Guest essay by Don J. Easterbrook, Dept. of Geology, Western Washington University
Last week in my post ‘‘The cause of pause in global warming,” I presented data showing that the lack of global warming was not the ‘biggest mystery in climate science,’ “but, in fact, it really isn’t a mystery at all, it was predicted in 1999 on the basis of consistent, recurring patterns of the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) and global climate.” This precipitated an avalanche of caustic comments by Bob Tisdale, almost all of which were totally irrelevant to what I said. This post is to set the record straight so there is no misunderstanding of the situation.
I like Willis Eschenback’s caveat: “if you disagree with something that I or someone else said, please QUOTE THEIR EXACT WORDS and state your objection. That way we can all understand just what you are objecting to, and the nature of your objection.” With that in mind, here is the crux of what I said.
“Each time the PDO was warm, global climate warmed; each time the PDO was cool, global climate cooled.” “Each of the two PDO warm periods (1915-1945 and 1978-1998) and the three cool periods (1880-1915, 1945-1977, 1999-2014) lasted 25-30 years. If the flip of the PDO into its cool mode in 1999 persists, the global climate should cool for the next several decades. “
Figure 4. (Top) PDO fluctuations and projections to 2040 based on past PDO history.
Figure 4. (Bottom) Projected global cooling in coming decades based on extrapolation of past PDO recurring patterns.
I plotted the oxygen isotope measurements made by Stuiver and Grootes (1997) for the past 450 years, which,
”showed about 40, regularly-spaced, warm/cool periods with average cycles of 27 years, very similar to the PDO cycle. There was no way to determine what the PDO looked like that far back, but the GISP2 warm/cool cycles were so consistent that correlation with PDO 25-30 year cycles seemed like a good possibility. Historically known warm/cool periods showed up in the GISP2 curve, i.e., the 1945-1977 cool period, the 1915-1945 warm period, the 1880-1915 cool period, the Little Ice Age, Dalton Minimum cooling, the Maunder Minimum cooling, and many others, lending credence to the validity of the GISP2 measurements.”
Figure 5. Warm and cool periods to 1480 AD from oxygen isotope measurements from the GISP2 Greenland ice core. The average length of a warm or cool cycle is 27 years.
“The ‘mysterious pause’ in global warming is really not mysterious at all. It is simply the continuation of climatic cycles that have been going on for hundreds of years. It was predicted in 1999, based on repeated patterns of cyclical warm and cool PDO phases so it is neither mysterious nor surprising. The lack of global warming for the past 17 years is just as predicted. Continued cooling for the next few decades will totally vindicate this prediction. Time and nature will be the final judge of these predictions.
What drives these oceanic/climatic cycles remains equivocal. Correlations with various solar parameters appear to be quite good, but the causal mechanism remains unclear.”
Bob Tisdale immediately launched an insulting verbal attack in which he said:
“Easterbrook’s post is misleading, it misinforms, it is contrived, it is far from good science”
“Easterbrook continues to present his misunderstandings of the PDO”
“Easterbrook does more to mislead and misinform than to teach and inform”
“He insists on misinforming readers”
“Easterbrook’s bogus-looking global temperature anomaly data”
“I suspect it’s a fantasy dataset”
Now I enjoy a spirited discussion of issues as much as anyone and am always willing to discuss any scientific issue, but these unprofessional, insulting remarks are not what I call science and do nothing to advance the understanding of issues. Tisdale completely missed the point of what I said and the basis for saying it. Virtually everything he said was irrelevant to the data that I presented and nothing he said disproves any of my data or my predictions (which so far seem to be right on track). Tisdale missed the boat when he ignored my statement at the outset, “it was clear that PDO drove global climate (Figs. 2,3), but what drove the PDO was not apparent,” and again at the end, “what drives these oceanic/climatic cycles remains equivocal. Correlations with various solar parameters appear to be quite good, but the causal mechanism remains unclear.”
In other words, I was correlating the chronology of the PDO with global climate and glacier fluctuations without worrying about the cause of the PDO. I don’t know what causes the PDO nor does anyone else, including Tisdale. I then used GISP2 Greenland ice core oxygen isotope data to show that 40 warm/cool cycles back to at least 1480 had 27 years cycle patterns very similar to those of the PDO and global warming cycles that we have observed in the past century. Tisdale vented his criticisms of my work on the basis of his interpretation of what causes the PDO, which is totally irrelevant to the data that I presented. The point here is I start with recognition of the existence of the PDO and it really doesn’t matter what the cause is—that’s a separate issue. Tisdale’s interpretations of the relationship of ENSO to the PDO may well be correct, but that does nothing to invalidate the data that I presented. As one of the commenters pointed out, “In addressing Don Easterbrook you assert repeatedly that the PDO is an “aftereffect” of the ENSO. This in no way contradicts anything that Don said, he left the cause of the PDO as unknown.” Tisdale failed to understand that none of his discussions about the cause of the PDO in any way invalidated the data presented.
Tisdale was very critical of figure 4, repeatedly calling it “bogus” (= false, fake, phony, counterfeit, sham) and “a fantasy dataset” (= made up, invented, fictional, imaginary, unreal) because the source of part of the curve from 1900-2000 wasn’t indicated. The logic of such a conclusion is not valid—just because you don’t know the source of data on a graph doesn’t render it ‘bogus’ or a ‘fantasy.’ Yes, it is perfectly reasonable to ask for source data and can reserve judgment until you get it, but Tisdale’s statements were way off base–not logical and unnecessarily insulting. Here is the original graph used for part of figure 4—it is neither ‘bogus’ nor a ‘fantasy.’
This curve is now 14 years old, but because this is the first part of the curve that I originally used in 2000, I left it as is for figure 4. Using any one of several more recent curves from other sources wouldn’t really make any significant difference in the extrapolation used for projection into the future because the cooling from 1945 to 1977 is well documented. The rest of the curve to 2010 was grafted on from later ground measurement data—again, which one really doesn’t make any difference because they all show essentially the same thing. The extrapolated parts of the curve show three possible projections: (1) cooling similar to 1945-1977, (2) somewhat deeper cooling, perhaps similar to 1880-1915, (3) somewhat deeper cooling, perhaps similar to that of the Dalton Minimum. The last two are diagrammatic only– really guesses, but are shown to illustrate possible options. Nothing that Tisdale says in his comments in any way invalids this figure.
The last three graphs in my post are intended merely as illustrations of the global cooling that has occurred since 1998, confirming (so far) the predictions that I made 14 years ago. If you don’t like figure 6, throw it out–Figures 7 and 8 make the same point. Tisdale’s conclusion that “cooling is not occurring from the peak around 2001 through 2010” is easily proven false by the Christopher Monckton graph below.
Global cooling from 1996 to 2013. Graph by Christopher Monckton http://wattsupwiththat.com/2013/08/07/the-agu-policy-statement-as-redrafted-by-monckton/
1. I have neither the desire nor reason to quarrel with Bob Tisdale—I suspect our differences are less than one might imagine. His Enso interpretations may well be correct, but they have no relevance to the data presented in my WUWT post.
2. Nothing in any of Tisdale’s comments invalidates any of the data that I presented.
3. The global cooling predictions that I made in 2000, based on recurring patterns of PDO and global climate, have so far proven to be correct.
4. Nature and time will ultimately prove whether or not my all of my predictions are correct.
5. I hope that we can now move on to more productive issues, especially what is the principal driving force of climate changes. I welcome open discussions of scientific issues with anyone, including Bob Tisdale, but I confess to having little patience with argumentum ad hominem.