Glitch: clicking on Hansen et al (1981) produces another version of Realclimate: Evaluating a 1981 temperature projection.
[Response:It is an automatically generated link to the reference list (from which you can click on the DOI for the original article). I've added a direct link to the pdf version in the text too. - gavin]
So this prediction from 1981 is “falsifiable” even though it doesn’t contain any error bounds? And is off by 30%? I readily admit, to me, given the understanding back then, that this is a pretty good prediction. However, I think the understanding should have improved since then such that going from a 30% overestimation to a 30% underestimation would have some element of falsity in there, no? Even considering the voluminous research [typos corrected] that has gone into improving our understanding over the last 30 years?
Since there was no margin of uncertainty in the original model, but the uncertainty bands are being appealed to now in the present models… are you saying that for this 1981 paper falsifiability only would come for temperatures that are below the observed trends? Or is the “only” theory available for falsifiability is simply whether or not, over generational time scales, that temperatures will be warmer than before (nothing about magnitude is available to be falsified?) The naive continuation of 1850-1981 dataset trend would also be positive.
I recall around the same time frame of 70s/80s reading an article in Science that discussed climate models. IIRC, the authors were perturbed by the fact that small changes in the input-value mix of the model produced large differences in the rate of climate change. A couple of runs suggested climate could change in a few hundred years or less, which in geologic time scales means “instantly.” I remember discussing this with my senior students, inferring that climate change could be a far more urgent problem than anyone at the time thought likely.
We have all heard the hoopla regarding how many years it takes to evaluate a climate projection from the denialistas who wish to make something of a short term trend. These statistically challenged clowns also often want proof that models are useful, but they usually refer to projections from current research. So, you want a 30 plus years projection validated, behold- Hansen et al., 1981.
Years ago I bought a second hand book “The Environment” from the editors of Fortune. It is from 1969 with a statement of president Nixon. The possible effects of rising CO2-emissions are already mentioned. As a student of economics I did a major in environmental sciences (1983). Climate change was also here one of the topics. Working at the Ministry of the Environment we introduced an environmental tax on fossil energy use in the first National Environmental Policy Plan (the Netherlands). Off course there was severe opposition from industries, but I cannot remember that sceptic arguments were ever part of the debate.
An Economist would possible have received a Nobel price if he developed a model with such an accurate performance.
Just looked at GISTemp global profile. Looks like a better fit has the zero crossing in 1976, and some negative values between 1950 and 1976. Net result is to drop the apparent purple line about 0.6C, which puts reality at the high end of Hansen’s projections. Of course HadCru, with less Arctic data, has somewhat less for a temp rise, as do the satellites. But still, he is still in the ballpark.
Which is weird, as a prior (Jan 2011) review had him at the “C” level of projections, the no-more-fossil-fuel scenario, didn’t it?
4 Salamano said, “However, I think the understanding should have improved since then such that going from a 30% overestimation to a 30% underestimation would have some element of falsity in there, no?”
The OP addresses that. They believe what is being falsified is the handling of aerosols. Since aerosols should decrease drastically by 2050 and climate after 2050 is the issue, the error doesn’t significantly affect the model’s usefulness for policy decisions. Interestingly, this error could actually offset another error in the models. They tend to underestimate ice loss.
Salamano, read a little closer. They’re not talking about a model being falsified here, but a “statement based on (greenhouse) gas) theory”. If temps had stayed flat or continued falling the statement it will warm would have been falsified, and it wasn’t. Ellipses mine.
According to a recent study, between 1990 and 1999 emissions rose by 1.1% a year, while from 2000 to 2004 they increased by more than 3% a year. The post-2000 growth rate exceeds the most fossil-fuel-dependent A1F1 emissions scenario developed by the Intergovernmental Panel on Climate Change (IPCC) in the late 1990s.
2) The best validation of a climate model projection is probably the Pinatubo eruption response.
This study highlights the role of water vapor feedback in amplifying the global cooling after the eruption of Mount Pinatubo. We note, however, that Mount Pinatubo does not provide a perfect proxy for global warming, because the nature of the external radiative forcing obviously differs between the two. Nevertheless, the results described here provide key evidence of the reliability of water vapor feedback predicted by current climate models in response to a global perturbation in the radiative energy balance.”
Salamano @4 — I prefer a BAysian approach. Call the naive linear projection from the obs H0 and the Hansen et al 1981 projection H1. Then use the additional 30 years of data now available to us to see whether the weight of the evidence better supports H0 or H1 and by much much [Bayes ratio]. Ignoring model complexity for now, which is the better fitting?
In principle H0 could have been (in some alternate universe) and indeed enough better not to support model equivalence. In that sense H1 is in principle falsifiable and obviously has not been.
Just looked at GISTemp global profile. Looks like a better fit has the zero crossing in 1976, and some negative values between 1950 and 1976. Net result is to drop the apparent purple line about 0.6C, which puts reality at the high end of Hansen’s projections.
The purple line is GISTEMP. You’re assuming that Hansen’s projections use the same baseline as the current GISTEMP dataset, which is 1951-1980. Given the publication date, that seems unlikely.
‘…easily beating naive predictions of no-change or a linear continuation of trends.’ – can you clarify what a naive prediction of linear continuation would have been, and how that would have performed against observations?
A linear extrapolation over 1880-1980 of the GISTEMP meteorological station series gives a temperature anomaly of 0.2 K in 2012, much lower than the lowest curve drawn. Extrapolating 1951-1980 gives the same central value (with a larger uncertainty).
Thanks. I’ll use this next time they say climate scientists were predicting an ice age in the 70s, or Hansen extremely over-estimated the warming (or sensitivity), or climate models don’t work and and are rigged to suit the scientist’s bias, etc…
WUWT has a post on paleoclimate reconstructions, saying (of course) that they’re all wrong. It is not as obviously amateurish as many contributions on that site.
I am not expert in this, but an expert could perhaps look at the arguments proffered and offer a cogent criticism.
Or you could just quote the relevant sections of Arthur Holmes’s standard textbook “Principles of Physical Geology” that spells out a century’s worth of observations, a calculation of CO2 rise due to oil and coal combustion, a 12 degree F temperature rise, and the resulting impact on glaciers and sea level–all published in the 1960s. And all well known to pre-politicized geologists.
Comment by Douglas Hagerman — 3 Apr 2012 @ 6:00 PM
Historical temperature estimates have change since 1980. What would these projections be if the latest estimates were applied to the calculations that Hansen et al. did back then?
Some “skeptics” contest global warming on the grounds that temperature in the past decade or so has leveled off. They should be reminded that the more this criticism is correct, the more these projections are correct.
I’m doing my graduate work in the area of oxygen isotope paleothermometry (which I do think has a lot of advantage over dendroclimatology), so I’ll just say a few general things, but I don’t plan on reading the WUWT article in enough depth to disentangle it piece by piece (note for people who reply that I’d rather continue this in the April Open Thread since it is OT and this thread is still young).
First, I do think that there is a lot of work to be done in the interpretation of oxygen/hydrogen isotope values obtained at a site, and there’s still plenty of disagreement in the paleo-community on how to best connect the isotopic signal in a record with climate. However, there are also many well understood thermodynamic, physical principles at play. There are also a number of paleoclimatic recorders of oxygen isotopes, including lake/ocean records, speleothems (in caves), corals, ice cores, etc. The factors and caveats that impact all of these different recorders are also widely available in the literature, and more recently isotope-enabled general circulation models have become more widely used in sync with observations (e.g., see Gavin Schmidt and others 2007 paper)
There have been countless studies documenting the spatial gradients in oxygen isotopes (and also interest in the temporal slope, not necessarily the same!) and there’s a lot of basic physics that stem from simple principles (e.g., precipitation is more depleted than the water from which it evaporated, the high latitudes are more depleted than lower latitudes, etc).
Oxygen isotope values for forams in the ocean relate primarily to both temperature and ice volume (and involve species-dependent vital effects), and salinity relationships and it’s not a trivial issue to disentangle these. For records such as ice cores, caves, etc the controls on an isotopic time series can vary by region: in the mid to higher latitudes, there’s definitely a temperature signal; in the lower latitudes, you see a big “amount effect” associated with precipitation in moist convection. (I think some of Lonnie Thompson’s work on interpreting low-latitude oxygen isotope values as temperature signals in ice cores led to some issues). Further, the oxygen-18 signal in precipitation integrates a history of the air mass travel and in some cases reflect nonlocal changes upwind of the site (see e.g., Lewis et al., 2010; Clim. of the Past). Moreover, in monsooon regions proxy records tend to be highly seasonally biased (e.g. in South America they record precipitation only a couple months and the rest of the year is not retained).
The interpretation of oxygen isotopes has been studied for a lot of different time periods and a lot of different locations, so you’d have to do a literature search for specific questions. But in summary, there’s an abundant literature on this, and a lot of knowns and a lot of pieces still left to sort out. The WUWT article that suggests it is all useless junk and no one knows what they are talking about is ultimately just a self-description. The typical drivel I expect from that blog.
Lazarus: thank you for the link. Of course we also found the article via the same TED talk, no coincidence there. I am a bit less sanguine about his speculation (clearly indicated as such) on regional effects; the CMIP5 models do not show a drying trend in the US and I am not sure there is a strong influence of Arctic ice on the midlatitude circulation (for model studies see eg Balmaseda et al, QJ, 2010 and Benestad et al, Tellus, 2011; for observational analysis see http://climexp.knmi.nl). Even CMIP3 did not do a particularly brilliant job reproducing observed trends (eg van Oldenborgh et al, 2009, CP: Western Europe is warming much faster than expected; van Haren et al Clim.Dyn. submitted: SST and circulation trend biases cause an underestimation of European precipitation trends).
Thanks for the link at 12, richard. But as ike at 20 points out, we are now already past the worst projections for CO2 emissions laid out by the IPCC. So the range will have to include much the possibility of much greater heating much sooner. Feedbacks are also kicking in much faster than earlier expectations, show these should also steepen the curves a bit at least.
It shows that climate scientists already had a good understanding of the physics 30 years ago, and that their conclusions about anthropogenic warming have been validated by observations. It’s also another piece of evidence that is consistent with fast feedback climate sensitivity of around 0.75°C/W/m².
‘…easily beating naive predictions of no-change or a linear continuation of trends.’ – can you clarify what a naive prediction of linear continuation would have been, and how that would have performed against observations?
AIUI Hansen addresses that in the paper when he talks about the range of unforced natural variability – it’s illustrated in Fig. 7. In the absence of external forcings, 1σ would represent a maximum of about 0.1°C of warming by today, and 2σ would be about 0.2°C. In reality we’ve seen about 0.5 – 0.6°C of warming above mid-20th Century temperature, so perhaps at the 5σ level or 99.9% confidence that the warming is due to external forcing (principally CO2) rather than natural variability.
“For the Hansen 2007 data, the 1980s – 1990s temperatures were reduced from the Hansen 2001″
I’m assuming there is a very simple explanation which I’m missing? Thanks in advance.
[Response: The GISTEMP analysis uses only publicly available data and the code is open to all. The results over time may vary as a function of a) the input data (which change due to corrections, increasing archived data, changes in homogeneity adjustments, bias corrections etc. made by others - including the National Met Services), b) the method (all of which are documented in the various papers). Over the longer term, there are also different indices calculated - specifically a met-station only dataset and the land-ocean index (which additionally uses SST). Insinuations that just because something has changed over time that there is something underhand going on (as on that website) are unfounded and extremely lame. - gavin]
@37: “Insinuations that just because something has changed over time that there is something underhand going on (as on that website) are unfounded and extremely lame. – gavin”
I am not comfortable with a constant rewriting of history, whatever noble purpose it may serve.
[Response: This is not what is happening - and there is no 'noble purpose' for it in any case. These analyses are products created from the raw data - they don't rewrite anything, but you do use as much information as is possible to get the best estimate for what the global mean change was. That means using meta-data, using corrections of known biases, comparing near-by stations, correcting for UHI etc. All that is constantly updated, and the analyses change as a function of that. - gavin]
Prof. Christoph Keller spoke last night at the Academy in Utrecht The Netherlands and said that Hydrogen and Stupidity are the two most occuring elements in universe, not necessarily in this order. Economy seems to be todays mantra and only a minority of mankind seems to be interested in the outcomes of science reports like these. It is time for a new paradigm with radical different human behavior, taking the lessons from the ‘past’ (1981) into account. Thank you for sharing this lesson with us.
“I am not comfortable with a constant rewriting of history..”
I’m sorry, but putting it in the simplest possible terms, that’s like saying that you’re not comfortable with jet airplanes because their creation is mysteriously dishonest on the subject of biplanes.
Science works so well in large part because it corrects errors, makes improvements, updates itself, and moves forward–and does it very quickly on a historical scale. One should be more ill at ease with the institutions in society that don’t work that way.
“KiwiCM” and “curiuos george” — where are you reading the claim that history is being revised? Someone is lying to you — and it’s not the science journals. Estimates are published; models are revised; new estimates are published. This is progress. Nobody has gone back and changed history.
But someone is lying to you by claiming that’s happening.
Where are you getting this? Why do you trust the source you’re relying on?
How could you check whether you’re being told the truth?
I’m assuming by addressing this to those userids that there are real people behind them, who’ve actually been fooled, but can think about stuff — not just userids created to repeat the lies about history being changed.
george@38 “I am not comfortable with a constant rewriting of history, whatever noble purpose it may serve.”
I, along with many other people, am involved in “rewriting” history. You could help. Just sign up to one of the historical meteorological records sites and share the load of getting heaps and heaps of data out of its paper prison and into the electronic data set.
The more data from old radiosondes, ships’ logs and small meteorological stations is included, the better our picture of how things were 80 or more years ago will be. And the better our picture of how climate is changing will be.
You don’t need to be a scientist to help with science. You just need patience and reasonable eyesight to read horrible scanned copies of cramped writing.
This “rewriting history” stuff is partly a consequence of the philosophy of the adjustments, which are designed to estimate what the historical observations would have been had they been taken with the same instruments and at the same locations with the same microclimate as the current observations. As the current observations change, the historical estimates have to change to catch up.
Another alternative would be to use some historical reference year, such as 1960. This would have the advantage of minimizing future adjustments to historical data, but then people would object that the current data was being adjusted. (The present approach uses the current data ‘as is’.)
But…once the records are converted to anomalies relative to some baseline such as 1961-1990, there would be absolutely no difference in the results of the two approaches for global temperature anomalies!
A third approach, by BEST, is to treat each change in observations as the end of one observation set and the start of a new independent one. There are no adjustments in this approach. But…there’s still essentially no difference in the results!
Back on topic: This post is dangerous because it over-simplifies what is required for falsification. The difference in trends between observations and projections tells you absolutely nothing useful. You need to know quantitatively the difference between observed and projected forcings. If volcanic activity between 1980 and today had caused the global temperature to be 2 C cooler now than 1980, would Hansen have been falsified? No.
Somewhat different point that John;s, a simple global temperature anomaly doesn’t tell you much. It would be better to develop a figure of merit that looked at observed and predicted geographic patterns of temperature and precip.
Eli, having looked in detail at the predicted forcings in the 1988 paper is somewhat less skeptical than John, they were pretty good, at least in broad strokes.
I hope someone challenges Professor Will Happer about this. You’ll recall that he’s the Princeton nonclimatologist physicist who’s one of the leaders of American Physical Society opponents of APS’s position on climate change, and that he served as director of energy research at the Department of Energy from 1990 to 1993. And you might recall that his March 27 Wall Street Journal op-ed “Global warming models are wrong again” called the climate’s “observed response” to more CO2 “not in good agreement with model predictions.” At the end of that piece, he quoted Richard Feynman concerning the empirical nature of the search for new scientific laws, and then closed with this assertion: “The most important component of climate science is careful, long-term observations of climate-related phenomena, from space, from land, and in the oceans. If observations do not support code predictions — like more extreme weather, or rapidly rising global temperatures — Feynman has told us what conclusions to draw about the theory.” Professor Happer: What conclusions should we draw from this RC posting? (The op-ed appears at http://online.wsj.com/article/SB10001424052702304636404577291352882984274.html — but if there’s a paywall problem, see my Physics Today Online report about it at http://www.physicstoday.org/1.2751144.)
Slightly off topic. Post 42 adelady. I contribute to “Oldweather”, could you provide information on the other record recovery projects you mentioned? In part so they can be added to library/school presentations on citizen science.
Marco @ 47: I see what you mean about the general relevance and importance of the posting that you cited, but I’d still like to see someone of stature in science or someone of high visibility in the national media challenge Professor Happer specifically about the contrast between the very headline on his WSJ op-ed (“Global warming models are wrong again”) and what’s asserted by this RC posting (and by Lazarus @ 31) about the retrospective reliability of Hansen et al. (1981). Note please that this RC posting has already gained the attention of James Fallows at the Atlantic: http://www.theatlantic.com/technology/archive/2012/04/now-this-is-interesting-a-climate-prediction-from-1981/255658/ . Thanks.
Steven @48: I also understand what you mean, but there is a limit to how much and how often you can fight these misinformers. The WSJ isn’t exactly known for being very happy to publish a dissenting voice. Last time it did, in response to a letter filled with false statements (to the extent that even Nordhaus felt it necessary to point out the misrepresentation of his work), it followed that response a few days later with yet another op-ed containing a supposed rebuttal, adding further injury to insult. And now yet another Op-ed from Will Happer. How do you challenge this? Don’t think Happer will come to an NBC programme to get grilled, especially if there’s a real climate scientist of stature on the other side of the table. He knows he’ll be shown a fool.
You might then get a piece in another newspaper, but what’s the use? Most likely that is a newspaper that is not read by the same audience as the WSJ. Preaching to your own choir…
Marco, thanks. Because I write the “Science and the Media” column for Physics Today Online (though I’m speaking only for myself in these RC comments), and because I’ve always thought that the Wall Street Journal’s climate editorials and commentaries merit particular attention precisely because of that paper’s influential audience, I’ve actually done at least four PTOL media reports so far this year on the recent WSJ opinion skirmishes that you mention. (I’ve listed the postings with URLs below.) I also understand and respect the discouraged resignation that you and many other commenters at RC often express. Nevertheless I say again that I’d like to see someone of stature in science or someone of high visibility in the national media challenge Professor Happer specifically about the contrast between the very headline on his WSJ op-ed (“Global warming models are wrong again”) and what’s asserted by this RC posting (and by Lazarus @ 31) about the retrospective reliability of Hansen et al. (1981). Here are those four postings:
It seems that NASA scientists do not approve of Hansen’s version of science.
[Response: Love the way that 49 retired astronauts and administrators (and one meteorologist) suddenly become some all-encompassing 'NASA scientists'. Especially since they haven't actually provided any specific example of what they are complaining about, and despite the fact they are calling for the bureaucracy to censor the ability of real NASA scientists to talk about their work. This is ably dissected here. - gavin]
Comment by Schrodinger's Cat — 12 Apr 2012 @ 6:41 AM
#52–It seems that Gavin (and Skeptical Science) were the ones who actually “opened the box” and took a look…
I dont understand your reply to #52, why would you imply that astronauts are not scientists ? I guarantee you that most Americans believe the people involved in the Apollo missions have done more for science than all of todays climate scientists together.
[Response: Some astronauts are scientists, some are not. None of the '49' have any climate expertise, however capable they might be in other fields. They are of course entitled to their opinions, but the vague and unsourced accusations they level at NASA and GISS, and in particular their call for scientists to be censored for talking about their research is unbecoming, and not compatible with the high regard that many of them retain for their impressive actions in the manned space flight program. My respect for those achievements is very strong, but that doesn't make their opinion about NASA's climate research valid. I presume you are not taking the position that authority should be granted to an argument purely on the basis of the past history of the arguer? - gavin]
I dont understand your reply to #52, why would you imply that astronauts are not scientists ?
The early astronauts were all jet fighter pilot jocks from the miliary.
Even today, 60% have military backgrounds.
Only 36% have doctorates, and many of those are in engineering or other fields, not science, certainly not climate science.
So what made *you* assume that astronauts are “scientists”? After all, each bird needs a pilot and co-pilot. Do you think commercial airline pilots are “scientists”? Fighter pilots?
I guarantee you that most Americans believe the people involved in the Apollo missions have done more for science than all of todays climate scientists together.
Yes, we’re all aware that most Americans are sadly lacking in scientific knowledge.
One can “do for science” without being a scientist, as any working scientist will tell you when asked about their lab technicians if they’re involved in experimental science, or field techs if they’re doing field research. So even if your statement’s true, it doesn’t make astronauts “scientists”. The landing targets for the Apollo flights were chosen by scientists on earth in conjunction with NASA engineers (who had to decide whether or not the areas of scientific interest included safe landing zones) – *NOT* the astronauts themselves. At best, the astronauts were field techs when walking on the moon. Those working on the space station spend a lot of time being glorified construction workers, bolting this, duct-taping that, yanking on the other, sometimes a good kick or two.
But the unmanned space exploration program has done far, far more to push forward scientific knowledge than those missions that include astronauts, which mostly have been limited to earth orbit, other than a few jaunts to the moon that brought back a few rocks, so valuable to science that some have ended up as souvenirs. Hubble alone dwarfs the entire scientific output of every astronaut or cosmonaut that’s ever entered space.
On the other hand astronauts acting as lab/engineering techs saved the Hubble from a serious manufacturing flaw, and later upgraded the camera system. They weren’t doing science, though, and the skills required weren’t those of a scientist.
It takes guts to blast off into orbit with a giant rocket strapped to your tail. That doesn’t make those who do so scientists.
Comment by David B. Benson — 13 Apr 2012 @ 11:29 PM
“None of the ’49′ have any climate expertise, however capable they might be in other fields.”
I think this is a bit cheap, the achievements of this remarkable group of people speak for themselves.
Their criticism is based on an understanding of what does, and does not, constitute “Science” – a discipline constrained by imperical evidence, objectively determining what you can and cannot say. It is not based on the emotional fears for the well-being of one’s grandchildren, how cuddly polar bears are, or an eagerness to support the prevailing political “will”. This is obvious surely.
The first part “None of the ’49′ have any climate expertise” is particularly galling. Science is science. No doubt homeopathists would feel equaly justified in dismissing challenges from the medical profession on the grounds that they had no “Homeopathy expertise”.
“…the concepts and conclusions have not changed all that much.”
I think this rases an interesting point. Despite dramatic increases in model complexity and computation power over the last 30 years, conclusions haven’t changed that much. Our understanding of zero order results such as climate sensitivity, mean global surface temperature haven’t advanced much from the relatively simply models Hansen was using then. I suggest we’ve been overly focused on increasing model complexity and resolution, an approach that isn’t delivering good returns on the investment.
Well, that would be one rather bizarre interpretation. Another would be that we have understood such concepts as sensitivity for a long time now and that none of the advances made (and they are advances) has changed that understanding.
The models have allowed us to understand a great many other things–prompt response to volcanic eruptions, the build-up of ice inland in Antartica even as ice shelves disappear, and so on. If you only look at Anthropogenic climate change, you are missing half the circus.
But, Ray, we don’t have a very good understanding of climate sensitivity today, nor of global mean surface temperature. That’s my point, the dramatic improvement in computer power and model complexity hasn’t narrowed the uncertainty on sensitivity nor, brought all the AR4 models, for example, into agreement when recreating 20th C. mean surface temperature.
Say what? We’ve nailed computer sensitivity down to between 2 and 4.5 degrees per doubling–reduced from 1.5-5.5 a decade ago. That is significant progress. The current range is sufficient to establish that we have a serious problem at best and a civilization-threatening problem if the upper end turns out to be true.
Perhaps you should read up on the problem, and then you might understand why smaller grid size is not necessarily going to answer all questions and why getting all the models to agree on everything is neither necessary nor sufficient for them to be useful.
GSW, these “49″ wouldn’t know science if it bit their peckers off. Anyone who knows anything about science realizes that expertise matters. I do not opine about brain surgery or string theory, because I am do not possess professional level competence in them.
The facts are that 97% of experts say we are changing the climate. This is not just the NAS study, it’s consistent with the results from Bray and von Storch, no great advocates of the consensus. The consensus has been vetted and vindicated by countless independent reviews by national scientific academies from around the globe, by professional organizations of scientists.
The rules in science: You don’t publish in the field, you don’t get to play.
GSW: “It is not based on the emotional fears for the well-being of one’s grandchildren, how cuddly polar bears are, or an eagerness to support the prevailing political “will”. This is obvious surely.”
You are correct that this is not science. Neither is science based on the emotional fear that taxes will go up if climate change happens to be true. This should be obvious but has obviously been the one connecting thread between all of the denialists I have seen. They have no coherent scientific story, but they all think climate change will hit their pocket book so it must be wrong.
I would like to post your figure in my blog on the CBI web site. Is it proprietary or can I just take it? I will of course be glad to give you and Hansen credit for the graphics and the paper.
Please let me know as I would like to post it next week.
Our blog page is: http://www.consbio.org/newsroom/blog
[Response: Please contact Geert for permission. - gavin]
After I saw that Hansen cited his 1981 paper in his recent TED talk I read it. One thing I’ve thought about often since I read the paper is the first line in the third paragraph:
“The major difficulty in accepting this theory has been the absence of observed warming coincident with the historic CO2 increase.”
I’ve only been observing climate change debate and considering the issues involved since 1988. I wonder if this sentence counts as a prediction Hansen got wrong. I am still astonished that so many who would count themselves as leaders of this civilization still reject the theory even as the observations pile up.
Maybe Hansen in 1981 was referring to his colleagues?
Ray Ladbury @68: “The rules in science: You don’t publish in the field, you don’t get to play.”
That’s just ridiculous. Free inquiry is open to anyone. It is a bit frightening that you would say or believe otherwise. Personally, it’s completely obvious to me that these astronauts probably don’t have a lot of facts or well-founded arguments to back up their cases, but you shouldn’t just be a jerk and shut them out completely. Just address their arguments and if anyone says “They’re astronauts”, you say, “So what” and turn back to the arguments. Now that’s science.
[Response: Some vaguely interesting background has come to light. Apparently the genesis of the letter was a meeting of the NASA Alumni League at JSC in September, where Cunningham and Steward gave some heavily contrarian talks. Their slides (linked) are remarkable only in how bad they are. For instance, they use multiple figures that have simply made up data on them - purported temperature reconstructions that are two different series with different baselines plotted together, inconsistent measures of solar forcing to get better fits with different data, and most bizarrely of all, multiple slides all claiming that only ~3%' of atmospheric CO2 is anthropogenic and that this is "0.12%" of the greenhouse effect. This is nonsense of the highest order (CO2 is up over 40% because of human activities, and CO2 as a whole is roughly 20% of the greenhouse effect when judged by the effect it has on upwelling longwave radiation). The lack of understanding in what they are showing is evident and that is a little sad. - gavin]
From an interested layperson: the complexity and opacity of contemporary climate models cause me to be skeptical of the anthropogenic hypothesis. Although it deals with purely physical, chemical, and maybe a few biological processes, the flavor of the models and their statistical analysis seems to be quite different from other branches of the natural sciences. There seem to be free parameters floating around (“climate sensitivity”) that are not well-understood. (Or if they are well-understood, we can’t really know they’re well-understood, since so few precise predictions can be made and verified in a convincing way in less than a few decades.) Knowledge of the basic physical processes seems to be in flux as well: how long ago was the importance of the ozone layer and aerosols discovered? Really, not long at all. Many of the basic physical processes involved also seem to be approximated with plausible dynamics, but again, they are only indirectly based on foundational first principles, which everyone agrees on. (There are no deniers of quantum physics that I know of.)
That said, this chart does sway me. It is precisely this type of longer-term, non-trivial prediction that I’ve been looking for. If it withstands scrutiny, my assessment of the likelihood of the anthropogenic hypothesis being correct will grow considerably.
Can someone respond to Roger Pieilke’s critique of the Atlantic article?
[Response: Roger Pielke's critique doesn't make much sense. He appears to be claiming that a single month anomaly with respect to the last 30 year baseline (0.11ºC) should be compared to a trend from 1979 onwards. That isn't correct at all. Instead one should use the trend in the UAH TLT data, which is 0.144ºC per decade (Pielke's graph of the trend is possibly out of date). That gives an overall increase of 3.2*0.144 deg C from 1979-2011 i.e. 0.46ºC, which is a pretty good match to the roughly 0.45ºC change in that period in the Hansen figure. Of course there is uncertainty in the trends (both from fitting the OLS line, +/-0.6ºC, and structurally, since RSS has slightly different numbers), and there is no expectation that TLT and surface air temperature should have identical trends (overall, TLT should be increasing a little faster than SAT - but this is also subject to noise over relatively short periods). Overall, I see no way in which either Geert or Fallows are guilty of 'cherry-picking' or that there is any biased presentation here. There was a prediction of surface air temperatures and the comparison was made against that same metric for the entirety of the period predicted. A much better critique would examine questions of the net forcing used in the 1981 paper versus what really happened - but that gets complicated quickly because of the uncertain changes in aerosol. - gavin]
#73–”Just address their arguments and if anyone says “They’re astronauts”, you say, “So what” and turn back to the arguments. Now that’s science.”
Yes, but in any scholarly pursuit the only place where arguments can be meaningfully ‘addressed’ is in the professional literature. That’s the case primarily in order that all contributions to the ‘conversation’ can be readily ‘found’ and so taken into account. (Secondarily, it’s to weed out arguments that aren’t up to snuff–this may sound like elitism, but it’s very important because the rates at which new knowledge is being generated are such that it’s really, really time-consuming to keep up, and there really aren’t enough hours to waste on junk. Preferentially presenting the best work is a service that journals do (or at least, should) provide their readers.)
It’s in that sense that Ray says “You don’t publish, you don’t get to play,” not the sense you seem to take from it–ie., that because somebody says something in an ‘out of bounds’ place, one should arbitrarily cut off consideration of their point of view.
Of course ‘side conversations’ are possible; in this sense all of RC is ‘side conversation.’ But if you want to ‘play’ at scholarship–whether it’s climate science, comparative literature, pitch-class set theory or what have you–the only places to do that are in the journals that collectively form the relevant professional literature. That’s where the scholarly ‘game’ takes place.
So when the ’49′ chose to publish where they did, they were choosing not to ‘play climate science.’ Instead, they were playing politics.
#74–”(There are no deniers of quantum physics that I know of.)”
You’d be surprised, Walt; I could name one vociferous commenter on a prominent Canadian news site who is just that. In addition to climate change and quantum physics denial, he also contests that HIV causes AIDS, (IIRC) the Big Bang, and the utility of OLS for calculating trends.
Yes, he’s deeply ignorant–an ignorance directly proportional to his cock-sureness. (Cf., Dunning-Kruger.)
But he can be convincing for the unwary, because he doesn’t superficially sound ‘stupid’ or ‘illiterate’ unless you already know a bit about the subject.
I think deny is the wrong choice of word here. There are astrophysicists who disagree with the Big Bange theory(Fred Hoyle comes to mind), but denial gives the impressions that they are closing their mind to the truth, as opposed to having other ideas. BTW, Einstein disagreed with the quantum physics theory.
In reference to your Canadian, you might want to add that his hot air is increasing faster than the atmospheric changes due to CO2.
From an interested layperson: the complexity and opacity of contemporary climate models cause me to be skeptical of the anthropogenic hypothesis.
Were you also skeptical of the Boeing 787 before it was built and flown? The models used to develop it (skilled enough that Boeing built the simulator to train the test pilots long before the plane was built, and skilled enough that when the plane was finally flown, the pilots found virtually no difference between the real plane and the pre-built simulator) are easily as opaque as climate models.
And, of course, you’re stating a strawman in the first place, climate models help with the understanding of various details of climatology, but the basic understanding that CO2 is a GHG, that warming temps increases the absolute humidity leading to a positive feedback, etc etc would stand even if the complex climate models you disparage didn’t exist.
And lastly, you’re arguing from personal ignorance – you’re not capable of understanding the models, therefore you’re skeptical.
Anyone is welcome to learn about climate science,just as anyone is welcome to watch pro football on television or in the stands. However, should you decide to suit up for a game, I think your career would be brief, painful and followed by surgery and a long recuperation.
Climate scientists study for decades before they contribute significantly to the field. It is simply silly to assume your opinion will contribute anything to the understanding of a complex technical field unless you devote your life to understanding it.
I find your comparison between climate models and aerodynamic flight simulations deeply misleading. (1) The fundamental physics of flight and aerodynamics is understood to a vastly, incomparably larger extent than climate dynamics. (2) The leap from first principles (e.g., Navier-Stokes) through to a full-fledged flight simulation is really not a great conceptual leap. Completely new, important mechanisms significantly affecting flight are not discovered very often. That doesn’t seem to be the case in climate science: there is a gigantic gap between first principles and the climate modeling equations, and rather fundamental new mechanisms are being discovered every decade or two it seems. This suggests the models may still be incomplete. (3) It is much easier to validate aerodynamic models: experiments can be performed, parameters tweaked and responses noted and compared to predicted behavior. None of this is possible with planetary climate. (4) The learning feedback loop is much, much shorter with aerodynamics: experimental results confirming or refuting a model’s accuracy are available within a few months to a few years. With climate science, most predictions will take decades to validate with much certainty. (5) Even with the relatively simple dynamics of flight (simple compared to climatology), enormous and catastrophic simulation failures are certainly not uncommon: http://abcnews.go.com/Technology/hypersonic-flight-darpa-launches-htv-plane-test-loses-contact/story?id=14280849#.T5DR3at5PTk.
Oh, and I am not “disparaging” climate models. I am skeptical. There’s a big difference.
And as for the comment about “arguing from ignorance”: do not make your statements personal. It makes you look weak and as if you have a hidden agenda based on emotion. I may not know all the specific details of climate models, but the basic ideas are quite clear. Also, I’ve had a lot of experience with simulations and complex statistical analysis in other contexts. The experience taught me to be very skeptical of very complex simulations. Parameter tweaking and seemingly innocuous tweaks of dynamics can have profound impacts on simulation outcomes.
Do not take my skepticism personally. If I had to put a probability on it, I’d say the “climate scare mongers” (probably such as yourself) are essentially right with probability ~70%. That’s mainly based on two things: (1) the fundamental plausibility of their assertions based directly on first principles (rather than complex climate models) and (2) the mainstream climatologic opinion does not seem to have varied much in 20-30 years.
Gavin @74: I’ve looked more closely at Pielke’s critique. I agree with your comment, and I have to say, I’m a little amazed that Pielke would have made that critique in the first place. As with most things I have encountered in climate science, even the esoteric, really-super-big-brain-required-to-understand stuff turns out to be pretty darn elementary. I’d only add: Pielke compares the +0.11 C UAH figure for the temperature anomaly above 30 year average observed in March 2012 with Hansen’s (1981) prediction of ~+0.5 C change over the whole 30 years. The first figure is departure from a mean, the second is expected difference between the start and end points. The later should be roughly twice the former for a linearly increasing time series. So Pielke should really be comparing ~0.22 C with ~0.5 C. And as you say, that ~0.22 C is just one noisy data point in a rather noisy time series that proves very, very little.
Walt Finerman says: “(1) The fundamental physics of flight and aerodynamics is understood to a vastly, incomparably larger extent than climate dynamics.”
This is utter bullshit–as one might guess by the piling on of adjectives. They physics of climate change is pretty fundamental as well. It is basically conservation of energy and molecular/electomagnetic interactions. Yes, there are subtleties, but what we do not know does not invalidate what we do.
Walt: ” there is a gigantic gap between first principles and the climate modeling equations, and rather fundamental new mechanisms are being discovered every decade or two it seems. This suggests the models may still be incomplete.”
Again, bullshit. Where are you getting this crap? Global Circulation Models are first-principles, physics driven models. New mechanisms, huh? Care to name one?
Walt: ” It is much easier to validate aerodynamic models.
Wrong. It takes a while to do so is all. However, you also have millions of years of climate data the models must explain–that is a pretty strong test. You have the occasional volcanic eruption–every one of which is different.
As to the rest of your screed, all I can suggest is that “argument from ignorance” is a perfect description. You do not know of the validation studies that have been done, so you assume they don’t exist. I suggest you read the following and the references therein:
Walt, ignorance is not a sin. This is not your day job. It isn’t a simple field. Everything now depends on how you respond to criticisms of ignorance. You can actually look at what people have said, read the resources they’ve supplied and learn, or you can become a Dunning-Kruger Jedi.
All of us started out there. I have a PhD in physics and had to work about 2-3 years before I really felt comfortable with even the basics.
I think RealClimate would be best advised to pull this article. If the author actually bothered to read the paper rather than fixating on a single graph, he’d understand that Hansen acknowledges a huge number of unknowns at the time. The reason why the term Synfuels is used because Hansen assumed that oil and gas would rapidly become uneconomic to produce and would be replaced by synthetic equivalents. Hansen also includes a graph showing that the capacity of the ocean to absorb increased heat was unknown, as indeed it remains unknown at this time. Hansen also makes the claim in this paper that the CO2 signal will have overcome all natural variability factors by the 1990s, whereas natural variability is still trotted out by warmists including Hansen himself as the reason why global temperatures haven’t appeared to have increased significantly since 1998. The author of this article needs to at the very least provide a graph showing a comparison between actual growth in energy usage since 1980 and the scenarios that Hansen provided, so we can see which line on the graph we’re supposed to be comparing observed temperature with.
Really, this paper provides a whole arsenal of evidence to tear the credibility of climatologists apart. Hansen has never associated himself to this paper, but his 1988 model is compared on an annual basis by his co-author on a number of papers Dr Sato of Columbia university, a link to which can be found from Hansen’s GISS website (see page 2).http://data.giss.nasa.gov/gistemp/graphs_v3/