Deep Kimchi
28-06-2006, 18:23
http://www.tcsdaily.com/article.aspx?id=062806F
Not to say that global warming isn't a problem, but isn't this one of the major studies underlying the whole theory? And it's the National Academy of Sciences saying it's erroneous!
Last week's release of a National Academies of Science (NAS) report entitled "Surface Temperature Reconstructions for the Last 2,000 Years" was the result of a congressional request to look into the controversy surrounding the now-famous "hockey stick" temperature curve. The media portrayed the findings of the NAS review panel as some sort of new statement about how warm the Earth is at present, and totally missed the real news: that the original claim of Mann et al. of unprecedented warmth in the last 1,000 years -- based mostly upon tree ring data, especially from the southwest U.S. -- was dubious at best.
For the last several years, the hockey stick has been a poster prop for manmade global warming. For instance, it figures prominently in Al Gore's new movie, "An Inconvenient Truth." But the statistical and data analysis methods that Mann et al. used to arrive at their 1,000 year temperature reconstruction were strongly criticized by some. The hockey stick played down the warmth of the "Medieval Warm Period" of 1,000 years ago, as well as the later coolness of the "Little Ice Age."
Also, the uncritical acceptance of the hockey stick for inclusion in the U.N.'s Third Assessment Report on global climate in 2001 gave many scientists the impression that the editors of that report wanted to believe the hockey stick more than they were convinced of its validity.
In their attempt to not publicly scold Mann and his coauthors for questionable data analysis methods, the authors of the new report instead chose to restate the evidence for how warm the Earth has gotten recently. What the media didn't notice, however, is that the 1,000 year figure that was central to the whole hockey stick debate had now been replaced in the report by a figure of 400 years. Since most of the last 400 years was dominated by the "Little Ice Age," the warming during the 20th century should be welcomed by humanity.
The report says that surface temperature reconstructions before this period (about 1600) have "less confidence" and that "uncertainties...increase substantially backward in time..." for any of these proxy estimates of ancient temperatures. One review panel member told me that the statisticians on the panel were amazed when it was revealed that the method underlying the hockey stick had essentially no statistical skill when validated.
Not to say that global warming isn't a problem, but isn't this one of the major studies underlying the whole theory? And it's the National Academy of Sciences saying it's erroneous!
Last week's release of a National Academies of Science (NAS) report entitled "Surface Temperature Reconstructions for the Last 2,000 Years" was the result of a congressional request to look into the controversy surrounding the now-famous "hockey stick" temperature curve. The media portrayed the findings of the NAS review panel as some sort of new statement about how warm the Earth is at present, and totally missed the real news: that the original claim of Mann et al. of unprecedented warmth in the last 1,000 years -- based mostly upon tree ring data, especially from the southwest U.S. -- was dubious at best.
For the last several years, the hockey stick has been a poster prop for manmade global warming. For instance, it figures prominently in Al Gore's new movie, "An Inconvenient Truth." But the statistical and data analysis methods that Mann et al. used to arrive at their 1,000 year temperature reconstruction were strongly criticized by some. The hockey stick played down the warmth of the "Medieval Warm Period" of 1,000 years ago, as well as the later coolness of the "Little Ice Age."
Also, the uncritical acceptance of the hockey stick for inclusion in the U.N.'s Third Assessment Report on global climate in 2001 gave many scientists the impression that the editors of that report wanted to believe the hockey stick more than they were convinced of its validity.
In their attempt to not publicly scold Mann and his coauthors for questionable data analysis methods, the authors of the new report instead chose to restate the evidence for how warm the Earth has gotten recently. What the media didn't notice, however, is that the 1,000 year figure that was central to the whole hockey stick debate had now been replaced in the report by a figure of 400 years. Since most of the last 400 years was dominated by the "Little Ice Age," the warming during the 20th century should be welcomed by humanity.
The report says that surface temperature reconstructions before this period (about 1600) have "less confidence" and that "uncertainties...increase substantially backward in time..." for any of these proxy estimates of ancient temperatures. One review panel member told me that the statisticians on the panel were amazed when it was revealed that the method underlying the hockey stick had essentially no statistical skill when validated.