Cherry Picking in Climate Studies

by DR. TIM BALL on MAY 25, 2016


A revealing comment about the corruption of climate science occurred before a Joint Congressional Inquiry. They were seeking to determine the claims by Canadians Steve McIntyre and Ross McKitrick about the scientific inaccuracy of Michael Mann’s ‘hockey stick.’ The graph (Figure 1) appeared in the 2001 Intergovernmental Panel on Climate Change (IPCC) Report and became the poster child for the proof of human-caused global warming.

Figure 1 shows the graph Mann produced that rewrote climate history by eliminating a warmer than today period between 900 and 1300 AD called the Medieval Warm Period (MWP). They established an Ad Hoc committee under the chair of Edward Wegman to determine who was correct.

Figure 1

When questioned by the Congressional Committee one researcher, Rosanne D’Arrigo, made a comment that reflected naiveté and duplicity. When asked why data was narrowly and selectively chosen D’Arrigo replied:

“that you had to pick cherries if you want to make cherry pie.”

Cherry picking involves picking the start and end point of a section of the temperature record to argue for warming or cooling with evidence. In teaching students about the dangers, I drew the “UP” portion of Figure 2 on the blackboard, then added two lines for a “DOWN” claim, and finally two more lines for a “UP” trend.

Figure 2

One of the first examples that confirmed my suspicions about what was going on with the corruption of global warming research by the Intergovernmental Panel on Climate Change (IPCC) is shown in Figure 3. The top graph was presented in Chapter 8 of the 1995 IPCC Report to support the claim that,

“The body of statistical evidence in chapter 8, when examined in the context of our physical understanding of the climate system, now points to a discernible human influence on the global climate.”

Benjamin Santer lead author of the Chapter personally inserted the sentence to replace one that already agreed to by the other chapter authors.

“While some of the pattern-base discussed here have claimed detection of a significant climate change, no study to date has positively attributed all or part of climate change observed to man-made causes.”

The bottom graph shows the longer record, which supports that conclusion. Dennis Avery and Fred Singer noted in 2006,

“Santer single-handedly reversed the ‘climate science’ of the whole IPCC report and with it the global warming political process! The ‘discernible human influence’ supposedly revealed by the IPCC has been cited thousands of times since in media around the world, and has been the ‘stopper’ in millions of debates among nonscientists.”

Figure 3

Recently, reports of the warmest years in the record circulate to amplify the false stories about human-caused global warming. For example, The Guardian newspaper headline for 24 March 2014 says,

13 of 14 warmest years on record occurred in 21st century – UN

Of course they have! The global temperature rose from 1680, the coldest period of the Little Ice Age (LIA) to 1998. Since then temperatures levelled and declined slightly, in what is known as the hiatus. Figure 4 illustrates the situation for the period of the instrumental record starting in 1880. It is not surprising that the highest temperatures occur in the most recent portion, even though they have levelled off.

Figure 4

Figure 5 shows the same graph as Figure 4, but now the temperature is extended back to the nadir of the LIA. The trend from 1680 was problematic for the IPCC because it showed the current warming was part of a longer natural trend.

Figure 5

We know the objective of the hockey stick to rewriting climate history was deliberate.

“During testimony before the Senate Committee on Environment & Public Works Hearing on Climate Change and the Media in 2006, University of Oklahoma geophysicist Dr. David Deming recalled “an astonishing email from a major researcher in the area of climate change” who told him that “we have to get rid of the Medieval Warm Period.”

The ‘hockey stick,’ or as some prefer the ‘hokey stick,’ achieved the goal. It replaced a graph that appeared in the 1990 Report (Figure 6) showing the longer trend warming.

Figure 6

It also showed the MWP was warmer than the current temperatures, something that is still true, despite the claims of the “warmest years on record”. All this confirms Disraeli’s observation about “Lies, damned lies, and statistics.” It is especially applicable to the deception about global warming.