Some Comments on the Lindzen and Choi (2009) Feedback Study
by Roy W. Spencer, Ph. D.
I keep getting requests to comment on the recent GRL paper by Lindzen and Choi (2009), who computed how satellite-measured net (solar + infrared) radiation in the tropics varied with surface temperature changes over the 15 year period of record of the Earth Radiation Budget Satellite (ERBS, 1985-1999).
The ERBS satellite carried the Earth Radiation Budget Experiment (ERBE) which provided our first decadal-time scale record of quasi-global changes in absorbed solar and emitted infrared energy. Such measurements are critical to our understanding of feedbacks in the climate system, and thus to any estimates of how the climate system responds to anthropogenic greenhouse gas emissions.
The authors showed that satellite-observed radiation loss by the Earth increased dramatically with warming, often in excess of 6 Watts per sq. meter per degree (6 W m-2 K-1). In stark contrast, all of the computerized climate models they examined did just the opposite, with the atmosphere trapping more radiation with warming rather than releasing more.
The implication of their results was clear: most if not all climate models that predict global warming are far too sensitive, and thus produce far too much warming and associated climate change in response to humanity’s carbon dioxide emissions.
A GOOD METHODOLOGY: FOCUS ON THE LARGEST TEMPERATURE CHANGES
One thing I liked about the authors’ analysis is that they examined only those time periods with the largest temperature changes – whether warming or cooling. There is a good reason why one can expect a more accurate estimate of feedback by just focusing on those large temperature changes, rather than blindly treating all time periods equally. The reason is that feedback is the radiation change RESULTING FROM a temperature change. If there is a radiation change, but no temperature change, then the radiation change obviously cannot be due to feedback. Instead, it would be from some internal variation in cloudiness not caused by feedback.
But it also turns out that a non-feedback radiation change causes a time-lagged temperature change which completely obscures the resulting feedback. In other words, it is not possible to measure the feedback in response to a radiatively induced temperature change that can not be accurately quantified (e.g., from chaotic cloud variations in the system). This is the subject of several of my previous blog postings, and is addressed in detail in our new JGR paper — now in review — entitled, “On the Diagnosis of Radiative Feedbacks in the Presence of Unknown Radiative Forcing”, by Spencer and Braswell).
WHAT DO THE AMIP CLIMATE MODEL RESULTS MEAN?
Now for my main concern. Lindzen and Choi examined the AMIP (Atmospheric Model Intercomparison Project) climate model runs, where the sea surface temperatures (SSTs) were specified, and the model atmosphere was then allowed to respond to the specified surface temperature changes. Energy is not conserved in such model experiments since any atmospheric radiative feedback which develops (e.g. a change in vapor or clouds) is not allowed to then feed-back upon the surface temperature, which is what happens in the real world.
Now, this seems like it might actually be a GOOD thing for estimating feedbacks, since (as just mentioned) most feedbacks are the atmospheric response to surface forcing, not the surface response to atmospheric forcing. But the results I have been getting from the fully coupled ocean-atmosphere (CMIP) model runs that the IPCC depends upon for their global warming predictions do NOT show what Lindzen and Choi found in the AMIP model runs. While the authors found decreases in radiation loss with short-term temperature increases, I find that the CMIP models exhibit an INCREASE in radiative loss with short term warming.
In fact, a radiation increase MUST exist for the climate system to be stable, at least in the long term. Even though some of the CMIP models produce a lot of global warming, all of them are still stable in this regard, with net increases in lost radiation with warming (NOTE: If analyzing the transient CMIP runs where CO2 is increased over long periods of time, one must first remove that radiative forcing in order to see the increase in radiative loss).
So, while I tend to agree with the Lindzen and Choi position that the real climate system is much less sensitive than the IPCC climate models suggest, it is not clear to me that their results actually demonstrate this.
ANOTHER VIEW OF THE ERBE DATA
Since I have been doing similar computations with the CERES satellite data, I decided to do my own analysis of the re-calibrated ERBE data that Lindzen and Choi analyzed. Unfortunately, the ERBE data are rather dicey to analyze because the ERBE satellite orbit repeatedly drifted in and out of the day-night (diurnal) cycle. As a result, the ERBE Team advises that one should only analyze 36-day intervals (or some multiple of 36 days) for data over the deep tropics, while 72-day averages are necessary for the full latitudinal extent of the satellite data (60N to 60S latitude).
Lindzen and Choi instead did some multi-month averaging in an apparent effort to get around this ‘aliasing’ problem, but my analysis suggests that the only way around the problem it is to do just what the ERBE Team recommends: deal with 36 day averages (or even multiples of that) for the tropics; 72 day averages for the 60N to 60S latitude band. So it is not clear to me whether the multi-month averaging actually removed the aliased signal from the satellite data. I tried multi-month averaging, too, but got very noisy results.
Next, since they were dealing with multi-month averages, Lindzen and Choi could use available monthly sea surface temperature datasets. But I needed 36-day averages. So, since we have daily tropospheric temperatures from the MSU/AMSU data, I used our (UAH) lower tropospheric temperatures (LT) instead of surface temperatures. Unfortunately, this further complicates any direct comparisons that might be made between my computations (shown below) and those of Lindzen and Choi.
Finally, rather than picking specific periods where the temperature changes were particularly large, like Lindzen and Choi did, I computed results from ALL time periods, but then sorted the results from the largest temperature changes to the smallest. This allows me to compute and plot cumulative average regression slopes from the largest to the smallest temperature changes, so we can see how the diagnosed feedbacks vary as we add more time intervals with progressively weaker temperature changes.
RESULTS
For the 20N-20S latitude band (same as that analyzed by Lindzen and Choi), and at 36-day averaging time, the following figure shows the diagnosed feedback parameters (linear regression slopes) tend to be in the range of 2 to 4 W m-2 K-1, which is considerably smaller than what Lindzen and Choi found, which were often greater than 6 W m-2 K-1. As mentioned above, the corresponding climate model computations they made had the opposite sign, but as I have pointed out, the CMIP models do not, and the real climate system cannot have a net negative feedback parameter and still be stable.
But since the Lindzen and Choi results were for changes on time scales longer than 36 days, next I computed similar statistics for 108-day averages. Once again we see feedback diagnoses in the range of 2 to 4 W m-2 K-1:
Finally, I extended the time averaging to 180 days (five 36-day periods), which is probably closest to the time averaging that Lindzen and Choi employed. But rather than getting closer to the higher feedback parameter values they found, the result is instead somewhat lower, around 2 W m-2 K-1.
In all of these figures, running (not independent) averages were computed, always separated by the next average by 36 days.
By way of comparison, the IPCC CMIP (coupled ocean-atmosphere) models show long-term feedbacks generally in the range of 1 to 2 W m-2 K-1. So, my ERBE results are not that different from the models. BUT..it should be remembered that: (1) the satellite results here (and those of Lindzen and Choi) are for just the tropics, while the model feedbacks are for global averages; and (2) it has not yet been demonstrated that short-term feedbacks in the real climate system (or in the models) are substantially the same as the long-term feedbacks.
WHAT DOES ALL THIS MEAN?
It is not clear to me just what the Lindzen and Choi results mean in the context of long-term feedbacks (and thus climate sensitivity). I’ve been sitting on the above analysis for weeks since (1) I am not completely comfortable with their averaging of the satellite data, (2) I get such different results for feedback parameters than they got; and (3) it is not clear whether their analysis of AMIP model output really does relate to feedbacks in those models, especially since my analysis (as yet unpublished) of the more realistic CMIP models gives very different results.
Of course, since the above analysis is not peer-reviewed and published, it might be worth no more than what you paid for it. But I predict that Lindzen and Choi will eventually be challenged by other researchers who will do their own analysis of the ERBE data, possibly like that I have outlined above, and then publish conclusions that are quite divergent from the authors’ conclusions.
In any event, I don’t think the question of exactly what feedbacks are exhibited by the ERBE satellite is anywhere close to being settled.
“To conclude, it is perfectly physically consistent to expect that increasing greenhouse gas driven warming will heat the oceans – as indeed is being observed.”
from your referenced article – what is being claimed amounts to colder atmosphere heats warmer water. What’s more, the presumption is present that because there is an extremely minor increase in the skin temperature, that this means the oceans will warm. there’s plenty of other references around as to 2nd law violations.
as for relative humidity staying constant with increase in temperature – that’s a so what. It offers nothing as to suggest a change in the way cloud cover behaves. It does offer something entirely different though.
If one presumes constant relative humidity, one has the problem that the increase in absolute humidity cannot provide anywhere close to the positive feedback being promised from h2o vapor.
Lindzen’s early ideas concerned high level clouds. I believe that his view has changed some with time. I think there is an iris effect and it associated with low level clouds. Those cirrus clouds of the original iris effect are rather high up and the factors involved are quite complex and still not well understood but include factors such as dissipating thunderstorms. Just for the record, Lindzen is an expert on clouds and cloud formation and I am definitely not.
One problem with the more radiation escaping to space is that thick clouds (radiatively speaking) not only substantially block radiation from the surface, they also are composed of particles, ice and water droplets which also radiate a continuum – like a surface. That’s not to say exactly like a surface but then again, continuum emissions from small particles I think is still an active and ongoing area of research. Also, the temperatures are a bit cooler there so the total radiation is not as much – although only about 70% of the surface radiation under clear skies makes it to space. Then again, clear skies radiate around 260-270 w/m^2 and the balance point with current albedo is around 235 w/m^2 so we’d be in real trouble if that 60% + cloud cover radiated much over around 220 w/m^2 anyway.
While ice may have high reflectivity in the visible, both it and liquid water reflectivity plummets as one enters the micron wavelength range.
Since the claim is that cirrus clouds are supposedly quite transparent to visible, making them low albedo, their disappearance should result in increased clear skies and more outgoing radiation. However, despite what Lindzen’s view is, my own view is closer to the surface for the main iris effect. We’ll just have to see how that one plays out.
Also, less cirrus doesn’t necessarily mean less of the ‘averaged’ cloud that provides the overall averaged effect. There’s still plenty of opportunity for that as well.
Concerning again, the notion of relatively fixed rh, it should be obvious that rising temperatures cannot increase the absolute humidity in places where there is no available additional water to become vapor. Hence, one cannot expect a uniform increase. I think though that the important concept to draw from this arena is that CO2 without feedbacks is capable of around 1/2 to 1 deg C rise in temperature for a doubling. If one assumes a 5 deg C rise in temperature due to the co2 doubling and the h2o feedback, one finds that the permissible increase in absolute humidity caused by a 5 deg. C rise is roughly comparable to the same power absorption increase for water vapor as for the CO2 doubling. That leaves one short by 3 degrees C in causality. If one assumes only a 2 deg C rise total, again with the co2 around 1 deg.C, one finds that this rise only increases absolute humidity by a small fraction of the previous amount. Net result is that there is still insufficient feedback to produce a 2 deg C because the water vapor feedback increase is much less than the forcing from a doubling in co2. Consequently, anything resembling catastrophic warming due to water vapor feedback is missing the causality needed for it to occur.
cba (14:39:52)
heh. Its quite intellectually degrading to follow the logic on that particular forum at RC. Anyway, since most heat leaves by convection, clouds inhibit convection and explains why its warmer during cloud cover.
addendum: convection, not radiation. Its believed that overcast nights are warmer because of infrared radiation from earth being held by clouds. In fact, overcast skies means that convection is being limited, whilst on clear nights, convection isn’t limited
p wilson,
clouds are a product of convection. There is nothing to inhibit convection in a cloud and in fact, that is what is going on in spades inside big clouds. What is blocked is infrared and visible light, i.e. radiation. Clouds absorb and radiate. In the visible, they also are good at reflecting. Very little is good at reflecting in the IR though. Cloud bottoms are warmer than cloud tops. Cloud tops radiate away power at a lower rate due to lower temperatures but they still radiate. Cloud bottoms are lower down and receive and capture a lot of surface radiation and they radiate downward at their temperature. Power primarily convects inside the cloud to feed the upper areas which are losing power (and would drop even lower in temperature without getting additional heat energy from below). Have you ever wondered how baseball sized hail in a severe thunderstorm grows to become baseball sized? It’s due to some really serious upward convection inside the cloud.
p wilson,
P.S.
that was the first time I’ve been to real climate this year. I avoid it as I find their claims about being scientific to be quite nausiating.
I think I’ve never heard so loud
The quiet message in a cloud.
=================
I mean something else. I think it is convection holding in heat when cloud cover makes it warmer at night when there is clou cover. Its not much considered as a possibility in the climatologist community, just like oceans were not much considered hitherto -very little radiation leaves the earth. A clear sky gives to heat convection occuring, whilst cloud blocks convection, as overcast nights give stable air layers so it is warmer at the surface. Sure, radiation takes place, though quite negligible.
addendum: That is: heat convection is not occurring during overcast nights. Duh
Here’s something else that uses the satellite data to preclude AGW. The data is used to extract the response of the climate system to hemispheric specific seasonally variable solar forcing. One of the things it shows, is that the ratio between the surface energy and incident energy gets smaller as surface temperatures increase. This is the signature of strong net negative feedback acting on the climate system.
http://www.palisad.com/co2/eb/eb.html
George
cba says:
No…What is being claimed is that the increase in the skin temperature reduces the flow of heat from the oceans to the atmosphere. A violation of the Second Law would occur if there was a net flow of heat occurred from a colder body to a warmer body. No such flows are posited and claims of violations of the 2nd Law are pernicious nonsense that I frankly think you are smart enough to know are wrong
More nonsense, frankly. The models that predict that the relative humidity remains constant have the positive feedback due to water vapor that they have. (It is roughly enough to double or so the climate sensitivity, although a part of this is then taken back by the lapse rate feedback, which is a negative feedback.)
Some places may be limited by lack of water…but over the globe as a whole, water is very accessible. Noone is saying that the increase in absolute humidity (or the constancy of relative humidity) is uniform. However, what does happen to be true, for what it is worth, is that the strength of the feedback is about the same whether you assume the relative humidity is uniform everywhere or whether you allow it to vary.
The 1 dec C number is approximately correct. I am not sure where you get the 1/2 C number from.
As I said, the water vapor feedback roughly doubles the climate response. It does not bring it up to 5 deg C. Models with feedbacks up around 4.5 C get that from a combination of water vapor, albedo, and cloud feedbacks (and the negative lapse rate feedback).
Smokey,
Repeating posting up plots that are nonsense doesn’t do anything but discredit the arguments of the so-called climate “skeptics” by illustrating how little skepticism you actually have and how the skeptic movement is based on just repeating the some debunked arguments over and over. It makes it easy for the policymakers to ignore you because you are dooming yourself to irrelevancy. It also shows a deep and profound lack of personal responsibility. (Perhaps you would behave more responsibly if you didn’t hid behind a pseudonym, a point that Anthony makes when those who disagree with his point of view use them.)
Your first plot is from radiosonde sensors, for which the long term trends in humidity are simply unreliable due to changes in sensor technology and other problems. The short-term variations in humidity both from radiosondes and satellite data in fact show that the water vapor feedback is operating as expected…and the long-term trends from the satellite data (which also have to be treated with some caution but are better than the radiosonde data) support this too. See http://www.sciencemag.org/cgi/content/abstract/sci;310/5749/841 and http://www.sciencemag.org/cgi/content/full/323/5917/1020
Your other two plots suffer from the problem that they look at temperature trends over short periods of time, conveniently cutting off the data at shorter times as well as the data since 2008. Here in Rochester, it got well into the 60’s the last 2 days and I am quite sure that a plot of temperature over the last week would show not only an upward trend but quite a strong one. Do you think this provides convincing evidence disproving the seasonal cycle theory whereby the temperature trend in Rochester should be negative at this time of year? Furthermore, if it is then cooler in the next few days, is it okay for me to continue to show a plot ending today when I try to convince people that the “seasonal cycle theory” is wrong?
Joel,
When Radiosonde measurements feature in ‘skeptic studies’ they are “unreliable”. But when the same measurements are used in AGW papers, they are “robust”.
WUWT?
cba says:
I am just trying to understand where you are coming from. And, as I noted to Smokey, people who use pseudonyms and disagree with Anthony Watts on AGW and post here tend to be given a hard time about using pseudonyms rather than posting under their real name.
Yeah…I said “lower albedo” when I should have said “raising albedo” in that post that you are referring to.
No, it seems to be you who are only considering radiation. The author’s point, as illustrated in the flow chart is that the warming of the skin layer reduces conduction of heat from the ocean to the atmosphere through that layer.
How do you know what the cloud variation of albedo has been…and are you also considering the change in LW radiation that the clouds produce?
No…I am not confusing a large inertia with a large effect. The effect is what it is given the radiative forcing produced. The inertia just tells you how long it takes to reach radiative balance. I’m not claiming that the ocean increases the amount of warming; I am claiming that it slows down the warming so it takes a longer period of time to occur (and if you start talking about oscillatory forcings, such as the seasonal forcing, then it can even reduce the effect because the delay in the response of the system means that it never gets into radiative balance).
Nonsense. If this were the case, then models with high sensitivities would show such problems when one ran them with the sort of insolation variations that you describe. Do you have any evidence whatsoever that this occurs?
Joel said, “Do you think this provides convincing evidence disproving the seasonal cycle theory…?”
Huh? I haven’t heard about this theory… I thought seasonal cycles are fact… Climate change is fact… Natural variability is fact… And only the much discredited and disproven CAGW theory is limping around as desperate climate scientists try to prop it up along with their endangered carreers….
The only way a doubling of c02 could lead to an increas of 1/2 to 1C could take place is if c02’s molecular structure changed to increase its bandwidth of absorbtion. This is not a possibility. Regardless of quantity, whether 200ppm or 500ppm, it still absorbs at an optimum 15micron peak, so over its entire shoulders and peak, this is less than 8% of longwave radiation (which, incidentally, is a small fraction of outgoing heat. Most is convection and evaporation). Only 8% or less radiation is available to c02 to be absorbed, and this doesn’t increase with doubling. so: Assuming 33C (neither proven nor falsified) – 33Cx2% outgoing radiationx8%=0.05 for all c02
even if we were to accept the exagerrated claim that 41% radiation leaves earth, the scenario still can’t be justified.
So 33°C X 41% X 8% = 1.08°C — The total heat that CO2 supposedly produces.
however, as maintained above, there is no physical mechanism for c02 causing a water vapour feedback. Water vapour could cause a negligible amount of its own feedback, as it has more absorbtion spectra than c02, although it is a feedback from solar forcing.
In truth though, neither ghg can absorb much LW radiation, as cooling via radiation takes place below the bandwidths available to them, and largely escapes them.
The most potent of the ghg’s – is water vapour, though it doesn’t react with c02 as an amplified product. thats a purely philosophical notion from computer models.
The ocean doesn’t have a skin. It has the same molecular structure as any other layer within its vicinity, and turns over regularly. (being a liquid).
stephen Wilde explained the process well in his link above
However, there is much scepticism regarding whether Stephen Wilde is correct about a warming effect over land through c02. It is an intensively studied gas. Those of Angsrom’s follower’s by experimental procedure maintain that a doubling doesn’t increase temperatures. Those followers of Keeling and Arrhenius maintain that it theoretically increases temperatures with quantity. Today, we have enough information on absorbtion spectra of various ghg’s and a fair enough knowledge of thermodynamics to form an impartial conclusion about the effect of “greenhouse gases”
George E. Smith (14:23:48) :
“Negative feedback systems subtract from the input signal AT ZERO FREQUENCY; while Positive feedback system add to the input signal AT ZERO FREQUENCY.”
That is a rather arbitrary distinction which would make all Type II stabilizing feedback “positive”. Really, you are more interested in the gain at the crossover frequency.
Joel Shore (13:30:20) says:
Poor Joel. Anything he disagrees with gets hand-waved away like this: “Plots that are nonsense”. In fact, he repeatedly labels cba’s different opinion ‘nonsense’. It’s becoming clear who’s spouting the nonsense.
Joel was referring to these 3 charts that I posted up @19:32:24:
click1
click2
click3
I doubt that the people who made those charts would accept them being labeled “nonsense.” Joel is simply throwing a hissy fit, because they contradict his mistaken belief that CO2=CAGW. I posted those charts because Joel made the incredible claim: “…both temperature and water vapor are increasing as the climate system warms.”
Earth to Joel: the climate has been cooling, not warming. [That graph reflects data from GISS, two satellite systems, Hadley, and the ARGO buoy system. Cue the Joelism: “B-b-but, they don’t start where I want them to start! They’re too long! Or too short. They don’t prove that CO2 means we’re all DOOO-O-O-O-M-E-D! So that makes them total nonsense!”]
Joel also believes that just about all the increase in CO2 has been due to human activity. But not even the UN’s IPCC believes that canard.
Smokey (16:42:09) :
Poor Joel. Anything he disagrees with gets hand-waved away like this: “Plots that are nonsense”. In fact, he repeatedly labels cba’s different opinion ‘nonsense’. It’s becoming clear who’s spouting the nonsense.
——————————
Not totally true Smokey. He has other tools besides hand-waving. All, of course, designed to get the new reader to believe that there is still some controversy in the field regarding the now farcical doomsday scenario.
For example:
(1) He also doesn’t respond to certain “unpleasant” comments, such as my remark to his suggestion that the 2006 book on temperature reconstruction proxies is “respected”. Since the Briffa expose, I suggested obliquely that the hard copy of this work is probably about as “respected” as toilet paper right about now.
(2) When lost for data, he also falls back on the “trust me I’m a doctor” approach and suggests that the poster believe “some” or “all of” the models by unnamed “peer-reviewed by their mates” scientists, that are not even referenced, let alone what the inputs are (since he likely doesn’t know himself – or care for that matter).
(3) ….. and then, presumably to try to impress the mentally soft reader, he will also explain how the world as Joel Shore sees it is the only way possible that the world could be, and people who really should know better should see the world exactly as Joel Shore sees it, and he’s totally dumbfounded as to why they don’t.
I kinda like him on here. I suspect that the number of converts he has to his name is, in round numbers, probably a round number. He provides good talking points for other posters, with more knowledge in specific areas, to demolish in public.
Joel,
“To conclude, it is perfectly physically consistent to expect that increasing greenhouse gas driven warming will heat the oceans – as indeed is being observed.
”
If you want people to stop accusing warmers of theories that violate the 2nd law of thermo, then they need to stop making statements implying that they are promoting theories in violation of the 2nd law. The (lack of) rigor in the statement leaves them open to the charge, regardless of whether the actual mechanism being presumed does or does not violate it.
as for my id or pseudonym, I’ve seen people persecuted for their non mainstream views and even attempts made to have them fired or arrested on trumped up allegations. I do not maintain any presence on the web like a facebook page or personal information website, either in my name or any pseudonym. That is other than what is required for work and for some unknown reason, there has been a minor failure in that area to properly include any photo. As for Anthony, he is provided a private email address which carries a bit more information than some blind third party blind address.
“No, it seems to be you who are only considering radiation. The author’s point, as illustrated in the flow chart is that the warming of the skin layer reduces conduction of heat from the ocean to the atmosphere through that layer.
”
Actually, I’m considering conservation of energy and all modes of power transfer. Transfer of power from the skin depends on the temperature of the skin and temperature change of the skin depends upon the difference in power out versus power in. The fact that there is a temperature difference between skin and 5cm down means that the heat flow from below is insufficient to keep the skin temperature elevated.
Again, the fact is the outgoing power is a function of skin temperature, not a direct function of power from below. Heat capacity and conservation of energy determines the temperature.
If this decrease in differential temperature between 5cm and skin resulted in less heat flowing from below, then the skin temperature would have to decrease for energy flow balance. You’d think a decrease in T at the skin would increase the skin-5cm differential in T.
Cloud albedo variation? One reconstruction of albedo is via ashen light – Palle’ & Goode ’07. It’s based on a combination of cloud cover measurement and ashen light measurement for calibration. It seems that the direct measurements of albedo via satellite has some serious holes at the most inopportune times.
Albedo has a massive effect. It is the difference between 341 w/m^2 coming versus about 235 w/m^2 using averaged values. Clear skies in the averaged case have about 270W/m^2 outgoing after atmospheric absorption after losing around 30% or 120 W/m^2. Clouds absorb a tremendous amount of the outward IR. Some radiates back down based on the cloud base temperature (and optical thickness) and some of this energy convects/conducts up to the top of the cloud where it radiates out at the cloud top temperature – which is usually less than the cloud bottom. Note that since clear skies is 270 and required balance is 235 W/m^2 or so, one must have somewhat less than 235 W/m^2 for top of cloud emissions. Remember the top of the clouds are above most all of the water vapor and hence above most all of the ghgs. This is going on regardless of minor changes in co2 forcings.
The inertia isn’t just time duration, it’s intensity too. Large inertia with a long time delays have far less effects than does a large inertia with very a short time delay. Do you realize that the Earth’s center is about the same temperature as the Sun’s photosphere? The mass of the Earth is far far larger than the mass of Earth’s oceans. The time to reach equilibrium is in the billions of years and the effect of that additional geothermal power does not on average provide any significant fraction of a degree C of surface temperature rise.
you’re asking me if I have proof that solar insolation varies by about 90 W/m^2 between aphelion and perihelion?????? Look up the distances and calculate it!
P Wilson (14:37:07)
I accept that even the effect of more CO2 over land is in debate but the effect of it over land is nevertheless very different from it’s effect over water and that was the point I was trying to get across.
I felt it prudent not to challenge the so called consensus regarding the effect over land because that would have distracted from the main point.
That said, I am not yet convinced by the suggestions that CO2 does not have a warming effect even over land. Of course it will be largely offset by increased convection, radiation and some evaporation and evapotranspiration but those effects are as nothing compared to the evaporation effect over water.
tallbloke says:
Where did I say that the measurements are “robust” when used in “AGW papers”? What does tend to be true for the satellite measurements and I think also the radiosonde measurements is that fluctuations on a timescale of a year or so are robust whereas the long-term multidecadal trends are more problematic because they are subject to artifacts. This is not that hard to understand actually…Going back to temperatures for example, just imagine adding a spurious trend of 0.1 C per decade to the data; You will see that this makes a large change in the multidecadal trend (changing it by 0.1 C per decade) but will actually make very little change to a fluctuation on the timescale of a year or so, such as occurs due to ENSO.
cba says:
Frankly, I think this is a poor excuse for putting up bogus arguments. The statements seem to only imply such things to people who want to interpret them in the most critical light. And, if people think that the lack of rigor in the statement is a problem, they could do what Alistair Fraser does ( http://www.ems.psu.edu/~fraser/Bad/BadGreenhouse.html ) and suggest more rigorous pedagogy rather than pretending that they have a substantive disagreement. That what a real scientist would do rather than someone who just sees himself as a lawyer trying to raise doubts about AGW. I know it is always tempting to set up “strawmen” and know them down but such temptation should be resisted.
Right…and in some cases, he has used that information to say publicly where people using pseudonyms are posting from and has challenged them to drop their pseudonym and post under their real name. You are fortunate enough that you are on the “correct side” as far as he is concerned. When this happens, I hope you will defend the right of people on “my side” of the argument to use pseudonyms if they so desire.
At this point, I am no longer sure what we are even arguing about in regards to the skin temperature and the albedo.
As near as I can figure out what you are saying, I don’t think this is a good analogy. For the case of heat transfer out from the earth’s center, one can calculate that in W/m^2 and find that it is very small. We can also calculate the radiative imbalance due to an increase in greenhouse gases and it is considerably larger…and, in fact, large enough to be important. I don’t see where the thermal inertia provided by the oceans is going to make the response to this radiative imbalance smaller. I think it will just delay the re-establishment of radiative balance.
I frankly don’t see how you could interpret me as asking for that. My statement was: “Nonsense. If this were the case, then models with high sensitivities would show such problems when one ran them with the sort of insolation variations that you describe. Do you have any evidence whatsoever that this occurs?” So, what I am contesting is not how much the insolation varies between aphelion and perihelion (although it is worth noting that this insolation needs to be divided by 4 to account for the difference between the earth’s surface area & the cross-section area of the sun’s insolation that it intercepts and then multiplied by 0.7 to account for albedo in order to convert it to an average radiative forcing).
Rather, I am contesting your notion that such variations along with high sensitivity would cause the “Earth [to] burn up totally”. In particular, I am asking you for evidence that climate models that have these “high sensitivities” (which you didn’t precisely define but which I assume means sensitivities in the IPCC likely range of 2 to 4.5 C) show dramatically unphysical effects when the insolation is varied in this way. Basically, you are making a claim that high climate sensitivities are incompatible with the observed behavior under the variations in when aphelion and perihelion occur (relative to the earth’s axial tilt) and I want you to back that claim up.
Of course, “know them down” should be “knock them down” in my previous post.
This is the real issue as regards the ocean skin:
1) The location at which Fourier’s Law applies is dictated by the interplay between forces within the ocean and forces within the air. Without evaporation the location would be at or very near the very topmost molecules of the oceans. With evaporation and radiation it is 1mm down from the surface.
2) Below that point 1mm deep, solar effects and convective effects are dominant. Above that point 1mm deep, evaporative and radiative effects are dominant.
3) What does it take to change the temperature differential at that point 1mm deep if there is extra downwelling IR ?
4 ) Either the warming effect of the IR in the top 10 microns has to change the differential 1mm down or the cooling effect of increased evaporation in the remaining 990 microns of the ocean skin has to change the differential 1mm down.
5) The ocean skin theory requires that the warming of the topmost 10 microns somehow magically leaps across the evaporative cooling effect in the remaining 990 microns to decrease the differential.
6) I say that the warming effect in the top 10 microns has no effect on the differential. Instead the differential is increased by extra IR because it enhances the evaporative cooling of the lower 990 microns of the ocean skin.
That about sums it up.