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.
Julian,
Some of your questions arise, I believe, because you are not clearly distinguishing between the surface of the planet and the top of atmosphere (TOA) where the emissions are being measured here. While it may be legitimate to assume in some models that the planetary surface acts as a blackbody, or more accurately a greybody, radiator, one cannot treat the TOA as one.
If one goes back to the original Kiel and Trenbarth paper to calculate radiative forcing from GHGs, it is clear that they EXPECTED to see a reduction in outgoing radiative emissions in the CO2 bands if atmospheric CO2 increased. This is not compatible with blackbody or greybody radiative behaviour at TOA. If you go to this site:
http://www.skepticalscience.com/How-do-we-know-CO2-is-causing-warming.html you will also see some slightly dubious but probably valid empirical evidence supporting a reduction in radiative flux in the CO2 bands at top of atmosphere over a timeframe (taken from Harries in a series of accessible post-2001 papers) as CO2 has increased.
What I am saying therefore is that while your inferences about greybody behaviour at the surface may be correct, the results being considered here are not “blackbody” nor even “greybody” radiation. They are look instead at the emitted spectrum from the Earth’s surface after it has been filtered and “processed” by Earth’s atmosphere as well as those wavelengths reflected by Earth’s albedo. The variation in these emissions therefore does become a function of: variation in GHGs, changes in albedo and feedback effects on flux induced over different periods of time by the different impacts of changesin temperatures. I hope this helps.
Julian (23:46:09) :
these are indeed the simple headed principles borrowed from physics and engineering to explain the complexities of nature and ecodiversity. They’re used in physics to expedite technology.
how it became applied to explain a sophisticated paramenter like the earth -well, its probably due to NASA. I’ve always thought that NASA’s grasp of earth science and even physics were dense and incredible. Incidentally, the planet cools through low frequency infrared radiation (below the wavelength absorbed by “greenhouse gasses”); and therefore greenhouse gasses do not reduce the rate of cool-down. Its only through introducing physics used in engineering that the system is contrived otherwise. They just don’t apply.
Bill Illis,
first off Bill – did you ever get the last info I posted for you back on the 350 co2 thread last week???
Second, while the 1997 activity is undoubtedly strongly impacted or caused by ENSO, it also resulted in a massive change (drop) in albedo due to reduced cloud cover as well. I think the peak to peak magnitude of that facet was about 10 W/m^2. Since balance indicates an average emission close to 239 W/m^2 and clear skies tend to emit something in the order of 260 W/m^2, it’s only natural to expect that top of cloud emission be in the rough vaccinity of 210 W/m^2 (averaged) as cloud cover runs about 60% (and cloud tops are cooler for emissions which bring it down towards that level. The variable cloud cover (and hence variable albedo) are capable of causing both a change in the incoming solar and in the variation of outgoing LW without direct regard to the SST. Greater cloud cover reduces OLR (replacing surface outgoing with top of cloud) and it reduces incoming SW even more. a Stefan’s law solution for Earth including the variation of albedo for SW would result in about a 10 deg C rise for clear skies over what we have at present. A total overcast (100% cover) is much more subjective but it would result in somewhat lower mean T than we have now. Net result suggests that the radiated power is not just a function of SST but also of the cloud cover. It also suggests the presence of a major negative feedback (cloud formation) that creates a setpoint control over the cloud fraction to stabilize it (Lindzen Iris effect or something similar).
Consequently, I don’t see how the system can be analyzed without taking into account the albedo variation as well and what albedo measurements seem to exist have a failure and missing data around the most critical 1997 time frame (except for the proxy by Palle’ & Goode).
This letter to Congress, March 2009 explains it fairly well
http://scienceandpublicpolicy.org/images/stories/papers/reprint/markey_and_barton_letter.pdf
Lindzen’s analyses are widely quoted therein
Bill Illis,
These figures in wm/2 are quite absurd. Are they from the Steffan Bolzzman constant? If so they apply to electronics, engineering and incandescent metals. They can’t be borrowed for gases and liquids
on th eSteffan Bolzzman: someone calculated with this that the human emits 500wm/2. Calorimeters and remote sensors detect 85w/m2
500 w/m2 is the required energy to boil sunflower oil
oops, sorry. that was addressed to CBA
Bill Illis (06:14:37)
it could be calculated according to temperatures. The troposhere loses 6C for every kilometre. At the top of the troposphere, typical temperatures are -60C, varying on season, and equator/pole. At this point c02 has 5% of its peak efficiency, so absorbs at the shoulders where it competes in the same wavelengths as nitrogen and oxygen. There are millions of times more 02 and N2 molecules in the upper troposhere than c02 molecules.
the greenhouse effect takes place at the 1st 15 metres from ground level.
The period of time a molecule like c02 holds heat is a trillionth of a second before it transmits to other molecules with which it thermalises, such as 02 and N2
Bill Illis says:
No…The time constant in question is determined by how long it takes to heat up the system when a give radiative imbalance is applied, which is quite long once you consider the fact that the oceans provide a lot of thermal inertia. There are some legitimate questions about exactly how long this is since it depends quite sensitively on mixing between the mixed layer and the deep oceans…but even if one assumes the mixed layer is completely isolated from the deep ocean, one still gets a time constant of about 5-10 years. Mixing with the deep ocean then makes the effective time constant even longer.
cba (06:53:37) :
first off Bill – did you ever get the last info I posted for you back on the 350 co2 thread last week???
No, sorry I didn’t see it until now. I checked back a few times but I guess I lost track of the thread. Sorry.
Let’s continue the discussion there, but give me till later tonight to go through it in more detail
“”” Julian (23:56:40) :
I guess what I’m saying is, if the surface of a planet warms due to the effect of a greenhouse gas, a satellite measuring outgoing black body irradiation shouldn’t see it. It shouldn’t see any change in outgoing black body irradiation at all. “””
I’m not sure you are seeing the picture Julian. The earth continually receives 1366 W/m^2 from the sun, over a projected area of pi.R^2, which constantly illuminates a bit more than twice that area (2pi.R^2); actually about 50.4% of the total earth surface area of 4pi.R^2.
That EM radiation has the typical solar spectrum distribution, which approximates a black body radiation spectrum, at a temperature of roughly 6000K. That spectrum has it peak spectral irradiance at about 0.5 microns wavelength; and about 98% of that energy is contained between the points at half the peak to 8 times the peak; or 0.25 to 4.0 microns wavelength range. That is what continually bathes half of the planet’s surface area. The extra 0.4% results from the angular diameter of the sun being 0.5 degrees, and the atmosphereic refraction adds about another half degree.
As a result of atmospheric refractionwhen the sun appears to be sitting just touching the horizon, it is actually already completely below the horizon. The twilight condition adds some extra area to the fraction of the earth that is sunlit at all times.
That solar spectrum radiation is partly absorbed by the earth and partly reflected (albedo). The major contributors to albedo are clouds and snow/ice which roughly reflect the whole solar spectrum. Other surfaces may be more spectrally selective; but what they refelct is still within that solar spectrum 0.25 to 4.0 micron range (1% residual below 0.25 microns, and 1% above 4 microns).
Most of the non reflected solar energy goes into the oceans; but some of it is absorbed by the land, and some also is absorbed by the atmosphere. As a result, the oceans, the land, and the atmosphere are all directly heated by solar spectrum radiation; which as I said is roughly 6000K BB radiation.
In turn the components of the earth are heated to temperatures ranging from about -90 C to about +60 C in the extremes (183K to 333K).
ALL of these components in turn emit thermal radiation which approximates black body radiation corresponding to whatever the local temperature is; but modified by non spectrally constant emissivities; but they all still generally follow a fourth power of T law for total emittance.
At the “global mean” temperature of about 288K, the emitted LWIR spectrum peaks at about 10.1 microns; but has 98% of its energy from about 5 microns up to 80 microns. The hotter tropical deserts emit a shorter wavelength spectrum (Wien’s Displacement Law), and the colder polar regions emit a longer wavelength spectrum.
Overall, then the total emission spectrum is not black body, because the earth is not an isothermal emitter; but it generally still follows the fourth poower law as to total energy emitted; which ultimately must balance the energy absorbed from the sun.
The thermal radiation emitted by the atmosphere is emitted in all directions; so some of it goes downwards towards the surface, and some of it goes upwards to escape to space as LWIR; which can be seen from a satellite; which of course can also see the LWIR emitted from the surface areas.
One can argue that the atmosphere emissions are warming the surface; but really that is energy that came from the sun; and either heated the atmosphere directly or indirectly as a result of so called GHG capture of LWIR emissions from the surface. In that the GHG capture process results in a delay of the escape of the LWIR; that slows the cooling of the planet, and in the meantime more sunlight arives, so the temperature moves up a little.
Anyone who believes that the atmosphere does not emit LWIR thermal emissions, (BB like) just as the surface does; might like to come up with a quick alternative explanation for why it is that the gaseous sun emits a BB like thermal radiation spectrum; but the gaseous earth atmosphere does not.
As for the downward thermal radiation emitted from the atmosphere; that is mostly absorbed in the top ten microns or so of the oceans urfaces; whcih comprise about 73% of the earth surface; and intercept decidedly more that 73% of the total absorbed incoming solar energy. (the tropics are somewhat more oceanic than land).
All of the plots I have ever seen of the earth’s radiation as seen from outer space; show a spectrum that looks very much like a black body spectrum; with a somewhat flattened peak due to the range of temperatures actually emitting; but with some cuts in it, mostly due to CO2 and Ozone absorption holes. These curves are often calculated; and they pretty universally omit water vapor as a component of the atmosphere; even though water vapor is always present in the atmosphere in amounts that are greater than the CO2 abundance. I suspect that in the stratosphere the water content is small; but then so is the atmosphereic gas content as in N2 and O2 and Ar; and the amount of CO2 up there can hardly be capturing much LWIR energy.
Be that as it may; what little LWIR is captured by CO2 in the stratosphere; when distributed to the normal atmosphere gases in collisions; will raise the temperature; because there is so little mass to heat anyway. But as a source of heat to warm the surface it must be rather puny.
George E. Smith (23:08:51) : “Sorry; but I don’t agree…The system will only be unstable when the Nyquist condition says it is unstable…
That is the very definition of dominant positive feedback.
That condition can occur in “negative feedback” systems, because the propagation delays in ….
Then, the negative feedback has become ‘positive feedback’. Why? Because a transport lag can be modeled as a network with right half plane zeros. When you put in a negative feedback, the open loop poles necessarily are attracted to the open loop zeros. If the gain is too high, the poles go over into the right half plane. The feedback becomes self-reinforcing, i.e., an induced positive feedback.
I did not say a more powerful negative feedback will always stabilize a plant. I said it is necessary. But, it is not sufficient. The general rule is, when you have a right half plane pole, for stability, your negative feedback has to be ‘faster’ than the unstable pole. But, it has to be ‘slower’ than any right half plane zero, or ate least some (it only takes one) closed loop poles will migrate into the right half plane.
I’ve actually thought this effect could be used to vet some of the climate models and possibly disqualify some, if anyone involved has the know-how to derive the zero dynamics. Non-minimum phase (right half plane for a linear system) zero dynamics constrain the magnitude of negative feedbacks which would yield a stable system. If we take it as given that the Earth climate is autonomously stable, then any unforced model which became unstable in the presence of known feedbacks would be inadmissible. An instability might be very long term, and so not be observable in a practical time domain simulation.
anna v (05:27:40) : “If as Bart says the CMIP protocol runs are dependent on the AMIP protocol…”
I’m not saying it and expecting anyone to take my word for it, because I have not offered any curriculum vitae for people to take me seriously on the subject. I provided a link, and that is how I interpret it. Make your own determination.
The link.
Thanks, KevinUK. I truly believe clouds are the ultimate factor in all of this. But, nobody really knows clouds, at all.
Bill is quite correct. It takes radiation little time to leave the atmosphere. Heat via convection stays around in the atmosphere for considerably longer. Oceans however, can absorb a great deal of heat without increasing ocean temperatures. This is from where the atmosphere is in fact heated.
“The general rule is, when you have a right half plane pole, for stability, your negative feedback has to be ‘faster’ than the unstable pole. But, it has to be ’slower’ than any right half plane zero…”
More generally, it has to be bracketed by the two. Most non-minimum phase systems I deal with are of the former type.
Paul:
> Some of your questions arise, I believe, because you are not
> clearly distinguishing between the surface of the planet and
> the top of atmosphere (TOA) where the emissions are being
> measured here. While it may be legitimate to assume in
> some models that the planetary surface acts as a blackbody,
> or more accurately a greybody, radiator, one cannot treat
> the TOA as one.
Well that’s an interesting concept, and it goes towards the question, what exactly are these satellites measuring? My understanding, is that the Earth Radiation Budget Experiment (ERBE) carried on the ERBS satellite, which is the source of data for these discussions, was designed among other things to measure total radiative output from earth – not just from the top of the atmosphere. While in fact the satellite may be positioned somewhere near the top of the atmosphere, it should be measuring not only radiative output originating from the atmosphere, but also the radiative output from the earth surface that manages to be transmitted through the atmosphere out to space. See:
http://en.wikipedia.org/wiki/Earth_Radiation_Budget_Satellite
This is in contrast to the satellites which form the basis for the UAH and RSS data sets, which actually measure atmospheric temperatures at different altitudes according to the amount of radiative heat visualized originating from the atmosphere at different altitudes. By my understanding this is done by looking at radiation intensities at specific wavelengths (rather than a measure of total radiative output) and by calculations from different view angles. These satellites are not typically measuring total radiation budget as per my understanding. See:
http://en.wikipedia.org/wiki/Satellite_temperature_measurements#The_satellite_temperature_record
But if in fact ERBE is measuring total radiative budget, then I think that the W in vs. W out argument should hold in a steady state system. If it does not hold, then I think it should be clear that ERBE is measuring something other than total radiative budget.
Paul
> If one goes back to the original Kiel and Trenbarth paper to
> calculate radiative forcing from GHGs, it is clear that they
> EXPECTED to see a reduction in outgoing radiative
> emissions in the CO2 bands if atmospheric CO2 increased.
In the CO2 bands, true. But in the steady state the total radiation budget must be balanced. In the steady state, where CO2 rises, outgoing radiative energy in the CO2 bands decreases. This causes an increase in temperatures. Then, outgoing radiation across a broad spectrum increases to compensate for the low amount of outgoing radiative nerve in the CO2 bands. But in the steady state the radiation budget must still be balanced.
Illis:
> There is a time lag to consider though. How long does it
> take for “W out” to equilibrate with “W in” if there is an
> imbalance? The climate models consider this to be lag
> to be very long.
Wilde:
> Wouldn’t the satellite record a discrepancy between energy
> in and energy out during the period of time that the system
> is adjusting it’s temperature to an ongoing change, such as
> a steady increase in a particular greenhouse gas ?
This is particularly true. The Earth is probably almost never in a complete steady state. But still, it becomes difficult for me to grasp what exactly is being measured in the ERBE experiments and what the analysis of the data is seeing.
And maybe that is the point. The paper posits to measure feedback response to changes in temperature. So, we look at the planet at a time where temperature is increasing. For example, increasing global temperatures may release of additional water into the atmosphere which is in a form (vapor or cloud at a given altitude) that it can act as a greenhouse gas, then the radiative output from the earth will initially decrease. But how gradually would the vapor enter into the atmosphere after the increase in global temperatures and how gradually would the feedback increase in atmospheric vapor increase global temperatures such that the outbound radiative budget completely compensates for the shielding effect of the additional vapor?
I understand how the results seriously challenge the models. I’m just not sure what it means in terms of forming an estimate for tactual climate sensitivity. Can an estimate of climate sensitivity really be derived in this fashion in a reliable manner?
I tried to put my head around this but I can’t. I must be too dumb. Which is just as well, because I don’t understand how a bunch of crapped up computer models can come up with a realistic estimate of climate sensitivity either.
George,
solar radiation is coming from a much hotter gas.
In general, you need a solid or liquid to achieve a bb type spectrum. Now whereever there are clouds, you have very small solids and/or liquids. Also, it seems there are dimers – present that create a broadening to spectral lines in the atmosphere. This gives one a bb spectrum at even lower temperature than surface radiation.
For gases, one is limited to spectrums that are preferential to molecules present. The bb spectral distribution actually gives one the population of excited states or the liklihood of emission at each wavelength that can radiate but a particular molecule is limited to its lines which are the same as the absorption lines. These are broadened by temperature and pressure (and by doppler shifting when there is massive convection like at the solar photosphere “surface”P). As it turns out, the difference between a gas absorbing spectral lines from a radiating source behind it or whether it radiates spectral lines is a function of how hot the gas is relative to the radiating source. If it’s the same – there will be neither emission nor absorption lines evident and if it is hotter – there will be emission lines.
As one goes up above the cloud layer area, one finds most of the h2o vapor gone. The top of the clouds is also where one finds the particles of h2o liquid or solids capable of radiating a continuum. It’s much colder up there so it radiates somewhat less than the surface – but then again – there’s very little to stop any of it. Note that while one sees the climate 101 books describing the reduction in temperature with altitude as a consequence of the ideal gas law and the gravitational potential energy – the presence of h2o vapor and co2 and other ghgs in significant quantities really means that the temperature lapse rate is a function of energy balance.
joel shore,
shortwave incoming energy does penetrate to significant depths. Any effect caused by ghg warming is going to be LW. THat means, it’s not going to penetrate the ocean radiatively for any distance. Above 4 deg C, warmer water is lower density than colder so it rises. There is plenty of discussion around concerning the skin effect where the skin is at a lower temperature than the area just underneath – supposedly impeading the outward heat flow. That’s because the skin is able to radiate some energy out and to evaporate, carrying the heat of evaporation out of the water. This is also where all of that energy from the GHG generated IR is blocked and absorbed. All you’ve got to convey heat down into the oceans from IR at the surface is conduction and whatever convection might actually move low density water down – in opposition to its tendency to rise. In short, you are stuck with no serious mechanism to bring the heat down into the deep ocean in any meaningful way. I’d like to see you try to boil a beaker of water by heating only from the top using IR. All you can succeed in doing is to evaporate it from the top at a higher rate.
As for the ocean capacity being massive but taking decades to transfer energy, that’s another crock. Surface radiation at 288K mean temperature is dealing with emissions of 390w/m^2 with about 70% radiating off into space. Once you extend the time frame out for these massive ocean sink/source of energy, you’ve just restricted the flow of energy to or from to the point of miniscule levels relatively speaking. The atmosphere will reach equilibrium in days to weeks, if not hours – proven by the existence of seasons with warm and cold weather. Who cares what an almost infinite energy source is going to do at limiting a return to full equilibrium if the actual energy transfer contribution involved is so low as to cause a T imbalance of only 0.01 deg C ???? The longer it takes for that equilibrium to come about, the less temperature contribution will be possible.
Since you claim to be a phd physicist, here’s a tidbit concerning the real system. Orbital differences between aphelion and perihelion is around 90 w/m^2 with peak solar being December. Doing an rms calc., one should see there is a substantial difference in annual energy going to the southern and northern hemispheres when compared to the ghg variations of the last century or so with the southern hemisphere receiving quite a few W/m^2 more than the nothern one. Of course, most of the land mass is in the NH and most of the Pacific ocean is in the SH. We know too that winter time is much colder than summer time for much of each hemisphere indicating that yes indeedy folks – there is sufficient time for the atmosphere to adapt to the various seasons. Despite the significantly greater power hitting the SH, NH summer when the incoming solar is at a minimum is actually the hotter hemisphere during summer.
cba (22:24:39)
“Above 4 deg C, warmer water is lower density than colder so it rises.
…
All you’ve got to convey heat down into the oceans from IR at the surface is conduction and whatever convection might actually move low density water down – in opposition to its tendency to rise.”
If I remember rightly from my undergratuate physical oceanography (Southampton Univ) water at depths below 2-3 km is always at 4 deg C, it is thermodynamically fixed at that temp due to pressure, not heat exchange. Since this temp indeed is where water (idiosyncratically) has its density maximum, it would require too much energy to change the temperature and thus lift the whole water column. (If by contrast 0 deg C – the melting point – was the density maximum, like with most other liquids, then we would have a frozen bottom to the oceans and no deep circulation.)
I believe the most important mechanism of taking water down – and the heat that the water has down with it – is downwelling at cold locations: an important example is the Norwegian sea. Major downwelling at the Norwegian sea drives a southward deep current; the North Atlantic drift is a surface current going the opposite direction, perhaps in a compensatory manner.
However downwelled water at the Norwegian sea will be colder than 4 deg C. Relative to the 4 deg C deep water, downwelled water from the surface brings down cold (so to speak) not heat. So the interesting question is – when this water reaches the bottom and attains the forced temperature of 4 deg C, where does the energy come from to raise it to that temperature? Does gravitational pressure effectively heat the water?
CBA.
one of the laws of energy is that it can be transformed into other form of energy. Some solar energy is converted into biomass. There’s no way of knowing how much solar energy entering the oceans is converted, or how much total solar energy absorbed at land and sea level is converted into other forms or how much is disippated. It opens the question as to whether the “budget has to balance”. Its too mechanical a concept.
What happens to the heat that water systems cool? It either disippates or else it is transferred elsewhere. If you had a piece of aluminium at 200C cooled by water then its heat disippates as its electrons become unexcited.
There is a notion that heat is a constant, although no form of energy is a constant.
Phlogiston (01:57:22) :
cba (22:24:39)
“Above 4 deg C, warmer water is lower density than colder so it rises.”
Water also has the unusual property of to start expanding below 4C and contracting above 4C as its polarities of molecules attract with greater force. Its usually thought this happens at the interface between liquid and solid
Wilson:
> one of the laws of energy is that it can be transformed
> into other form of energy. Some solar energy is
> converted into biomass. There’s no way of knowing
> how much solar energy entering the oceans is converted,
> or how much total solar energy absorbed at land and
> sea level is converted into other forms or how much
> is disippated.
True, the earth is not a steady state system – though I doubt that the difference between biomass formation and decompensation has a very large effect on the blanace of heat tranfer in and out of the planet. The oceans in particular however, are a very large heat sink.
But if in your words “there’s no way of knowing” how much is going this way and how much that way, then how can an estimate of climate sensitivity be derived from this type of analysis?
1. If in fact there is a significant contribution of GHG to climate sensitivity…
2. … and if in fact global climate responds to increased concentrations offeed back GHG by increasing temperatures over the time scale of the measurements analyzed in the Lindzen paper…
3. … and if ERBE measures endergy budget as it is said to measure energy budget..
… then ERBE will not detect a GHG component to climate feedback. Granted, it’s no more or less valid than modeling, but is that saying much?
Here’s a couple proposals: is there satellite data that is capable of detecting reduction in outgoing radiative from earh in the CO2 and water vaopr bands? Is there a change in outgoing radiative flux in the CO2 and water vapor bands in response to changing temperatures across the globe? IMO, this would go much further toward quantifying at least some component of climate sensitivity, though it is limited in that it doesn’t encompass all types of feedback mechanisms which contribute to climate sensitivity (e.g. clouds).
Unless someone has reasoning otherwise though, ERBE seems potentially at least, blind to the effects of GHG.
Phlogiston (01:57:22) :
cba (22:24:39)
“Above 4 deg C, warmer water is lower density than colder so it rises.
…
All you’ve got to convey heat down into the oceans from IR at the surface is conduction and whatever convection might actually move low density water down – in opposition to its tendency to rise.”
If I remember rightly from my undergratuate physical oceanography (Southampton Univ) water at depths below 2-3 km is always at 4 deg C, it is thermodynamically fixed at that temp due to pressure, not heat exchange. Since this temp indeed is where water (idiosyncratically) has its density maximum, it would require too much energy to change the temperature and thus lift the whole water column. (If by contrast 0 deg C – the melting point – was the density maximum, like with most other liquids, then we would have a frozen bottom to the oceans and no deep circulation.)
You’ve described freshwater, saltwater has its maximum density at the freezing point. Salinity is also a major factor in density, the expulsion of brine from freezing ice being a player in the thermohaline circulation.