In its 2007 Fourth Assessment Report (AR4), IPCC made the claim that "intense precipitation events" have been increasing in severity across more than half of the globe since 1950. It based the finding on a method called the fixed bin approach, which categorizes average daily rainfall into ranges or "bins" (e.g., one-half to one inch, one to two inches, or more than two inches) and ranks these bins as a percentile of all precipitation events.
However, when used to determine trends in annual precipitation, the fixed bin method can produce false results indicating extremely severe storms that were not actually so harsh. Long before AR4's publication, researchers with the University of Virginia, the University of Colorado, the Cato Institute, and New Hope Environmental Services exposed fixed bin flaws in the 2004 International Journal of Climatology.
They demonstrated how the fixed bin method can erroneously reveal an "increase in total annual rainfall ... disproportionately occurring on the wettest days." This is because extreme weather naturally contributes more rain than light showers do. Considered in terms of annual precipitation and an overall increase in rainfall, fixed bin can make conditions seem as though bad storms are getting worse.
The authors used several examples of actual rainfall measurements in the United States wherein total precipitation increases were brought about by entirely proportionate weather events. They also proposed a more foolproof method of characterizing precipitation increases.
Yet the IPCC chose to ignore the fact its methodology is faulty and spurned the proven approach. AR4 authors used fixed bin and assumed all events with high amounts of precipitation to be out of proportion with "normal" weather. AR4 leads readers to believe extreme weather events are on the rise, all due to AGW. (The natural assumption is a risk to human life, though deaths from extreme weather events worldwide have actually plummeted in the past 100 years.)
The fixed bin snafu is important for two reasons. First, many governments worldwide, including our own, have used AR4 to frame their public environmental policies. Industry is crippled, tax dollars are thrown away on fruitless "alternative" energy scams, and fuel costs are soaring due to bogus claims in IPCC assessment reports.
Second, this latest fib adds to the ever-growing list of problems with AR4 and further calls into question the scientific credibility of its authors. Consider these whoppers:
- AR4 claims massive Himalayan glaciers will shrink to extinction by 2035. This was later exposed as idle speculation by a lone glaciologist who works for an energy research institute dedicated to studying the effects of AGW.
- More than half of The Netherlands is below sea level, warns AR4, and is in imminent danger of floods due to melting polar ice caps. Though the Dutch Environment Ministry announced a correction, IPCC never edited its report.
- According to AR4, grassland will soon replace the Amazon jungle because of rainfall disruptions and forest fires. IPCC gleaned the information from a World Wildlife Fund promotional piece published in 2000.
- IPCC authors discarded temperatures from China and cherry-picked Russian measurements. The resulting corrupt data indicates global warming when temperatures were actually quite stable.
Interestingly, one of the scientists who determined AR4's "conceptual basis for changes in precipitation" (i.e., the fixed bin method) was Kevin Trenberth, head of climate analysis at Colorado's federally funded National Center for Atmospheric Research. He is famous for his Climategate e-mail admission, made while working on the IPCC report: "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't."
Trenberth was one of two lead authors of the AR4 chapter on precipitation. The other was Philip Jones, a professor of climatology at the University of East Anglia in Britain where the Climategate e-mails were pirated. The correspondence implicated Jones conspiring to thwart a Freedom of Information request by asking his colleagues to "delete any e-mail you may have had ... re AR4." He also planned to deceitfully exclude scientific research that questioned the link between human activities and global warming. "I can't see either of these papers being in the next IPCC report," wrote Jones in an e-mail labeled HIGHLY CONFIDENTIAL. "Kevin [Trenberth] and I will keep them out somehow — even if we have to redefine what the peer-review literature is!" (Was the fixed bin research on his blacklist?)