Fun with correlations!
) We are forever being bombarded with apparently incredible correlations of various solar indices and climate. A number of them came up in the excoriable TGGWS mockumentary last month where they were mysteriously 'improved' in a number of underhand ways. But even without those improvements (which variously involved changing the axes, drawing in non-existent data, taking out data that would contradict the point etc.), the as-published correlations were superficially quite impressive. Why then are we not impressed?
To give you an idea, I'm going to go through the motions of constructing a new theory of political change using techniques that have been pioneered by a small subset of solar-climate researchers (references will of course be given). And to make it even more relevant, I'm going to take as my starting point research that Richard Lindzen has highlighted on his office door for many years:
That's right. Forget the economy or the war(s), the fortunes of the Republican party in the US Senate are instead tied closely to the sunspot cycle.
"Oh yes", the sceptics might say "but that's just a couple of cycles and doesn't use up-to-date numbers. What happens after 1986?"
Well, that is a little problematic, however, the good early correlation is obviously still important (r=0.52! 1960-1986) and so we should be able to refer to it over and over again without noting that it breaks down subsequently (cf. Svensmark, 2007 referring to Marsh and Svensmark (2000)). But more importantly, it just demonstrates that the theory needs a little adjustment.
Let's look at the second half of the record. Well, there's another strong correlation for that period as well (r=-0.63, 1988-2006). Only this time the correlation is inverted, but that shouldn't be surprising to anyone - solar-senator effects are complicated!
If we now put it all together, we can see that there is a reasonable match over the whole period…. well, except that break in the period 1984 and 1988 and, unfortunately, last year's elections didn't fit the pattern either. But 1984-1988 was Ronald Reagan's second term and clearly no theory of Republican senators can ignore that. We therefore propose that the 'Ronald Reagan second term phase shift' combined with the change of sign of the Hale solar magnetic cycle in 1986, obviously changed the dynamics. This kind of phase shift is frequently seen in solar studies (cf. Landscheidt and many others), where it is rarely taken as a sign that two time series with decadal spectral power are in fact completely independent. Finally, it is permissible to leave off the more recent data points (cf. TGGWS) for "graphical convenience". So after just a little work, we have managed to rescue the original theory to match a much longer amount of data:
Some readers may scoff and suggest that in the absence of any mechanism, these powerful correlations are numerological artifacts arrived at using post hoc fallacious reasoning that have no predictive capability. That might appear to be a valid argument. However the ultimate test will of course be experimental. On the basis of these intriguing results, we propose exposing Republican senators to varying levels of cosmic rays in a basement and monitoring their electability. Any refusal by the funding agencies or ethical review panels to support this would simply be confirmation that the political science establishment are scared of what this research would imply for their so-called "consensus".
Convincing, eh?
The data for sunspots and senators can, I'm sure, be manipulated even more effectively than I've done here. I've made no use of various lags or filters (which can be altered as you go along cf. Friis-Christensen and Lassen (1991)), or of partial detrending (cf. Marsh and Svensmark (2003)), or of splicing of unconnected data sets (cf. Svensmark and Friis-Christensen 1997, Nir Shaviv). More ideas could be taken from "New evidence for the Theory of the Stork" (Höfer et al, 2004)". A special RealClimate commendation for anyone who can do better!
9 May 2007 at 1:08 PM
A respectable linear relationship (rising over time) could be fitted to the data.
9 May 2007 at 1:08 PM
he he he that`s great post
good job
9 May 2007 at 1:33 PM
I had always suspected that the Democrats and Republicans had undergone a role reversal on October 22, 1986. It is nice to see proof. I am sure that if you had a statistics package designed specifically for the social sciences you could tie that role reversal to a specific sun spot event (or lack there of.)
9 May 2007 at 1:33 PM
Well done, Gavin. I halfway expect Dennis Wingo to not only agree with you for once but also to actually be happy with the results you’re getting.
9 May 2007 at 1:36 PM
Gavin,
I think you should know that contrarians are being especially easy on the climatologists at this point. With evolutionary biology, we have to deal with the young earth creationists, the old earth creationists, the special creationists (who accept the fossil record, but claim that each kind was created in the era in which it appears indendently of all the rest), then all the possible variations.
For example, omphalosian creationists argue that the world is young but accept the existence of all the evidence that the world is old, arguing that the world was created only 10,000 yrs ago, including all of the evidence which gives it the appearance of being very ancient. Of course one could argue that it was really created only five minutes ago, including even our memories which give it the appearance of being older. But then one isn’t talking empirical science - one has left that behind quite some time ago in favor of a freshman philosophy course bullsession.
9 May 2007 at 1:36 PM
Carl Wunsch has published an email exchange with Durkin, the producer of that phoney documentary.
Durkin does not respond well to critique. “You’re a big daft cock,” he wrote to journalists and scientists.
Durkin also asks why the issues raised in his wonderful opus have not come up in the “hours and hours of shit programming on global warming shoved down our throats by the BBC?”
“Go and fuck yourself,” he ends.
Seems like a nice guy. I’m sure that’s why Wunsch is publishing the emails, since Durkin did him such a nice favor by selectively editing an interview.
9 May 2007 at 1:52 PM
A nice job of explaining “correlation does not equal causation”. However, your point would be stronger if you had concluded with a comparison to the CO2-temperature correlation issue: why we have strong reasons to believe a causal link in that case, but not in the case of sunspots and temperature. The two cases are not the same, but it would behoove you to point out why they are not the same, lest the fence-sitters in your audience accuse you of hypocrisy, or conclude that there is equally no reason to believe that CO2 has influenced temperature.
9 May 2007 at 2:06 PM
I notice you “conveniently” left out the data before 1962. Close scrutiny of the entire time series will show that over the long term, Republican senate membership is much more strongly tied to the length of the solar cycle, all the way back to the election of President Lincoln in 1860. Your mistaken correlation is simply due to the “urban liberal bias” in the historical record.
And well before that, I can show strong correlation between solar intensity and conservative-vs-liberal dominance in politics. Contrary to IPCC claims, I can prove that the “medieval conservative period” was in fact even more conservative than modern times. Using Beryllium isotope abundances in meteor fragments as a proxy for solar activity, and the consumption of cheap beer as a proxy for conservative control of politics, I have shown a near-perfect correlation all the way back to Julius Caesar’s triumph over the bleeding-heart liberal Gauls.
Just because I don’t have any actual data, doesn’t mean you can discount my theory.
I came, I saw, I correlated.
9 May 2007 at 2:15 PM
This is odd to read. It looks like statistics and correlation is all new to you guys. If you pick 2 time series randomly from many time series, there is ~ 5 % likelihood that the two time series will significantly correlate at the 5 % level. It is therefore the science also must show that it is likely that the correlation is scientifically meaningful and logical. But this problem is the same for all research - whether you are a sceptic or a believer is not relevant.
9 May 2007 at 2:21 PM
http://www.time.com/time/magazine/article/0,9171,758405,00.html
[the comma in the URL breaks the link with this forum’s software; cut and paste works]
Monday, Nov. 22, 1937
“… it means more when one scientist with impeccable credentials declares that sunspots may have a physiological and emotional influence on mankind than when a thousand astrologers and other cultists affirm flatly that they do. …”
“… Harlan True Stetson … His colleagues have voted him an asterisk in American Men of Science for distinguished research.”
9 May 2007 at 2:26 PM
Gavin:
Great post, but don’t you think that this also makes the general point that in the absence of a ‘mirror Earth’ to act as a control group it is extremely challenging to conduct reliable attribution studies in climate science?
It seems to me that one common feature of economics, political science and climate science that distinguishes these disciplines from, say, physical chemistry, is the difficulty in ever executing a sufficient number of replicable falsification tests for such a highly over-determined outcome when we have only one experimental instance (the Earth). As an example, suppose I decided to test the predictiveness of the Sunspot - Republican Senate model by evaluating its performance in 2008, and it “predicts” the actual result perfectly? Even if we dreamed up some a priori potential causal relationship, I don’t think you or I would conclude that we had a useful tool, because there are so many factors that drive any election result.
In the same way, suppose a GCM perfectly predicts a climate result for the next several decades — how reliable a falsification test is that one result? In the case of GCMs, this problem is exacerbated by the fact that a single falsification test requires 30+ years, so it’s not clear we even time to do one before we have to make decisions about changes to our behavior.
It seems to me that the physics of infrared absorption and redirection (i.e., the known causal link) + common sense are what make the compelling case that human activities are most likely driving some amount of warming.
Best,
Jim Manzi
[Response: Climate science by correlation is not in the least bit satisfying, and yet it gets cited frequently - particularly by contrarians. I agree with you that physical modelling is the much better way to go (obviously since I work in a GCM group). However, I disagree that this cannot be tested. The models that are built can be tested in dozens of ways to verify key feedbacks and mechanisms - response to volcanic eruptions, solar forcing, orbital forcing, ENSO variability, NAO or SAM responses, the last glacial maximum etc. And frankly, the projections from simulations done 20 years ago stand up very well to what actually happened. A single ‘validation’ is of course not sufficient, but the hundreds of validations that have been done start to add up. - gavin]
9 May 2007 at 2:36 PM
Brilliant! Here’s more proof that CO2 emissions are not the cause of the observed temperature increase, and that in fact, we have nothing to worry about.
Fact #1: World population growth rates correlate very well with the global temperature trend. There is a spike around 1940 (the war years, when people were more active) followed by a post-war lull (when people were less active) - which just supports the mechanistic explanation that’s it’s human body warmth that’s causing this trend.
Fact #2: As the above population link shows, global population growth rates are slowing, and in fact there is a top-heavy population structure in most European countries. As Third World countries develop, they too will follow this trend. See US census predicts slowing growth rate… yes, that’s a slowing rate, not a decreasing population, but if you extrapolate that trend forward one must conclude that global population will begin to decline late in this century.
Conclusion: we should expand fossil fuel use as fast as possible in order to bring the Third World up to the development level of the US and Europe, which will lead to a decrease in human population - and that means less body heat, and therefore, global cooling.
Cheers!
9 May 2007 at 2:38 PM
Timothy Chase wrote: “For example, omphalosian creationists argue that the world is young but accept the existence of all the evidence that the world is old, arguing that the world was created only 10,000 yrs ago, including all of the evidence which gives it the appearance of being very ancient. Of course one could argue that it was really created only five minutes ago, including even our memories which give it the appearance of being older.”
Actually the entire universe, including our memories and everything else that makes the universe appear “old”, came into existence one nanosecond ago. And this happens continually. Each and every nanosecond, a new universe comes into existence which is then replaced by a new one the next nanosecond.
9 May 2007 at 2:56 PM
You can explain GW in the same way. It correlates quite nicely with the number of TVs in the world.
However, your analysis is just stupid and you miss the point.
There is a clear correlation with solar activity over the long term record.
That is not explained by solar radiation.
Then the AGW activist claim that the solar activity can’t be the cause.
A clear error in logic. There is another mechanism that does explain the correlations. The science is missing a mechanism and the AGW advocates have got quite rightly hot under the collar about one of the proposals.
The reason is that it blows out of the water the anthropogenic effect of GW.
9 May 2007 at 3:14 PM
@Nick (Post#14)
Was your post intended to be nonsensical?
9 May 2007 at 3:23 PM
Gavin,
You said this:
“And frankly, the projections from simulations done 20 years ago stand up very well to what actually happened.”
Could you provide pre-1987 citations for for the simulations you believe stand up well to what happened in the past 5 years? And could you provide pre-volcanic explosion citations that agreed well with what happened after said volcano exploded. And so on?
Presumably, if these predictive simulations were published before the events occurred, and later validated against what happened, it should be possible to post the early publication dates.
Thanks!
[Response: Hansen et al, 1988 (simulations done in 1986/87), Hansen et al, 1992. - gavin]
9 May 2007 at 4:01 PM
How do you know that senators of a certain type aren’t affecting sunspot activity? It seems to me that you’re assuming sunspots to affect electability when maybe the effect works in the other direction.
9 May 2007 at 4:03 PM
Having spent 30 years in the U.S. television industry as a meteorologist (something I at times am slow to admit for obvious reasons), I have encountered many people who “do not get it”. Happily most I have encountered will defer to someone with a base of knowledge to ensure the accuracy of the final product. The “it” some do not get is that attention to minute details is what often separates “good science” from “bad science”. In that vein “adventure science” often crosses the line.
There are many examples of “production value” trumping “scientific accuracy”. Sadly the very definition of “creativity” is convoluted in the process. What is ultimately described as creative by writers and producers of a science program is just the opposite, not creative and just maybe the easy (read - lazy) way out.
The truly creative TV writer/producer finds a way to grab the audience and keep its attention using the facts at hand but many ignore the facts or invent situations because they cannot adequately deal with what they perceive as mundane. Of course we cannot ignore blatant advocacy and willful distortions, a possibility in the case described above. Then again maybe that situation is just ignorance.
Before I go on I must emphasize that a TV program cannot read like a peer reviewed journal article. No one will benefit if the bored audience yawns then changes the channel. Even PBS ( for those not familiar it is the non-commercial Public Broadcasting System funded by tax payer dollars in the U.S.) seems to be catching on. “Brains boiled and heads exploded,” is how they promoted an episode of “Secrets of the Dead” about the encounter of the residents of Herculaneum with a pyroclastic flow from Mt. Vesuvius. I watched and the program delivered an accurate and very interesting portrayal of the sciences involved. Though it accurately describes what happened, I still am uneasy with the “brains boiling and heads exploding” imagery used for promotional purposes.
Who can forget the giant block of permafrost swinging beneath a soviet helicopter with the ancient tusks of a mammoth protruding against the Siberian sky in a Discovery Channel documentary. The problem is the tusks were recovered three years earlier and this one scene mislead the audience about the tedious work of excavating in a harsh environment. The tusks were attached by a TV crew for dramatic effect.
Or the “educational documentary” in a local TV market on the plate subduction volcanoes surrounding the Pacific Ocean called “The Ring of Fire”. The problem is that the show was video taped in Hawaii and to the amazement and disgust of geologists in that market no distinction was made between “hot spot” volcanoes like Hawaii and the volcanoes that result from the subduction of continental plates like those found in the Andes, the Aleutian Islands, Japan and Indonesia. I suppose Hawaii was an easier destination to deal with. The uninformed audience was mislead.
My experience has shown that there is a dual problem in many lower budget TV productions: 1) Too many in the TV industry lack a broad base of knowledge and when it comes to science they are stumbling around in a wilderness bare foot and blind folded. 2) Without the economic resources to hire “experts” to guide the course of the program’s science writers and producers often opt for conventional wisdom, which of course is not always correct.
9 May 2007 at 4:26 PM
I like this theory. At least it seems more plausible than the idea that the majority of voters actually chose some of these guys. But forget about manipulating the data, what’s really important now is figuring out a way to adjust the number of sunspots so the Democrats win in 2008.
9 May 2007 at 4:34 PM
Personally I prefer the inverse pirate theory of global warming, showing that the lower the number of pirates the higher the global temperature
9 May 2007 at 4:40 PM
I loved your correlations and I loved the explanation in 2004 that even though the first 800 years of warming in a 5000 year trend were not caused by CO2, that didn’t mean that the other 4200 years couldn’t be.
By that logic, I can say that just because some very wealth individual didn’t give me money in my first 6 decades they won’t from now on.
Sorry, that a logical non-sequitur. Saying that because there wasn’t the proposed correlation in the past doesn’t preclude a future relationship, is a thinly veiled attempt to imply that there is/will be the proposed correlation (and reverse causation) in the future.
Doesn’t work that way. Dung does not cause full stomachs in cows either.
9 May 2007 at 4:58 PM
1987,1988… hey, this isn’t a phase shift, it’s just that global sulphur emissions started to decline since then.
>http://www.rpi.edu/%7Esternd/Sulfur.html
We all know this changes a lot because our level of scientific understandig with respect to sulphur emissions is rather low.
9 May 2007 at 5:27 PM
Gavin, there’s no such word as excoriable. I think you mean execrable - which fits perfectly. On the other hand, you could excoriate the programme, perhaps making it “excoriable”… but I think we’d better leave constructing new words to the psychosolar connectionists.
Yours,
A Pedant.
[Response: Hmmm… excoriate (def. #2) means to censor strongly; to denounce. Excoriable means capable of excoriation, and so implicity means ‘capable of being denounced’. I’d be happy with execrable as well of course…. - gavin]
9 May 2007 at 5:51 PM
RE # 20, Eli,
I find your source for the higher priates and global warming is hardly credible. It carries less scientific rigor than that of a theory I found on another blog which attributes increasing SST with the repeatedly observed setting of the sun into the Pacific Ocean.
9 May 2007 at 5:56 PM
Thomas,
Not in the least bit nonsensical.
The arbiter in cases such as GW has to be statistical.
Climate change is not weather, it is long term observation and statistical analysis. You will no doubt agree that anyone who claims that a hot month in a particular local is proof of GW is barmy. The reason is that it is statistical proof that matters.
In the case of GW, even the IPCC admits that there might (only might) be proof on the 50 year average. This is a very weak standard.
Statistical methods in this case, because the evidence being claimed is statistical, is the way to go.
Now the original article is clearly a spoof as you know. However, within it is the nub of the argument. The writer believes in AGW. They have attempted to show that correlation is not causation. In this case because there isn’t a physical explaination behind the causation.
However they have missed the point. If there is correlation, it doesn’t mean that one particular causation explains all the correlation.
i.e. To say that solar radiation explains only a small percentage of the correlation, doesn’t mean that solar effects are not present. It could be random chance (unlikely in this case) or more likely, that a particular physical explaination has been missed.
Think about the statistical tests of this part.
Nick
9 May 2007 at 6:56 PM
Re:21 “By that logic, I can say that just because some very wealth individual didn’t give me money in my first 6 decades they won’t from now on.”
That’s not logic, it’s rhetorical analogy. And a pretty stupid one at that.
9 May 2007 at 7:05 PM
I had a look at Hansen et al, 1988, how much of the temperature change over the last 20 years has been due to the present getting warmer and how much to the past getting colder?
9 May 2007 at 7:55 PM
I had been told by a colleague that “RealClimate” was a good source for disinterested information on clmiate change. Not the right day to check in, I guess, but “Fun with Correlations” is a disqualifying front page article in that regard. I’ll keep searching, but have fun with your site, anyway!
9 May 2007 at 7:57 PM
This post really is a poor effort at humor. Not that long ago you lost a debate because you were unable to present arguments sufficient to convince an audience of the merits of a position which, I suggest, you consider unassailable. Now we see this rather silly post. Try to stick to science rather than bad attempts at statistical satire. Otherwise you run the risk that readers will agree with poster #9’s comment that “This is odd to read. It looks like statistics and correlation is (sic) all new to you guys”.
9 May 2007 at 8:24 PM
Re: #20
Eli, the problem with the inverse pirate theory is that there is never any evidence presented that the number of pirates globally has actually decreased, in fact the opposite seems to be the case. Putting aside software piracy, actual maritime piracy may have decreased in the Caribbean and the Americas generally, but it flourishes elsewhere in the world, most notably in the Malaca Strait. To quote from Wikipedia:
“Piracy in the Strait has risen in recent years. There were about 25 attacks on vessels in 1994, 220 in 2000, and just over 150 in 2003 (one-third of the global total).”
Indeed according to one estimate “The total damage caused by piracy-due to losses of ships and cargo and to rising insurance costs-now amounts to $16 billion per year.” <http://www.foreignaffairs.org/20041101faessay83606/gal-luft-anne-korin/terrorism-goes-to-sea.html>
So much for the inverse pirate theory. I hasten to add that this in no way undermines FSM theory in general.
9 May 2007 at 8:56 PM
#25 Nick, I still can’t tell if you’re joking or not. Are you trying to make fun of statistical analysis of correlations, i.e. r-factors?
Assuming for a second that you’re being serious, an increased greenhouse effect due to increased greenhouse gases should cause cooling of the stratosphere…but warming due to increased solar output should cause warming of the stratosphere… or am I missing something? I feel like I’m falling for a joke, though.
9 May 2007 at 10:02 PM
Doc Martyn puts the steel toed boot in his mouth. Since, as far as we know the past is not currently changing and we have no good observations of the future, one can only compare predictions made in the past with what happened until today. The fit is quite good, excellent in fact, but Doc appears to have some unspoken problem with that.
As to Gavin’s experience on the West Side, this little jibe is exactly what he needed. Something to illustrate, in an amusing way the falacies he was bombarded with.
9 May 2007 at 10:15 PM
Is the purposed of this forum to discuss climate change? The 20th century warming was 0.6C in a 100 years. The 8200 yr cooling event was a 2C to 3C cooling in 100 years. Why did the Pacific Ocean cool 3C during the 8200 kyr event?
The paleoclimatic record has a series of warm events followed by cold events. I will take bets that a cold event will follow the 20th century warm event.
The 8200-year Climate Event
http://www.geo.arizona.edu/palynology/geos462/8200yrevent.html
I am curious how an abrupt stoppage or perturbation of the North Atlantic thermohaline circulation (THC) �Could have caused an:
“Abrupt tropical cooling 8,200 years ago”, (3C cooling in 100 years) in Alor Indonesia, which is in the Pacific Ocean not the Atlantic Ocean, 3C cooling in 100 years.
From M.K. Gagan et al.’s paper:
“We drilled a sequence of exceptionally large, well-preserved Porites corals within an uplifted palaeo-reef in Alor, Indonesia, with Th-230 ages spanning the period 8400 to 7600 calendar years before present (Figure 2). The corals lie within the Western Pacific Warm Pool, which at present has the highest mean annual temperature in the world’s ocean. Measurements of coral Sr/Ca and oxygen 18 isotopes at 5-year sampling increments for five of the fossil corals (310 annual growth increments) have yielded a semi-continuous record spanning the 8.2 ka event. The measurements (Figure 2) show that sea-surface temperatures were essentially the same as today from 8400 to 8100 years ago, followed by an abrupt 3C cooling over a period of 100 years, reaching a minimum 8000 years ago. The cooling calculated from coral oxygen 18 isotopes is similar to that derived from Sr/Ca. The exact timing of the termination of the cooling event is not yet known, but a coral dated as 7600 years shows sea-surface temperatures similar to those of today.”
9 May 2007 at 10:18 PM
I’m sure RC already know this, but now even the solar variability theorists have complained about TGGWS, for embellishing the solar variability data and unduly ruling out any AGW contribution: http://news.independent.co.uk/media/article2521677.ece
9 May 2007 at 10:31 PM
There does appear to be some strange correlation of solar activity and 20th century warming. Is this only a coincidence? Note the period of high solar activity is over. Will there be coincidental cooling also? Anyone one to make a bet?
2005 paper by Georgieva, Bianchi, & Kirov �Once again about global warming and solar activity�
http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf
CMEs, however, are not the only source of high speed solar wind. Early in the 20th century it was noticed that many geomagnetic storms occur without any visible solar disturbance. Such storms tend to recur every 27 days - the period of solar rotation, therefore they originate from long-living regions on the Sun which come back into geoeffective position rotation after rotation. Only when X-rays telescopes were flown above the atmosphere, it was found out that are large regions of open magnetic field geometry, and sources of high speed solar wind. They are now known as Coronal Holes (CHs) because, due to their lower density and temperature compared to the surrounding corona, they look darker in X-rays.
In Figure 6 the long-term variations in global temperature are compared to the long-term variations in geomagnetic activity as expressed by the ak-index (Nevanlinna and Kataja 2003). The correlation between the two quantities is 0.85 with p<0.01 for the whole period studied. It could therefore be concluded that both the decreasing correlation between sunspot number and geomagnetic activity, and the deviation of the global temperature long-term trend from solar activity as expressed by sunspot index are due to the increased number of high-speed streams of solar wind on the declining phase and in the minimum of sunspot cycle in the last decades.
9 May 2007 at 10:32 PM
Nick (#25), you are being disingenuous.
No one in their right mind claims that the solar forcing plays no role. In fact the IPCC views the variation in solar behavior as having played a substantial role, perhaps even the majority role in forcing climate changes during the earlier half of the twentieth century. As such, you are being misleading when you state, “However they have missed the point. If there is correlation, it doesn’t mean that one particular causation explains all the correlation.”
However, clearly carbon dioxide has played a substantial role over the past 500,000 years - and we have a considerable amount of evidence for that. As such, you are being misleading when you state, “In the case of GW, even the IPCC admits that there might (only might) be proof on the 50 year average. This is a very weak standard.”
*
What we have is evidence from a vast number of independent lines of investigation all pointing to the same conclusion: that anthropogenic forcing is resulting in a dangerous rate of climate change. We can measure the level of carbon dioxide being emitted. We can identify its manmade origin by tracking the isotopes. We can identify the highly robust correlation between carbon dioxide and global temperatures which have existed for at least the past 500,000 years.
Moreover, we know how the physical principles by which global temperatures and levels of carbon dioxide are related. Increased temperatures in the past (e.g., due to changes in the earth’s orbit) have resulted in the earth’s climate entering a state of non-equilibrium, where more carbon dioxide is emitted than naturally sequestered, leading to a positive feedback loop. For example, with higher temperatures, the ocean’s capacity to sequester the carbon dioxide that it is already saturated with is lowered, resulting in the emission of carbon dioxide into the atmosphere.
However, as carbon dioxide absorbs wide bands of infrared light (i.e., the earth’s blackbody radiation), it absorbs then re-emits thermal energy, some of which is reabsorbed then re-emitted by the surface. As a consequence, there exists positive feedback between the thermal energy emitted by the ground and the thermal energy emitted by the atmosphere - but where some of the thermal energy is lost to space in each successive round - necessarily avoiding a vicious “run-away” effect.
For the earth-atmosphere system to reach a new equilibrium, the amount of energy going into the system has to equal the amount of energy leaving the system, but with more carbon dioxide in the atmosphere slowing the dissipation of such energy from the earth, this can only be achieved at a higher temperature where the thermal energy radiated by the system as a whole into space is once again raised so that it equals the thermal energy being received from the sun.
If one increases the temperature of of the earth by increasing the the amount of energy it receives from the sun, this raises the level of carbon dioxide. But likewise, if one raises the level of carbon dioxide, this increases the temperature. Positive feedback - like the “thermal flux” feedback between the earth and its atmosphere that keeps the average temperature of the earth above freezing. It effectively comes to an end when a new equilibrium is reached. Simple, demonstrable physical principles.
*
You know that hot bodies emit radiation: you have seen embers and hot metals glow with heat. You know that infrared radiation exists: you have seen infrared night vision - and you know that bees are able to navigate by the sun on an overcast day. You know that materials can be opaque to a given part of the spectrum: you have seen colored filters. You know that when matter absorbs radiation, it heats up: no doubt you have seen and felt this in the case of asphalt on a hot summer day. You know that we can measure different parts of the electromagnetic spectrum, from gamma rays to longwave radio frequencies. You know that the sky is blue because it is opaque to and scatters blue light.
Each and every step is something which you can no doubt understand. Undoubtedly you realize that empirical science has a genuinely scientific grasp of the principles involved - which goes well beyond what either you or I could know without a great deal of study. Yet you fall back upon upon freshman philosophy in opposition to what is known by means of modern empirical science. You latch on to Hume’s critique of causality as if to claim that no matter how many times we see a hammer fall to the ground when released, we have no more reason to think that it will fall if released again than if we were as innocent of experience with hammers as a newborn babe. You avoid what should now be as clear as day, like a modern-day Descartes staring at his hand with limitless doubt.
Why?
9 May 2007 at 11:56 PM
Re # 9, 29 [It looks like statistics and correlation is all new to you guys.]
Let’s see what qualifications these RC contributors have:
Schmidt: BA (Hons) in Mathematics from Oxford University, a PhD in Applied Mathematics from University College London
Mann: undergraduate degrees in Physics and Applied Math from the University of California at Berkeley, an M.S. degree in Physics from Yale University, and a Ph.D. in Geology & Geophysics from Yale
Steig: BA from Hampshire College at Amherst, MA, and M.S. and PhDs in Geological Sciences at the University of Washington
Connelley: B.A. in maths from St Edmund Hall, Oxford; doctorate in Numerical Analysis at Oxford
Bradley: Director of the Climate System Research Center at the University of Massachusetts, Amherst and a University Distinguished Professor in the Department of Geosciences. B.Sc. 1969 University of Southampton, England; Ph.D. 1974, M.A., 1971 University of Colorado, Boulder; D.Sc 2003 University of Southampton
and so on. Nope, no evidence I can see that anyone here knows beans about statistics.
Re# 18 A bit off-topic, but years ago I knew a grad student who, while at Texas A & M Univ., had spent several months on a cruise in the Gulf of Mexico aboard Jacques Cousteau’s Calypso. He said they routinely staged shots, such as a “migration” of spiny lobsters which had just been pushed out a PVC pipe, and footage supposedly filmed in Antarctica, but in fact shot in the Gulf of Mexico in September, in 90 degree (F) heat - the crew wore shorts under their down-filled parkas. And J.C. himself (Cousteau, that is) was helicoptered out to the ship so he could appear in a few segments. And I just read about some well-publicized, and quite stunning, video footage of a human fetus in the womb - turns out the fetus was a wax model. Fortunately, as the Discovery Channel’s Planet Earth series shows, it is possible to depict nature as it really is, if you’re willing to spend a lot of money and a heck of a lot of time, and put the photographers at great risk, to get the shots.
10 May 2007 at 12:08 AM
Re. 11 Gavin said, “…physical modelling is the much better way to go (obviously since I work in a GCM group). However, I disagree that this cannot be tested. The models that are built can be tested in dozens of ways to verify key feedbacks and mechanisms - response to volcanic eruptions, solar forcing, orbital forcing, ENSO variability, NAO or SAM responses, the last glacial maximum etc. And frankly, the projections from simulations done 20 years ago stand up very well to what actually happened.”
This raises the complex issue of the link between types of experiment and quality of evidence.
True, “correlation does not equal causation”, but we rely on this equality for randomised controled trials (i.e. experiments). Controlled experiments are generally regarded as providing the best level of evidence linking cause and effect. One variable is manipulated in the test group while held constant in the control group. Ideally all other variables are held constant or experimentally units are randomly allocated to the two groups so that statistical tests of outcome are valid. The difference in outcome between the test and control groups is observed. This experimental process also underlies the discovery of the physical laws programmed into GCMs.
As for physical models, George Box said, “All models are wrong, some models are useful.”
http://www.garyfeng.com/wordpress/2005/05/11/all-models-are-wrong-some-models-are-useful/
A classic recent example in supernova SN2006gy, the largest supernova ever observed, which fell outside the standard models of supernovae explosions (and provided physical evidence for an alternative model, the “pair instability model”):
http://en.wikipedia.org/wiki/SN_2006gy
A recent failure of modelling bearing on GCMs may be that ice sheets are melting much faster than predicted - due to poorly understood mechanisms. (Ice sheets don’t just melt from the top.)
http://www.realclimate.org/index.php/archives/2006/06/ice-sheets-and-sea-level-rise-model-failure-is-the-key-issue/
Like astronomical models, climate models are not susceptible to normal experimental verification - test vs control. However, as Gavin opoints out, they make predictions and can be checked against those predictions. Together with environmental evidence, GCMs provide the best evidence of climate change in response to GHGs. It is possible that poorly understood mechanisms could invalidate aspects of the link between GHGs and temperature in GCMs, but the error could go either way. So only a fool would bet on GCMs being wrong. And it would be immoral for such a fool to make decisions over energy policy etc. on behalf of the rest of us.
10 May 2007 at 12:35 AM
On the topic of confusing data - can anyone tell me why the two global temperature graphs at
GISS and the Hadley Centre (shown below) look so different for the last six years? The Hadley Centre graph appears to show a leveling off but the GISS graph does not. Is there some subtle difference in what they are measuring? If so, can anyone refer me to a resource that explains the differences?
[Response: There is a difference in how the interpolate between data stations, particularly in the Arctic - HadCRU does not estimate Arctic ocean temperatures from nearby coastal data, while the GISS analysis does - given the warmth of the Arctic in recent years, that gives make the GISS anomalies slightly warmer. The ongoing sea ice retreat is probably corroborating evidence that this is a reasonable procedure. Look at the spatial maps of anomalies to see this more clearly. -gavin]
10 May 2007 at 3:33 AM
I am a believer. Actually, I have been convinced by the aliens who took me from my island into their spacecraft : the Republicans are definitely a species which evoved from planet Neptune, where World Climate has found their best correlation proof.
10 May 2007 at 4:38 AM
Thanks Gavin for pointing out that just because C02 has risen
and temperatures have risen, it does not follow that one causes the other.
As an alternative to the pirate theory, there is also the skirt hem height
theory, levels of which were very low in the early 20th century but have risen
alarmingly in recent years, correlating well with increased temperatures!
Several possible mechanisms suggest themselves, such as increased metabolic
rates of observers.
This would also explain why warming has not occurred in Antarctica.
As for Friis-Christensen and Svensmark, suggesting that the Sun might have
something to do with the Earth’s climate, well, how ridiculous.
Next they will be suggesting that the Pope is catholic.
[Response: You misunderstand my point. I have no problem with the sun affecting the Earths climate - I have been an author on multiple papers demonstrating this (most recently Shindell et al, 2006) - and nowhere have I ever claimed that CO2 is important based solely on a correlation. FC&S 91 was bad not for what it purported to conclude, but for how it did it. That was evident at the time, and subsequent data showed that the relationship they found had no predictive quality. - gavin]
10 May 2007 at 4:49 AM
Hmmm. I can do you a theory which ties mineral oil production to isotope signals — I don’t think the conventional CO2 theory does this very well as isotope signals appear in 1850 and AFAICT the real effect of greenhouse warming doesn’t show up until later. My theory even covers the SST temperature spike during WWII when the oil spill in the NH was enormous, mostly because of the Kreigesmarine submarine offensive. This inadvertent experiment shows a perfect rise in accordance with my oil sheen hypothesis.
You now go and look at the Hadcru graphs and come back with the reasonable point that the SSTs begin to rise two years earlier than the submarine offensive. Aha, I riposte, you need to use the unadjusted graph: the graphs normally available are adjusted for a change in how the temperatures were taken, by bucket or in the engine intake. If you eliminate the adjustment then my theory is triumphantly vindicated. Intrigued by this, I wondered about the correction: apparently, without an SST correction, the GCMs don’t produce a realistic land temperature during the 30s and 40s. This is a great shame. In order to make the world fit my theory then I have to change back data which was altered to fit a rather more expensive theory. Perhaps my horse is at rather long odds in this race, not being the result of science crossed with supercomputer technology, but isn’t it a pity that the data was altered in the first place? Back to the drawing board.
While on the subject of isotopes, is there a graph anywhere which covers a couple of hundred years of delta C13 values? I’ve looked round the web and can’t find anything. It needs to be a graph because I am a nurseryman of little brain and I need to look at pictures. I reckon I might be able to correlate leachate composition of volcanic ejecta and delta C13 values. Now that would be a really good bit of crackpot science!
The whole article shows, of course, how important it is to use raw data and not to quibble when things go wrong. That’s why the oil sheen theory was born, an object lesson in the error of post hoc ergo propter hoc. Using raw data I think it’s still on all four legs. Just.
JF
10 May 2007 at 5:08 AM
Timothy,
I’m quite aware of what the proposed causes are for anthropogenic C02 affecting climate.
However, the mistake you have made is this.
You have made your plausible explanation the null hypothesis and not applied a test that shows that your plausible explanation is what actually has taken place.
The null hypothesis is that there is no AGW.
Part of the proof of AGW is to show that current climate diverges from the null hypothesis by a statistically significant amount. That has not been done at all.
If it had been done, then the IPCC would be able to point out just how much of climate is affected by particular forcings. It can’t yet do that.
[Response: You are incorrect. This cannot be given exactly due to the uncertainties in the forcing history (particular for aerosols), small variations in efficacy, and the remaining uncertainty in climate sensitivity. However, you can easily compare the impacts of different forcings - see here or here. -gavin]
Let me explain more about the null hypothesis and a statistical test.
The null hypothesis is no AGW. So we take climate prior to 1900 (industrialisation) and take the historical record for climate. Here we are talking about temperature proxies, orbital mechanics, solar proxies, vocanic eruptions, C02 records.
Given this data it is possible to build an analysis that shows if a particular input affects the output, the extent to which it effects the output. At the end should be a random residual. If it is not random, then there is a missing input into the system.
The systems will clearly be guided by the sorts of models of which you are aware. For example, its pretty clear how volcanos affect climate. We have lots of data to make an accurate model.
Once you have a good model for the long term climate, you know look at the data post 1900.
You can ask the question, do we need to introduce any extra variables such as anthropogenic C02 to get a fit?
You can also ask, just how much of a difference does this extra C02 make and is it statistically significant.
The IPCC can’t yet do this.
Does it matter?
Of course it matters. If anthropogenic C02 only makes up a small fraction of the change in climate, then a lot of money is going to be spent with very little resulting effect.
Nick
10 May 2007 at 5:27 AM
Huh. Your theory doesn’t explain Bernie Sanders. Because of that, I reserve the right to dismiss everything you say about anything, ever.
10 May 2007 at 5:50 AM
I think that a distinction has to be made between prospective versus retrospective scientific studies. For instance, what is the probability that one could open a large phone book and find, at random, a page that contained five listings that ended in the same number? Answer: Quite low. However, start at the beginning of the phone book and search every page until the end, what then, is the probability of finding five listings that end in the same number? Answer: Virtually one.
When was global warming identified as a major issue? Late 1970s? Certainly, by the mid-1980s, because the National Academy of Sciences was sponsoring educational programs on the subject! Are we to believe that it is mere coincidence, that is, “natural variability,” that the warmest years on record have occurred since then? Improbable, to say the least!
10 May 2007 at 6:26 AM
#35, Svet,
Vose et al; “An intercomparison of trends in surface air temperature analyses at the global, hemispheric, and grid-box scale.” GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L18718, doi:10.1029/2005GL023502, 2005
They find that when you use the same method of processing you get the same results for GHCN/GISS/CRU.
The reduction of trend is because the Southern Hemisphere is warming less rapidly than the Southern Hemisphere, and CRU (on whom the Met Office graph is based) average the 2 hemispheres - that causes the difference. GISS use grid-box averaging. The apparent reduction of trend appears to be an artefact of processing.
#28, Walter Manny,
Your friend was right, this is an excellent site. If you’ve actually read the papers Gavin mentions the point of his seemingly frivolous article becomes all too apparent. There is a very serious point behind it about some dubious “science”.
Gavin,
Thanks for another excellent post.
10 May 2007 at 6:28 AM
I always found that RealClimate was just a political propaganda blog from a small group of climate politicians, so I am happy to note that there are actually real scientific discussions on your site.
10 May 2007 at 7:37 AM
#35 - Svet
The GISS and Hadley Centre datasets that you point to terminate at different years - Hadley runs to 2006, whilst GISS runs to 2003.
10 May 2007 at 7:37 AM
The truth of the republican reign has now been revealed. It is our duty to improve the world, even if all republicans must be tagged and sent to Australia.
10 May 2007 at 8:12 AM
More fun with correlations; some have even appeared in the peer-reviewed literature.
10 May 2007 at 9:13 AM
Great post! And what a debate - I especially love the pirate vs. temperature correlation, a graph of which I have on my office wall. Maybe you should change the name of the blog to Real Humor.
[Response: Maybe, but I’m not going to give up the day job… - gavin]
10 May 2007 at 9:42 AM
Re: 38, 16, 45
Re: 38, Bruce:
Thanks for the excellent post. I agree that we are discussing a spectrum of theory validation ranging from replicable tests of a roughly isolatable phenomenon like dropping a ball in a near-vacuum to test F = MA at one end and something like econometric models predicting global GDP growth at the other.
I find your astronomy analogy interesting and useful (but I used to do astrophysics, so I’m probably biased!). The big distinction, I think, between astronomy and climate modeling is that there are many, many “natural experiments” in the observable universe. Therefore, while we can’t conduct controlled trials (as you say, the scientific gold standard for asserting causality), there is an opportunity to make numerous observations of different events and compare them to post hoc controls.
I agree that “doesn’t meet the highest asserted level of possible scientific proof” does not equal “valueless”, and that it would be foolish to ignore the information provided by climate science just because it is imperfect, though I do think that trying to understand this uncertainty, and ideally bound it, is an incredibly important activity to support policy development.
Re: 16, Margo / Gavin:
I think it’s only fair to include Hansen’s own review of the predictive performance of these models in the NAS paper that he authored in 2006:
http://www.pnas.org/cgi/content/full/103/39/14288?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=hansen+2006&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT
Hansen’s take, expressed in this article, was that “a 17-year period is too brief for precise assessment of model predictions”.
Gavin, we’ve had this discussion before, and I know that you (reasonably) draw a distinction between an assessment and a “precise assessment”. I won’t (re-)bore everyone with a repeat of the model evaluation discussion. Margo, you strike me as a very sophisticated analyst of model performance, and I’m sure you’re competent to read the base papers and come to your own conclusions.
Re, 45, Don:
That strikes me a great, commonsense point. An issue, though, arises if the series under consideration is autocorrelated. Such a series will usually have sub-series trends (e.g., temperatures increasing) that will run for some amount of time and then reverse to create a sub-series running in the opposite direction, rather than simply being random walks. This kind of a series - think of certain parts of the stock market - is notorious for fooling people into thinking they have built predictive models that are “right” for a while until they are suddenly, unexplainably wrong.
Best,
Jim
10 May 2007 at 10:00 AM
Gavin great comment.
Similar to the global warming/pirate graph circulating as well.
enjoyed listening to you on “TWIS” as well.
Keep up the good work!
10 May 2007 at 11:20 AM
Hansen et al 1998 predictions seem to be off now by a factor of 2.
His scenario A prediction was for a 1.0C increase (from 1958 to 2007) and his scenario B prediction was for a 0.8B increase.
Actual emissions have increased pretty close to the scenario A level although the trace gas assumption for scenario B is closer to what happened with that group.
Temperatures have only increased by 0.4C (lower than scenario C in which GHG concentrations stabilize by 2000.)
So it is good that a prediction was published but the models should adjusted now that we know they are off by a factor of 2. I’m assuming that has happened.
[Response: This is incorrect. The projections were from 1984 onwards and scenario B, which was within 10% of the actual forcings over that period were 0.23 +/- 0.06 deg C/decade compared to observations of 0.23+/-0.04 or 0.20 +/- 0.03 deg C/decade (different datasets). Error bars are just for the linear fit -i.e. the weather noise. Under no circumstance can you describe that as a factor of 2 error. This is however something that is not well appreciated and so I will do a post specifically on this at some point soon (including all the numbers so you can test it for yourself). -gavin]
10 May 2007 at 11:46 AM
Re #11
Observational vs. Historical Sciences
You might hear practitioners of “historical sciences” refer to their science as “historical,” or practitioners of “observational sciences” refer to their science as “observational,” where one is able to “control the variables” in the observational sciences. At this point, one should point out that even the term “observational science” is itself fairly misleading, at least to a novice. “Observation” is normally thought of as being passive, but in this context it is being used to refer to active methods rather than passive methods of study, suggesting what is in fact the opposite of what it is intended to imply.
The distinction has some utility in terms of the division of cognitive labor between “historical” and “observational” sciences, although it should properly be understood as not as a difference in kind but degree, with different sciences or scientific theories lying along the same continuem. However, creationists (for example) almost inevitably try to treate the distinction as a dichotomy, then claim that any science which is observational is real science consisting of knowledge, whereas any historical science is simply a matter of belief no different from matters of faith.
*
What must be remembered is simply that was we are dealing with is a continuum where the the most essential distinction which is being made is between active and passive methods of discovery, or more accurately, the degree to which one is actually able to manipulate the objects objects of study. Beyond that, some sciences are more historical than others, but that too is a matter of degree. Additionally, the subject matter of “observational” and “historical” sciences will overlap, with principles from “observational sciences” being appealed to by the “historical sciences,” or the so-called “observational science” of sub-atomic particle physics speaking of deep-time phase transitions which broke the symmetry between the four fundamental forces, further blurring the distinction. Then there is the even more basic point that when refering to earlier experiments in which one “controlled the variables,” in logic it is still possible that there are some variables that one didn’t account for and thereby hold constant.
*
For an example of where it gets properly applied, you might look at:
Edwin C. Allison Center for Historical Science http://www.geology.sdsu.edu/facilities/allisonctr/
… a center which is devoted to the “historical sciences” of “paleontology, paleoclimatology, geochemistry, sedimentology and organismal biology.”
Outside of the lingo of specialized disciplines, there are usually only two sets of occasions in which I hear of the distinction itself: one is when the distinction is being applied only in order to demonstrate that it is not a dichotomy or even particularly helpful, and the other is when creationists use it to try to argue that evolutionary biology isn’t hard science, or that for example, the soft historical science of evolution might argue for life having a natural origin, but hard observational science demonstrates otherwise.
It has a basis in the philosophy of science, but this is of little more than historical value, much like reading Descartes in a standard philosophy course. For one thing, there is no hardfast dichotomy between observational and historical science: all science is a continuum. Difference branches of science use both “observational” (by which the speaker actually means “controlled experimental”) procedures and historical methods: for example, while evolutionary biology might be thought of as essentially historical, we can observe how viruses and bacteria mutate into new species and even affect their environment so as to bring about this change, and may occasionally observe speciation at the multicellular level, particularly in plants, such as the creation of species through an active process of hybridization or polyploidy.
Likewise, astronomy would seem to be “observational” insofar as we “observe” stars and galaxies, but it generally cannot be performed in a lab, we are usually unable to set up experiments where we control the variables and thus manipulate the object of study, and what we are actually observing is what took place thirteen billion years ago or eight minutes ago in the case of the sun. So in this sense, it would it seem to be historical. But is it? At one point the moon was something we could simply observe from a distance — but now it is a place we can visit, we send probes places like Titan or Europa. Moreover, when one says that “observational sciences” make predictions in the sense that they are with regard to future events, these are oftentimes passive in the sense that one does not control the variables as one might in a lab. Furthermore, even historical sciences using “historical” methods make predictions of a sort: postdictions where they predict things which will be found.
*
Empirical science itself is a unity because reality is a unity. There exists degrees of justification, but greater and lesser degrees of justification exist throughout all of empirical science, particularly if there is any area of active study, and no one branch is truly privileged over another. There necessarily exists a cognitive division of labor due to the limitations of individual human awareness, but the criteria employed for establishing the permeable boundaries between disciplines are ultimately pragmatic in nature.
10 May 2007 at 11:46 AM
Re #42: [I can do you a theory which ties mineral oil production to isotope signals — I don’t think the conventional CO2 theory does this very well as isotope signals appear in 1850 and AFAICT the real effect of greenhouse warming doesn’t show up until later.]
Before the early 20th century, virtually all the isotope signal would have been coming from coal, not oil. The amount of greenhouse warming depends on the total amount of CO2 in the atmosphere, not on the amount being emitted at any given time. So you emit a little bit each year (and keep increasing the size of that bit), and over 150 years, it adds up to enough to produce measurable effects.
10 May 2007 at 12:18 PM
#52: Jim,
“Time will tell,” I suppose. IMHO, this is a case where Pascal’s Wager would be appropriate! Agreed?
Don
10 May 2007 at 12:26 PM
Does not matter which party is in power, it is the people who do not get elected every four years that run the Governemnt like the tri laderal commisioners and the Generals in the Armerd Forces and ofcourse the Pentagon
10 May 2007 at 2:12 PM
While y’all are having fun with the weird correlations, I’d also ask that you go down the hall (or over the web) to the other NASA-related groups that are doing solar cycle work and see if you can get a thread going on watching what effects can be observed on and near Earth — because prediction is interesting, and because predictions of a small effect followed by observations that can test whether the effect is indeed present and of the expected order of magnitude are fascinating.
Who else could we trust, eh?
If you look at these two NASA links, the latter for the next cycle, the former for the one after that — they’re expected to be quite different. If you all can get some info from the people watching whatever measures might correlate in interesting ways and make it an ongoing thread (or point us to one elsewhere) it’d be good to watch the science as it’s actually being done.
http://science.nasa.gov/headlines/y2006/10may_longrange.htm
http://solarscience.msfc.nasa.gov/predict.shtml (Updated 2007/05/03)
10 May 2007 at 2:40 PM
Gavin,
Re #16
You offer Hansen, et al. 1988 as evidence of the predictive ability of climate models. In that paper, the predicted temperature rise from 1987 to 2007 is about 0.55 ºC. This is for scenario A (continued increase in GHG emissions), which is what the world has followed since then. In fact, the actual temperature rise has been about 0.1 ºC.
I do not see how this paper supports your point.
[Response: See inline response above. Scenario B is the relevant one since that was both the ‘most plausible’ (and described as so at the time), and had net forcings that are with 10% of the actual forcings. The projection was from 1984 and temperature trends are around 0.2 deg/decade in both obs and modelling. -gavin]
10 May 2007 at 3:00 PM
RE #55
“The amount of greenhouse warming depends on the total amount of CO2 in the atmosphere, not on the amount being emitted at any given time.”
Careful about the semantics of this argument. If all emitted carbon dioxide (and other greenhouse gasses) could easily be absorbed and then sequestered by Earth’s oceans and other systems would there be any measurable global warming due to GHGs?
Is it not true that the component of global warming due to GHGs occurs because the rate of emission of GHGs exceeds the rate at which the GHGs can be sequestered?
The global average temperature at a point in time is a function of the concentration of GHGs while GH warming (the change of the global average temperature) is a function of the accumulation of GHGs.
Any one have any thoughts on this?
10 May 2007 at 3:58 PM
Steve, I think you’re confusing the greenhouse effect — which keeps the planet warmer than it would be without the greenhouse gases —- with “global warming” (increase in the planet’s temperature until a new equilibrium is reached, that follows the change in the level of greenhouse gases above the baseline).
10 May 2007 at 4:03 PM
Re: #61 (Steve Horstmeyer)
This would be true if the planet responded to GHG forcing instantaneously. But because of the thermal inertia of the oceans, it takes decades for the full response to a given GHG level to be reached. According to Hansen’s research, we have another 0.6 deg.C warming already in the pipeline, even if GHG gas levels instantly stabilize today.
10 May 2007 at 4:04 PM
‘Excoriable’? Surely you mean ‘execrable’.
10 May 2007 at 4:22 PM
#61
The rate of greenhouse warming at any given moment will be a function of the amount of greenhouse gas that is in the atmosphere and the current temperature (neglecting the spatial distributions, convection, etc.), not the rate at which greenhouse gases are emitted by sources or sequestered by sinks. However, if you wish to calculate these interdependent variables over time, ideally you would be employing partial differential equations, tracking the system to its new equilibrium state - but this is highly unrealistic. Absent the differential equations or exact solutions to them, you would employ numerical models (distributions and all), calculating each state in a sequence of states from the previous state - which is I believe how it is actually done.
10 May 2007 at 4:55 PM
The article Marsh and Svensmark 2000 requires a subscription, so I’m not sure what the object of your attack is.
In the PDF Fig 3. there’s a correlation of low cloud cover with two sunspot cycles. Is that what you were referring to? If so what’s the problem with it?
[Response: The fit to the second cycle is solely because of an added trend to the cloud cover data which has no justification in anything. See this comment - gavin]
10 May 2007 at 5:53 PM
RE #62
I think we are all saying the same thing. That is we all understand the concept but how we say it either clarifies or confuses.
My point is that for any given time period the concentration of GHGs determines how much infrared radiation is retained by the atmosphere. During the next time period if the concentration of GHGs increases, all other factors being equal, the temperature can be expected to be higher. Both time periods have a greenhouse effect but the second time period has an enhanced greenhouse effect, because of the accumulation of GHGs.
So the change of greenhouse effect is “global warming” in this example. If we detected no increase of average temperature there would still be a greenhouse effect but no global warming.
So global warming ocurs over time because during that time GHGs accumulate.
RE #63
I have to think about your comment. Nothing happens instantly and because the response time of the climate system has a measurable lag doesn’t seem to change my thinking.
I made the point because I was listening to a “progressive” radio talk show (The Ed Schultz Show) as I was reading the comments here and a caller made several points including citing Milankovitch (”…that name I cannot pronounce…”, he said),Hertzberg (the explosives expert) and the lag of the build up of cabron dioxide after warming begins. He had many snippets of information but was confused by it all and certainly did not have a coherent picture of the various processes. From his tone though I thought he was earger to understand. I therefore posted my comments to make the point that clear language is essential if the public is to be educated on global warming.
Comments?
10 May 2007 at 5:59 PM
Very Interesting! As a registered democrat(in the U.S.) I would like to see a minimum of sunspot activity in the coming decades for the sake of our planet. This analysis corroborates the old saw ” there are liars, damned liars and statistics”. It seems as though there are lots of the two former categories on the skeptic side of the aisle.
10 May 2007 at 6:16 PM
“But because of the thermal inertia of the oceans, it takes decades for the full response to a given GHG level to be reached.”
Well there seems to be an easy test, take a pair thermally isolated tank of salt water, some 30 meters deep and irradiate the surafce, open to the atmosphere with additional IR source masked by a CO2 shroud. Measure the temperature of each tank at half meter depths and monitor any temperature difference. You might also wish to monitor the depth of the tank.
This model is a very good test for the impact of elevated levels of CO2 on the ocean temperature.
If the surface of one of the tanks is blasted with an additional 8w/m2 of IR radation, what will be the steady state temperature difference in the two tanks after a year?
My estimate is as close to zero as the noise allows, although the debth will have changed.
What is your prediction?
10 May 2007 at 7:10 PM
In reponse to #50 and #60 Gavin, you note that from Hansen et al 1998 - “net forcings are within 10% of the actual forcings”
What exactly does that mean?
I note that the emissions have grown somewhere between Hansen’s Scenario A and Scenario B.
Scenario A’s forecast had temperatures increasing 0.85C from 1984 to 2006 and Scenario B had temperatures increasing 0.6C from 1984 to 2006.
By my reckoning, the Hadley Centre’s global temperature estimate is an increase of 0.25C from 1984 to 2006.
So the forcing estimate was within 10% but the temperature prediction was off by more than 100%??
[Response: This isn’t going to be clear until I show the figures and analysis, so give me a few days to put it together properly. The numbers are as I stated above. - gavin]
10 May 2007 at 7:30 PM
There is another point about statistics that seldom gets mentioned and is widely misunderstood, and that is that attribution of variance is not the same thing as an attribution of a trend.
If one does an analysis of continuously measured temperatures, for example, the strongest terms would be the daily and seasonal cycles. Whether it is day or night, summer or winter, are the strongest determinants of temperature. If one did such an analysis even over a hundred years of steadily rising temperatures, that would still be the case. So then there would be some that dismiss the temperature rise as being irrelevant to the temperature outside; after all, time of day and season of year are the main contributors to variance. So why even consider that there is a warming trend?
Actually, I’ve seen this sort of reasoning used pretty regularly on hurricane data. Cycles dominate the variance statistics, so trends must not matter.
10 May 2007 at 9:09 PM
Re 52 Jim,
Thanks for the kind comments and the reference to the Hansen paper, which is fascinating, particularly with it’s warning of increased likelihood of El Ninos, a major concern in our part of the world (Australia).
I agee with your comments. I have a chemical engineering - biomedical engineering and biostatistics background, the last of which often has me asking about the quality of evidence.
To take a medical example, we don’t have experimental evidence (the gold standard) that smoking causes lung cancer in humans (imagine trying to enrol people in an randomised trial). Yet the observational evidence (from “natural” experiments) is so overwhelming that only a tobacco industry executive could fail to see it.
The science of climate change is perhaps one rung lower on the quality of evidence scale, but the moral issues are overwhelming. In essence we have an N=1 observational study. But unlike the smoker, the outcome of this natural experiment has significant likelihood of harming those with little or no control over the “manipulated variable”.
Cheers,
Bruce
10 May 2007 at 9:16 PM
Just saying,
The correlation of sunspots to global temp actually fits much better than this, especially over time.
[Response: For very similar reasons…. -gavin]
10 May 2007 at 9:50 PM
Re #69 Doc Martyn,
“Well there seems to be an easy test, take a pair thermally isolated tank of salt water, some 30 meters deep and irradiate the surafce, open to the atmosphere with additional IR source masked by a CO2 shroud. Measure the temperature of each tank at half meter depths and monitor any temperature difference. You might also wish to monitor the depth of the tank.
This model is a very good test for the impact of elevated levels of CO2 on the ocean temperature.
If the surface of one of the tanks is blasted with an additional 8w/m2 of IR radation, what will be the steady state temperature difference in the two tanks after a year?
My estimate is as close to zero as the noise allows, although the debth will have changed.
What is your prediction? ”
I’ll do a crude calculation to give you my prediction:
Assume the area of the 30m tank is 1 m2. First the energy added:
8w/m2 in one year is 8 J/sec *3600sec/hr+24hr/day*365 days/year = 252 MJ
Now the water’s response. The sepcific heat of water is about 4.2 J/g.C, which is 4.2 MJ/tonne.C. 30 metres of water with cross section 1 m2 is 30 tonnes.
Assuming the water is well mixed and the heat distributes evenly it will take 30*4.2=126 MJ to raise the water by 1 degC
So with 252 MJ we have a temperature rise of 252/126=2.0 deg C.
Sounds like a good high school experiment. You could measure it with a lab thermometer. Certainly well above the noise assuming you can properly isolate the test and control tanks.
Bruce
10 May 2007 at 10:31 PM
In 70, John Wegner states:
“Scenario A’s forecast had temperatures increasing 0.85C from 1984 to 2006 and Scenario B had temperatures increasing 0.6C from 1984 to 2006.”
To understand the kind of sophistry John is practicing you have to look at the graph of the predictions vs. the obervational record.
1984 in the model was a very low point, due to variability in the model and a bit from El Chichon. By measuring from a low point, John exaggerates the predicted increase in temperature.
“I note that the emissions have grown somewhere between Hansen’s Scenario A and Scenario B.”
I challenge John to document that. He could start from the figures and the discussion here and here and here which discusses methane in detail Then he might want to go on with with a discussion of how A and B (and C until 2000 when it goes flat) nail the CO2 forcing. He might also want to discuss how the difference between forcing in A and B (and C until 2000) is principally in the trace gases with A having more forcing than B after 1990. In FACT B somewhat overestimates ACTUAL emissions/forcing in the principal trace gases, CH4 and CFCs.
11 May 2007 at 3:40 AM
It feels ominous, somehow, that the number of Republican senators actually has an impact on the sun…
When it comes to GW, however, you may only look at the number of cell phones in the world and the change in global temperatures over the last 20 years to realize what’s going on. Cell phones emit microwaves. Microwaves heat water. You connect the dots.
11 May 2007 at 4:53 AM
[[The reduction of trend is because the Southern Hemisphere is warming less rapidly than the Southern Hemisphere]]
<snark>Parallel worlds must be involved.</snark>
11 May 2007 at 5:12 AM
Gavin, are you 100% certain that CO2-emissions from humans are the reason for Global Warming?
I have trouble understanding your views since you report and write about all things so completely unbiased and devoid of a particular agenda.
I need to see the black & white of this, since all political decisions regarding GW are very particular and decisive, and affects so many people, and more.. Right?
11 May 2007 at 5:41 AM
By the way, a conspiracy to keep the “Milankovitch effects” out of North American textbooks may have been unearthed, as noted in a presentation before the US House Subcommittee on Climate Change on March 20, 2007. Tim Ball, a retired geographer, has discovered the importance of this factor and noted that it is not included in most textbooks. This may explain why you have probably never heard of the Milankovitch effect, unless you have taken an introductory course, or read a book, that included discussion of ice ages, climatology, paleoclimate, geography, geology, or related issues, or unless you are aware of how to use libraries or the internet.
Ball also noted that the cosmic effect is largely due to “the gravitational pull of the planet Jupiter”, which apparently is one of the major forces that pulls earth’s orbit into “an extreme elipse”, although luckily it is currently almost circular, whew.
Tim Ball’s testimony -US House Subcommittee on Climate Change,
http://www.fcpp.org/main/media_file_detail.php?StreamID=575
Search http://fcpp.org/main/index.php
From the talk (which begins with ice ages, etc.):
quote
“… The explanation for that melting is primarily given by these factors, which is called the Milankovitch effect, and interestingly enough, this is not included in most of our textbooks across North America today, I’ve checked them out. What it shows in the lower right, is the orbit of the earth around the sun, as an almost circular but slightly eliptical orbit. That’s the situation right now. But the orbit is changing every single year, pulled by the gravitational pull of the planet Jupiter, and what you see on the lower left is the orbit of the earth as it was 22,000 years ago, an extreme ellipse. So the orbit is changing every single year. And in the center of the diagram you see that the tilt is shown at 23 and a half degrees. It isn’t; it’s just close enough for government work, but it also constantly changes from 21.4 to 24.8, …” etc., etc.
end quote
Powerpoint Slides: www.ff.org/centers/csspp/docs/20070321_ball.ppt
Could this choice of the Universities and publishers to keep mention of Milanokovitch cycles from us, combined with sloppy government measurement of the earth’s tilt, be the real reason that climate models appear so compelling?
Elsewhere, Ball explains the rest of the effect with this observation:
“TB: Basically, when sunspots are active, the earth is warmer and, when they are less active, it is colder. “
http://www.fcpp.org/main/publication_detail.php?PubID=1669
It is too late to tell them about the secret Milankovitch effect, but the clear correlation of climate warming with sunspots should not be kept from students. So, I’ve posted the NOAA data in a spreadsheet for them:
http://people.uleth.ca/~dan.johnson/sunspots.htm
(PS. Ball doesn’t mention whether the effect of Jupiter altered by the impact of Comet Shoemaker-Levy 9, but if I ever again have the unpleasant experience of being the speaker following him at a public meeting, I will put this bug in his ear at coffee time.)
11 May 2007 at 5:57 AM
Gavin: I agree with you 100%! Spurious correlations are the enemy of good science. Let’s hear more.
11 May 2007 at 8:13 AM
Re: Eli #75
Eli - that is good stuff you referenced in post 75. I am a bit new to the site and have not seen such data and analysis before. Interesting to see how this plays out, and I await Gavin’s post on the Hansen predictions. One question, any reason the observed temps stop at 1998? Temps have dropped a bit since and seem to diverge from the Hansen predictions.
11 May 2007 at 9:07 AM
Entertaining article, Gavin. I actually like use of humour. Cheers!
11 May 2007 at 9:22 AM
Here’s what the British Meteorological Office(www.metoffice.gov.uk) has to say about solar activity and climate change:
“There are many factors which may contribute to climate change. For example, over the last million years most of the long-term changes in climate were probably due to small but well understood changes in the Earthâ��s orbit around the Sun. Over much of the last 1,000 years most of the variability can probably be explained by cooling due to major volcanic eruptions and changes in solar heating.
However, the situation in the 20th century is more complicated. There is some evidence that increases in solar heating may have led to some warming early in the 20th century, but direct satellite measurements show no appreciable change in solar heating over the last three decades. Three major volcanic eruptions in 1963, 1982 and 1991 have led to short periods of cooling. Throughout the century CO2 increased steadily and has been shown to be responsible for most of the warming in the second half of the century.
The final piece of the jigsaw is that as well as producing CO2, burning fossil fuels also produces small particles called aerosols which cool the climate by reflecting sunlight back into space. These have increased steadily in concentration over the 20th century, which has probably offset some of the warming we have seen. Only when all of these factors are included do we get a satisfactory explanation of the magnitude and patterns of climate change over the last century.
The bottom line is that changes in solar activity do affect global temperatures. However, what research also shows is that increased greenhouse gas concentrations have a much greater effect than changes in the Sunâ��s energy over the last 50 years.”
11 May 2007 at 10:06 AM
Tim Ball’s argument is simply amazing. (see post 79). Has he read ANY intro textbook? All the standard intro texts discuss Milankovitch orbital cycles in their discussion of ice ages. Given the long time scales of the rather modest orbital forcing, I’m not sure how they could explain substantial warming on decadal time scales. Then again, he “nicely” conflates Milankovitch forcing with sunspots.
11 May 2007 at 10:18 AM
Re #78: [Gavin, are you 100% certain that CO2-emissions from humans are the reason for Global Warming?]
I’m not Gavin, but a simple answer from a non-expert is that, like a lot of people, you’re getting things backwards. CO2 has an insulating effect - we know this because people have measured it. Humans have been putting more CO2 in the atmosphere - we know this too, because we’ve measured it. Putting those two facts together, we deduce that the Earth should get warmer as a result of the CO2. We look at temperature records, and lo and behold, we see that the Earth is in fact getting warmer.
Where exactly is the problem in this? It seems really simple to me, about at the level of figuring out that you’re feeling too warm because you’re wearing an extra sweater
11 May 2007 at 11:09 AM
#82
Aha, but you are just being fooled by a coincidence. If fact while in a lab CO2 will absorb energy and act as an insulator, when it is in the atmosphere pixies cast magical spells on the CO2 so that the radiation passes straight through it. Of course we would have realised this long ago if it wasn’t for the fact that, completely coincidentally, as human CO2 output has risen unicorn wave emission from the sun has increased at the same time. Now unicorn waves have the strange property that they curve away from detectors (they are shy), so the satellites and other systems that monitor the sun continuously don’t see them, and this is actually what has caused the warming.
Of course on its own this would still be detectable, as the upper atmosphere would be warming up as well as the lower parts, showing us that the GHG model of climate was flawed. However by complete fluke there has been a massive increase in cold dragon activity in the upper atmosphere in recent decades. These dragons of course keep themselves completely invisible to humans, so we can’t tell that the are massively cooling the upper atmosphere, more than offsetting the warming of the unicorn waves, and hence making us unaware of the actions of the pixies at messing up our understanding of how physics works in the real world.
11 May 2007 at 11:09 AM
Nice work. See also, “Political Innumeracy: Encounters with Coincidence, Improbability, and Chance,” by Carol Mock and Herbert Weisberg, Am. J. Pol. Sci. 36(4) 1023-46 (1992), which discusses the effect of astrological birth sign on political party affiliation. Perhaps there’s a Ph.D. dissertation in unscrambling the connections between astrological sign, control of senate, and climate. Then we could shortcut the expensive and laborious scientific research that goes into understanding climate and just consult a handy horoscope instead. As all the Republican hopefuls for 2008 are scrambling to appropriate Reagan’s mantle, this would be a timely research topic.
11 May 2007 at 11:37 AM
Re # 78
100% certainty? Black and white?
I’m afraid very little new scientific knowledge comes with absolute certainty - rather it comes with degrees of confidence, colored in shades of gray.
11 May 2007 at 12:16 PM
#79 Dan, Mr Ball has not been observing the sun for its spots lately, especially during the warmest winter in history just past, someone must also tell him that there wasn’t many spots. You may do him a favor, and perhaps he will revisit his “basic” sun spot correlation theory….
11 May 2007 at 12:30 PM
RE #81. Temps have not dropped since 1998. 1998 was exceptionally warm, the following few years were not quite as warm but still very consistent with the general trend if you exclude 1998. That same trend can still be seen up to 2005, which was almost as warm as the exceptional 1998, or equally warm depending what data set you look at. What is important to consider is that 2005 was warmer than 1997 or 1999. From what I read, 2006 is consistent with the trend as well, although I don’t know if all the data have been compiled (haven’t seen it yet). RC has analyzed this and Gristmill also has a good discussion on it.
11 May 2007 at 12:33 PM
In answer to M. B. Buckner #81. No the updated GISS global temperature series, shows that although 1998 was exceptionally hot due to a strong El Nino, the smoothed five year average continues to rise. The image next to the temperature series shows that the global rise masks much stronger local ones, esp at far northern latitudes. The images come from Global temperature change, James Hansen, Makiko Sato, Reto Ruedy*, Ken Lo*, David W. Lea, and Martin Medina-Elizade Proceedings of the National Academy of Sciences September 25, 2006, 10.1073/pnas.0606291103
11 May 2007 at 12:46 PM
This was just Slashdotted:
http://www.spiegel.de/international/germany/0,1518,481684,00.html
Don’t we still expect superstorms?
11 May 2007 at 1:06 PM
I just checked the current and former Earth Science text books (by different publishers) used in the high school where I work, and both of them describe Milankovitch cycles as a cause of ice ages, although not mentioned by name.
It’s just another example of Ball talking out of his posterior.
11 May 2007 at 1:19 PM
Thanks to B. Buckner, I went back and found the PNAS article which also had an updated comparison of observations, vs. Scen. A-C.
11 May 2007 at 1:29 PM
Marian (#78) wrote:
Chuck Booth (#88) wrote:
Quite right - and I have little doubt that Gavin would claim otherwise.
However, when you have a large number of independent lines of investigation justifying a given conclusion, the justification that the conclusion receives is far greater than that which it receives from any one given line of investigation alone.
Empirical science never reaches absolute certainty, but it can approximate it. Afterall, I suspect that you are reasonably confident that the ocean won’t suddenly reverse current trends and freeze within the next five minutes. Likewise, we are reasonably confident that neither carbon dioxide nor water vapor will suddenly become transparent to infrared radiation, or for that matter, that Planck’s law describing the spectrum of radiation emitted by a warm body will suddenly be suspended.
11 May 2007 at 3:01 PM
> Josef H. Reichholf
Hmmm. His expertise is in mites that live in the feathers of birds, according to Google Scholar.
He also has opinions. Has anyone read his book?
Josef H. Reichholf
Evolution. What is true? Facts and answers
ISBN 978-3-451-05779-3
The biblical story of the creation - big bang or intelligent design? Which laws does evolution follow? Which power is active in the cosmos and in nature? Is everything just chance or is there a plan behind it all? ….
11 May 2007 at 3:11 PM
Re #86: Very nice, Stuart. IMHO it’s perfect for use in public debates.
11 May 2007 at 3:13 PM
My son reviewed Milankovitch cycles in his 8th grade AP Science course last month. He was so fascinated he talked about them for a week. My daughter got a simpler version in 5th grade. Ball clearly has no idea what’s going on with textbooks.
Gavin, thank you for the excellent post. And I’d like to thank Ike Solem, Hank Roberts, Tamino, Eli, and Barton Paul Levenson. I always learn from your posts.
11 May 2007 at 3:24 PM
Rionn Fears Malechem (#92) wrote:
The expert they are undoubtedly getting this from is Hans von Storch who they interviewed only a couple of months ago:
It is only within the past few years that climate models have achieved the resolution needed to “see” the formation of hurricanes. The models currently predict a moderate increase in the strength of the the more severe hurricanes. In contrast, what we have seen is a fairly strong response to increased oceanic surface temperatures. Part of what appears to be happening is that the water which is now warmer extends further down than it did previously, further fueling the hurricanes - and as of yet we aren’t taking this into account in our models.
In any case, Hans von Storch views climate change as largely inevitable, with whatever Germany does as having little effect, particularly given that the major players (the United States, China and India) are doing very little to stop it. He views mitigation as Germany’s best strategy. (See the interview cited above.) Given this, perhaps he has chosen to downplay the effects of climate change to some degree. Of course, what he says in Germany is heard in the United States…
In any case, if you are particularly interested in this topic, you might want to check out the following posts:
Hurricane Spin
Michael Mann and Gavin Schmidt
24 Apr 2007
http://www.realclimate.org/index.php/archives/2007/04/shear-turbulence/
21 Cat 4-5 Storms for 2006?
Posted on: January 4, 2007 6:55 AM, by Chris C. Mooney
http://scienceblogs.com/intersection/2007/01/21_cats_45.php
Unlike the previous few yeares, last year was slow for the Atlantic due to dust blowing off of north Africa reducing the temperature in that region, but it was busier than ever in the Pacific.
You might also try the search box at the top: hurricanes are a recurring subject here.
11 May 2007 at 3:35 PM
Think people, seriously, …what would happen if Gavin…or anyone else submitted this “article” to the peer-reviewed Journal SCIENCE…Now how about if submitted to a “journal” that was funded by a special interest group? Could it be used politically?
11 May 2007 at 4:00 PM
#74 Re #69 Doc Martyn,
“I’ll do a crude calculation to give you my prediction:
Assume the area of the 30m tank is 1 m2. First the energy added:
8w/m2 in one year is 8 J/sec *3600sec/hr+24hr/day*365 days/year = 252 MJ
Now the water’s response. The sepcific heat of water is about 4.2 J/g.C, which is 4.2 MJ/tonne.C. 30 metres of water with cross section 1 m2 is 30 tonnes.
Assuming the water is well mixed and the heat distributes evenly it will take 30*4.2=126 MJ to raise the water by 1 degC
So with 252 MJ we have a temperature rise of 252/126=2.0 deg C.
Sounds like a good high school experiment. You could measure it with a lab thermometer. Certainly well above the noise assuming you can properly isolate the test and control tanks.
Bruce”
I see, so you expect that
“Assuming the water is well mixed and the heat distributes evenly”
although it doesn’t in any standing body of water on the planet.
Moreover, I can’t help but notice that you have not considered the difference in evaporation rate of the two systems. Nor if there is salt present in water, the effect that thermal expansion of water will have on the salts activity. If there is thermal expansion, what effect will it have on the pressure/depth and temperature/depth profiles.
As I stated, this is a very simple system, however, I very much doubt if any climate scientists would be interested in doing any actual, physical, expirements.
11 May 2007 at 5:21 PM
RE # 78 & “Gavin, are you 100% certain that CO2-emissions from humans are the reason for Global Warming? I have trouble understanding your views since you report and write about all things so completely unbiased and devoid of a particular agenda. I need to see the black & white of this, since all political decisions regarding GW are very particular and decisive, and affects so many people, and more.. Right?”
Hi Marian,
Actually the question non-scientists should be asking is, are you 100% sure GHGs do NOT cause GW….a