Guest Post by Ira Glickstein
A multi-modal probability distribution, such as the graphic below [from Schmittner 2011], cries out “MULTIPLE POPULATIONS”. Equilibrium Climate Sensitivity (expected temperature increase due to a doubling of CO2 levels, all else being equal) is distinctly different for Land and Ocean, with two peaks for Land (L1 and L2) and five peaks for Ocean (O1, O2, O3, O4, and O5).
When a probability distribution includes more than one population, the mean may, quite literally, have no MEANing! All bets are off.
Example of a Multi-Modal Distribution
According to the basic tenets of System Science (my PhD area) probability distributions that inadvertently mix multiple populations often lead to un-reliable conclusions. Here is an easy to understand example of how a multi-modal distribution leads to ridiculous results.
Say we graphed the heights of a group of infants and their mothers. We’d get a peak at, say 25″, representing the average height of the infants, and another at, say 65″, representing the mothers. The mean of that multi-modal distribution, 45″, would represent neither the mothers nor the infants – not a single baby nor mother would be 45″ tall!
If some “alien scientist” re-measured the heights of the cohort of children and their mothers over a decade, the mean would increase rapidly, perhaps from 45″ to 60″. If that “alien scientist” did not understand multi-modal distributions representing different populations, he or she might extrapolate and predict that, a decade hence, the mean would be 75″! Of course, actual measurements over a second decade, as the children reached their adult heights, would have a mean that would stabilize closer to 66″ (assuming about half the children were male). The “alien scientist’s” extrapolation would be as wrong as some IPCC predictions seem to be.
Implications of Multi-Modal CO2 Sensitivity
Schmittner says:
The [graph shown above], considering both land and ocean reconstructions, is multi-modal and displays a broad maximum with a double peak between 2 and 2.6 K [1 K = 1ºC], smaller local maxima around 2.8 K and 1.3 K and vanishing probabilities below 1 K and above 3.2 K. The distribution has its mean and median at 2.2 K and 2.3 K, respectively and its 66% and 90% cumulative probability intervals are 1.7–2.6 K, and 1.4–2.8 K, respectively. [my emphasis]
The caption for the graphic says:
Marginal posterior probability distributions for ECS2xC. Upper: estimated from land and ocean, land only, and ocean only temperature reconstructions using the standard assumptions (1 × dust, 0 × wind stress, 1 × sea level correction of ΔSSTSL = 0.32 K…). Lower: estimated under alternate assumptions about dust forcing, wind stress, and ΔSSTSL using land and ocean data.
So part of the cause of multi-modality is due to different sensitivity to dust, wind, and sea surface temperatures for the combined Ocean and Land data, and part due to differences between Ocean and Land. But, that is only part of the story. Please read on for how Geographic Zones seem to have different sensitivities.
Geographic Zones Have Different Sensitivities
Another Schmittner 2011 graphic, shown below, indicates how different the Arctic, North Temperate, Tropics, South Temperate, and Antarctic zones are. Indeed, there is a startling difference between the Arctic and Antarctic.
The thick black line represents the “climate reconstruction” (change in temperature in ºC) between current conditions and those of about 20,000 years ago during the Last Glacial Maximum. The LGM was the coldest period in the history of the Earth in the past 100,000 years. Note that the Tropics were about 2ºC cooler than they are now, the South Temperate zone was about 3ºC cooler, the North Temperate zone about 4ºC cooler, and the Antarctic about 8ºC cooler. However, according to the climate reconstruction, the Arctic was about 1ºC WARMER than it is today!
The estimated CO2 level during the LGM is 185 ppm, quite a bit below the estimated Pre-Industrial level of about 280 ppm, and about half that of the current measured level of about 390 ppm. Thus, IF CO2 DOUBLING CAUSED ALL of the temperature increase from the LGM to the present, the sensitivity for the geographic zones would range from +8ºC (Antarctic) to +4ºC (South Temperate) to +3ºC (North Temperate) to +2ºC (Tropics) to -1ºC (Arctic).
Of course, based on the Ice Core temperature records for several ice ages over the past 400,000 years, the warming 20,000 years after a Glacial Maximum tends to be significant (several degrees). Thus, while increases in CO2, all else being equal, do cause some increase in mean temperatures, it is clear from the Ice Core record, where temperature changes lead CO2 changes by from 800 to 1200 years, that something else causes the temperature to change and then the temperature change causes CO2 to change. Thus, it would be wrong, IMHO, to assign more than some small fraction of the warming since the LGM to CO2 increases.
The colored lines in the above graphic correspond to modeled temperatures based on different assumed CO2 sensitivities, ranging from 0.3ºC to +8.4ºC. The darker blue line, corresponding to a sensitivity of 2.3ºC, is the best match for the thick black climate reconstruction line.
IPCC CO2 Sensitivities are Mono-Modal and have “Fat Tails”
So, how do the IPCC AR4 Figure 9.20 graphs of Equilibrium Climate Sensitivity compare to the Schmittner 2011 results? Not too well, as the graphic below indicates!
First of all, notice that NONE of the individual IPCC graphs are multi-modal! Yet, taken as a group, there are several distinct peaks, indicating that each of the researchers characterized only one of a number of multi-modal peaks, and were inadvertently (or purposely?) blind to the other populations. Thus, the IPCC curves, taken as a group, seem to support Schmittner’s results of multi-modality.
For example, compare the green curve (Andronova 01) to the red curve (Forest 06). They hardly overlap, indicating that they have sampled different populations.
There is another, less obvious problem with the IPCC curves. Notice that they each have a relatively “normal” tail on the left and what is called a “Fat Tail” on the right. What does that mean? Well, a “normal curve” has a single peak, representing both the mode and the mean, and two “normal” tails that approach zero at about +/- 3ơ (Greek letter sigma, representing standard deviation). A mono-modal curve may skew to the left or right a bit, which would put the mode (peak) to the left or right of the mean.
The problem with the IPCC curves is that, in addition to the skew, the right-hand tail extends quite far to the right, out to 10ºC and beyond, before approaching zero. According to Schmittner 2011:
…High sensitivity models (ECS2xC > 6.3 K) show a runaway effect resulting in a completely ice-covered planet. Once snow and ice cover reach a critical latitude, the positive ice-albedo feedback is larger than the negative feedback due to reduced longwave radiation (Planck feedback), triggering an irreversible transition … During the LGM Earth was covered by more ice and snow than it is today, but continental ice sheets did not extend equatorward of ~40°N/S, and the tropics and subtropics were ice free except at high altitudes. Our model thus suggests that large climate sensitivities (ECS2xC > 6 K) cannot be reconciled with paleoclimatic and geologic evidence, and hence should be assigned near-zero probability….[my emphasis]
Based on the above argument, I have annotated the IPCC figure to “X-out” the Fat Tails beyond 6°C. I did that because any sensitivity greater than 6°C would retrodict a “total snowball Earth” at the LGM which contradicts clear evidence that the ice sheets did not extend equatorward beyond the middle of the USA or corresponding latitudes in Europe, Asia, South America, or Africa. Indeed, if Schmittner is correct, the tails of the IPCC graphs that extend beyond 5°C (or perhaps even 4°C) should approach zero probability.
Conclusions
Schmittner 2011 contradicts the IPCC climate sensitivity estimates and thus brings into question all IPCC temperature predictions due to human-caused CO2 increases.
It is clear from the several, widely-spaced peaks in the IPCC AR4 Figure 9.20 curves that Equilibrium Climate Sensitivity is indeed multi-modal. Yet, ALL the individual curves are mono-modal. Thus, the IPCC figure is, on its face, self-contradictory.
If Schmittner 2011 is correct that sensitivity beyond about 6°C is impossible based on the fact that Tropical and Sub-Tropical zones were not ice-covered during the LGM, the Fat Tails of all the IPCC Equilibrium Climate Sensitivity curves are wrong. That calls into question each and every one of those curves.
The multi-modal nature of CO2 sensitivity indicates that the effects of CO2 levels are quite different between geographic zones as well as between Ocean and Land. Thus, the very concept of a whole-Earth Equilibrium Climate Sensitivity based on a doubling of CO2 levels may be misplaced.
Finally, if CO2 is as strong a driver of surface temperatures as the IPCC would have us believe, how in the world can anyone explain the apparent fact that, given a doubling of CO2 levels, the modern Arctic is about 1°C COLDER than the LGM Arctic?
BOTTOM LINE: The Climate System is multi-faceted and extraordinarily complex. Even the most competent Climate Scientists, with the best and purest of intentions are rather like the blind men trying to characterize and understand the elephant. (One happens upon the elephant’s leg and proclaims “the elephant is like a tree”. Another happens to grab the tail and says with equal certainty “the elephant is like a snake”. The third bumps into the side of the elephant and confidently shouts “No, the elephant is like a wall!”) Each in his or her way is correct, but none can really understand all the aspects nor characterize or predict the behavior of the actual Climate System. And, sadly, not all Climate Scientists are competent, and some have impure intentions.
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Ira,
Thanks for your thoughtful and educated response. I asked an open question and you provided one possible set of answers. Of course the sequestration of CO2 during cooler glacial periods doesn’t just involve the ocean’s uptake, but biological uptake and even increased uptake through rock weathering and the carbon- rock cycle. As CO2 is a non-condensing GH gas, it is not so directly affected by temperature changes as water vapor is, and thus, it can maintain temp in a range.
I am still of the opinion that global temps will reach about 3C higher per the doubling of CO2 from pre-industrial levels. This meets both the average of many GCM’s as well as what has been seen from paleoclimate studies when fast and slow feedbacks are considered.
R. Gates;
As I’ve got no personal “horse in this race”, it would be hard for me to be disappointed or encouraged>>>
followed by:
R. Gates;
I am still of the opinion that global temps will reach about 3C higher per the doubling of CO2 from pre-industrial levels. >>>>
Which is it R. Gates? Do you have a horse in the race? Or not?
jimmi_the_dalek, I do not accept the numeric ECS(2xC) results of Schmittner any more than those of the other computer-based models. Although Schmittner moves the mean value down a bit from the IPCC 3ºC to a slightly lower number, which is at least in the right direction, I still believe the correct range is closer to 0.5ºC than to any number in the IPCC range of 2ºC to 4.5ºC.
The value of Schmittner to me is in three aspects:
1) Schmittner got the FORM of the ECS correct. It seems blindingly obvious to me that the effect of doubling CO2 levels has got to be very different for each geographical zone, for areas over Land vs over Water, for mountaneous vs flat terrain, for areas over warmer water that net outgases CO2 vs cooler water that net absorbs CO2, for cloudy vs clear areas, and for various combinations of aerosols (dust, etc.) and cosmic rays and so on and on.
2) Schmittner should be congratulated for letting the results show their true multi-modal form. I think the IPCC totally misunderstands the complexity of the Climate System and they totally missed the meaning of the multi-modal aspect of Climate Sensitivity even though it was staring them in the face in the form of those multiple mono-modal curves in figure 9.20 of AR4. I think at least some of the prior modelers got multi-modal results and, thinking they were wrong, diddled their data to get a mono-modal result.
3) Schmittner also demolishes the IPCC “Fat Tail” fettish. I understand that at least one of the curves in the IPCC ensemble was, in its initial form, devoid of a Fat Tail, and, like the monkeys they are, the IPCC modified the data to pin a Fat Tail on that donkey. Schmittner effectively places an upper bound of 6.3ºC on ECS(2xC), which should slim down all future right-hand tails.
Davidmhoffer,
Apparently your sensibilities are not quite refined enough to differentiate the difference between having an opinion as to an outcome and having a vested interest in such. A pity for you.
Well, of course it is. The reason is that the 24hr LWIR emitted by these different land areas are different and that is what “greenhouse” warming is acting on. Look at the LWIR radiation from the surface of the ocean off San Francisco an hour after sunset on July 1. Then look at it an hour before dawn. It is practically unchanged. Now check the LWIR emitted from the Black Rock Desert near Gerlach Nevada an hour after sunset and again an hour before sunrise. WAY different.
But overall, I believe we are going to find that the climate sensitivity they have claimed for CO2 has been overstated generally. About half of the warming out of the LIA happened before 1940. Most of that was in the 1920’s. We had nearly an identical period of warming in the late 20th century which I believe is now completed. If we are *really* lucky, we might have another such period around 2035 or so but I am beginning to doubt that. The best we might get is a hiatus of cooling for 30 years rather than any warming.
I don’t think that is accurate. Their “mission” (The Cause) is to produce a plausible mechanism by which CO2 emissions can be shown to cause “unsustainable” conditions. It is a multi-front effort that includes the IPCC reports in addition to gatekeeping of the published literature in the field of climate science, gatekeeping of research grants, pressure applied to keep the rest of the researchers in the field in line, smearing of any who get out of line, damaging any journal or information outlet that provides a conduit for information counter to the notion that CO2 emissions cause an “unsustainable” future, and coaching of mass media outlets in a coordinated public propaganda campaign. All of this has been revealed in the climategate emails and in the experiences of people in the field of climate research. It really has nothing at all to do with really “understanding” how the climate works, it is about creating a mechanism whereby fossil fuel use can be regulated globally.
Or they were told in the review process or by informal review by peers before submission that the multimodal result was not going to be allowed to be published. If the paper was in any way a “threat” to the cause or something “skeptics” could latch onto, it is going to be shot down.
Of course they did because that makes the case against CO2 more plausible and THAT is the point. This isn’t about real climate change at all, that is orthogonal to the purpose of all of this. The “mission” is to show a reason why CO2 emissions must be centrally regulated by a bunch of unelected, self-appointed, bureaucrats. I’m wondering how they even got it published. I’ll look for the “hockey mask” statement in the document, it must have been in there somewhere.
Here’s the thing: You can only have a uniform response to increased CO2 if LWIR is uniform. If I have a major La Nina condition and the equatorial Pacific gets much colder than normal, there just isn’t going to be much LWIR. If I get a lot of snow that reflects visible light before it has a chance to be converted to LWIR, all the CO2 in the world isn’t going to make any difference. Heck, if I paint enough roofs white, you could have an atmosphere of pure CO2 and it won’t cause any warming because so much visible light is being reflected.
The extent to which CO2 is going to cause warming is going to depend on the nature of the LWIR aimed at it.
Also note that atmospheric CO2 acts both ways, it also blocks LWIR from the sun. So the more CO2 you get, the less IR you get to the surface (that is absorbed and re-radiated). But even that doesn’t matter, either, because the atmosphere is already opaque at the CO2 absorption wavelengths. ALL of the LWIR being emitted is already being absorbed by the atmosphere. Adding some more CO2 is like taking a solid wall, applying a coat of paint, and claiming it is now more “light proof”.
The entire conversation is silly. It isn’t about CO2 and it isn’t about climate change. It is about an enabling mechanism for “sustainable development” which is the real underlying UN mission. Google it.
David Springer says:
“Now throw the general benefits of higher CO2 levels for plant growth and water usage and longer growing seasons and raising CO2 level is such a good thing it’s kind of nutty to worry about it. Don’t be nutty, Gates.”
—–
Seems a bit of a bit of a gamble. To raise CO2 to levels not seen in 800,000 years to prevent a return to glacial conditions? It might even be a gamble worth taking were it not for the side effects, such as the acidification of the oceans that seems to be accompanying the rapid buildup of CO2. I suppose I’d like to be more assured that we’ll be able to grow enough grains and the ocean food chain will remain healthy with such geologically rapid changes.
And once you have Googled “sustainable development” move on to “education for sustainable development”. It is a HUGE multinational UN project that practically every nation, state/province, district, county, town has bought into and CAGW is the enabling mechanism for the entire thing. Without CAGW, they would have to come up with and entirely new foundation for what amounts to probably THE primary focus of the United Nations and many local governments.
R. Gates
When modern species first appeared, CO2 levels were much higher than today, Today’s CO2 levels are DANGEROUSLY LOW for most plant species now living on this planet. People do not realize how quickly CO2 is scrubbed out of the atmosphere (and ocean). The PETM saw an absolutely ferocious release of CO2 into the atmosphere. Within the period of one single modern glacial cycle (about 150,000 years) it was all gone and back to previous levels. During that period, mammals thrived, spread out, became dominant and primates appeared and began to diversify.
R. Gates says:
December 18, 2011 at 9:24 pm
Davidmhoffer,
Apparently your sensibilities are not quite refined enough to differentiate the difference between having an opinion as to an outcome and having a vested interest in such. A pity for you>>>
Wow. First you said you had no “horse in the race” regarding what sensitivity actually is, and then you claim to believe that sensitivity is 3 degrees C per CO2 doubling. On the one hand, you proclaim to be a neutral observer interested in the data and what it shows, and on the other hand you state clearly that you are not a neutral observer, you have already draw your conclusions before the data to do so is actually in.
You defended Al Gore’s experiment as being an accurate illustration, but it was demonstrated to be a fake. You bet with me that it would show the warming effects of CO2 if it was done as illustrated, but it did the opposite. I’ve challenged you multiple times to produce a single statement made by you that was supportive of the skeptic position, which you cannot do, though this blog is laden with your pro warmist remarks and defense of various members of the “the team” with some truly lame excuses, yet you continue to pretend you are neutral.
You also appear to be a formula writer, Each time you engage with someone, you begin with a compliment like “Thanks for your thoughtful and educated response.” followed by a tangential argument that is mostly true, partly wrong, but cleverly worded to draw to conversation in a different direction like “Of course the sequestration of CO2 during cooler glacial periods doesn’t just involve the ocean’s uptake, but biological uptake and even increased uptake through rock weathering and the carbon- rock cycle. As CO2 is a non-condensing GH gas, it is not so directly affected by temperature changes as water vapor is, and thus, it can maintain temp in a range.”
Then you follow that with a conclusion based on an out of context remark that draws as itz evidence the not quite relevant “facts” that you’ve tabled under the guise of being a nice guy making a compliment toward the original author, and then using your nice guy persona to throw in some more “facts” and spin a whole picture around it to support the conclusions that you then announce.
On the one hand, I’m sure it is easier for you to write by following this pattern, but it is also easier to debunk since the pattern is so obvious.
Under the “sustainable development” framework of the UN which the US has signed onto, there comes into play a concept called the “precautionary principal” where something doesn’t have to be proved to be acted upon, it simply has to be deemed plausible and a potential danger to “sustainable development” of the planet. So the mission of the IPCC is to create a plausible threat that can be acted upon under the concept of the “precautionary principal”.
In short, to justify spending hundreds of billions of dollars, something has to simply be deemed plausible by “consensus” (consensus is a huge deal in sustainable development concepts). In order to be no longer considered, it has to be absolutely proved to be implausible. It is impossible to prove a negative. In this way, the UN can then justify whatever it wants by simply cooking up a plausible scenario, gaining consensus that it is, indeed plausible, and then may act in accordance with the “precautionary principal”.
George Orwell would be proud. George HW Bush signed the US up to it and Clinton confirmed it.
http://en.wikipedia.org/wiki/Precautionary_principle
It doesn’t matter if CAGW is actually happening or not. It only matters that it is PLAUSIBLE.
ferd berple, I may have jumped the gun… again. That seems to be just a coincidence for those two factors don’t seem related physically. Will get back if I can find a tie.
The proposed mechanism for global warming is that long wave IR emitted at the Earth’s surface is absorbed by CO2 in the atmosphere and almost instantly re-radiated, with 50% back toward the surface. This slows the rate of radiative cooling of the Earth’s surface, and thereby leads to conductive warming of the atmosphere. However not all of the Earth’s surface responds equally to incident LWIR. As can be seen from this simple experiment –
http://tallbloke.wordpress.com/2011/08/25/konrad-empirical-test-of-ocean-cooling-and-back-radiation-theory/
– water that is free to evaporatively cool is not greatly effected by LWIR. This is significant as 71% of the Earth’s surface is ocean.
I believe the multi-modal sensitivity proposed in Schmittener 2011 is likely correct in form, but the values shown for sensitivity are still way too high. However I hope that this new discussion of “multi-modal sensitivity” may lead to Willis and Joel revising their previous positions on the issue.
Taking the claimed basic “black body” sensitivity figure of around 1.2 degrees for a doubling of CO2, reducing that by 70% over the oceans and allowing for negative water vapour feedback of 0.5, my crude calc for “multi-modal” sensitivity is 0.3 degrees. Which is neither dangerous nor catastrophic, especially when the pre-industrial figure for CO2 of 280ppm is most likely far too low.
The amount of CO2 in Earth’s atmosphere is (the emission rate) – (the scrubbing rate)
The thing is that the scrubbing rate varies. One thing it varies with is the amount of CO2. If you put more CO2 into the atmosphere, the scrubbing rate of CO2 goes up. This is because of things like CO2 fertilization of plants (mostly phytoplankton), they respond with higher growth rates causing an increase in the rate of biomass production. Another increase in scrubbing will come from increased carbonic acid in rainfall causing more reaction with rock during erosional processes. Scrubbing rates can also change due to uplifting of mountain ranges exposing more rock to be eroded, removal of surface soil exposing rock, glacial retreat exposing rock to erosion.
The greatest natural sources of CO2 emissions are volcanic activity and natural gas seepage. As Earth cools, the amount of CO2 produced from volcanism declines. This results in a reduction of CO2 emissions into the atmosphere and a decline in atmospheric CO2 as it is scrubbed out. Now to some extent this is self-regulating at the low end because as atmospheric CO2 declines, its scrubbing rate slows. Rain water is not so reactive, plants don’t put on as much biomass and so the scrubbing rate reaches rough equilibrium though does continue to slowly fall as insoluble carbonates are deposited on the ocean floor over time.
A mass release of CO2 simply means that biological and geological scrubbing processes speed up and remove the CO2 from the air. A new uplift of a mountain range can suddenly (in relative geological terms) increase the geological scrubbing rate and reduce atmospheric CO2 to a new equilibrium level by causing an offsetting reduction in biological scrubbing (plants don’t grow as well causing them to reduce the amount of biomass they put on and thereby reduce the CO2 they remove from the atmosphere).
At the current atmospheric levels of CO2 (record low levels on a geological scale), additional CO2 is more beneficial than removing CO2. As many plant species are near the lower edge of their ability to survive, adding CO2 will provide a growth benefit to plant species globally. This additional CO2 will be scrubbed out very quickly, probably within a couple of centuries, once fossil fuels have become too scarce to burn and power generation is finally switched to nuclear.
crosspatch says:
December 18, 2011 at 9:26 pm
“Now check the LWIR emitted from the Black Rock Desert near Gerlach Nevada an hour after sunset and again an hour before sunrise. WAY different.”
This raises a further interesting question. As materials cool, their emission spectra should down shift. For a rapidly cooling desert this could mean that the spectral peak of outgoing long wave IR could sweep across the 15 micron band. That is to say that 15 micron LWIR emitted from the desert surface may not be a constant percentage of total emitted IR. LWIR back radiated to the surface would be re-emitted at a longer wavelength, bypassing CO2. It may be in areas of the Earth’s surface that can cool rapidly CO2 can cause a short period in which cooling is reduced, but not long enough to trap heat over a diurnal cycle.
R. Gates;
“As I’ve got no personal “horse in this race”, it would be hard for me to be disappointed or encouraged”
Aye, ‘Tis no horse, but a male donkey. Are you not longer 75% warmist? And what were you before that? Your dissembling brand of sophistry fools no one.
Bah! Humbug! All this talk about CO2 and temperature and not a single valid explanation as to how CO2 in the atmosphere warms the surface more than the sun did when it was shining. Or even when the sun is not shining.
This R Gates person seems to be particularly concerned about the rising levels of CO2 and our doom by fire.
Think sir what the records tell us for around 800 years ago the world suffered thermagedon and life and humans prospered. Strangely this 800 year number rears its head in many ways, one is the increase in CO2 after such a warming event.
The inertia in all things planetary is huge in both time and scope, temperature and CO2 are not immune, many life times must be lived to see both cause and effect. The time has come for scientists involved in AGW to walk away some distance, then turn around and look back at what they have done.
Mr Gates you are supporting a fallacy, a fantasy even, CO2 in our atmosphere in larger quantities is a bonus for the entire planet.
The calculated sensitivity appears to be a balance between the water vapour positive feedback and the convective negative feedback. Because one effect would send temperatures hundreds of degrees kelvin higher, and the other effect brings it back to just a few tens of degrees above blackbody, then calculations based on these “large signal” results will generally have the positive just shading the negative, leading to feedback amplification.
However, compared to the large signal results, the positive water vapor feedback is greatly saturated, and the negative convective feedback is massively amplified, so for mine negative feedback predominates in the “small signal” real world.
It is very common to lump all these global effects together to understand a physical system, so I have no problem with anyone doing that.
davidmhoffer says:
December 18, 2011 at 6:58 pm
“For once you’ve managed a retort with relevant information, though your perserverance in demonstrating that your are a complete and total jerk is also on full display. ”
Morons like you bring out the jerk in me.
“Finally, if CO2 is as strong a driver of surface temperatures as the IPCC would have us believe, how in the world can anyone explain the apparent fact that, given a doubling of CO2 levels, the modern Arctic is about 1°C COLDER than the LGM Arctic?”
Lots of ways? Even warmists don’t deny things like continental drift, geological time changes in oceanic circulation patterns, geological time changes in orbital eccentricity and so on. 20,000 years ago, the pole star wasn’t even Polaris — the Earth’s axis wasn’t even close to Polaris (just as in a couple hundred more years, it will stop being particularly close to being Polaris for us, as well).
I appreciate your argument about multimodality, and I think that the argument concerning sensitivity is dead on the money — there are various sanity checks and the more extreme values of climate sensitivity fail them (Roy Spencer, in his book, points out that even time LOCAL measurements of temperature susceptibility — how fluctuations in temperature respond to solar variability — don’t agree with large positive sensitivity and may actually be consistent with negative feedback that STABILIZES temperatures rather than AMPLIFIES them, which of course makes a lot of sense in an open system that hasn’t been driven to either “snowball Earth” or “fireball Earth” extremes by natural variation.
However, this argument is ill-placed and if anything distracts from your otherwise powerful conclusions. The IPCC is asserting that “geological time variability being more or less constant on a timescale of a few centuries, CO_2 is the important driver”. That is, given more or less constant patterns of oceanic circulation, steady patterns of decadal oscillations, irrelevant fluctuations in solar insolation, no major variations due to volcanic or other aerosols, and a complete lack of coupling between the magnetic state of the Sun or solar wind and the climate of the Earth, CO_2 is the major driver.
They don’t deny that all of those things vary on millennial time scales. Only decades or centuries, although in their sillier papers they try to extend the hockey stick back a thousand years or more. The fact that they all vary on decadal time scales and that there is evidence that all of them are indeed important contributers to climate is what they are ignoring, but citing a thermal record from 20,000 years ago isn’t evidence against this as even they know that the last ice age happened, right?
rgb
crosspatch says:
December 18, 2011 at 10:16 pm
“If you put more CO2 into the atmosphere, the scrubbing rate of CO2 goes up.”
Interestingly this is a typical reaction for an equilibrium system being forced out of equilibrium i.e. the more out of equilibrium it becomes the harder it “tries” to regain equilibrium. The transfer of heat between two bodies of different temperatures is one example.
Here’s my take. The ocean contains far more CO2 than the atmosphere and its average surface temperature sets the equilibrium point with the atmosphere. At the interglacial average temperature of 16C that equilibrium point is 280ppm. Trying to reduce or increase atmospheric CO2 without changing average SST of the ocean will cause the ocean to take up the excess or emit the shortfall. The biosphere I think is probably pretty close to neutral as plants taking up CO2 are offset by more organisms which eat plants and emit CO2. That won’t be instantaneous but pretty fast. Probably the same for weathering if for no other reason than most of the surface is ocean where acid rain won’t have any rocks to fall upon.
So my hypothesis is that if anthropogenic CO2 emission ceases then the PPM in the atmosphere will decrease at the same rate it increased – quickly at first then slower and slower as the natural equilibrium point of 280ppm is approached.
The equilibrium point in relation to temperature can be gauged in the ice core data. Average temperature during an interglacial is about 3C higher than during a glacial period and atmospheric CO2 is about 80ppm higher during the interglacial. That works out to about 25ppm per degree C. If average SST is half a degree warmer now than in 1950 that might account for 10ppm of the higher CO2 level today while the other 80ppm is due to something else. I suspect that “something else” is anthropogenic.
Konrad says:
December 18, 2011 at 10:01 pm
“water that is free to evaporatively cool is not greatly effected by LWIR. This is significant as 71% of the Earth’s surface is ocean.”
Yes. In working through the physics this is what you discover. It is borne out by ocean heat budget studies which find that 70% of ocean heat loss on average is by evaporation, 25% by radiation, and the remainder by conduction. Land surfaces on the other hand lose most of their heat via radiation. The key to this while thing is that downwelling LWIR is absorbed by the first couple of microns of water surface which instantly raises the evaporation rate and the energy is removed as soon as it arrives. Water vapor being lighter than air the energy is carried aloft insensibly and released at the cloud layer where it becomes sensible again.
Once the physics involved is understood and accepted all the data falls neatly in place. The greenhouse effect is a land-based phenomenon. So-called sensitivity that the IPCC says is between 1C and 3C is actually 1C because two thirds of the earth’s surface is uneffected by greenhouse gases. The northern hemisphere gets twice as much greenhouse warming because there’s twice as much land surface in the northern hemisphere. All the temperature measurements are in agreement with this. There is no Trenberthian missing heat hiding in the ocean and it can’t be found because it never entered the ocean in the first place. It was instantly rejected as latent heat of vaporization and carried up to the cloud layer where it then made its way out of the atmosphere into space. The “missing heat” is in a spherical volume of space about 100 light years in diameter surrounding the earth. Trenberth is looking in the wrong direction for it! 🙂
Dave Springer says:
Your comment is awaiting moderation.
December 19, 2011 at 3:02 am
davidmhoffer says:
December 18, 2011 at 6:58 pm
“For once you’ve managed a retort with relevant information, though your perserverance in demonstrating that your are a complete and total jerk is also on full display. ”
Morons like you bring out the jerk in me.
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I see the above was selectively skipped over and left in the moderation queue since subsequent comments of mine have appeared. All I ask is that moderators be fair about this. Hoffer called me a jerk and the comment was approved. In a fair world that entitles me to respond in kind. Tit for tat, so to speak. Moron for jerk.
I have no problem with being snipped but I do have a problem when there is a double standard employed in the process.
All the Last Glacial Maximum climate model studies are tuned so that they get 3.0C per doubling (or 2.3C per doubling as in this case). They are done by pro-AGW’ers after all.
They are tuned because they use artificially low Albedo (the amount of sunshine reflected back to space) values. This provides almost no change at all in the Solar Forcing and lets the GHG Forcing take more of the credit for the temperature decline.
Here is the current Solar Forcing and Albedo by 10 degree Latitude bands and what this study (and all LGM climate model studies) use as the change at the LGM.
http://img404.imageshack.us/img404/6724/solarforcingalbedobylat.png
The study values are NOT what the Earth surface conditions at the LGM would have produced.
http://img9.imageshack.us/img9/2845/solarforcingcurrentvslg.png
Take another -15 W/m2 off the Solar Forcing (to reflect realistic conditions) and redo the math – then you are down to 1.0C to 1.5C per doubling.
Konrad says:
December 18, 2011 at 10:25 pm
“This raises a further interesting question. As materials cool, their emission spectra should down shift. For a rapidly cooling desert this could mean that the spectral peak of outgoing long wave IR could sweep across the 15 micron band. That is to say that 15 micron LWIR emitted from the desert surface may not be a constant percentage of total emitted IR. LWIR back radiated to the surface would be re-emitted at a longer wavelength, bypassing CO2. It may be in areas of the Earth’s surface that can cool rapidly CO2 can cause a short period in which cooling is reduced, but not long enough to trap heat over a diurnal cycle.”
If I’m not mistaken GCMs take this into account. Surface temperature doesn’t “sweep through” a 15um blackbody peak. Surface temperatures don’t vary through the right range to do that.
http://www.spectralcalc.com/blackbody_calculator/blackbody.php
At 100F peak emission is 9um. At -20F peak emission is 11um.
However that “sweep” does move the peak emission frequency closer to or further from the CO2 sweet spot at 15um so there is definitely a relationship between surface temperature and CO2’s effectiveness as a greenhouse gas. The colder it is (within the normal range of earth surface temperatures) the greater the greenhouse effect. This handily explains why higher latitudes get more AGW than lower latitudes.
Follow the physics if you want the truth about climate. Follow the money if you want the truth about climate scientists. 😉