA climate modeler Gavin Schmidt—who has been a key source for the media over the last two week and posted a couple methodical explanations such as this one at RealClimate.org—explained the log this way: “Anyone who has ever worked on constructing a database from dozens of individual, sometimes contradictory and inconsistently formatted datasets will share his evident frustration with how tedious that can be.” But it appears no reporter has yet contacted Harris himself.
There are perhaps half a dozen other science-related points of criticism in the e-mails, which have been discussed in blogs and in comments sections, but haven’t received much attention in the mainstream press; I haven’t had chance to look over them sufficiently to comment here. At this point, however, there doesn’t seem to be anything that undercuts the fundamental science indicating that human-generated greenhouse gases are warming the globe.