The Intergovernmental Panel on Climate Change (IPCC) has recently drafted a third assessment report (TAR-2000) intending it for restricted circulation only to `experts' (as determined by the IPCC) for review. The wider community who stand to be most affected by the policies flowing from this report were excluded from this process. The restricted URL containing this report has since been withdrawn.

This forum is open to expert and non-expert alike to submit comments. Comments should be addressed to daly@microtech.com.au with `TAR-2000 Review' in the subject line.

There are also related two other ongoing reviews and debates where issues may overlap with those discussed here - Surface v. Satellites? and Solar-Climate Interactions    - John L. Daly

Subject: Jarl's good explanation--some additional thoughts
Date: Fri, 4 Feb 2000 16:49:20 +0100
From: "Onar Åm" <onar@netpower.no>
To: "S.A.Boehmer-Christiansen" <S.A.Boehmer-Christiansen@geo.hull.ac.uk>, "Chick Keller" <cfk@lanl.gov>

<Chick Keller said:>

Right now, global models can reproduce most of the gross features of the climate, and the most recent runs with the latest improvements are looking very promising. But the largest problem to me is the very coarse resolution of these simulations. We're usually forced to run with grid cell sizes of 100-400 km in the horizontal. Such large zones are just too large to capture the processes we need to have in the codes. And they can't make use of the better physics we already know.

Why don't we run at finer resolution--say 30 km or with variable resolution to capture topography, etc? The simple answer is that here in the US, people don't care enough to give the modelers what they need. The computer that could do this could be in place now. It would cost less than a single fighter aircraft!! Why don't we provide our scientists with such a machine? You tell me. I think it's a scandal.

What you say here is pretty scary. We know for a fact that model improvements have tended to reduce warming predictions, and it is therefore reasonable to assume that further improvements of GCMs would reduce predicted warming even more, likely rendering drastic CO2-reducing actions that will cost hundreds of billions of dollars unnecessary. And you are telling me that the US government is not willing to put up, say, $100 million dollars to improve the model output? That is indeed a scandal.

However, there is an alternative to the super-computer approach, namely that of SETI@home. The combined power of home computers and servers around the world is several orders of magnitude greater than the best computers used for GCMs. SETI@home has become a smashing hit. It has now reached a computing capacity of 11.12 TerraFlops per second, which makes it the largest civil supercomputer in the world, and the power is increasing rapidly. It was launched about a year ago and it now has almost 2 million users. I suggest a Climate@home or GCM@home project to get the computer power needed to make the best GCM ever. I don't know exactly how good/bad the computers currently used are, but I am pretty confident it should be possible to increase the computing power by a factor of 1000. This should be sufficient to get the horizontal grid cell size down to 3-10 km.

Onar.

Subject: Jaworowski's GW article
Date: Wed, 02 Feb 2000 17:18:14 -0800
From: Hugh Ellsaesser <hughel@home.com>
To: Thuene@aol.com

Dear Thuene,

The best way to get a concept for the GHW phenomena is to remember that the outgoing IR radiation of the planet is emitted near the altitude where the optical depth of the absorber/radiator reaches a value of unity when integrated from outer space inward.

The wavelength of maximum energy or color temperature of the earth is about 255K, that means most outgoing radiation originates near an altitude where the temperature is 255K, or 33K lower than the surface temperature. Very little of the IR going out to space originates from the surface and makes it up through the atmospheric window without absorption and reradiation.

The principal radiator is water vapor and the first optical depth of H2O is around 10 km. So the humidity of the atmosphere between this level and the tropopause is one of the major factors in the equation and one that is almost completely unknown from current observations.

It is my argument that any surface warming will lead to intensification of the Hadley circulation, that is not only the ITCZs will intensify but also the downwelling over the subtropics, which creates our present deserts, will intensify. This will force the outer optical depth of water vapor over the subtropics to a lower and warmer altitude allowing even greater outflow of IR to space from this nearly half of the globe, i.e. over these regions the water vapor feedback will be negative. Since the water vapar feedback accounts for 30 to 60% of the radiative forcing, this will significantly reduce the computed 4 W/m2 of radiative forcing.

Regards,      Hugh.

Subject: Jarl's good explanation--some additional thoughts
Date: Fri, 4 Feb 2000 12:06:58 -0500
From: Mike MacCracken <mmaccrac@usgcrp.gov>
To: "Onar Åm" <onar@netpower.no>, "S.A.Boehmer-Christiansen" <S.A.Boehmer-Christiansen@geo.hull.ac.uk>, "Chick Keller" <cfk@lanl.gov>

Dear Onar--Just a couple of notes:

1. The main reason the estimates of climate change have come down is because there have been changes in the emission scenarios, first the reduction in projected CFC emissions due to international agreements, and then the introduction of SO2 emissions increases that, I would note, are likely way too high given people's interest in having a healthy environment (so this will likely not be as effective at reducing temp change due to GHGs as was indicated in the IPCC 1995 report). The actual model sensitivities to a given forcing have changed relatively little in the last 20 years (or even since Arrhenius 100 years ago), and paloeclimatic analyses indicate that the sensitiivity cannot be much lower or one cannot explain all the glacial-interglacial changes (that is, how does one get an ice age and a Cretaceous if the climate is not sensitive to forcings, given that the change in solar radiation, etc. that we are aware of from geological evidence?). So, unless you are right and new technologies will cause very low emissions of fossil fuel CO2 in the future, it is wishful thinking to suggest that the climatic response in the future will drop below IPCC estimates--they are as likely to go up (due to less sulfate emissions, release of methane clathrates, nonlinearities, etc.) as down (due to reduced fossil fuel emissions, lower populations, etc.), it seems to me.

2. On the notion of distributed computing for GCMs, while it is great for SETI because they can so widely disassociate the signal detection effort (a particular wavelength band and sky sector, so a pretty big problem independent of what is happening elsewhere), this is not very practical for the global climate simulations (it could be done for the surface ecosystem evolution, but those calcualtions are a small part of the effort). While the climate models are using massively parallel computers, so some dissassociation is possible, many do this basically by calculating the different vertical column physics on different processors (and this is helpful because radiation transport takes time), but one must do the various horizontal transport calculations together (in spectral transport models becuase they are global functions, one can split mainly by wave number; in finite difference models one can subdivide a bit location becuase it is incompressible, but one still has internal gravity waves to be dealing with). In any case, one really has to interchange information among all the calcualtions quite frequently (say every few tens of minutes of simulated time in a few hundred simulated year time period), so one needs everyone at full attention and not just getting the idel time from around the world (although a bit of this has been attempted among major supercomputers by doing the atmospheric model on one computer, oceans on another, etc.--for these coupling might be once a day, but this is pretty long). So, neat as it sounds as a solution, Chick is right--there is need for really leading computational capabilities and we (the scientific community) are not doing as well as we understand needs to be done because of these limitations, which I think is really embarassing--we ought to be working at the limit of what our scientific knowledge allows, and we are not.

That this needs to be fixed is being proposed by agencies in US (and I have variously pushed since first coming to DC for the USGCRP)--it just has not made it into budget and through the Congress.

Regards, Mike

Michael C. MacCracken, Ph.D.
National Assessment Coordination Office
Suite 750
400 Virginia Avenue Washington DC 20024

Tel: (202) 314-2230 (Main number for NACO and for Robert Cherry, Admin. Asst.)
Tel: (202) 314-2233 (office and voicemail)
Fax: (202) 488-8681 or (202) 488-8678
E-mail: mmaccracken@usgcrp.gov USGCRP
Home Page: http://www.nacc.usgcrp.gov/

Subject: sensitivity history
Date: Sat, 5 Feb 2000 12:37:50 -0800
From: "Vincent Gray" <vinmary.gray@paradise.net.nz>
To: "Steve Hemphill" <steve@hemphill.net>

Dear Folks

You do not answer my objections

Let us start again.

The uncertainties imposed on model outputs by the large error levels in the parameters dealing with water vapour, clouds and aerosols are so great that it is futile to bother with sensitivity studies on minor and unimportant parameters, since they have little influence on the result. Most of you, anyhow, behave as if these huge uncertainty levels did not exist.

Few of you have appreciated the truth of the statement I quoted from Chapter 5 of the draft IPCC Third Assessment Report, to the effect that there is a good chance that there has been no net radiative forcing, and a fair chance that it has been negative. Chick even thinks the statement is "extraordinary". Can anybody deny it?

Onar Am expressed the opinion that "global models can reproduce most of the gross features of the climate, and the most recent runs with the latest improvements are looking very promising" Where is the evidence for such a statement? There are no figures for the degree of correlation of any model with any feature of the climate, gross or otherwise; unless you include the studies on Mount Pinatubo, and even these are vague about the uncertainties. I am afraid his opinions, and that of so many others listed in the TAR report are purely subjective, based on little more than wishful thinking.

I do not have access to the data, the resources, or the skills to carry out professional style statistical correlation exercises. I merely pointed out that the National Research Council, given the task of considering whether MSU and surface temperature measurements correlate, failed even to try to find out. My opinions on what they would have discovered if they had tried are my opinions, and some of you have yours. But why are you so scared of actually doing it?

Whatever your opinions on the matter there is no doubt that both the surface and MSU records reacted strongly to the 1998 El Nino , and both the NRC and the IPCC have used this to try and argue that the MSU record really increases after all, and that the two can be reconciled (again, without any mathematical support). That this presumption is incorrect is shown by the fact that the MSU record has gone right back down where it belongs - at zero.

As for your insulation theory, Steve, I don't exactly understand it, but do you have any factual, statistically based evidence for it, outside anecdotes and sheer subjective opinion?

The use of terns like "urban heat islands" has diverted attention from the influence of increased population, fuel usage and economic activity on all surface measurements, whether "urban" or "rural". This influence has been underestimated and under investigated, and may be entirely responsible for the rise in the surface record.

I find the remarks of Jarl Ahlbeck   "I have got the impression that the main difference of trend between the surface and the MSU/balloon originates from the oceans." baffling.

My study at    http://www.john-daly.com/graytemp/surftemp.htm

reaches the opposite conclusion. I downloaded the MSU records for the high temperature regions in the surface temperature map and found that the MSU did not recognise them. On the other hand, there are two ocean regions on the surface map (S Indian and S Atlantic oceans) which show a cooling, where the MSU records also show a cooling. So I conclude that the MSU does correlate with the real climate, but not with localised human artifacts

I would like to see Jarl's evidence.

Enough for now

Regards      Vincent Gray

Subject: sensitivity history
Date: Sat, 05 Feb 2000 09:42:12 -0700
From: Steve Hemphill <steve@hemphill.net>
Organization: Earth
To: Jarl Ahlbeck <jarl.ahlbeck@abo.fi>

Jarl,

In the light bulb experiment we have 100% of the energy coming in from the outside as well, through an electrical cord running through, say, the lid. On Earth we have the same thing with visible light. The IR, however, is "produced" entirely on earth, as is the heat from the light bulb in the thermos.

I have not actually performed this experiment, but I don't have a vacuum pump either. I am, however, confident it would show the results predicted.

Also, did you ever find anything more definitive concerning that 3rd variable that you previously had considered not significant?

Subject: sensitivity history
Date: Sat, 05 Feb 2000 09:43:18 -0700
From: Steve Hemphill <steve@hemphill.net>
Organization: Earth
To: Vincent Gray <vinmary.gray@paradise.net.nz>

Vincent,

you can do a lot of things with a combination of 1-2-3 and Excel. Excel actually doesn't do well in my experience with larger spreadsheets, and I find the good old Lotus macro will run slowly overnight, but then again Lotus'll run all night. At the bottom of this sheet is one, with an explanation as well, about CO2 and atmosphere-ocean flux: http://home.earthlink.net/~hemphlls/climchng.html It clearly indicates CO2 follows Temperature, at least in the short run, but with some bias of the long run as well. The length of time to come to equilibrium ( from the present imbalance) is unknown but long, at least for anything anyone argues for or against concerning lack of response is concerned. We have been undergoing this for only a few hundred years, but may have stopped the beginning of the next ice age anyway. Maybe the beginning of the ice age developed our use of and skill with fire. Who knows. Certainly we jumped in civilization during the Holocene Maximum (a.k.a. Eden?).

We need to analyze a myriad of delays in velocity and acceleration, I believe the only problem is number crunching.

Maybe somebody could start a SETI type experiment with a high definition and adaptable GCM program for a screensaver?

Steve

Subject: Scenarios
Date: Sun, 6 Feb 2000 09:15:56 +1300
From: "VINCENT GRAY" <vinmary.gray@paradise.net.nz>
To: <big list>

Dear Folks

The thing about this correspondence is that it offers far too many soft targets.

Mike McCracken points out rightly that the future projections of models depend on the choice of scenario.

They have had to abandon the IS92 scenarios because they have been so spectacualarly unsuccessful in predicting the past. They ranged from the outright absurd (IS92e and IS92f), the ridiculous (IS92a, the "central" scenario a.k.a. "Business as Usual") and the merely exaggerated (IS92c and IS92d).

So they have a whole new set of scenarios. This time, any number can play, so they have 40 scenarios, ranging from raving loonies who confidently predict armageddon and the end of the world, to sober scientists who try to extrapolate existing trends. Since we have to be fair, ALL ARE EQUALLY LIKELY. And there is no longer a "central" scenario or a "Business as Usual" scenario.

But this causes a serious problem. How are we going to satisfy the unshakeable beliefs of our green/eco sponsors and continue to scare Governments sufficiently that they will still pay our salaries?

So, as usual, we go to the oracle at Boulder, Uncle Tom Wigley, for a pronouncement. And, as usual, he has the answer, an "INDICATIVE SCENARIO" which is sufficiently absurd and scary to satisfy our joint masters. And this can be jacked up a little higher, if need be, by arguing that perhaps the aerosols will disappear.

Of course, this scenario. and indeed all the others, including those of the sober scientists, are still spectacularly incapable of predicting the past. For example, carbon dioxide emissions have been falling. This deep dark secret has been omitted from the IPCC Third Assessment Draft, in the hope that things will "pick up" before they have to publish. Despite their wide range, all scenarios routinely overestimate world population, economic development, fuel usage etc. however sober they are.

All this has to be coordinated with the climate modellists. Let us, for a moment, consider their procedure. They produce their set of equations coupling the atmosphere and the ocean, and they select parameters from the latest and most accurate climate and physical quantity measurements. But, wait. Each has to be multiplied by a PRECAUTIONARY PRINCIPLE FACTOR, which is currently 250%.

For example, the measured rate of increase of carbon dioxide in the atmosphere, for the past 35 years, is 0.4% a year. So the figure incorporated in the model is 250% times 0.4, 1% a year. The projected figures for atmospheric carrbon dioxide must be boosted by this amount.

For the past 15 years the rate of rise of methane in the atmosphere has been falling, and is expected to reach zero in the yerar 2004, and thereafter to become negative. But the modellist cannot tolerate this. The trend must be instantly reversed. A similar adjustment awaits all the other parameters.

And if your eyes have strayed inadvertently to these shocking revelations, sit down in your armchair, restore the blinkers on your eyes, and repeat after me, five times.

"Every day, in every way, our models are getting better and better."

Regards

Vincent Gray
75 Silverstream Road
Crofton Downs
Wellington 6004
New Zealand
Phone/Fax 064 4 4795939
Email vinmary.gray@paradise.net.nz

Subject: Jarl's good explanation--some additional thoughts
Date: Sun, 6 Feb 2000 05:15:02 +0100
From: "Onar Åm" <onar@netpower.no>
To: "Sonja A. Boehmer-Christiansen" <S.A.Boehmer-Christiansen@geo.hull.ac.uk>,
"Chick Keller" <cfk@lanl.gov>, "Mike MacCracken" <mmaccrac@usgcrp.gov>

Hi Mike,

thanks for your comments. The crux of the problem in my view is the water cycle, especially cloud cover. I don't think 400 km sized cells accurately capture the dynamics of cloud cover. It would surprise me greatly if the models' behaviors didn't change significantly with a much greater resolution. Until I see convincing evidence of the contrary I maintain that there is a very real possibility that there are negative feedbacks that are badly underestimated in the current models.

And the physics is most certainly incomplete until the secondary solar forcings (the Svensmark effect etc.) have been properly understood or dismissed. You have previously said that the idea that most of the warming in the 20th century could not be due to solar forcing because it is impossible that the solar effect leads to warming while CO2 forcing does not. I submit again the possibility that the secondary solar forcings combined are large, but that there are strong negative feedbacks that dampen both the sun's effect and the CO2-effect, i.e. the climate sensitivity is low. Can you with great confidence say that there are no such underestimated negative feedbacks? That we will make no more discoveries about cloud physics or other climatically important factors that will significantly change the predictions of the GCMs? That all the Sun-Earth correlations are pure coincidence and that mostly CO2 is to blame?

Personally I am reasonably confident that we do not yet have a sufficiently complete understanding of the climate to make accurate predictions 100 years into the future and that further improvements to GCMs and of our climate understanding will force this to be acknowledged.

I am, however, very confident that the CO2 emission scenarios will have to come down dramatically. Nanotubes will change everything, and they are not taken into consideration in IPCC's future emission scenarios whatsoever. They will give rise to flywheels that are fundamentally superior to ICEs in every respect. These will be in every single new car on earth in less than 30 years. The very same flywheels will enable electric airplanes, and airplanes made by nanotube composites will weigh only a fraction of todays airplanes, reducing electricity consumption per passenger dramatically.

Already today a significant portion of the economic growth in the world is due to the Internet. Growth in the future will be even more virtual than it is today. The underlying backbone of this growth is the hardware on which it all runs. In this world of mobility that hardware is in for some dramatic power improvements. Recently the silicon valley company TransMeta has produced a CPU (Crusoe) that uses only a fraction of the energy of a conventional CPU without sacrificing performance.

The Norwegian company Opticom is producing a plastic storage system which combines the storage capacities of hard-disks, with the speed and size of RAM. One chip the size of a credit card has the potential storage capacity of 5000 CDs. AND it uses only a fraction of the power of a hard-disk or conventional RAM.

Another Norwegian company, PolyDisplay, is developing a passive polymer display that competes with LCDs in quality, but uses only a fraction of the energy of an ordinary LCD because the display has optical memory. That is, it "remembers" images for years and therefore does not need to use any energy to maintain a still image. Combine these elements and you have a mobile system that can run on about 1 Watt. I.e. your laptop can run for 30 hours without recharging.

Ironically the horrible quality of batteries will force computer systems to become ultraefficient. Eventually batteries will be replaced by miniaturized nanotube flywheels which in the future may allow laptops to run for hundreds, maybe thousands of hours, without recharging. Add in now that all metal wires that today are used for electricity transportation -- to and inside devices -- will be replaced by near superconducting nanotube wires, greatly reducing their power consumption. From this it is easy to deduce that despite dramatic growth in the use of electronic devices worldwide, energy consumption will not significantly increase from this activity. It may even decrease.

Then of course there is China, India, Indonesia and South-Africa. Most of the world's growth in fossil energy consumption (primarily coal) is expected to come in these few populous countries. Today the efficiency of the coal in China is about 10-15%. With new technologies (among them my own fuel cell technology for biomass, solid waste and coal) will increase this efficiency to more than 60% in less than 30 years.

In this period the energy consumption is expected to quadruple. In other words, it is likely that the overall increase in efficiency will compensate for increased consumption. China may very well not use more coal in 30 years than they do today, and that completely based on economical and local environmental incentives. There is an analogous situation for the other three big countries. From this I deduce that CO2 emissions in third world countries will not significantly exceed current emission levels in 30-40 years time.

The question is: am I right about my technology projections? Well, I have to confess that it has annoyed me greatly that what I consider an obvious technological escape to the problem (much like the car obliviated the horse dung scare at the end of the 19th century) is not being promoted. I sometimes hear that my projections are unrealistic, but why are they unrealistic? Technically there is nothing unrealistic about them at all. All of the technology required to do it exists today in immature forms. So it must be the economic aspect of it, i.e. the idea that no-one is willing to put money and long term effort into making it realistic. But that's hardly a constructive criticism, or what? Here's a bunch of technologies that can spare the world of a meaningless self-inflicted economic recession, and we're not going to invest in them!? That's insane! I for one am therefore prepared to do my part in materializing these technologies, one of which I myself have participated in developing. And I note with joy that a lot of other people are doing this too. The more people who choose to participate in making these technologies a reality, the less unrealistic my projections are. Considering the amount of influence the IPCC has I find it discouraging that it uses its energy on promoting self-fulfilling pessimism rather than self-fulfilling optimism.

Onar.

Subject: sensitivity history
Date: Sun, 6 Feb 2000 12:11:30 +0200
From: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>
To: "Steve Hemphill" <steve@hemphill.net>

Steve, you insulation theory is not good.

You did not understand my explanation at all, or you did not want to. It is not the point that 100 % the IR is generated from the earth (like the lamp bulb), the point is that an increase of clouds reflect more of the incoming SW energy back to space, thus offsetting a warming do to increased "insulation", simply by the fact that less energy is avaliable for creating the IR.

regards    Jarl

Subject: sensitivity history
Date: Sun, 6 Feb 2000 12:19:37 +0200
From: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>
To: "Vincent Gray" <vinmary.gray@paradise.net.nz>, "Steve Hemphill" <steve@hemphill.net>

<Vincent Gray said:>

I find the remarks of Jarl Ahlbeck - "I have got the impression that the main difference of trend between the > surface and the MSU/balloon originates from the oceans." baffling. My study at http://www.john-daly.com/graytemp/surftemp.htm reaches the opposite conclusion. I downloaded the MSU records for the high temperature regions in the surface temperature map and found that the MSU did not recognise them. On the other hand, there are two ocean regions on the surface map (S Indian and S Atlantic oceans) which show a cooling, where the MSU records also show a cooling. So I conclude that the MSU does correlate with the real climate, but not with localised human artifacts.    I would like to see Jarl's evidence.

*** See regional distribution of trends for different measured records, published by Christy. J., USGCPR National Seminar, May 20:th, 1995, showing a condiderable difference in trends for ocean regions but not much for land regions (latitudal mean). I have not the graph in digital form, but I could fix it to you. This finding, of course, does not say that there is no urban warming trend at all in the surface data, but point towards something strange in the ocean data.*****

regards,   Jarl

Subject: sensitivity history
Date: Sun, 06 Feb 2000 10:12:56 -0700
From: Steve Hemphill <steve@hemphill.net>
Organization: Earth
To: Jarl Ahlbeck <jarl.ahlbeck@abo.fi>

Jarl,

That's a different mechanism. I'm talking about a basic physical response in heat transfer theory.

You have a point about an increase in cloudiness decreasing the available generated IR, but do we have any quantitative analyses concerning this and correlation with water vapor, surface insolation, etc? I agree they should be there, but what are the orders of magnitude? What are the relative response rates of water vapor vs. clouds?

These are questions we don't know the answers to (at least to my knowledge) and we should not confuse them with the basic physical law that the temperature of the outside of the thermos (at equilibrium) will be that which will transfer energy out of the system at the same rate it's coming in.

Steve

Subject: sensitivity history
Date: Mon, 7 Feb 2000 15:30:10 +1300
From: "VINCENT GRAY" <vinmary.gray@paradise.net.nz>
To: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>, "Steve Hemphill" <steve@hemphill.net>

Sorry, Jarl, I misread your letter.

My study actually agrees with you, and with John Christie. The MSU detects changes in the SST but not in the "hotspot" regions which are influenced by local heating.

There is one proviso, though. It applies only to SST readings of the past 20 years. Before that SST was more and more unreliable, and Hansen and the Americans have always refused to believe them.

Regards

Vincent Gray

Subject: sensitivity history
Date: Mon, 7 Feb 2000 09:28:31 +0200
From: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>
To: "Steve Hemphill" <steve@hemphill.net>

<Steve Hemphill said:>

Jarl, That's a different mechanism. I'm talking about a basic physical response in heat transfer theory.

You have a point about an increase in cloudiness decreasing the available generated IR, but do we have any quantitative analyses concerning this and correlation with water vapor, surface insolation, etc? I agree they should be there, but what are the orders of magnitude? What are the relative response rates of water vapor vs. clouds?

I don't know, but neither do anybody else. A NASA calculation some years ago (NASA-fire group, 1996) estimated that a 4 % increase in clouds is enough to completely offset a doubling of the CO2 . The influence of clouds is still a subject to much research

Jarl

Subject: sensitivity history
Date: Mon, 07 Feb 2000 20:42:18 -0700
From: Steve Hemphill <steve@hemphill.net>
Organization: Earth
To: Jarl Ahlbeck <jarl.ahlbeck@abo.fi>

Feedback logic error... How can we have 4% more clouds to completely offset warming due to CO2 if we have no warming?

Yep, 1996 was SOME time ago in climate research. Sounds like a statement from a "biaser"...

Steve

Subject: sensitivity history
Date: Tue, 8 Feb 2000 04:59:54 +0100
From: "Onar Åm" <onar@netpower.no>
To: "Steve Hemphill" <steve@hemphill.net>, "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>

<Steve Hemphill said:>

Feedback logic error... How can we have 4% more clouds to completely offset warming due to CO2 if we have no warming?

This is a valid point. It is simply physically impossible for there to be warming, yet all of the warming due to CO2 being offset. This is a point brought up by others, among them Mike (MacCracken), and it should be addressed. So let me therefore hasten to say that I think I speak for all the GW skeptics when I say that some of the observed warming must be due to the increase in CO2. And absolutely no-one disagrees with the notion that this warming is much, much smaller than it "should" have been. Something is dampening the warming. But what? IPCC says it's aerosols, and that's where views start to diverge.

Much of the answers will come in the next 3 years. According to Landscheidt the ENSO is controlled by solar eruptions or other solar phenomena correlated with them. If the next major El Niño peaks around December 2002 as he has predicted a year ago then this will be a significant boost to the solar theory.

Onar.

Subject: sensitivity history
Date: Tue, 08 Feb 2000 15:10:46 +1100
From: John Daly <daly@vision.net.au>
To: Steve Hemphill <steve@hemphill.net>

Dear Steve

Steve Hemphill wrote:

Feedback logic error... How can we have 4% more clouds to completely offset warming due to CO2 if we have no warming?

I wrote on this topic a couple of years ago, as part of a critique to similar claims by Prof Ann Henderson-Sellers in her 1988 book. I reproduce the relevant section here -

Quote:

If the author's (Henderson-Sellers) physics appears not so sound, they also make some unproved assertions about basic climatology.

"It is important to recognize that the negative feedbacks can only dampen the (greenhouse) effect. They cannot reverse it. Clouds, however they may change, cannot give us a cold greenhouse. All they can do is give us a slightly less warm greenhouse." (Page.44)

These `negative feedbacks' are effects such as increases in cloud reflectivity (albedo), snow/ice albedo, etc. caused by an initial global warming, and which might act to dampen that warming. Most importantly, the authors assume that some warming is needed before these cloud feedbacks can take effect.

While this conclusion may appear superficially sound, it is also simplistic, and quite wrong. They are confusing Energy with Temperature. Temperature change is a possible, but not an essential outcome from an energy change. Cloud negative feedbacks can take effect even without a prior warming to initiate them.

This happens most easily in the tropics where the sea temperature has reached a critical temperature of around 28 deg C. At this point, the vapour tension of the water surface is such that any additional radiant energy is consumed almost entirely in evaporation, leaving the sea surface temperature, and thereby the overlying atmosphere, unchanged, or even slightly cooler.

(This process is analogous to a gas refrigerator, where applied heat causes the cabinet to cool, due to evaporation in the pipes).

The evaporated moisture then condenses out much later as cloud, providing negative feedback from additional cloud albedo, without any actual surface warming to cause it. The sea temperature rarely exceeds 28 deg. due to the sheer power of this evaporative effect, even though total radiation is otherwise sufficient to push sea temperature into the high 30's. Above 28 deg, the vapour tension of evaporation at the sea surface is so strong that heat is even drawn from the atmosphere.

At higher latitudes where sea temperatures are less than 28 deg, the same process occurs to a lesser extent, depending on whether the additional cloudiness can offset any excess warming over and above the heat lost through evaporation.

Another by-product of enhanced cloudiness resulting from increased tropical evaporation, would be a buildup of surface snow and ice in Arctic permafrost areas which are presently cold and arid, but ice-free. Once ice is laid down, albedo increases markedly and thus has a permanent cooling effect on all future climate. This phenomenon was first postulated in the 1930's by Sir George Simpson, who went so far as to suggest that an ice age could even be induced this way.

In effect, we get two cloud-driven negative feedbacks without actually needing any surface warming to create it. The `Simpson Effect' hypothesis suggests that the author's `less warm greenhouse' might end up as a very cold greenhouse indeed.

Unquote:

Basically, IR is radiation, not temperature. The sea surface absorbs the energy, cooling evaporation results, and the heat is finally manifested, not at the ocean surface, but high up when the clouds condense - above the main part of the greenhouse effect. That's what I mean by "Cloud negative feedbacks can take effect even without a prior warming to initiate them". IR is not itself warmth. It is only radiant energy. It is only when that energy is converted into sensible heat that `warmth' results. In the tropics, the transformation into sensible heat occurs in the condensing clouds, not at the ocean surface.

Regards     John Daly

Subject: sensitivity history
Date: Tue, 8 Feb 2000 08:42:27 +0200
From: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>
To: "Steve Hemphill" <steve@hemphill.net>

Dear Steve,

OF COURSE THERE IS A WARMING, A SMALL ONE ! You are probably not familiar with basic control theory, let me explain. A bi-metallic car thermostat of the old fashioned type opens when the motor gets warm and the water flows to the cooler. In summer, when the surroundings are hot, the motor must get more cooling than else. The thermostat is thus more open than during cold weather. But how does the thermostat know that it should be more open ? Yes, because of the higher temperature of the water, 1/2 - 1 degree or something over the set-point. This is the bias for the proportional controller. Only with a more complicated controller, a PI-controller, the bias can be forced to zero.

Without any thermostat ( a constant valve opening percentage), the temperature of the water would have been several degrees higher during hot conditions.

Increase of stratocumulus clouds due to climate forcing should principally work in the same way, as a P-controller, or reducing the waming to a small percentage of what it would have been without this "negative feedback". Thus we could get a little more clouds and rain, but not much warming.

The 4 % increase of clouds that can completely offset the doubling of CO2 is only a estimated energy balance number from climate forcing calculations (in W/m^2), which means that the increase of reflection heat flow theoretically is the same as the increase of the IR-trapping heat flow. In order to calculate the warming (the control bias) we must know how the cloud cover is dependent on the warming (in degrees) and what warming (uncontrolled) should be expected from the IR-climate forcing. Then we should know all other feedbacks, both positive and negative too ......

Nice and simple work, isn't it ? Nothing for me to earn my living with anyway.

regards Jarl
(professional modeler of chemical processes for control and optmimization purposes)

Subject: sensitivity history
Date: Tue, 8 Feb 2000 08:50:42 +0200
From: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>
To: John Daly <daly@vision.net.au>, "Steve Hemphill" <steve@hemphill.net>

Dear John, Steve, Onar and others.

I agree John that what you describe above is possible. As a process engineer I would call it a possible "natural integration control function" that works to offset the proportional control bias.. I admit that I have over-simplified my process control explanation because temperature and energy flows are not directly (by any continuous function) convertible to each other in a system with change of phases (evaporation / condensation).

regards, Jarl

Subject: TAR Reviews / sensitivity history
Date: Tue, 08 Feb 2000 12:28:55 +0100
From: 091335371-0001@t-online.de (P. Dietze) Reply-To: 091335371@t-online.de
To: Onar Åm <onar@netpower.no>

Dear Onar,

this warming is much, much smaller than it "should" have been. Something is dampening the warming. But what?

Please read my TAR review at daly/tar-2000.htm. There are of course positive and negative feedbacks, and clouds are the most shaky candidates - but damping cannot make up for IPCC's parameter errors! The CO2 climate sensitivity is most probably three times less. This makes sense when you cope with solar amplification and smaller (realistic) aerosol effects.

Moreover I did not at all agree with your former statement that more computing power is required (Mike McCracken was delighted of course) to solve more precisely using smaller grids than what can be done today. You seem to misunderstand the modelling errors, sheer arguments for more hardware, more model funding and excuses for discrepancies. For global warming it does not matter at all whether a cloud over Birmingham can be modelled or Dover gets close to Rotterdam! All you need is correct sensitivity parameters, good physics and just a calculator.

I am not at all convinced that you have to compute the weather around the globe (excluding polar regions) just for taking the average temperature value - which indeed mostly depends on the global sensitivity parameters that you have used. Only if you want to compute regional changes including precipitation patterns etc and you really have verified your models to be excellent enough for this job - what is by far not achieved - you need this sort of weather forcast models with high resolution.

Apart from these discussions I would like to remind all that this site was originally meant for TAR reviews. A lot of personal GW mail discussions not related to any specific statements in the TAR will make it difficult for TAR authors to allocate corrections - if at all.

Best regards,    Peter

Subject: sensitivity history
Date: Tue, 08 Feb 2000 18:29:01 -0700
From: Steve Hemphill <steve@hemphill.net>
Organization: Earth
To: Jarl Ahlbeck <jarl.ahlbeck@abo.fi>

I wasn't insinuating you believed the 4% cloud cover thing, I was only reflecting on its inadequacy. I'm trying to cover many bases here...

I am quite familiar with control theory, and that was a good explanation. However, clouds are already compensating for warming, and have been ever since there were clouds. That doesn't mean, however, that even if cloudiness compensates completely at the equator they also compensate completely over the rest of the earth. In fact, they could overcompensate at the equator and still not compensate completely over Earth. They won't compensate completely for reasons you bring up below, which is one reason why the temperature differences will be felt mostly at the poles.

Actually I disagree with your second paragraph, although it's somewhat off the subject. Without the restriction to flow of a thermostat (even fully open), the engine will always run cooler.

Back to business... Without geographic modeling, a formula to represent global warming can only be instantaneously accurate, therefore it would be by definition inaccurate.

Interesting how NASA has "correlated" our climate pattern with one from 50 years ago and is predicting a drought in the SW USA. Actually, to predict a weather pattern based on one from 50 years ago is not interesting, it's ludicrous.

Steve

Subject: sensitivity history
Date: Wed, 09 Feb 2000 17:05:48 +1100
From: "John L. Daly" < daly@vision.net.au>
To: Steve Hemphill <steve@hemphill.net>

Dear Steve

you wrote:

That doesn't mean, however, that even if cloudiness compensates completely at the equator they also compensate completely over the rest of the earth. In fact, they could overcompensate at the equator and still not compensate completely over Earth.

I was not just referring to the equator, but to the tropics generally (ie. all the surface area of the earth between the tropics of Cancer and Capricorn - about half the earth's surface). This represents a much larger area than that implied by the term `equator'. In your message suggesting that cloud negative feedback requires some warming to initiate it, you seem to have been comparing the earth to a simple incubator model. Give it heat and it warms, even with feedback it still warms, but only less so.

The earth is not like an incubator. It behaves more like a heat pump. It takes energy in, but the result of that energy can be more clouds here, more warmth there, more cooling somewhere else. A heat pump, just like a refrigerator. In the tropics, IR energy is taken in ok, but this is quickly converted into latent heat (not sensible heat), thanks to vigorous evaporation. The resulting vapour rises up in the high troposphere, condensing into clouds, releasing all that latent heat into sensible heat as it does so. A simple and neat way of by-passing the main part of the greenhouse effect. In the tropics this is not only total, but in many areas `over-compensated' as you characterised it. For example, the daytime temperature at Darwin, Northern Territory, Australia (a sea port), never, never, exceeds 33°C. But go inland a few hundred miles and the temperture soars into the high 40s, even into the 50s in a few places. That's how powerful this evaporative buffer is in the tropical oceans.

As for the poles, instrumental records from the Antarctic and also the Arctic show little change there either, so that rules out another 10% of the earth's surface from your scenario. That leaves 40% where the competition between IR, evaporation, and cloud formation is more a mixed contest with an uncertain outcome.

They won't compensate completely for reasons you bring up below, which is one reason why the temperature differences will be felt mostly at the poles.

`Will'? That's got an air of finality not supported by instrumental evidence. Here (above) is the annual mean temperature record from the US scientific base at the South Pole (data from Univ of Wisconsin-Madison). No warming at all since 1957, a hint of cooling even. That's in spite of increases in CO2 during that period. `Will' will need to be modified to a mere `might'.

Regards

John Daly

Subject: sensitivity history
Date: Wed, 9 Feb 2000 06:14:57 -0500
From: Jack Barrett <100436.3604@compuserve.com>
To: "John Daly" <daly@vision.net.au>

Dear John,

I'm enjoying the argument about warming. Your point about the tropics is spot on. I lived for three months in Freetown, Sierra Leone and just like Darwin it was never hotter than 33, but five miles inland up to 45 in no time. The water thermostat must operate over a great area so the warming arguments must be about a relatively small one. With regard to temperature increases only 1°C increases the saturated water vapour pressure by 6.6% at 288K and must have a tremendous effect on cloud coverage. The climate models first calculate the warming effects of the greenhouse gases and then apply the result to the atmosphere to get positive radiative feedback from the extra water and seem to forget the effect on cloud coverage.

Keep up the good work. I'm collaborating with Peter Dietze and Heinz Hug at the moment and we hope to have some calculations for people to argue about soon.

Best wishes     Jack

Subject: sensitivity history
Date: Wed, 09 Feb 2000 05:42:36 -0700
From: Steve Hemphill <steve@hemphill.net>
Organization: Earth
To: daly@vision.net.au

I agree the "will" needs to be "might", but the reason is possible volcanic activity.

The reason the poles aren't warming much now is because of the latent heat requirements of the ice. The average thickness of the Arctic sea ice has declined by 40% over the last 30 years, from 3.1m to 1.8m: http://psc.apl.washington.edu/thinning/thinning.html I would say that's more than a little change.

Add this delay to the heat requirement of the entire ocean vs. the difference in heat retained, and we have a couple of big reasons we're still "waiting".

I'm not going to argue with you though, Mr. Daly. You've already shown your propensity for snipping out relevant pieces of discussions, then posting that which is favorable to your position on your website.

Ground Control

Subject: : sensitivity history
Date: Thu, 10 Feb 2000 00:31:38 +1100
From: "John L. Daly" <daly@vision.net.au>
To: Steve Hemphill <steve@hemphill.net>

Dear Steve

you wrote:

The reason the poles aren't warming much now is because of the latent heat requirements of the ice. The average thickness of the Arctic sea ice has declined by 40% over the last 30 years, from 3.1m to 1.8m: http://psc.apl.washington.edu/thinning/thinning.html I would say that's more than a little change.

See my item on the Arctic ice issue at http://www.john-daly.com/thin-ice.htm

Bottom line is that the ice thickness was measured by sonar during the 1960s and 1990s. A known cold period (1960s) compared with a known warm period (1990s). Something would be seriously wrong with the laws of physics if the ice had not been thinner now than in the 60s. More interesting is what the ice thickness was during the 1930s, another warm period. Probably about the same thickness as today.

Regards John Daly

Subject: sensitivity history
Date: Wed, 9 Feb 2000 15:03:24 +0200
From: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>
To: "Steve Hemphill" <steve@hemphill.net>, <daly@vision.net.au>

*** Now this discussion starts to go round and round in a rather unscientific way, how about a break ?

Ice, especially covered by snow, has a low heat conduction coefficient (extremely good good insulation properties). Anybody who has grown up among snow an ice knows that. If there is an atmospheric climate forcing at the poles, you will certainly see a higher air temperature, the ice/snow cannot do anything about it. You don't even have to stay under the freezing point, I have been skiing in + 15°C degrees air temperature with no sign of snow melting at all because the heat transfer rate down from the boundary layer at the surface was close to zero. The heat transfer from the ocean water that may cause changes in the ice cover thickness is a different thing, this heat may be transported from distances far away. So if there is no warming of the air temperature over the ice, there is no climate forcing at that point. ******

regards, Jarl

Subject: sensitivity history
Date: Wed, 9 Feb 2000 08:15:39 -0500
From: Mike MacCracken <mmaccrac@usgcrp.gov>
To: John Daly <daly@vision.net.au>, Steve Hemphill <steve@hemphill.net>

John--The debates seem to cover so many issues that keeping a focus is awfully hard. Let me just chime in on one of your comments regarding what seems to me to be an important misperception in your analysis:

At 1:20 AM -0500 2/9/00, John L. Daly wrote:

The earth is not like an incubator. It behaves more like a heat pump. It takes energy in, but the result of that energy can be more clouds here, more warmth there, more cooling somewhere else. A heat pump, just like a refrigerator. In the tropics, IR energy is taken in ok, but this is quickly converted into latent heat (not sensible heat), thanks to vigorous evaporation. The resulting vapour rises up in the high troposphere, condensing into clouds, releasing all that latent heat into sensible heat as it does so. A simple and neat way of by-passing the main part of the greenhouse effect. In the tropics this is not only total, but in many areas `over-compensated' as you characterised it. For example, the daytime temperature at Darwin, Northern Territory, Australia (a sea port), never, never, exceeds 33°C. But go inland a few hundred miles and the temperture soars into the high 40s, even into the 50s in a few places. That's how powerful this evaporative buffer is in the tropical oceans.

I think it was nearly 20 years or so ago that Prof. Reginald Newell of MIT published an article making the case that there was no way tropical ocean waters could get warmer than 33 C, even in an increased CO2 world. He cited the observed limit and also evaporation pan experiments indicating, as I recall, that, due to the increasing rate of evaporation, it took something like 16 Watts per meter square to raise water temps by one degree--since the CO2 increase he said was 4 Watts per meter square (that is at the tropopause rather than the surface however), he calculated a tropical ocean temp increase of 0.25 C. Thus, like you, he suggested that evaporative cooling would limit the temperature rise in a CO2-warmed world.

Prof. Robert Watts (a fortuitous, but confusing, name, given his thermodynamic studies) of Tulane published a response and a number of the rest of us chimed in in other places. The point of the responses was to note that, while this limit exists today, what is important to do is to track the latent heat involved in the evaporation is released in the atmosphere and see what happens to it. You suggest it is released in the upper atmosphere and simply lost to space. Watts did, again as I recall, one dimensional radiative-convective model experiments and calcualated that the heat is radiated both up and down, and when this recycling of energy is taken into account, then one gets a temperature rise of, as I recall, about 1°C -- that is, the energy recycles several times.

I should note in all of these analyses a few important issues:

1. The assumption about whether how the humidity (absolute or relative) changes is key (note that Newell's experiments assumed, implicitly, a constant absolute humidity even though evaporation increased markedly) -- I believe Watts analyses kept the relative humidity constant (which is probably closer to what might happen, even if not exactly) and this is a key feedback that your analysis seems to ignore, both on the evaporation and on the radiation processes. If one increases the absolute humidity, it is harder to evaporate, so the temperature rises, and if one evaporates more water into the atmosphere, one strengthens the water vapor feedback (and we all agree water vapor is the most important GHG). Your analysis seems to ingore both of these factors.

2. These were 1-dimensional analyses. One could argue that the excess heat released would cause the atmospheric circulation to change in ways that would move the heat around (e.g., I think Dick Lindzen and Hugh Ellsaesser would argue that this warming would lead to circulation or convective efficiency changes that would have the effect of drying the upper tropical (and/or subtropical) troposphere, and the increased circulation might even lead to higher windspeeds and/or lower boundary layer humidity, both of which might make evaporation easier (so it would happen at lower temepratures). While this chain of logic might seem plausible, models that exist and try to include all of these processes quantitatively generally don't seem to give these results (some would argue due to poor paarameterizations)--basically, the models seem to yield more upper troposhperic water vapor as the temperature goes up (and note that it is observed to go up towards the equator compared to the poles, and arguing that it would go down seems to me to mean that it would have to go up as one went into an ice age, and it would seem hare to get an ice age with lots more upper tropospheric water vapor--so geologically, it seems implausible to me for upper tropospheric water vapor to go down as surface temperatures rise).

3. Finally, just a phenomological note. One reason it took 16 W per square meter to warm Reggie Newell's water pans by 1 degree was that the water vapor and downward IR feedbacks that Bob Watts found so important in his 1-D model do not come into force. Basically, Reggie was dispersing the latent heat over the whole tropics, actually the whole world, and so it would be a very small local feedback. But, if, as for the CO2 case, this were happening everywhere on Earth (at least over the oepn oceans where evaporation dominates), when one integreates this all together, it is much like the 1-D model of Bob Watts--all the energy going into evaporation locally must escape to space locally, and the water vapor feedback and boundary layer humidity change must also both be accounted for.

Hence, your suggestion of this limit of 33 C is based, I believe, on improperly extrapolating a local situation to a global one where there will be flux changes everywhere. And when these problems are accounted for in a quantitative way, as in the models, the tropical temperatures rise and are not limited to their present value of 33 C, which is determined not by some absolute rule, but by the interactions of processes in particular ways--and these ways will be changed.

Mike

Michael C. MacCracken, Ph.D.
National Assessment Coordination Office
Suite 750, 400 Virginia Avenue
Washington DC 20024

Tel: (202) 314-2230 (Main number for NACO and for Robert Cherry, Admin. Asst.)
Tel: (202) 314-2233 (office and voicemail) Fax: (202) 488-8681 or (202) 488-8678
E-mail: mmaccracken@usgcrp.gov USGCRP
Home Page: http://www.nacc.usgcrp.gov/

Subject: Re: sensitivity history
Date: Thu, 10 Feb 2000 01:56:40 +1100
From: "John L. Daly" <daly@vision.net.au>
To: Mike MacCracken <mmaccrac@usgcrp.gov>

Dear Mike

Mike MacCracken wrote:

Watts did, again as I recall, one dimensional radiative-convective model experiments and calcualated that the heat is radiated both up and down, and when this recycling of energy is taken into account, then one gets a temperature rise of, as I recall, about 1 C--that is, the energy recycles several times.

A repetitive recycling would be a logical outcome of latent heat release in the upper troposphere. But at each cycle, the amount re-radiated to the ground would be less than half that on the previous cycle, until all the energy had been dissipated to space. The time lapse for this recycling would also be very quick, speed of light stuff.

The additional IR flux to the ocean from this process would still hit the evaporative limit.

1. The assumption about whether how the humidity (absolute or relative) changes is key (note that Newell's experiments assumed, implicitly, a constant absolute humidity even though evaporation increased markedly)--I believe Watts analyses kept the relative humidity constant (which is probably closer to what might happen, even if not exactly) and this is a key feedback that your analysis seems to ignore, both on the evaporation and on the radiation processes. If one increases the absolute humidity, it is harder to evaporate, so the temeprature rises, and if one evaporates more water into the atmosphere, one strengthens the water vapor feedback (and we all agree water vapor is the most important GHG). Your analysis seems to ingore both of these factors.

With a relative humidity, there will indeed be more water in the atmosphere than pre-forcing. But we also know that the tropical atmosphere is radiatively saturated, with water vapour, dimers, with the radiation windows effectively closed up. There is really no room for further surface warming to take place via the Greenhouse Effect.

2. These were 1-dimensional analyses. One could argue that the excess heat released would cause the atmospheric circulation to change in ways that would move the heat around

While I would subscribe to Ellsaesser's `deep tropical convection' feedback, we could leave that particular mechanism aside for the purpose of this issue.

Hence, your suggestion of this limit of 33 C is based, I believe, on improperly extrapolating a local situation to a global one where there will be flux changes everywhere. And when these problems are accounted for in a quantitative way, as in the models, the tropical temperatures rise and are not limited to their present value of 33 C, which is determined not by some absolute rule, but by the interactions of processes in particular ways--and these ways will be changed.

I would accept that interpretation but for one observational reason. The earth's orbit is elliptical, resulting in a nearly 7% variation in solar radiation between January and July, an astronomical phenomenon unrelated to the seasons. 7% works out to about 24 w/m^2 variation in solar insolation in the tropics (we can quibble about the exact figure, but it would be in that range).

What happens in response to this massive forcing? A forcing which dwarfs anything CO2 can do (+4 w/m^2 in CO2x2 conditions). In places like Darwin (12°S), we see a temperature change of only 2°C during the year, even less in Singapore (on the equator). So, the real earth as distinct from models, demonstrates that tropical temperatures adjacent to the oceans do not warm up even under that massive annual forcing. It is difficult to believe that a place like Darwin which warms only 2°C (half of it being seasonally-forced anyway) during the year under a 24 w/m^2 plus forcing variation, can warm significantly under only 4 w/m^2. It suggests that CO2 doubling would only manage a few tenths of a degree at best.

Newell's conclusions do seem to hold good both for the CO2 forcing already in the system, and for the annual variation in solar radiation.

Since I watch the Darwin temperatures with interest every day on TV for the last 20 years, the lack of any climatic change there gives me confidence that Newell is right and the models are wrong on this point. While you say the models forecast a tropical temperature rise beyond 33°C, I have not seen any observational evidence to support this. Instead we have rival theories about what water vapour might or might not do. Meanwhile, Darwin goes on merrily clamped to a max of 33°C in spite of rising CO2 and elliptical orbital forcing.

Regards     John Daly

Subject: sensitivity history--Models are all we've got
Date: Wed, 9 Feb 2000 17:03:08 -0700
From: Chick Keller <cfk@lanl.gov>
To: "Steve Hemphill" <steve@hemphill.net>, "VINCENT GRAY" <vinmary.gray@paradise.net.nz>

Dear Jarl,

Lots of if's in your statement below. That of course is the problem. There are a myriad of warming and cooling mechanisms involved, and positive and negative feedbacks. But, until you can quantitatively take their coupled interactions into account, it's every person for themselves in the opinion page. I think stratocumulus clouds will increase and cool things off, but you think increased convection will lead to increased ice clouds that will heat things up. I think the dominant CO2 radiative mechanisms will be this, which warms, but you think the dominant CO2 mechansism will be that, which cools. And the problem is that unless all these are considered simultaneously to include how they interact and affect one another, there's no good way of saying for sure how things will play out on a rotating planet at different latitudes, land surfaces, etc.

Thus, while many of you just hate the models. They ultimately are our only hope of sorting all this out.

Sorry,     Chick

Subject: sensitivity history
Date: Wed, 9 Feb 2000 17:48:15 -0700
From: Chick Keller <cfk@lanl.gov>
To: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>, "Steve Hemphill" <steve@hemphill.net>

Folks,

I would caution in comparing regions too closely. Where there is deep convective activity coupling may be much stronger than when there is not. Further such comparison lends itself to picking the regions that look most interesting and ignoring others that are harder to interpret.

"Chick" F. Keller,

Subject: sensitivity history
Date: Thu, 10 Feb 2000 07:47:49 -0500
From: Mike MacCracken <mmaccrac@usgcrp.gov>
To: John Daly     daly@vision.net.au,

John--Again you oversimplify.

1. On there being enough water vapor to be saturated and so an addition having no effect, what happens is that there is saturation at a lower level of the troposphere from any given emission point (from the surface upward), and so the absorption and reemission comes from a lower, warmer layer, enhancing the greenhouse effect.

2. On your comment about the seasonal variation in incoming solar, this is happening at one latitude while at others the opposite is happening (averaged through the year), so what is happening is a redistributing of the energy through the year rather than a net change. The CO2 effect is quantitatively different in that it changes the net coming across the tropopause (for given conditions) and does so for all latitudes--so it is like a more powerful Sun for the whole Earth--not just for one part while another part gets less. [I should note here that I believe it is Dick Lindzen's argument that the climate is much more sensitive to a redistribution of incoming energy (as happened during the glacials) than to a globally uniform change, which is, I believe, how he explains how we can have ice ages (which orbitally have no net change in annual global forcing--it can change due to albedo, etc.) while the GHG effect will have a low sensitivity. GCMs results differ from Lindzen's conclusion, based on studies finding very similar near-term latitude-season responses to both doubled CO2 and 2 per cent increase in solar radiation. The seeming problem GCMs would then have in explaining how ice ages occur may be that there are other longer-term feedbacks involving ice sheets, isostasy, ocean circulation changes, surface-vegetation feedbacks, and, of course, CO2/CH4 changes as the ocean temperatures and land cover change.]

3. On the time-scale of the feedbacks, while any given increment would be expected to be quick as the vertical mixing time of the troposphere is short, and so is the radiative adjustment time--not instant, but likely days, it takes time for the downward radiation to warm the ocean, so such a process would build up slowly--this coming to equilibrium time is likely decade(s)--and since the GHG concentrations are constantly rising, we never really get there and cumulative lag to present GHG concentration is decades (and longer to really get there as one has to adjust the deep ocean--so upper ocean part fast, but deeper over longer times--and since tropical oceans are mixing upward waters that sank with climate conditions of many centuries ago, we have a ways to go to full equilbrium).

4. And not all latent heat gets released in the upper troposphere--it starts coming out at cloud base where condensation occurs. so you do not fully bypass the GH effect.

Basically, I would argue that rather than be arguing so much qualitatively, that climate models attempt to incorporate our best understanding and see how it all works out. If you do not want to believe all of this, your real obligation is to prepare and test a module for a process in a GCM, test it on field data and satellite observations, put it in and see how it works and how climate behaves. Arm waving is nice, but for a problem this important, one really must justify statements quantiatively considering all of the processes, and only a model can do this (and the variety of climatic events become very interesting test cases). Right now, it seems to me models are ahead of what we can do mentally--they test out pretty well in many cases, though still having a ways to go on others.

Regards, Mike

Subject: sensitivity history
Date: Thu, 10 Feb 2000 15:04:45 +0200
From: "Jarl Ahlbeck" <jarl.ahlbeck@abo.fi>
To: John Daly <daly@vision.net.au>, "Mike MacCracken" <mmaccrac@usgcrp.gov>

Right now, it seems to me models are ahead of what we can do mentally--

A small comment:

***
Right, but only if the statement lines of the computer program are based on such quantitative facts that can be verified separately, mentally, theoretically and/or experimentally. If you create a main simulation program based on subroutines containing too many uncertain equations and parameters you get simulation results that are not ahead of what we can do mentally, they are nonsense. People like me who must take economical responsibility for the results cannot do that. But it is, however, allowed in Climate Change research
*****
Jarl

Subject: sensitivity history
Date: Thu, 10 Feb 2000 18:40:32 GMT
From: richard@courtney01.cix.co.uk (COURTNEY)
To: Mike MacCracken <mmaccrac@usgcrp.gov>

Dear Mike:

Concerning a possible limit to sea surface temperature (SST) you say; "I would argue that rather than be arguing so much qualitatively, that climate models attempt to incorporate our best understanding and see how it all works out."

As you know, I always prefer measurements to models and, therefore, I offer the following information for consideration.

On the basis of satellite-derived data, Ramanathan. & Collins (ref. Nature 351, 27-32 (1991) ) suggested that cirrus clouds associated with tropical convection might act as a "thermostat" to limit tropical SSTs to less than 305 K by shielding the ocean from sunlight.

Wallace (ref. Nature 357, 230-231 (1992) ) proposed an alternative hypothesis to explain the apparent limit to SST. He argued that "large-scale dynamical processes will act to maintain uniform tropical tropospheric temperatures to within about 2 K, and that, in the absence of horizontal temperature contrasts in the atmosphere, a negatively skewed SST frequency distribution is bound to develop through equilibration between the atmosphere and spatially varying SSTs."

Ramanathan & Collins (ref. Nature 357, 649-649 (1992) ) disputed this alternative hypothesis saying, "We are not questioning the importance of evaporative cooling to the surface energy balance. At issue is the sign and magnitude of the feedback between SST and evaporation in regions of convection such as the warm pool. How warm would the sea surface be compared with observed values without the cloud reflection of solar energy? Wallace believes it would be about the same". Ramanathan and Collins disputed this similarity on the basis of model studies.

Then, Fu, Del Genio, Rossow, & Liu (ref. Nature 358, 394-397 (1992) ) published a direct contradiction of the findings of Ramanathan & Collins. Fu et al. had also assessed data on Pacific cloud cover and SST obtained using satellites but failed to find a correlation similar to that observed by Ramanathan & Collins. Also, Fu et al. questioned some of the statistical methodology used by Ramanathan & Collins.

Support for Ramanathan & Collins was provided by Waliser et al. (ref. Climate 6, 331-353 (1993)), so Fu et al. (ref. Nature 358, 412-412 (1993) ) provided further argument to dispute this support.

Ramanathan. & Collins (ref. Nature 361, 410-413 (1993) ) responded to the attacks from Fu et al. and pointed out that Fu et al. had measured the wrong things. Ramanathan. & Collins stood by their original finding saying: "Only a small fraction of the tropical Pacific, Atlantic and Indian oceans is warmer than 29.5 °C; about 50% of the tropical Pacific has an SST in the range 26-30 °C; only 1% is in the range 30-31 °C; and less than 0.01% is warmer than 31 °C. These results pertain to monthly mean conditions. Thus, the strong positive correlation between SST and convective-cirrus cloudiness is valid over most of the warm ocean."

And there the matter rests.

I hope the above is helpful.

All the best    Richard

Subject: sensitivity history
Date: Thu, 10 Feb 2000 14:07:37 -0500
From: Mike MacCracken <mmaccrac@usgcrp.gov>
To: richard@courtney01.cix.co.uk (COURTNEY),

Dear Richard--This is a terrific summary of articles on the subject. I would suggest, however, that most have to do with what makes the limit be 33 C under present conditions. And it is indeed very important to know how nature is managing to hold and move energy about to various parts of the world.

However, as we increase GHGs, we are changing the total level of energy in the surface-troposphere system--so it becomes more than a problem of redistribution of the energy. Now, how much the response will be can be controlled by the nonlinearities that are presently creating the current limit, so we need to understand them. But with more energy around, it seems implausible to me that we will not get a response. After all, going back to our geological record does give us some indication that changes could occur and that there is likely no absolute limit. The question is, as noted, the various slopes of the nonlinear processes and how they respond to more energy--whether the tropics and other regions warm together, or whether the increased amoounts of energy energy in the tropics are moved in such a way as to warm other regions or, as John Daly seems to be arguing, the response is such as to cause virtually no change anywhere. I lean toward the first rather than the second--the third seems unworkable to me.

Mike

Subject: sensitivity history
Date: Thu, 10 Feb 2000 23:22:25 GMT
From: richard@courtney01.cix.co.uk (COURTNEY)
To: Mike MacCracken <mmaccrac@usgcrp.gov>

Dear Mike:

You admit that there is a limit to the SST of 33°C under present conditions. And you assert that non-linearities in the climate system may cause this limit value to change if GHG concentrations increase.

It is not clear to me why non-linearities in the climate system should change this limit as a response to altered GHG concentrations.

Ramanathan and Collins find that as SST rises the transport of moisture into the upper atmosphere increases and this results in cirrus which reflects sunlight. The increased reflection of sunlight reduces the heat entering the system. This sets an upper limit of 305 K to the SST. Why should altered GHG concentrations affect this mechanism ? Are you claiming that GHG concentrations have significant effect on the probability of cloud formation and, if so, how ?

In order not to mislead, I should add the following two points. Ramanathan & Collins titled their first paper (ref. Nature 351, 27-32 (1991) ) "Limit to sea surface temperature ?" However, in responding to the attacks from Fu et al. they drew back from this and said they were not commenting on the ability of the effect they were reporting to compensate for GHG global warming (ref. Nature 361, 410-413 (1993) ).

All the best     Richard