Thoughts on Climate Change -- Part 11:Tamino's Trick

The "hiatus" -- the period from roughly 1998 to 2015, in which the steady rise of global temperatures, so strongly evident during the latter part of the 20^th century, appears to have leveled off, contrary to the expectations of "climate change" advocates, who've been trying desperately to explain it away for many years. At least 66 different explanations for the hiatus were published by 2014 and many more have been offered since. My own personal favorite was proposed by blogger "Tamino" back in 2014 (updated in 2018):

From The Unsettled Science of Climate Change: A Primer for Critical Thinkers:

While investigators such as Rahmstorff, Hansen, Cook, Cowtan, Way, etc. have attempted to account for the hiatus on the basis of a re-examination of either forcing factors or methods of data collection, others prefer to see it as some sort of illusion produced by misleading statistics. A leading member of the second school is Rahmstorff collaborator Grant Foster, posting as “Tamino” on his blog, Open Mind. On a post of Jan. 2014, titled Global Temperature: the Post-1998 Surprise, Tamino offers the following graph:

The red line is what he calls the “forecast line,” representing a hypothetical continuation of the warming trend indicated by the preceding black diagonal. The blue horizontal represents “our estimate of what we would expect if we had been given certain knowledge of no statistically significant warming from 1998 through 2013 . . .” What is his point?

It’s clear that if we expected a pause, we would expect most of the following years’ temperatures to be below the red forecast line, but about half above and half below the blue forecast line. On the other hand, if we expected continued warming, we would expect most of the following years’ temperatures to be above the blue forecast line, but about half above and half below the red forecast line.

As he demonstrates, however, almost all the data points from 1998 through 2013 are well above not only the blue line, but the red one as well. Here are the lines juxtaposed with the Hadcrut4 graph:

As Tamino explains,

What actually happened is that, according to the HadCRUT4 data, most of the data are above both forecasts. Twelve of sixteen were hotter than expected even according to the still-warming [red line] prediction, and all sixteen were above the no-warming [blue line] prediction.

He continues, demonstrating that more or less the same result can be seen using several other datasets, NCDC, GISS, RSS, and, not surprisingly, Cowtan and Way.

He then goes on to crow a bit:

Does this mean we need to launch a massive research effort to divine the reason for this sudden and pronounced warming? No.

Careful Tamino. That “massive research effort” has been chugging along for years, and still going strong. Do you really want to claim your cli. sci. colleagues have been wasting their time? More important: do you actually believe you’ve pulled a real rabbit out of your hat, rendering all other “explanations” superfluous? Or is this simply an instance of cleverly contrived statistical legerdemain?

It’s clever, I’ll give him that. But, yes, it’s a just a trick, one of many examples of how easy it is to deceive oneself (and others) with statistics. The basis for the trick is that old standby of magicians for centuries: misdirection. Tamino’s red line tells us that, indeed, as no one would dispute, the years between 1998 and 2013 were especially warm compared to the period between 1979 and 1997, and that is why most of the data points lie above the red line, because the red line predicts absolute temperature, telling us nothing at all about the rate at which temperature changes. As he himself states, “All sixteen years were hotter than expected even according to the still-warming prediction [red line], so of course they also were above the no-warming [blue line] prediction.” Yes. Precisely. Because they were hotter. Not because there was no leveling after 1998. The leveling of the warming trend remains clearly visible on the Hadcrut graph regardless of where those dots appear in relation to any red or blue line. That red line serves a function analogous to the matador’s red cape, directing our attention away from the actual hiatus toward the very different issue of absolute heat. Literally misdirection.

To properly demonstrate the existence of a hiatus, consider the following graph, also based on the Hadcrut4 data:

What’s pictured here is not simply a warming pause, but the breakdown of the correlation between global temperatures (in red) and CO2 accumulation (in green). As indicated by the arrows, it’s the difference between the two that produces the hiatus, not the difference in overall warmth between two periods of time. Moreover, as clearly indicated in the same image, there was no correlation prior to the late 70s either. The only period of clear and consistent correlation was between the late 70s and ca. 1998, roughly 20 years. Thus, despite the fact that the years between 1998 and the present have been warmer overall than those preceding, the upward trend required to maintain the correlation either halted completely or slowed to a crawl during that time. This is the basis for the hiatus.