There are Reasons to Celebrate!
At the climate website No Tricks Zone, there is a picture of various estimates of CO2 climate sensitivity estimates. These are the guesses of how much the temperature would increase if atmospheric carbon dioxide doubled from its pre-industrial levels.
This sensitivity is measured as a “transient climate response” (TCS), noting the near-terms effects, or by “equilibrium climate sensitivity” (ECS), which are the long-term effects, assuming that CO2 stops increasing. The higher either of these numbers is, the more we have to worry about.
Each estimate is taken from a peer-reviewed scientific paper. The first comes in 2001 from the authors Andronova and Schlesinger, with the estimate of 3oC. The highest estimate (in this graph) is 6oC in 2002 from Gregory.
Not All Jokes are Funny
After 2002, something funny happens.
Frame puts the estimate at about 2.8oC by 2005. Skeje guessed 2.8oC in 2014. Not pictured is a paper I co-wrote in 2015, which put the estimate of ECS at 1.0oC. (This paper led to a witch hunt and hysterical accusations of “climate denial.”)
Finally, Reinhart brings it down to about 0.2oC in 2017.
From this picture we can infer at least three things. First, the debate about global warming was not over in 2000, nor in 2001, nor is it over now. The sensitivity estimates would not have changed if the debate were over. Second, the good news is that we clearly have less to worry about than we thought. This is something to celebrate, right? Right?
The third inference is that we have seen this same graph before. Not once, but many times!
You Can’t Read My Mind
The picture looks exactly like the graph of extrasensory perception (ESP) effect size through time. (I wrote a book on the subject, available free at the bottom of this page.)
J.B. Rhine in the 1930s showed the backsides of playing cards to some folks and asked them to use their ESP to “read” the frontsides. Rhine claimed to have demonstrated parapsychological abilities, as did Charles Honorton and Sharon Harper in the mid-1970s using the so-called ganzfeld. The 1970s were a time of high excitement in ESP research, with extraordinary claims coming from every direction.
But then came the 1980s and 1990s, a time when researchers had learnt from magicians and their own errors how to do proper tests. (I designed some of these tests.) The effect size dropped and dropped. It finally fell into the statistical mud, where it remains to this day, in spite of the efforts of a few die-hards to resurrect the glory days.
It’s Colder than You Think
The climate sensitivity graph is also like the amount of excess heat in cold fusion experiments. Stanley Pons and Martin Fleischmann in 1989 claimed that by sticking some metal leads into a certain kind of water, “cold fusion” would take place, releasing heat. This heat in theory could be used to generate pollution-free electricity.
There was initial skepticism from many physicists to Pons and Fleischmann’s claim, but not enough to stop a lot of money being thrown into cold fusion research. Some groups claimed to reproduce the fusion, but eventually even the most optimistic heat estimates fell off a cliff.
Steps to Failure
The climate graph also resembles many Exciting New Medical Cure effect sizes through time. Who remembers interferon? And according to Ross Pomeroy at Real Clear Science it’s not unlike many scientific claims.
Pomeroy wrote the article “The Six Stages of a Failed Psychological Theory.” We start with “The Flashy Finding” (high initial effect-size estimates), move to “The Fawning Replications” (high, but slightly lower estimates), and land at “Proper Replications Pour In” (near-zero or zero estimates).
Stage 6 is “The Theory Lives On as a Zombie.” There will always be true believers.
The End is Nigh
One of these is that the claimed “effect is of a magnitude that remains close to the limit of detectability.” The closer you look, the more the effect recedes into the distance.
The most notable symptom is the political. “Ratio of supporters to critics rises up to somewhere near 50% and then falls gradually to oblivion.”
Few now remember cold fusion, and only specialists can recall how big parapsychological research was in the Twentieth Century. If it follows the same pattern, the gloomier predictions of global warming will soon be nothing but a bad memory.