Guest essay by Eric Worrall
In the wake of the science committee testimony, Climate Scientist Kevin Trenberth has insisted that Climate Science does follow the scientific method. But Trenberth himself may have strayed outside accepted scientific methodology.
Yes, we can do ‘sound’ climate science even though it’s projecting the future
Nobody can observe events in the future so to study climate change, scientists build detailed models and use powerful supercomputers to simulate conditions, such as the global water vapor levels seen here, and to understand how rising greenhouse gas levels will change Earth’s systems. NCAR/UCAR, CC BY-NC-ND
April 6, 2017 4.01am AEST
Authors
Kevin Trenberth
Distinguished Senior Scientist, National Center for Atmospheric Research
Reto Knutti
Professor, Eidgenössische Technische Hochschule (ETH) Zürich
Increasingly in the current U.S. administration and Congress, questions have been raised about the use of proper scientific methods and accusations have been made about using flawed approaches.
This is especially the case with regard to climate science, as evidenced by the hearing of the House Committee on Science, Space and Technology, chaired by Lamar Smith, on March 29, 2017.
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Chairman Smith accused climate scientists of straying “outside the principles of the scientific method.” Smith repeated his oft-stated assertion that scientific method hinges on “reproducibility,” which he defined as “a repeated validation of the results.” He also asserted that the demands of scientific verification altogether preclude long-range prediction, saying, “Alarmist predictions amount to nothing more than wild guesses. The ability to predict far into the future is impossible. Anyone stating what the climate will be in 500 years or even at the end of the century is not credible.”
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Why climate scientists use models
The wonderful thing about science is that it is not simply a matter of opinion but that it is based upon evidence and physical principles, often pulled together in some form of “model.”
In the case of climate science, there is a great deal of data because of the millions of daily observations made mostly for the purposes of weather forecasting. Climate scientists assemble all of the observations, including those made from satellites. They often make adjustments to accommodate known deficiencies and discontinuities, such as those arising from shifts in locations of observing stations or changes in instrumentation, and then analyze the data in various ways.
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Projections, not predictions
With climate models as tools, we can carry out “what-if” experiments. What if the carbon dioxide in the atmosphere had not increased due to human activities? What if we keep burning fossil fuels and putting more CO2 into the atmosphere? If the climate changes as projected, then what would the impacts be on agriculture and society? If those things happened, then what strategies might there be for coping with the changes?
These are all very legitimate questions for scientists to ask and address. The first set involves the physical climate system. The others involve biological and ecological scientists, and social scientists, and they may involve economists, as happens in a full Intergovernmental Panel on Climate Change (IPCC) assessment. All of this work is published and subject to peer review – that is, evaluation by other scientists in the field.
The question here is whether our models are similar enough in relevant ways to the real world that we can learn from the models and draw conclusions about the real world. The job of scientists is to find out where this is the case and where it isn’t, and to quantify the uncertainties. For that reason, statements about future climate in IPCC always have a likelihood attached, and numbers have uncertainty ranges.
The models are not perfect and involve approximations. But because of their complexity and sophistication, they are so much better than any “back-of-the envelope” guesses, and the shortcomings and limitations are known.
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Trenberth has a lot of faith in his models – so much so, a few years ago he demanded that the “null hypothesis” be reversed. If accepted, this would have meant a reversal of the burden of proof regarding the assumption of human influence on global climate.
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“Humans are changing our climate. There is no doubt whatsoever,” said Trenberth. “Questions remain as to the extent of our collective contribution, but it is clear that the effects are not small and have emerged from the noise of natural variability. So why does the science community continue to do attribution studies and assume that humans have no influence as a null hypothesis?”
To show precedent for his position Trenberth cites the 2007 report by the Intergovernmental Panel on Climate Change which states that global warming is “unequivocal”, and is “very likely” due to human activities.
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Read more: https://wattsupwiththat.com/2011/11/03/trenberth-null-and-void/
Trenberth’s demands for a reversal of the burden of proof with regard to climate were rejected by the scientific community. Even climate advocate Myles Allen, head of University of Oxford’s Atmospheric, Oceanic and Planetary Physics Department, thought Trenberth’s demands for a reversal of the burden of proof were wrong.
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“The proponents of reversing the null hypothesis should be careful of what they wish for,” concluded Curry. “One consequence may be that the scientific focus, and therefore funding, would also reverse to attempting to disprove dangerous anthropogenic climate change, which has been a position of many sceptics.”
“I doubt Trenberth’s suggestion will find much support in the scientific community,” said Professor Myles Allen from Oxford University, “but Curry’s counter proposal to abandon hypothesis tests is worse. We still have plenty of interesting hypotheses to test: did human influence on climate increase the risk of this event at all? Did it increase it by more than a factor of two?”
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All three papers are free online:
Trenberth. K, “Attribution of climate variations and trends to human influences and natural variability”: http://doi.wiley.com/10.1002/wcc.142
Curry. J, “Nullifying the climate null hypothesis”: http://doi.wiley.com/10.1002/wcc.141
Allen. M, “In defense of the traditional null hypothesis: remarks on the Trenberth and Curry opinion articles”: http://doi.wiley.com/10.1002/wcc.145
Read more: Same link as above
The problem with climate science is there is no way to test the core prediction, that the Earth will heat substantially in response to anthropogenic CO2 emissions, other than to wait and see.
Important secondary predictions which should be observable by now, such as the missing tropospheric hotspot, or a projected acceleration in sea level rise, have not manifested.
Even more embarrassing, mainstream models cannot even tell us what climate sensitivity to CO2 actually is.
Is equilibrium climate sensitivity 1.5C temperature increase per doubling of CO2? Or is it 4.5C / doubling of CO2? The IPCC Fifth Assessment Summary for Policy Makers cannot give you that answer.
… The equilibrium climate sensitivity quanti es the response of the climate system to constant radiative forcing on multi- century time scales. It is de ned as the change in global mean surface temperature at equilibrium that is caused by a doubling of the atmospheric CO2 concentration. Equilibrium climate sensitivity is likely in the range 1.5°C to 4.5°C (high confidence), extremely unlikely less than 1°C (high confidence), and very unlikely greater than 6°C (medium confidence)16. The lower temperature limit of the assessed likely range is thus less than the 2°C in the AR4, but the upper limit is the same. This assessment re ects improved understanding, the extended temperature record in the atmosphere and ocean, and new estimates of radiative forcing. {TS TFE.6, Figure 1; Box 12.2} …
Read more: IPCC Fifth Assessment WG1 Summary for Policy Makers (page 14)
Why is this range of possible climate sensitivities embarrassing? Consider the Charney Report, from 1979;
… We believe, therefore, that the equilibrium surface global warming due to doubled CO2 will be in the range 1.5C to 4.5 C, with the most probable value near 3°C …
Read more: http://www.ecd.bnl.gov/steve/charney_report1979.pdf (page 16)
As theories are refined, key physical quantities should be resolved with greater accuracy. For example, the first measurements of the speed of light, conducted in 1676, were 26% wrong – a remarkable estimate for that period of history, but still wide of the mark. More research – better quality measurements and calculations resolved the original uncertainty about the speed of light, which is now known to a high degree of accuracy.
This failure of climate science to follow the normal scientific progression to more accurate estimates should be a serious concern. This lack of convergence on a central climate sensitivity estimate, after decades of research effort, strongly suggests something is missing from the climate models.
Whatever the missing or mishandled factor is, it has a big influence on global climate. The evidence for this is the embarrassingly broad range of estimates for climate sensitivity to a doubling of CO2, and the failure of those estimates to converge.
If climate models were capable of producing accurate predictions, if they showed any sign of converging on a reasonable climate sensitivity estimate, if predicted secondary phenomena such as the tropospheric hotspot and sea level rise acceleration were readily observable, there would be a lot less resistance to Trenberth’s apparent demand that climate model projections be accepted as somehow equivalent to empirical observations.
It should be obvious to anyone there are way too many loose ends to even come close to such acceptance.
According to the Oxford English Dictionary, the scientific method is A method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.
Any suggestion that model projections should be accepted as a substitute for systematic observation and experiment, any suggestion that model output from models which have failed several key tests can be relied upon, any suggestion that defective model output constitutes proof of human influence on global climate, in my opinion utterly violates any reasonable understanding of what the scientific method should be.
During the bottom of the quietest solar minimum in 100 years in ’08/09, on 12 Oct 2009, Trenberth demonstrates his complete ignorance of the solar cycle influence to his mostly ‘solar stupid’ warmists:
“Hi all
Well I have my own article on where the heck is global warming? We are asking that here in
Boulder where we have broken records the past two days for the coldest days on record. We
had 4 inches of snow. The high the last 2 days was below 30F and the normal is 69F, and it
smashed the previous records for these days by 10F. The low was about 18F and also a
record low, well below the previous record low. This is January weather (see the Rockies
baseball playoff game was canceled on saturday and then played last night in below freezing
weather).”
It was cold because TSI was low and had been very low for over two years by that day. Doh!
That email was sent to all the world famous iconic warmists who we’re all supposed to kowtow to, who clearly live in a bizarre unscientific upside down world where a trace gas ‘nullifies’ solar variability.
The weird thing here is Schneider wrote Trenberth back and said
“On Oct 12, 2009, at 2:32 AM, Stephen H Schneider wrote:
Hi all. Any of you want to explain decadal natural variability and signal to noise and
sampling errors to this new “IPCC Lead Author” from the BBC? As we enter an El Nino year
and as soon, as the sunspots get over their temporary–presumed–vacation worth a few
tenths of a Watt per meter squared reduced forcing, there will likely be another dramatic
upward spike like 1992-2000.”
He was right then for the same reason I’m right about the same pattern repeating this minimum.
This tells me Schneider deliberately talked out of both sides of his mouth, saying to the public on one hand CO2 was the driver, while knowing, as I discovered myself, that the solar cycle influence controls the temperature series! So the question becomes why lie?
The IPCC science was not scientific in the sense that changes to the system input power were deemed unimportant and ignored before adequate evaluation had taken place – so they reversed the ages old null that the sun controlled the weather and climate, similar to Trenberth’s attribution and null stance, which came decades after Hansen’s and Schneider’s original false AGW claims.
Eric, your browser displays processing problems with alphanumerics beginning with ‘f’:
de fi ned
re fl ects
/ not the first time /
Cheers – Hans
It seems to me that when a computer program is written to show how climate warms when CO2 increases, will yield results that show that the climate will warm when CO2 increases. A self fulfilling prophecy.
The scientific method starts with a hypothesis. Realty is then compared to the hypothesis. If the real world data don’t agree with the hypothesis (in this case, predictions) then the hypothesis must be rejected. None of the climate computer models match the actual temperature and CO2 levels as measured by satellites and weather balloons.
Further, in proxy reconstructions going back 600 million years, there is no correlation between temperature and CO2.
It is claimed that the evidence of the human effects on climate have emerged beyond the background noise of natural variability. This is not true. I remember that when I first took notice of this subject, I was shocked to read that climate scientists were saying that carbon dioxide level was the major influence on our climate.
Intuitively, I realised that this was garbage. History tells of cold periods and warm periods long before human behaviour became a factor. It became clear that the scientists pushing the AGW scare actually knew very little about the natural variability of our climate.
They are not able to attribute causation because, by their own claims, they obviously underestimate natural variability. The temperature hiatus which was neither anticipated or explained and is contrary to the dominance of CO2 is the proof of that.
Cat, when the hiatus became a problem for IPCC AR6, temperature record providers attempted a rescue. The problems for them?
1. Even the upwards adjustments could not reach as high as the average of IPCC climate models. It looks like the IPCC will have to use “expert” judgment to reduce near-term model “projections” in AR6, just like they did in AR5.
2. AR6 may just have to acknowledge the satellite and weather balloons results.
3. People learned to ignore the IPCC Summary for Policy Makers (SPM) and looked into the backup data. Behold! The SPM lies. Expect massive circumlocutions in AR6. Good luck to the honest reviewers.
Any person proposing to turn over our lives to the UN SJWs is deluded.
Under strict adherence to the scientific method, if CAGW’s global warming model mean projections exceed reality by more than a statistically significant 2 standard deviations for a statistically significant duration (15 years), then the hypothesis can effectively be deemed disconfirmed.
CAGW’s hypothetical global warming projections already greatly exceed the disconfirmation criteria, so it has already been disconfirmed with a high confidence:
Any further increase in disparity and duration simply increases the confidence level of disconfirmation.
CAGW is already dead.
The hypothesis was born falsified.
The Druids of the cult try to get around your strictures by using absurdly wide error bars, rather than the average of their ludicrous projections. The margins of error keep getting increased, such that whatever happens can be called “expected”.
Chimp
It is a prediction that has a degree of statistical significance. A projection does not have a degree of statistical significance. An IPCC climate model makes projections and does not make predictions.
Terry– You’re missing the point.
The disparity and duration refers to the 102-model mean projections, which are now hilariously devoid of reality.
If the hypothetical mean projections are devoid of reality, then the hypothesis upon which these models are based is devoid of reality…
Sure, if from tomorrow, the global warming trend should suddenly start exhibiting a 0.3C/decade trend that miraculously continues for the next 15 years, the CAGW hypothesis is still plausible, but failing that highly unlikely event, CAGW is already dead.
CAGW suddenly is facing some stiff physical realities:
1) CO2 forcing is a logarithmic function, meaining that each incremental CO2 increase has less and less of a warming effect.
2) Both the PDO and AMO will be in their respective 30-year cool cycles from 2019 and global temp trends have always fallen when this phenomenon occurs.
3) The weakest solar cycle since 1790 starts from 2021, and the one after that (from 2032) will likely be the weakest since 1645.
There is a high probability these weak solar cycles will cause global cooling, although it’s not known for certain. We’ll see soon enough.
Cheers, mate.
Samurai:
The issue seems to be of whether or not CAGW is falsified by the evidence. In dealing with this issue from a logical perspective one is faced with the anomaly that while a “prediction” is a kind of inference, a “projection” is not a kind of inference. One of the consequences is for a “prediction” to have a probability of being true and for a “projection” to lack a probability of being true.
For a “prediction” a value of 0 for the probability of a specified inference signifies the falsity of this inference but as a “projection” lacks a probability it is impossible for it to be falsified by the evidence.
A hint to the IPCC’s purpose in setting up this anomaly is provided by the IPCC in the opening pages of AR4, Report of Working Group 1. The IPCC asserts that in the modern era, falsifiability is replaced by peer-review. Were this assertion true this state of affairs would bestow upon the climatologists the priestly power to determine whether an inference was true or false without making reference to instrument readings. This is the position that was taken by the Church in its conflict with Galileo.
Michael darby
re: your post of April 16 at 4:38 PM
Your argument is similar to one that is made by the IPCC in its various assessment reports. This argument is debunked by arguments made by Vincent Gray (“Spinning the climate”) and myself ( http://wmbriggs.com/post/7923/).