Update See my review of the BEST methodology here.
Muller concedes—in public—what many skeptics have claimed for years: that our temperature record is poor, especially over the oceans, that it is limited, filled with errors and biases, and when used as a basis for judgment, leads to over-certainty.
The temperature-station quality is largely awful. The most important stations in the U.S. are included in the Department of Energy’s Historical Climatology Network. A careful survey of these stations by a team led by meteorologist Anthony Watts showed that 70% of these stations have such poor siting that, by the U.S. government’s own measure, they result in temperature uncertainties of between two and five degrees Celsius or more. We do not know how much worse are the stations in the developing world.
Using data from all these poor stations, the U.N.’s Intergovernmental Panel on Climate Change estimates an average global 0.64oC temperature rise in the past 50 years, “most” of which the IPCC says is due to humans. Yet the margin of error for the stations is at least three times larger than the estimated warming. [link mine]
Even more delightfully, Muller admits that it has not been growing stormier (sorry, Big Al):
The number of named hurricanes has been on the rise for years, but that’s in part a result of better detection technologies (satellites and buoys) that find storms in remote regions. The number of hurricanes hitting the U.S., even more intense Category 4 and 5 storms, has been gradually decreasing since 1850. The number of detected tornadoes has been increasing, possibly because radar technology has improved, but the number that touch down and cause damage has been decreasing. Meanwhile, the short-term variability in U.S. surface temperatures has been decreasing since 1800, suggesting a more stable climate.
Nevertheless, the Berkeley project he led—which brought together physicists and (finally!) statisticians—were able to perform a complete re-analysis of all the temperature data, this time taking the main statistical statistical criticisms into account. Let’s leave aside whether these analyses were complete, rigorous, or recommended. Assume that they were. The findings?
We discovered that about one-third of the world’s temperature stations have recorded cooling temperatures, and about two-thirds have recorded warming. The two-to-one ratio reflects global warming. The changes at the locations that showed warming were typically between 1-2oC, much greater than the IPCC’s average of 0.64oC.
His conclusion is that “Global warming is real.” He hopes that “Perhaps our results will help cool this portion of the climate debate.”
But this blog, and all of the scientists who are critics, have agreed with this conclusion since this beginning. There simply is no debate on this question. There are no tempers to cool.
There has been, and still is, a vigorous disputation on the size of the warming and our confidence on this magnitude of warming. And Muller forgets that there has been a much more contentious argumentation about why the temperature has increased (in some places and cooled in others).
Just one thing about the first point of contention. If you look, say, at the year 1945 and compare it to the year 2010, you find warming of a certain size. But if you begin at 1940, just five years earlier, you find much less warming. Temperature increases (or decreases) are always relative to something (this is a point of logic, not physics). The choice of the comparator is arbitrary and subjective. Because of this, it is possible, and it has oft occurred, that someone wanting to stress the size of the increase will choose a comparator that best makes his case. Muller doesn’t state in his editorial what his comparator is; or why he has chosen just one.
However, we can afford to be as generous as Muller when he invited skepticism and allow that his statistical results are far more certain than any prior analysis. This merely brings us to the big question. As to that, Muller admits:
How much of the warming is due to humans and what will be the likely effects? We made no independent assessment of that.
From that he insists, “you should not be a skeptic, at least not any longer.” Somebody has to remind Mr Muller that skeptics aren’t skeptical of that some warming (and some cooling) has occurred. We are skeptics about our ability to explain this warming (and cooling), and to predict skillfully future warming (and cooling).
The fallacy—and it is a fallacy Mr Muller commits—is to suppose that because many climatologists have offered one theory for the observed warming (and cooling), and that, at least for the moment, they cannot think of one better, that therefore their theory is true. Thus, I remain skeptical.
Update Analysis of DJ Keenan’s BEST analysis coming tomorrow.