Global Warming: Still Not A Hoax!

Richard Muller is a man climate scientists love to hate. Among other things, the Berkeley physicist has questioned the professional integrity of people like Penn State's Michael Mann, one of the creators of the so-called “Hockey Stick” graph showing that temperatures shot up dramatically and unprecedentedly in the 20th century. Mann has been cleared of such accusations many times over; so have the main actors in the so-called “Climategate” affair, another of Muller's targets.

More broadly, though, Muller has also questioned the very fact of global warming itself. Like other doubters, he thought the appearance of warming might come partly from the fact that weather stations are often located in or near cities, where waste heat from buildings and cars, plus heat absorbed and re-emitted from roads and rooftops can cause artificially high temperature in a small area (it's known as the “urban heat island effect”).

In principle, that could certainly be a problem: climate scientists rely on a just 7,000 or so thousand weather stations that have long, uninterrupted data. That makes them more reliable in many ways than stations with shorter records—but the older the station, the more likely it is to be in an urban area. So Muller, working on the theory that if you want a job done right you should do it yourself, put together a team of scientists and statisticians to form the Berkeley Earth Surface Temperture (or BEST) study. It's mission: re-analyze the world's temperature records in a way Muller could trust.

One key difference in the BEST approach is that Muller's group used data from 39,000 weather stations, more than five times as many as most climate scientists use. Many of the 39,000 have short or interrupted records, but BEST statistician Richard Rohde came up with ways to assign them different weights, reflecting their varying reliability. Ultimately, the BEST studies would include about 1.6 billion individual measurements from 15 different collections of temperture records.

Last spring, a preliminary look at the results came out when Muller testified before Congress. To many peoples' surprise, including those who had asked him to testify, he said that his study largely supports what the climate-science community had been saying all along: the Earth has indeed warmed, by about 1.3° F since 1900.

Now Muller's group has released several new scientific papers, available on the team website, and also written an Op-Ed in the Wall Street Journal titled “The Case Against Global Warming Skepticism.” Further analysis, he says, makes the preliminary results even stronger. 

Some prominent critics of the conventional climate wisdom used to love Muller just as much as climate scientists disliked him. Now those same critics are less pleased—especially, one would guess, because of the subheading on the Op-Ed:

There were good reasons for doubt, until now.

It was a pretty shocking declaration — for the Journal's editorial page, anyway, given its history of pooh-poohing concerns about the planet's warming. For most of the scientific community, however, it was very old news.