How Have Contrarian Climate Predictions Performed?

If you follow popular discussions about AGW, you'll likely see many claims that climate scientists have been making terrible predictions and climate models invariably run too hot compared to observations. If you investigate these, almost all of so-called "predictions" of climate scientists turn out to be some combination of misinformed assessments by media personalities, reporters and politicians or claims by scientists that have been misread by contrarians. And while it's true that some climate scientists have said some things that have not panned out, this is clearly the exception, not the rule. In fact, overall, climate scientists have been slightly conservative with their predictions, and climate model have performed quite well.[1] In fact, Zeke Hausfather has done a pretty good job of tracking how model predictions compare to observations, and overall, they've done quite well.

So given all the rancor from contrarians about the predictions of climate scientists and models, we should evaluate how the predictions of contrarians have performed when compared to observations. If you investigate this, a feature of climate contrarian rhetoric becomes readily apparent; they don't make a whole lot of predictions, and I can see why. If you make predictions on the basis of unsound physics, they're highly likely to fail. So to preserve the illusion of being climate "skeptics," the best strategy is not to do any actual science or make any theoretical predictions. Doing so simply allows time to expose the flaws in your physics. The exception to this general rule appears to be during the time of the so-called "pause" in global warming - a time period of about 15 years following the strong  El Nino of 1998 in which we had no new annual GMST record record high temperatures. It seems that during this time, contrarians became more emboldened to make predictions. I have found a couple from before 1998, but not many. Here are quotes of predictions I've found, along with an evaluation of how these predictions have panned out.

Patrick Michaels

Here are three claims by Patrick Michaels that I think should qualify as "predictions" that can and should be evaluated against what actually has transpired since they were claimed.

1. "Here's an easy prediction: By the year 2000, plus or minus a few, the vogue environmental calamity will be an ice age. And this nouvelle apocalypse, revised version, will predict that global warming will cause sea level to fall, exposing Bangladesh to wrenching cultural changes, and therefore we should give more money to the Third World."
~Patrick Michaels, The Washington Times, 2/11/92

2. "Last year was so warm that it induces a statistically significant warming trend in the satellite data. Thus the second bet: Starting with 1998, there will almost certainly be a statistically significant cooling trend in the decade ending in 2007."
~Patrick Michaels, Cato, 1/18/1999

3. "Now, just for fun, let’s assume that on Jan. 1, another warming trend began, at the same rate that was observed in the last such period, from 1977 through 1998, or 0.17 C per decade. Running a large experimental sample reveals that, on average, the rate of warming will have to continue through 2020 before a statistically significant trend emerges in the post-1996 data. (Remember that a “trend” that does not meet the normal grounds for significance is one that cannot scientifically be distinguished from “no trend.”) In other words, it’s a pretty good bet that we are going to go nearly a quarter of a century without warming."
~Patrick Michaels, The Washington Times, 1/17/2013

It should be obvious that these three claims are clearly refuted by data. It should also be clear that he had to revise his predictions with time, as his predictions clearly weren't panning out. In 1992, he thought by 2000 scientists would be afraid of another ice age, but by 1999, that was ridiculous, so he had to revise that to a statistically significant cooling trend for 1998 through 2007. By 2013, he had to revise that again to a claim that we won't see a statistically significant warming trend from 1996 to 2020. And of course, none of these things happened. The trends for UAHv6 and RSSv4 (TLT) for the decade of 1998 to 2007 was not statistically significant, and the signs of the best-fit trend didn't even agree. The large uncertainty should have been expected with only 10 years of data:

UAHv6.0: -0.102 ±0.528°C/decade (2σ)
RSSv4.0: +0.123 ±0.545°C/decade (2σ)

And all global datasets (satellites, surface thermometers, and reanalyses) show statistically significant warming since 1998. Surface thermometers show that GMST has increased by an average of 0.2°C/decade for 1970-2024, a time period including the so-called "pause" in global warming.

BEST: 0.205 ± 0.018°C/decade (2σ)
HadCRUT5: 0.203 ± 0.018°C/decade (2σ)
NASA: 0.199 ± 0.018°C/decade (2σ)
NOAA: 0.193 ± 0.018°C/decade (2σ)

Clearly Patrick Michaels didn't have a good track record for climate predictions. By rejecting the sound physics that continued carbon emissions would drive continued warming at rates consistent with an ECS near 3°C, he had to constantly revise his predictions as they failed, and he never did get it right.

Don Easterbrook

Here's an examination of a couple predictions by Don Easterbrook and Joseph D’Aleo. Enough years have passed since these predictions to determine conclusively that these are failed predictions. 

1. "In a nutshell, in 2001, I put my reputation on the line and published my predictions for entering a global cooling cycle about 2007 plus or minus 3-5 years, based on past glacial, ice core, and other data. As right now, my prediction seems to be right on target and what we would expect from the past climatic record, but the IPCC prediction is getting farther and farther off the mark. Now with the apparent solar cooling cycle upon us, we have a ready explanation for global warming and cooling."
~Don Easterbrook, "RECENT GLOBAL COOLING: SUMMARY."

2. "The left side of Figure 24 is the warming/cooling history of the past century. The right side of the graph shows that we have entered a global cooling phase that fits the historic pattern very well. Three possible projections are shown: (1) moderate cooling (similar to the 1945 to 1977 cooling); (2) deeper cooling (similar to the 1945 to 1977 cooling); or (3) severe cooling (similar to the 1790 to 1830 cooling). Only time will tell which of these will be the case, but at the moment, the sun is behaving very similar to the Dalton Minimum (sunspot cycle 4/5), which was a very cold time. This is based on the similarity of sun spot cycle 23 to cycle 4 (which immediately preceded the Dalton Minimum)." 

~D’Aleo, J., Easterbrook, D., 2010. Multidecadal Tendencies in ENSO and Global Temperatures Related to Multidecadal Oscillations. Energy & Environment 21 (5), 437e460.

Of course none of these have panned out. GMST has increased by 1.3°C above the 1850-1900 mean, and temperatures have been rising at ~0.2°C/decade since 1970. The time stamp on his prediction was 2007 ± 5 years (so by 2013 at the latest), but the top 10 warmest years on record have occurred since 2015.

Richard Lindzen

Dr. Lindzen has, since 1989 at least, been saying that the greenhouse gas signal for global warming will not be detectable beyond the noise of natural variability over the next century. His words:

"I personally feel that the likelihood over the next century of greenhouse warming reaching magnitudes comparable to natural variability seems small."
~ Richard Lindzen, MIT Tech Talk, Sept 27, 1989

Admittedly, this is a bit of a wimpy prediction, since "personally feel" doesn't sound like it's based on rigorous analysis, but it's consistent with his "iris hypothesis"[2] and overall claims that ECS is very low (lower than 1.5°C, with his most recent claims below 1°C). To evaluate this, it's valuable to note that natural variability is on the order of 0.2°C to 0.3°C. If we interpret "over the next century" generously to be 2100, then I think it's fair to say that Lindzen in 1989 did not believe an anthropogenic signal would not be detectable above natural variability. GMST variability would be less than ~0.5°C. To illustrate this, I plotted the instrumental record for the major datasets and set Lindzen's to equal HadCRUT5 for 1970. I set it to a linear warming rate that would reach 0.3°C warming by 2025 (about 0.005°C/year) and used the variability of the annual GMST anomalies from the 1970-2024 trend for the variability in Lindzen's prediction. The trend I used for his prediction would lead to about 0.7°C warming above 1970 by 2100, which certainly would be detectable above natural variability, so I believe this is generous interpretation of Lindzen's 1989 claim. If anything, the graph below shows more warming than Lindzen's 1989 prediction.

To be absolutely clear, Lindzen did not produce this graph, but it's faithful and even generous to his 1989 claim, and it shows his prediction doing no better than Rasool and Schneider's model prediction at the top of the page. In fact, warming has progressed at about 4x the rate presented in this graph.

Judith Curry

Judith Curry (and co-author Marcia Wyatt) have made similar claims to the above under the heading of what they called the "stadium wave" hypothesis. The IPCC referred to the so-called "pause" as "unpredictable climate variability" having to do with large scale circulation regimes like ENSO; that is, the patterns created by oscillations between El Niño and La Niña years can explain superficial appearance of a lull in global warming; essentially the IPCC was saying that that ENSO can temporarily mask warming signals, especially following a very strong El Niño event. In contrast to this, Curry's post claimed that Wyatt and Curry[3]'s research showed that 

this ‘unpredictable climate variability’ behaves in a more predictable way than previously assumed. The paper’s authors, Marcia Wyatt and Judith Curry, point to the so-called ‘stadium-wave’ signal that propagates like the cheer at sporting events whereby sections of sports fans seated in a stadium stand and sit as a ‘wave’ propagates through the audience. In like manner, the ‘stadium wave’ climate signal propagates across the Northern Hemisphere through a network of ocean, ice, and atmospheric circulation regimes that self-organize into a collective tempo.

They believed this "stadium wave" was tied to patterns related to the AMO and has been detectable for at least 300 years. They claim to have

identified two key ingredients to the propagation and maintenance of this stadium wave signal: the Atlantic Multidecadal Oscillation (AMO) and sea ice extent in the Eurasian Arctic shelf seas. The AMO sets the signal’s tempo, while the sea ice bridges communication between ocean and atmosphere. The oscillatory nature of the signal can be thought of in terms of ‘braking,’ whereby positive and negative feedbacks interact in such a way as to support reversals of the circulation regimes. As a result, climate regimes — multiple-decade intervals of warming or cooling — evolve in a spatially and temporally ordered manner. While not strictly periodic in occurrence, their repetition is regular — the order of quasi-oscillatory events remains consistent. Wyatt’s thesis found that the stadium wave signal has existed for at least 300 years.

Curry used this "stadium wave" hypothesis to claim that we should expect what she considered a "pause" in 2011 to last for several decades and possibly as long as 2050. Here are several quotes long these lines on her blog and social media.

1. "Based upon previous regime shifts, it might be anticipated that this regime will continue for at least another decade. The challenge is to predict the change points for these regimes."

~Judith Curry, 2011

2. "We don’t know what the climate will be for the next several decades, there are a number of reasons to expect the continue flat trend for the next several decades. In terms of when global warming will come “roaring back”, it is possible that this may not happen for the first half of the 21st century."

~Judith Curry, 2012

3. The third comes from of a Tweet in 2013:

I believe that the "new paper" she mentions in this tweet is the one I quoted her referencing in her 2013 blogpost. But this also confirms that the posts from which I quoted in 2011 and 2012 are interpreted correctly. The graph below demonstrates what Curry's prediction would look like with respect to observations. I simply detrended HadCRUT5 data following 1998.

In 2012, Judith Curry believed that her "stadium wave" hypothesis should be understood to mean that we should expect to see the "pause" beginning in 1998 continue for several decades following 2013. So her consistent message from 2011 to 2013 and onward was that we should expect flat temperature trends for several decades following 1998 and up to perhaps until 2050. Clearly this has not been the case.

Conclusion

These predictions share a common vision for what contrarians expect for the future, whether a return to cooling (Easterbrook, early Michaels) or near flat trends indistinguishable from natural variability (later Michaels, Lindzen, Curry). In sharp contrast to these predictions, we have seen uninterrupted warming of 0.2°C/decade since 1970, and the so-called "pauses" are actually just cherry-picked time frames that begin in El Niño years and end in La Niña years.

In hindsight, if you squint you can pick out what may have looked like a "pause" from 1998 and 2013, but it's clearly now just an artifact of cherry picking and not something that is in the data. The last time there was anything that could be considered a "pause" was between the 1940s and 1970. GMST has increased by 0.2°C/decade since 1970, and if anything there has been acceleration in warming rates; rolling 30-year trends have increased rates since 1970. What we're actually seeing here are the results of what we might think of as a 30+ year experiment testing two competing hypotheses:

1. Consensus Hypothesis: The anthropogenic signal (human carbon emissions partially masked by aerosol pollution) swamps natural variability, and warming at least since 1950 is dominated by anthropogenic forcings.
2. Contrarian Hypothesis: Human carbon emissions influence exert a warming signal on global temperatures, but that signal is swamped by natural variability.

The graph below illustrates how well the contrarian hypothesis has performed relative to the consensus hypothesis shown at the top of this post.

The above graph shows all of these predictions in one graph. For the Easterbrook prediction, I show what he plotted in Figure 24 above, and I used the most conservative of his predictions with the least amount of cooling. I then show the difference between their predictions and observations as dotted lines with an offset of -0..5°C. The slopes of these predictions indicate that Easterbrook's failed the most, followed by Curry and Michaels, followed by Lindzen.

I don't fault these people for putting these claims down in writing. If the contrarian hypothesis were correct, then we should have expected temperatures to follow one of the potential paths that these scientists predicted. But that didn't happen. The consensus hypothesis from mainstream climate science has been making good predictions confirmed by observations. In fact, warming has progressed at rates consistent with ECS being ~3°C. 

This of course doesn't incontrovertibly "prove" AGW; we can't rule out with 100% confidence that there is a natural signal undetected by anyone that is responsible for a significant fraction of current warming. But as the warming signal continues to conform to theoretical predictions of climate science, the likelihood that such a natural signal exists is dwindling to the point of being negligible.

References:

[1] Hausfather, Z., Drake, H. F., Abbott, T., & Schmidt, G. A. (2020). Evaluating the performance of past climate model projections. Geophysical Research Letters, 47, e2019GL085378. https://doi.org/10.1029/2019GL085378

[2] Lindzen, R., M-D. Chou, and A. Hou, 2001: Does the earth have an adaptive infrared iris? Bull. Amer. Meteor. Soc, 82 , 417–432.

[3] M.G. Wyatt and J.A. Curry, “Role for Eurasian Arctic shelf sea ice in a secularly varying hemispheric climate signal during the 20th century,” (Climate Dynamics, 2013). The full manuscript can be downloaded here.