Trusting Experts and Their Models
Russ Roberts over at Cafe Hayek quotes from a Cathy O’Neill review of Nate Silvers recent book:
Silver chooses to focus on individuals working in a tight competition and their motives and individual biases, which he understands and explains well. For him, modeling is a man versus wild type thing, working with your wits in a finite universe to win the chess game.
He spends very little time on the question of how people act inside larger systems, where a given modeler might be more interested in keeping their job or getting a big bonus than in making their model as accurate as possible.
In other words, Silver crafts an argument which ignores politics. This is Silver’s blind spot: in the real world politics often trump accuracy, and accurate mathematical models don’t matter as much as he hopes they would....
My conclusion: Nate Silver is a man who deeply believes in experts, even when the evidence is not good that they have aligned incentives with the public.
Distrust the experts
Call me “asinine,” but I have less faith in the experts than Nate Silver: I don’t want to trust the very people who got us into this mess, while benefitting from it, to also be in charge of cleaning it up. And, being part of the Occupy movement, I obviously think that this is the time for mass movements.
Like Ms. O'Neill, I distrust "authorities" as well, and have a real problem with debates that quickly fall into dueling appeals to authority. She is focusing here on overt politics, but subtler pressure and signalling are important as well. For example, since "believing" in climate alarmism in many circles is equated with a sort of positive morality (and being skeptical of such findings equated with being a bad person) there is an underlying peer pressure that is different from overt politics but just as damaging to scientific rigor. Here is an example from the comments at Judith Curry's blog discussing research on climate sensitivity (which is the temperature response predicted if atmospheric levels of CO2 double).
While many estimates have been made, the consensus value often used is ~3°C. Like the porridge in “The Three Bears”, this value is just right – not so great as to lack credibility, and not so small as to seem benign.
Huybers (2010) showed that the treatment of clouds was the “principal source of uncertainty in models”. Indeed, his Table I shows that whereas the response of the climate system to clouds by various models varied from 0.04 to 0.37 (a wide spread), the variation of net feedback from clouds varied only from 0.49 to 0.73 (a much narrower relative range). He then examined several possible sources of compensation between climate sensitivity and radiative forcing. He concluded:
“Model conditioning need not be restricted to calibration of parameters against observations, but could also include more nebulous adjustment of parameters, for example, to fit expectations, maintain accepted conventions, or increase accord with other model results. These more nebulous adjustments are referred to as ‘tuning’.” He suggested that one example of possible tuning is that “reported values of climate sensitivity are anchored near the 3±1.5°C range initially suggested by the ad hoc study group on carbon dioxide and climate (1979) and that these were not changed because of a lack of compelling reason to do so”.
Huybers (2010) went on to say:
“More recently reported values of climate sensitivity have not deviated substantially. The implication is that the reported values of climate sensitivity are, in a sense, tuned to maintain accepted convention.”
Translated into simple terms, the implication is that climate modelers have been heavily influenced by the early (1979) estimate that doubling of CO2 from pre-industrial levels would raise global temperatures 3±1.5°C. Modelers have chosen to compensate their widely varying estimates of climate sensitivity by adopting cloud feedback values countering the effect of climate sensitivity, thus keeping the final estimate of temperature rise due to doubling within limits preset in their minds.
There is a LOT of bad behavior out there by models. I know that to be true because I used to be a modeler myself. What laymen do not understand is that it is way too easy to tune and tweak and plug models to get a preconceived answer -- and the more complex the model, the easier this is to do in a non-transparent way. Here is one example, related again to climate sensitivity
When I looked at historic temperature and CO2 levels, it was impossible for me to see how they could be in any way consistent with the high climate sensitivities that were coming out of the IPCC models. Even if all past warming were attributed to CO2 (a heroic assertion in and of itself) the temperature increases we have seen in the past imply a climate sensitivity closer to 1 rather than 3 or 5 or even 10 (I show this analysis in more depth in this video).
My skepticism was increased when several skeptics pointed out a problem that should have been obvious. The ten or twelve IPCC climate models all had very different climate sensitivities — how, if they have different climate sensitivities, do they all nearly exactly model past temperatures? If each embodies a correct model of the climate, and each has a different climate sensitivity, only one (at most) should replicate observed data. But they all do. It is like someone saying she has ten clocks all showing a different time but asserting that all are correct (or worse, as the IPCC does, claiming that the average must be the right time).
The answer to this paradox came in a 2007 study by climate modeler Jeffrey Kiehl. To understand his findings, we need to understand a bit of background on aerosols. Aerosols are man-made pollutants, mainly combustion products, that are thought to have the effect of cooling the Earth’s climate.
What Kiehl demonstrated was that these aerosols are likely the answer to my old question about how models with high sensitivities are able to accurately model historic temperatures. When simulating history, scientists add aerosols to their high-sensitivity models in sufficient quantities to cool them to match historic temperatures. Then, since such aerosols are much easier to eliminate as combustion products than is CO2, they assume these aerosols go away in the future, allowing their models to produce enormous amounts of future warming.
Specifically, when he looked at the climate models used by the IPCC, Kiehl found they all used very different assumptions for aerosol cooling and, most significantly, he found that each of these varying assumptions were exactly what was required to combine with that model’s unique sensitivity assumptions to reproduce historical temperatures. In my terminology, aerosol cooling was the plug variable.
By the way, this aerosol issue is central to recent work that is pointing to a much lower climate sensitivity to CO2 than has been reported in past IPCC reports.
Matthew Slyfield:
"It is like someone saying she has ten clocks all showing a different
time but asserting that all are correct (or worse, as the IPCC does,
claiming that the average must be the right time)"
Actually if you have ten clocks that are all different and the errors of the individual clocks are ~random in both magnitude and direction then the average should be a reasonable estimate of the correct time.
Of course "the errors of the individual clocks are ~random in both magnitude and direction" does not apply to the climate models as their forward projections are all high vs observations.
December 20, 2012, 11:06 amMikey Mannhole:
My climate models say it is getting warmer.
My actual data says "nahhh, not so much"
Eventually data driven reality imposes itself on computer spew.
December 20, 2012, 2:38 pmMingoV:
I'll chime in once again with "Planet Earth cannot have a greenhouse gas effect." Calculating the temperature effect of atmospheric carbon dioxide is nonsense. Solar rays that reach the lower atmosphere essentially are limited to two choices: A) They can pass through the air and warm the surface or B) They can be absorbed by air molecules (such as water and carbon dioxide) and warm the air. However, since the surface and the lower atmosphere are in thermal equilibrium, global temperatures are unchanged if the amount of B rises a bit and the amount of A falls by the same amount. Thus, no greenhouse gas effect.
December 20, 2012, 3:40 pmjohn mcginnis:
Whether Sol, climate follows.
December 20, 2012, 3:40 pmGil:
How then we all don't freeze to death at nighttime because heat retention is apparently impossible?
December 20, 2012, 6:08 pmmesaeconoguy:
Paul Krugman won a Nobel for some apparently legitimate economic international trade work.
He now practices amateur argumentum ad vericundium via press adoration, as nauseum, and is no longer considered a serious economist by other practitioners.
Those who understand statistics and mathematical modeling (some of whom happen to be scientists, in their spare time) like Matt Ridley, do the same to the likes of Nate Silver, only more detailed:
http://online.wsj.com/article/SB10001424127887323981504578179291222227104.html
The so-called “experts” are already naked; now they are being eviscerated and skinned.
December 20, 2012, 11:12 pmmesaeconoguy:
Gil, get thee to a nunnery, post haste.
December 20, 2012, 11:15 pmmesaeconoguy:
Whither, John, whither.
Tis but a nitpick.
Merry Christmas.
December 20, 2012, 11:24 pmSamWah:
The model is...rigged! I am shocked, shocked to...realize I expected that.
December 21, 2012, 2:49 pmAndrew M Garland:
Theories of Catastrophic Anthropogenic Global Warming should lose their credibility because they are not Science. It is a religion that has adopted a scientific tone, using equations and graphs, but based on selective data cooked through handcrafted computer programs.
The Difference between ‘True Science’ and ‘Cargo-Cult Science’
07/27/10 - pajamasmedia by Frank J. Tipler
The late Nobel Prize physicist Richard Feynman defined science in extra large type in his article “What is Science?”
Science is the belief in the ignorance of experts
Feynman: When someone says, "Science teaches such and such," he is using the word incorrectly. Science doesn’t teach anything; experience teaches it. If they say to you, "Science has shown such and such," you should ask, "How does science show it? How did the scientists find out? How? What? Where?" It should not be "science has shown." And you have as much right as anyone else, upon hearing about the experiments and after hearing all the evidence, to judge whether a sensible conclusion has been arrived at.
Feynman also observed that real science is a method for discovering facts about our world, and requires bending over backwards not to fool others, and especially not to fool oneself. He said it was particularly easy to fool oneself, and so required the greatest dilligence and openness to criticism and disproof to avoid being that fool.
EasyOpinions.blogspot.com
December 21, 2012, 10:06 pmDoug Cotton:
If anyone wishes to ask questions about my paper, 'Planetary Surface Temperatures A Discussion of Alternative Mechanisms" or if you believe you have an alternative explanation for the Venus surface temperature, please post your question or response below this post as I wish to keep all discussion on the one thread. There is also discussion there regarding today's article on PSI which I did not write myself, by the way.
December 22, 2012, 3:28 amGil:
All i can gather is that MV is doing the old "if temperatures get warmer then there'll be more cloud cover immediately negating any warming" line.
December 22, 2012, 8:44 amZachriel:
While the overall temperature of the Earth is in equilibrium, without the greenhouse effect the Earth's surface would be a chilly ≈-18°C rather than the balmy ≈+15°C that it is.
December 23, 2012, 9:53 amZachriel:
Coyote Blog: What laymen do not understand is that it is way too easy to tune and tweak and plug models to get a preconceived answer -- and the more complex the model, the easier this is to do in a non-transparent way.
Everything in science is a model, but models are judged by fit to data. There are a variety of independent measures of climate sensitivity, such as observed climate response to volcanic forcing, measures of the Earth's energy budget, and calculations based on historical climate change.
Knutti & Hegerl, The equilibrium sensitivity of the Earth’s temperature to radiation changes, Nature Geoscience 2008.
December 23, 2012, 10:01 amZachriel:
Coyote Blog: Like Ms. O'Neill, I distrust "authorities" as well, and have a real problem with debates that quickly fall into dueling appeals to authority.
An appeal to authority is valid when
* The cited authority has sufficient expertise.
* The authority is making a statement within their area of expertise.
* The area of expertise is a valid field of study.
* There is adequate agreement among authorities in the field.
* There is no evidence of undue bias.
The proper argument against a valid appeal to authority is to the evidence.
In this case, there is a strong consensus within climatology and related fields. The skeptics typically only argue on the fringes, rarely publish, and have yet to convince a substantial number of their peers.
December 23, 2012, 10:07 amZachriel:
Coyote Blog: By the way, this aerosol issue is central to recent work that is pointing to a much lower climate sensitivity to CO2 than has been reported in past IPCC reports.
We presume Lewis has submitted his analysis to peer review. Which publication?
December 23, 2012, 10:14 amAndrew M Garland:
Warmists cry out “the science is settled”. If so, then which of the 20 or so climate models is the settled science?
Who are the people who have determined that Catastrophic, Anthropogenic (man caused), Global Warming is scientifically certain? They took a vote. They were appointed by governments across the globe to reach a certain decision, as members and contributors to the United Nation’s Intergovernmental Panel on Climate Change (IPCC)
=== ===
Even IPCC worshiper William Schlesinger is now acknowledging that 80 percent of the IPCC membership have had absolutely no dealing with the climate as part of their academic studies.
=== ===
Richard S. Lindzen is the Alfred P. Sloan Professor of Meteorology in the Department of Earth, Atmospheric and Planetary Sciences at MIT
Global Warming: How to approach the science (PDF 58 pages)
Program in Atmospheres, Oceans, and Climate
Massachusetts Institute of Technology
Seminar at the House of Commons Committee Rooms
Westminster, London, 22nd February 2012
This is a careful, scholarly, clear, and readable presentation of claims and data. Global warming is not a hoax, but catastrophic, damaging global warming is a hoax not supported by evidence.
Prof. Lindzen points out that a doubling of carbon dioxide by 2050 would be expected to increase average world temperature by about 1 degree C (1.8 deg F). The alarmists pose that natural processes will multiply this warming to 3 deg C. Current data seems to give a multiplier of .5, giving .5 deg C of warming by 2050 (.9 deg F).
A major argument against an explosive, self-multiplying warming is that we are here to talk about it. If the Earth's climate system had a multiplier, rather than a brake, then prior much warmer and much colder periods would have spiraled to either a freezing or boiling extreme. Venus would be an example. Earth has been stable for 3 billion years.
=== ===
[edited excerpts] Lindzen: The debate is not about whether CO2 is increasing: it clearly is. It is not about whether the increase in CO2, by itself, will lead to some warming: it should.
The debate is how much warming the increase in CO2 can lead to, and the connection of such warming to innumerable claimed catastrophes.
The evidence is that the increase in CO2 will lead to very little warming, and that the connection of this minimal warming (or even significant warming) to the purported catastrophes is also minimal. The arguments on which the catastrophic claims are made are extremely weak, and are commonly acknowledged as such. They are sometimes overtly dishonest.
The usual rationale for alarm comes from models. The notion that models are our only tool, even if it were true, depends on models being objective and not arbitrarily adjusted. Unfortunately, these are unwarranted assumptions. [The models are not objective and they have been adjusted to produced desired outcomes -amg]
However, models are hardly our only tool. Models can show why they get the results they get. The reasons involve physical processes that can be independently assessed by both observations and basic theory. This has, in fact, been done, and the results suggest that all models are exaggerating the warming.
=== ===
A chart of IPCC predictions compared to satellite data.
The government-run IPCC predicted between .62 to 1.5 deg C of warming. Measured warming is .1 to .25 deg.
December 23, 2012, 12:36 pmDoug Cotton:
Regarding the models, some may like to watch this short video about new breakthroughs relating to CLIMATE CHANGE, which I have recorded in easily understood terminology: http://youtu.be/r8YbyfqUvfY
December 26, 2012, 4:12 amZachriel:
Andrew M Garland: Who are the people who have determined that Catastrophic, Anthropogenic (man caused), Global Warming is scientifically certain?
While nothing in science is certain, the vast majority of climatologists agree that humans will radically alter the climate if they continue on their present course.
Andrew M Garland: This is a careful, scholarly, clear, and readable presentation of claims and data.
Actually, it appears to be a rehash of skeptical claims. Like so many skeptics, he just pokes at the edges in the literature, while making much bigger claims to lay audiences.
Andrew M Garland: The usual rationale for alarm comes from models.
All science is models. However, there are a variety of measures of climate sensitivity. Experts in the field believe there is a high probability of significant sensitivity.
Andrew M Garland: A major argument against an explosive, self-multiplying warming is that we are here to talk about it. If the Earth's climate system had a multiplier, rather than a brake, then prior much warmer and much colder periods would have spiraled to either a freezing or boiling extreme. Venus would be an example. Earth has been stable for 3 billion years.
That is not correct. Modern climate model do not predict runaway processes. The Earth's climate is a complex system with many positive and negative feedbacks.
December 26, 2012, 7:42 amZachriel:
Andrew M Garland: Theories of Catastrophic Anthropogenic Global Warming should lose their credibility because they are not Science.
Even if climatologists are wrong, they are certainly working in a scientific manner. And important, they are supported by many related fields of study, from observations in oceanography to glaciology to ornithology to forestry to planetology, and so on.
December 26, 2012, 7:45 amTed Rado:
Models are just that: models. You can write a computer program that will predict that every man will become a mother in 2013. So what?
December 27, 2012, 8:28 pmA usable model is one that is based on first principles, with NO fudge factors. Empirical models are worthless excwept is a very few simple cases. The more complex the system, the more essential it is to base in ONLY of first principles.
One can always fit a model to a data set via a Fourier series or some other means. Every data point can be made to fit the equation perfectly. Again, so what? This says nothing about how NEW data will fit the OLD equation. This problem shows up every time the IPCC updates their work. The following data again does not fit well.
I am all for new ideas and hypothesese. However, to charge off and destroy the world economy based on the mere assertion that "My model is right" is utter stupidity. Further, there is no viable alternative to fossil fuels in the near future, so we can't do much about it anyway. Continuing study of the climate should proceed without all this mindless zealotry.
Andrew_M_Garland:
To Zachriel,
That is comforting. "Even if climatologists are wrong, at least they are working in a scientific manner."
The point about real science is to be self-sceptical until you have proof. That does not describe the collection of government appointees known as the IPCC.
EasyOpinions.blogspot.com
December 27, 2012, 9:32 pmAndrew_M_Garland:
To Zachriel,
I will continue to supply skeptical data from research. You can continue to supply your personal, anonymous opinions.
December 27, 2012, 9:35 pmZachriel:
All science is considered tentative, no matter how strongly supported, but some findings are so well supported that it would be perverse to withhold provisional assent. There is a large body of science, in many related fields, that support anthropogenic climate change.
December 28, 2012, 6:13 amZachriel:
"All models are wrong, but some are useful."
Ted Rado: Models are just that: models.
All of science is models. They are judged by their fit to the data. Climatologists have collected data from space, the polar regions, from the stratosphere, from the land and oceans. The science of anthropogenic climate change is supported not only by climate science, but related fields, such as physics and biology.
December 28, 2012, 6:18 amTed Rado:
Zachriel: There is no question that scientists have fit their equations to the data. That simply shows that data fittting works. Why did the temp not go up in the past 15 years as pedicted? Obviously, the models are wrong. They fit past data (easy to do) but bomb on future predictions.
December 28, 2012, 9:33 pmThe problem is that there is no way to stop the use of fossil fuels without wrecking the economy. To plunge ahead with this is madness.
Zachriel:
You just posited that climate models predict a spiraling process resulting in boiling oceans, which simply isn't the case.
December 29, 2012, 7:19 amZachriel:
Ted Rado: There is no question that scientists have fit their equations to the data.
Yes, that's exactly how science works. You fit the theory to the data, not the other way around.
Ted Rado: Why did the temp not go up in the past 15 years as pedicted?
http://www.skepticalscience.com/graphics/SkepticsvRealists_500.gif
If you take out solar activity, ENSO and volcanic activity, then the trend is even more obvious. See Foster & Rahmstorf, Global temperature evolution 1979–2010, Environmental Research Letters 2010.
http://ej.iop.org/images/1748-9326/6/4/044022/Full/erl408263f5_online.jpg
Ted Rado: The problem is that there is no way to stop the use of fossil fuels without wrecking the economy.
That's right. There has to be an orderly transition to the new economy.
December 29, 2012, 12:25 pm