I’ve had a closer look at the “bombshell” paper that Patrick Michaels described like this:
After four years of one of the most rigorous peer reviews ever, Canadian Ross McKitrick and another of us (Michaels) published a paper searching for “economic” signals in the temperature record. … The research showed that somewhere around one-half of the warming in the U.N. surface record was explained by economic factors, which can be changes in land use, quality of instrumentation, or upkeep of records.
There seems to be some problems with their work. To understand them you need to understand the two different ways of measuring angles.
|This angle is one degree.||This angle is one radian.|
Can you spot the difference?
If you do calculations and get degrees and radians mixed up, you get the wrong answer. Which is what McKitrick did. His analysis included a variable
cosablat, which was supposed to be the cosine of absolute latitude. Trouble is, the software he used expects angles to be measured in radians, his data has latitude in degrees, and he didn’t convert from degrees to radians. Consequently, every single number he calculates is wrong. I corrected the error and reran his regressions. The sizes of the “economic” signals were greatly reduced. They no longer “explain” half of the surface warming trend. Removing the effects of the economic variables now just reduces the warming trend for his sample from 0.27 degrees/decade to 0.18 degrees/decade, which is very close to the warming trend for the whole globe.
Even this overstates his results—McKitrick did not calculate statistical significance correctly—his analysis incorrectly assumes that each observation comes from a different country. His “economic signals” may not even be statistically significant.
Somehow these errors were not detected during the “four years of one of the most rigorous peer reviews ever”. Nor did peer review by Climate Research detect the problems. Unfortunately, this is not the first time that the peer review process at Climate Research has failed. Last year, several of the editors resigned after another defective paper slipped through peer review. Oddly enough, that paper also attempted to cast doubt on anthropogenic global warming.
If you’re new here: In previous postings on Ross McKitrick I have shown how he messed up an analysis of the number of weather stations, showed he knew almost nothing about climate, flunked basic thermodynamics, couldn’t handle missing values correctly and invented his own temperature scale.
Update: John Quiggin confirms my findings.
This article (scroll to page 13) by Clare Goodess has more on the problems with the review process at Climate Research that led to the resignation of half of the editors. Chris de Freitas, the same editor that published the previous improperly reviewed papers, also published the McKitrick and Michaels effort.
Update 28/8: A poster on the Internet Infidels forums demonstrates how easy it is to verify that McKitrick got it wrong.