February 2007 ISSUE
Readers’ Forum
Readers Take Aim at Hockey Stick Curve
We welcome Readers’ Forum letters of interest to the professions. Send them to George Lee, glee@apegga.org. Keep them to 300 words or less. Letters represent the opinions and not necessarily the expertise of writers. The PEGG reserves the right to edit or reject any letter.
Mutual Admirers
Perpetrate Thesis
Re: Hockey Stick Curve, Other Data Thoroughly Verified, J. Edward Mathison,
P.Geol., The PEGG, Readers’ Forum, November 2006.
The title should have read, Hockey Stick Curve, Other Data Thoroughly Destroyed. Mr. Mathison should follow his own advice by referencing published, refereed articles when he mentions that Dr. Michael Mann et al. has been substantiated by two independent studies.
Perhaps the studies he refers to are those described by Dr. Edward Wegman, who writes, “There is a tightly knit group of individuals who passionately believe in their thesis.” He continues: “However, our perception is that this group has a self-reinforcing feedback mechanism and, moreover, the work has been sufficiently politicized that they can hardly reassess their public positions without losing credibility.”
In other words, climate research often more closely resembles a mutual admiration society than a competitive and open-minded search for scientific knowledge. And Dr. Wegman’s social network graphs suggest that Mr. Mann and his hockey stick are at the centre of that network.
As to the hockey stick curve itself, the Wegman Report, prepared by Dr. Wegman and two other independent researchers, was submitted to the House and Commerce Committee in the U.S. The report looked at Mr. Mann’s methods from a statistical perspective and assessed their validity.
Their conclusion is that Mr. Mann’s papers are plagued by basic statistical errors that call his conclusions into doubt. Further, Dr. Wegman’s report upholds other findings that Mr. Mann’s methodology is biased toward producing “hockey stick” shaped graphs.
Mr. Mathison references a National Academy of Sciences review that concluded that the last few decades of the last century are the warmest in the last 400 years. Since the Earth’s climate was in the Little Ice age 400 years ago, it is not surprising that temperatures have warmed since that time!
Similarly, his mention of warming over the last 40 years suffers the same type of bias. In selecting 40 years ago, he starts from a time when the Earth was in a cooling period. Some scientists believed, in fact, that another ice age was imminent. Not surprising that temperatures have risen since then.
Much of Mr. Mathison’s letter is political in nature, not scientific. He even says that those disagreeing with the pro-Kyoto climate change message are not searching for truth but are interested only in power and a threat to their profits.
I wonder if Mr. Mathison is prepared to make those charges against, for
example, Dr. Tim Patterson of the Carleton University, Dr. Jan Veizer
of the University
of Ottawa, or many others with impeccable degrees relevant to climate
science.
For many of us with a science or engineering background, our interest
is an open-minded search of the science on climate change.
D. Barss, P.Geol.
Calgary
Hockey Stick
Less Than Convincing
The hockey stick curve of global temperatures may be “thoroughly verified,” as
far as Mr. Mathison, is concerned, but I am far from convinced. Anyone
who takes the trouble to study the graph properly would see its problems.
The graph is supposed to show a plot of world temperatures back to the year 1000. Very impressive. The problem is, the first temperature measurement device was apparently invented by Galileo sometime in the 1300s. Furthermore, people did not begin to keep temperature records until some time in the 1700s.
This raises the question of where did the temperatures come from that appear on the graph. The only answer can be that they were generated statistically. I tend to be skeptical of any argument which is solely supported by statistics, especially since there are companies who will, for a fee, generate the statistics to prove whatever point of view a client wishes to take.
A second problem is the vertical scale. Expanding the vertical scale on a plot of data to magnify variations is an age-old tactic. The hockey stick does this to make variations look severe.
Finally, the temperature data is plotted with respect to some baseline, but what does this line represent? Presumable the environmentalists would have us believe that this is a global “average temperature.” The problem with this is there is no such thing as an average temperature.
Last January there was a mild spell in Edmonton. The outdoor temperature went up to 10 C so I decided to wash my car. The water came through the hose fine, but when I tried to lather the car down I was slipping and sliding. Obviously, the air temperature was 10 C, but the ground temperature was still zero.
What then was the “average” temperature? We could take the average of 10 and zero and get five, but as a temperature this is meaningless as there was nothing in the vicinity that was that temperature. When temperature values are averaged, the result is no longer a temperature, it is simply a statistic.
As for the much-publicized greenhouse effect, there is none because there is no greenhouse. To create a greenhouse, a canopy that’s transparent to radiation but does not permit the upward movement of heat-bearing gases by convection, is placed over a designated area. No such canopy exists over the world.
The world climate is changing, all right, but instead of trying to lay a guilt trip on all Canadians, we would be better advised to figure out how we are going to adapt to it. Protecting our fresh water supply would be a good start.
J.R. Connell, P. Eng.
Edmonton
Hockey Stick Hokum
I think a better term for the famous hockey stick curve, quoting
from the Wall Street Journal, is “hockey stick hokum.”
Mr. Mann’s 1999 paper supposedly provided the smoking gun to prove that
20th-century industrialization had caused unprecedented global warming, backing
up the Intergovernmental Panel on Climate Change’s tweaked
computer models, on which the tenuous hypothesis is based.
Mr. Mann’s hockey stick eliminated the Medieval Warm Period when the Vikings settled Greenland, showing a nice steady temperature oscillation (the shaft) followed by a dramatic climb (the blade) in the last 100 years.
Mr. Mathison says that Mr. Mann’s curve has been thoroughly verified. However, two Canadians, Ross McKitrick and Steven McIntyre, published an article in 2003 in Environment & Energy showing Mr. Mann’s study to be extremely flawed. This is thanks to his cherry picking of data and his methodology, which could produce hockey sticks from any random data.
A report commissioned by the United States House Energy Committee
and released last summer completely supports McKitrick & McIntyre. The report by three
eminent statisticians headed by Dr. Edward Wegman of George Mason University
found the Mann et al. paper to be plagued by basic statistical errors.
Obviously, there is as yet no science backing man-made global
warming, or maybe the Vikings never settled in Greenland!
Roger Edmunds, P.Geol.
Calgary
A Closer Look
At NAS Report
Mr. Mathison, states that “the Earth’s temperature record over
the last few 1,000 years, the famous hockey stick of Mann et al., has been
substantiated by two independent studies using different data sets” and “has
been verified by the National Academy of Sciences in the U.S.” Closer
inspection of the NAS report reveals that it actually says:
• It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries. This statement is justified by the consistency of the evidence based on a wide variety of geographically diverse proxies.• Less confidence can be placed in large-scale surface temperature reconstructions for the period from A.D. 900 to 1600. Presently available proxy evidence indicates that temperatures at many, but not all, individual locations were higher during the past 25 years than during any period of comparable length since A.D. 900. The uncertainties associated with reconstructing hemispheric mean or global mean temperatures from these data increase substantially backward in time through this period and are not yet fully quantified.• Very little confidence can be assigned to statements concerning the hemispheric mean or global mean surface temperature prior to about A.D. 900 because of sparse data coverage and because the uncertainties associated with proxy data and the methods used to analyze and combine them are larger than during more recent time periods.
It is perhaps unsurprising that it has become warmer since the Little Ice Age, but perhaps Mr. Mathison could explain how the terms less confidence and very little confidence can be interpreted as “verified.” Furthermore, the work of Mann et al. was savaged by a recent congressional investigation led by Dr. Edward Wegman, chairman of the NAS Committee on Applied and Theoretical Statistics. This report recognized flaws in the methods used by Mann et al. and stated that:
The assessments that the decade of the 1990s was the hottest decade in a millennium and that 1998 was the hottest year in a millennium cannot be supported by the [Mann et al.] analysis. As mentioned earlier in our background section, tree ring proxies are typically calibrated to remove low frequency variations. The cycle of Medieval Warm Period and Little Ice Age that was widely recognized in 1990 has disappeared from the [Mann et al.] analyses, thus making possible the hottest decade/hottest year claim. However, the methodology of [Mann et al.] suppresses this low frequency information. The paucity of data in the more remote past makes the hottest-in-a-millennium claims essentially unverifiable.
Mr. Mathison also dismisses the points of skeptics by stating that “rarely do climate change skeptics publish refereed articles in scientific journals.” This statement is ironic in that the Wegman report examined the social networks of published temperature reconstruction authors and concluded that the peer review process was “not sufficiently independent.”
It further recommended that, contrary to what is presently the case, “the authors of policy-related documents like the IPCC report ... should not be the same people as those that constructed the academic papers.”
I encourage all readers to download the documents cited and draw their own conclusions. It might just turn you into a skeptic!
Nathan Schmidt, PhD, P.Eng.
Edmonton
MORE INFO
WEGMAN REPORT
Wall Street Journal article,
published July 14, 2006
http://online.wsj.com/article/SB115283824428306460.html
Full report
http://energycommerce.house.gov/108/home/07142006_Wegman_Report.pdf
NAS REPORT
www.nap.edu/catalog/ 11676.html