Talk:Climate model/Archive 1

Zero-d model

I recalculated the zero-D model: the Stefan-Boltzmann constant was 2 orders of magnitude off, giving silly results. After correcting this, I re-calculated again, getting answers that were sane, but 5% off from the original. I changed the text to match the results of my calculations. This needs double-checking against other sources.

(William M. Connolley 13:03 7 Jun 2003 (UTC)) I probably used an albedo of 0.33 when I first wrote the page. To some extent the real value is uncertain/uninteresting. Now you've put in the true-ish albedo, the numbers may as well correspond to those values.

Rv Ed re Singer

(William M. Connolley 21:46, 10 Aug 2004 (UTC)) Ed, you've got to get out of this habit of stuffing skeptic quotes (with no attempt to balance them) right at the start of articles where they have marginal relevance. The intro to this article *is not about gcm's*. Did you read it? You want to put Singer it, put him into the GCM section. Its a dumb quote though.

Talk talk not edit war

(William M. Connolley 15:16, 13 Aug 2004 (UTC)) Ed: the trop-vs-sfc point is well worth discussing. But could we possibly attempt to hammer out an agreed text here on talk rather than on the article page? You wrote: "satellite date are universally agreed to corroborate the satellite data" which seems to me to be fairly clear evidence that you need to slow down a bit.

"I'm a lover, not a fighter." --Michael Jackson. Sure, let's talk.

How about restoring quotes from contrarians like Patrick Michaels and Fred Singer who (a) assert that warmers use IPCC models as hypotheses with predictive value; and (b) feel that these hypotheses have been falsified by actual observations?

Or if IPCC models are officially asserted NOT to have predictive value, let's emphasize that point in the articles objecting to the Kyoto Protocol. "No theory says CO2 causes warming".

Which is it, doc? Models predict that more CO2 means warmer air? Or Models do NOT predict that more CO2 means warmer air? --Uncle Ed 16:54, 16 Aug 2004 (UTC)

(William M. Connolley 22:02, 17 Aug 2004 (UTC)) I'm a bit baffled here. There are two possible things to be talking about. The first is about using words like predict/project/scenario. The second is about quotes from PM/FS. For the first: people tend to be a bit vagua about this. Looking at the TAR (e.g. http://www.grida.no/climate/ipcc_tar/wg1/007.htm) it looks like "project" is still the word in vogue. OTOH the "projections" of greater warmth are given a "very likely" rating, ie 90-99% chance of being correct. The second point: well I guess you don't mean the Singer quote that is still in there. So which ones do you mean?

Typo

and a part of this research is work inproving the models

I would correct it if I knew whether it was meant to say "in proving" or "improving". Both make reasonable sense in the context. (Pretty minor, so please delete this from the talk page once it's corrected.) ~~,,,~~Trainspotter~~,,,~~ 19:57, 3 Nov 2004 (UTC)

Michael McElroy etc...

(William M. Connolley 16:22, 11 Nov 2004 (UTC)) Ed added (not including the bit that GO took away (thanks):

Others are equally certain that existing models have no predictive power at all. Richard Lindzen wrote:

"Another active advocate of global warming, Michael McElroy, head of the Department of Earth and Planetary Sciences at Harvard, has recently written a paper acknowledging that existing models cannot be used to forecast climate." [1]

This isn't good enough. Who is MMc, and why do we care about his opinions? Why are we quoting L quoting MMc rather than MMc himself? When were L's words written, and hence what do we understand by "recent"? What did MMc say, and is acknowledging that existing models cannot be used to forecast climate an accurate quote or a misleading paraphrase?

Good golly, man, don't you read Wikipedia? The article about ProfMMc was at least 5 minutes old when you wrote the above...

Michael McElroy is Gilbert Butler Professor of Environmental Studies at Harvard, heads Harvard University's Center for the Environment and chairs the Interfaculty Initiative on the Environment. He served as Founding Chair of Harvard's Department of Earth and Planetary Sciences and has focused his research especially on effects of human activities on the global environment. A 1984 paper he co-authored with Professors Wofsy and Prather on potential non-linear destruction of the ozone layer helped persuade the US Environmental Protection Agency to carry out a risk assessment of chlorofluorocarbons that laid the groundwork for the negotiation of the Montreal Protocol.

The comments of Lindzen quoted appeared in the Cato Review of Business & Government in 1992. Given the difference between 1992's models and 2004's, I suggest that Ed's use of the word "existing" is extremely misleading. -- GWO 16:29, 11 Nov 2004 (UTC)

(William M. Connolley 16:54, 11 Nov 2004 (UTC)) OK, thanks. 1992-or-before can't possibly be considered "recent" in this context. I read the wiki article you wrote, Ed, but it doesn't really tell us that much.

Subject of leading people in climate dynamics, where's Mike McIntyre (DAMTP)'s article? -- GWO

You might be confusing the American politician with the scientist. MIT's Technology Review magazine wrote, "A prime piece of evidence linking human activity to climate change turns out to be an artifact of poor mathematics." Putting random temperature data into Mann's computer program produces a Hockey Stick shaped graph. Talk about fudging data! They should put Mann in the penalty box or give him a "game misconduct" for such shenanigans.

Honesty is hardly ever heard, but mostly what I need from you. (singer from Long Island)

Well, MIT Technology Review are just parroting a paper by McIntyre and McKitrick, from last year. (Why now? Who knows? Elections???). It would be an understatement to point out that Mann, and others, refute their refutations. http://www.cru.uea.ac.uk/~timo/paleo/EandEPaperProblem.pdf (PS: Ed, when talking science, talk papers and journals, not second rate OpEd think-pieces in Technology Review.)

One cannot hope to bribe or twist

Thank God, the British journalist

But seeing what the man will do

Unbribed, there's no occasion too

PPS: McIntyre and McKitrick's article was published in Energy And Environment, a journal which takes a perverse and public pride in its biases.

-- GWO

I concede that I've been out-quoted. British poetry trumps American poetry every time. So does British and Irish fantasy. No American has come close to Alice in Wonderland, C.S. Lewis, J.R.R. Tolkien, or even the Harry Potter books. But finding bugs in computer software is my forté, and I'm an expert at maths. --user:Ed Poor (deep or sour) 17:38, Nov 11, 2004 (UTC)

(William M. Connolley 19:11, 11 Nov 2004 (UTC)) Jolly good. Then I suggest you review MBH's code against M&M's criticisms (available from http://www.wmconnolley.org.uk/sci/mbh/ and other places too) and point out the errors.

Satellite data discrepancy

I thought there had been results published in science in the '02 to '03 time frame that had resolved the discrepancy by properly correcting for the angles of observations, so that section is out of date. But I haven't run across the article again. Does someone else have the cite?--Silverback 05:49, 17 Nov 2004 (UTC)

I found the citation, Global Warming Trend of Mean Tropospheric Temperature Observed by Satellites by Konstantin Y. Vinnikov and Norman C. Grody Science Oct 10 2003: 269-272. [2]. Unless I have misunderstood, the sattelite section can now be deleted as resolved and out of date. I will leave this for a couple of days, in case someone has objections.--Silverback 06:16, 17 Nov 2004 (UTC)

(William M. Connolley 09:28, 17 Nov 2004 (UTC)) See satellite temperature record.

On the satellite temperature record page it states, "Climate models predict that the troposphere should warm faster than the surface, so only the Fu et al or Vinnikov and Grody versions of the satellite record are compatible with this and the surface records." Is the statement climate model compatibility for climate models before or after their radiative transfer models were improved to account for darker clouds? Presumably darker clouds would have an impact on troposphere warming, or did it not make much difference?--Silverback 12:21, 17 Nov 2004 (UTC)

(William M. Connolley 16:18, 17 Nov 2004 (UTC)) In detail, I'm not sure. There was some ho-ha a few years back about darker clouds but I think it all subsided again with no great changes. The GCMs we are calling "current" (eg hadcm3; all those used in IPCC 2001) were built in 1998-2000-ish anyway. But if more modern GCMs (climate or NWP) altered this prediction I think I would have heard, and I haven't.

There is a discussion of the dark clouds controversy, and its presumed resolution in Science, Vol 300, Issue 5627, 1859-1860 , 20 June 2003, "Making Clouds Darker Sharpens Cloudy Climate Models" by Richard A. Kerr. Here is an excerpt:

"Measurements published in 1995 cast a shadow over climate models: They indicated that clouds absorb 40% more incoming solar energy, and let less pass through to warm the surface, than the models predicted (Science, 27 January 1995, p. 454). The discrepancy was bad news because where the models take in energy--up in the clouds or down at the surface--makes a difference in how they run, affecting aspects such as the speed of the hydrological cycle and possibly the pattern of climate change. Researchers pointed the finger of blame every which way: the models, the measurements, and even something weird and mysterious about cloud behavior. Now, new observations indicate that the models were clearly at fault, with flawed observations possibly contributing as well. But the good news is that more sophisticated calculations have largely closed the absorption gap between real and model clouds, just in time for the next international assessment of climate change."

"Analysis of a major field experiment conducted in north-central Oklahoma and published 9 May in the Journal of Geophysical Research (JGR) shows a near match within the uncertainties between newly measured cloud absorption and the latest calculations; the clouds really do seem to be darker than once presumed. "The field has benefited from this controversy," says modeler William Collins of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. "We have much better climate models as a result." How much better will be clearer once they've finished running the new models."

Note that the actual research was published in JGR, apparently also in 2003. So, it looks like it would be newer models that incorporate the correction. So I am curious about the implications for the troposphere of more cloud absorbtion.--Silverback 17:39, 17 Nov 2004 (UTC)

(William M. Connolley 18:24, 17 Nov 2004 (UTC)) OK, fair comment. It is refreshing to have real science quoted at me. I will have a look at the Kerr thing and the original JGR and see how it fits into my world-view. In fact, I'll try to talk to a cloud modeller and see what he says...

(William M. Connolley 11:34, 18 Nov 2004 (UTC)) I've now had a look. I think the Kerr news item oversells the effects of this stuff on GCMs. And the "The field has benefited from this controversy," says modeler William Collins of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. "We have much better climate models as a result." appears disctintly dubious. Note that whatever it may mean, its not refering to the 2003 JGR results.

Looking at the JGR paper (Ackerman et al; v108, p4273): this dismisses the extreme anomalous absorption papers that appeared in '95: specifially Cess et al, Ramanathan et al, and Pilewski & Valero. A says: "ARESE II results provide compelling evidence that it is time for the atmos sci comm to lay to rest these discussions of extreme solar abs in cloudy atmos columns.", and "ARESE II results are incompatible with prev studies reporting extreme anomalous abs and can be modelled with our current understanding of radiative xfer". Incidentally, ARESE appears to be an acronym carefullt designed to avoid being ARSE, which would have been funnier. A says/implies that ARESE (I) obs are now believed to be wrong. ARESE-II was only 2 sunny/3 cloudy days but they seem to think that was enough.

The JGR paper doesn't provide obvious support for Kerrs Now, new observations indicate that the models were clearly at fault. K doesn't distinguish clearly between line-by-line calcs and the band calcs that GCMs use.

In conclusion: read the JGR paper, not Kerr.

(William M. Connolley 14:26, 18 Nov 2004 (UTC)) ps: a colleague suggests I should have written: It is refreshing to have real "Science" quoted at me instead. Still, it beats septic websites.

The paleo bit

WMC, in an edit summary, questioned the reliability of:

The paleo climate data, suggests that the predicted impact of CO2 should be lower than the models predict, although the paleo data reflects long term equilibria and cannot rule out higher temperature increases within the lifespans of humans living today

I would guess that whoever wrote this was referring to the findings that CO2 is a poor predictor of climate change on 10s of Myr time scales. Most believe that other factors, mostly geologic, are simply a bigger influence on long-term climate change. However, some authors have concluded that CO2 effects, when considered in equilibrium with long-term geologic processes, have a significantly reduced effect than when considered by themselves. I can provide references for this if requested, however I would still question whether this the passage is appropriate for this article. In its current position it would juxtaposed against human time scale CO2. Even the authors who believe that long-term geologic processes provide a negative feedback limiting the impact of CO2 do not seem to believe that this has any relevancy to understanding the impact of CO2 forcing on human time scales.

There may also be similar questions regarding relative CO2 impact in the context of ice age feedbacks, but I am not familiar with such discussions, assuming they exist.

Dragons flight 11:26, Mar 8, 2005 (UTC)

(William M. Connolley 11:59, 8 Mar 2005 (UTC)) I thought it might be referring to the ice age cycles. From discussions at RealClimate, I've seen it asserted that the palaeo (100 kyr) data doesn't provide any useful bound on the climate sensitivity; OTOH I've heard the reverse argued too.

I would be surprised to get any strong constraints on modern sensitivities out of the ice age environment, but I wouldn't want to rule it out. I mentioned geological time scales because there was a prominent paper a little while back that said CO2 sensitivity over geologic time was about 1/3 the IPCC value. A number of people picked up on this and started quoting it out of context even though the authors have explicitly repudiated the notion that it is relevant to modern climate change. Dragons flight 13:01, Mar 8, 2005 (UTC)

Still it is an inconsistency that needs to be reconciled. The inconsistency would not be so troubling if the models were accurate enough to specifically account for the long term equibrilation mechanism and show how it could not respond quickly enough to these human introductions of greenhouse gasses. The models deficiencies in clouds and aerosols, of course, need to be handled first, and may in fact be the mechanism and be able to respond quickly enough.--Silverback 14:59, 8 Mar 2005 (UTC)

(William M. Connolley 22:25, 8 Mar 2005 (UTC)) Well the first thing that needs to be resolved is a proper ref so we (and the readers) know what you are referring to and don't have to guess!

SEWilco vs. IPCC Figure 4

SEWilco, what gives? You removed both references to the climate models being able to reproduce recent warming and accompanying links to [3]. From your edit summary, I don't see why you are doing this?

Figure 4c on the linked page does indeed show a close match between model and experiment. Personally, I don't think this is any great discovery since I don't know how many knobs had to be played with to get that match, but they do seem to be able to match recent warming and that seems like a reasonable thing to mention in this article. Dragons flight 19:10, Mar 20, 2005 (UTC)

(William M. Connolley 20:48, 20 Mar 2005 (UTC)) I don't know what SEW is up to either. I've reverted, pending some explanation.

His edit summary seemed to be implying that the matches were only an approximate fit of the general structure of the temperature changes, which is quite true. We could get into the degree of the fit, but perhaps such a description is too statistically deep for an article at this level, so I have summarized this by replacing "close" with "rough" and "certainly" with "general features", to more accurately describe the nature of the fit. — Cortonin | Talk 23:20, 20 Mar 2005 (UTC)

Ed again

Ed added:

Whether these simualations actually have any predictive power is questionable. Tom Randall, of the National Center for Public Policy Research, wrote: "Every study predicting climate in the past has been wrong due to faulty computer modeling." [4]

Firstly, this is the wrong part of the article for anything like this. Most of the article doesn't talk about GCMs, it talks about EBMs etc. The single-point models have no predictive power anyway.

Secondly, The comment quoted is nonsense.

Thirdly, the comment is just policitcal propaganda and has no place in the article. It would be possible to find sensible quotes about GCMs, though... oh wait, that would belong in the separate GCM article... but Ed didn't read that far. Sigh. William M. Connolley 20:36, 3 October 2005 (UTC).[reply]

simple models enhancements

Dimensions usually refer to a set of three orthogonal dimensions. A one-dimensional model means that there is no change with respect to two of the dimensions. That is, the partial derivatives with respect to two of the dimensions are zero. There can still be change with respect to time. Considering this, the simplest climate models are one-dimensional. The one dimension is to the earth with direction described by sign (+ or -).

All of the climate models, including the simplest, are necessarily energy balance models. The fundamental concept is energy entering equals energy leaving plus energy change. In this case, change in energy means change in average earth temperature.

Earth’s albedo is directly measured from satellites [5] and from observations of the dark vs. illuminated areas of the moon [6] and the consensus is that it is very nearly 0.3.

The simplest model presented is missing the effective emissivity of earth. The effective emissivity is that which results in the observed average earth temperature. For an earth albedo of 0.3, an effective emissivity of 0.667 results in an average earth temperature of 282 °K. All references that I have found indicate an average temperature of the earth of about 288 °K [7] which requires an effective emissivity of 0.613.

The emissivities of terrestrial surfaces are all in the range of 0.96 to 0.99 [8] [9] (except for some small desert areas which may be as low as 0.7). Clouds, however, which cover about half of the earth’s surface, have an average emissivity of about 0.5 [10] and an average temperature of about 258 °K [11]. Taking all this into account including a cloud area fraction of 0.51 results in an effective earth emissivity of about 0.67 (earth average temperature 282 °K). If a cloud area fraction of 0.47 is assumed, the effective earth emissivity becomes about 0.61 (earth average temperature 288 °K).

This simple model readily shows the effect of changes in solar output or change of earth albedo or effective earth emissivity on average earth temperature. It says nothing, however on what might cause these things to change. One-dimensional models do not address the temperature distribution on the earth or the factors that move energy about the earth.

Comments are solicited on the above prior to incorporating it into the article which will involve extensive rewording. Dan Pangburn 00:59, 2 February 2007 (UTC)[reply]

The simplest model is referred in the literature as the "zero-dimensional" model since the parameters of the model are averaged over the entire surface of the Earth. A "one-dimensional" model would compute values of the parameters averaging along the latitudes.--Jbergquist 21:17, 19 June 2007 (UTC)[reply]

There can be zero-dimensional models but this is radiation heat transfer with energy balance which is here one-dimensional. See e.g. [[12]].Dan Pangburn 22:30, 20 June 2007 (UTC)[reply]

The dimension in this model is distance above earth (height, altitude). Averaging along latitudes, that is, ignoring variation with longitude results in a two-dimensional model with one of the dimensions being latitude and the other being altitude. See also [[13]] Dan Pangburn 16:12, 28 June 2007 (UTC)[reply]

Its a zero-D model; thats what everyone calls such things. The ref you provide [14] says the same William M. Connolley 08:27, 2 July 2007 (UTC)[reply]

The model is one-dimensional consistent with the noted reference which says "A one-dimensional energy-balance equation involving diffusive energy transport and taking into account the ice-albedo feedback is considered." In the reference, this is reduced to a zero-dimensional model by "A systematic elimination of the spatial degrees of freedom . . ." Dan Pangburn 17:20, 2 July 2007 (UTC)[reply]

You said "[t]he dimension in this model is distance above earth (height, altitude)", but height is not part of the model. It is a model with no variation in latitude, longitude, or altitude, and hence is zero-dimensional. A single number T is assigned to represent the temperature of the entire Earth. I'm not sure how much clearer one can make it than that. Dragons flight 17:38, 2 July 2007 (UTC)[reply]

The ref you give isn't completely clear, but Id guess the one-D bit has diffusive transport in latitude (probable, since it includes ice-albedo). This is then *reduced* to 0-D William M. Connolley 18:37, 2 July 2007 (UTC)[reply]

We live in a 3-D world, that is, a world with 3 spatial dimensions. That could be east-west, north-south, up-down. Collapse one of the dimensions, say east-west by averaging along a latitude, and you have 2-D. Collapse the north-south dimension and you are left with the one up-down dimension. The one-D up-down dimension remains in the energy balance equation, which uses averages over the entire planet and considers energy to and from the planet. The one dimension is to and from the planet. The equation results from the first law of thermodynamics. Dan Pangburn 19:59, 2 July 2007 (UTC)[reply]

The model would be 1-d in the sense you mean if the vertical dimension were left in - ie, if the model contained a quanity that varied with height. But it doesn't - it has a single point variable, which is why its a zero-D model. I'm afraid you're just wrong on this - its what models of this type are called, and its appropriate William M. Connolley 20:15, 2 July 2007 (UTC)[reply]

(edit conflict) No, that would require temperature to vary with height (which is a kind of model that gets used), but that is not the model described on the page. The transfer of energy to and from the system is not the same as saying the system as dimensional structure. The number of dimensions needed to describe the model is equivalent to the number of dimensions in the field describing the variables in the model. In other words T(x,y,z) would require a three dimensional model. T(z) is one dimensional. This is just T, a single number with no spatial structure at all, i.e. zero dimensional. Dragons flight 20:24, 2 July 2007 (UTC)[reply]

This is a radiation heat transfer problem. The radiation from the average-planet-temperature is to absolute zero (well, OK the cosmic background temperature, close enough). The complete equation for radiation heat transfer between two bodies includes the difference between the fourth powers of their absolute temperatures. The one body here is the planet and the other 'body' is the cosmic background. The temperature of the cosmic background is so low that it is assumed to be zero with insignificant error and since zero to the fourth power is still zero and subtracting zero doesn't change anything the equation is OK as presented. The temperature difference is from the average temperature of the planet to zero. You are probably used to using T(z) as being a function of altitude within the atmosphere which of course it is. But in this simple energy balance equation of radiation heat transfer, the variation of temperature within the atmosphere is ignored. The one dimension here is from the planet to the background. Dan Pangburn 21:35, 2 July 2007 (UTC)[reply]

We appear to agree entirely on the physics content of the model. But transfer of energy between the sun, earth, and deep space does not constitute a dimension in the way the terminology is routinely used. I'm sorry but your understanding of what constitutes a one-dimensional model is simply wrong. Dragons flight 21:54, 2 July 2007 (UTC)[reply]

There is no dimension associated with the radiation from the sun. It is given as a rate of heat input, a number that says nothing about the temperatures of the sun or earth or, for that matter, the direction. The radiation from the earth however is calculated by the temperature of the earth and the temperature of the cosmic background. The planet radiates heat to the cosmic background. For the planet to radiate heat it must be radiated in a direction. The direction is from the planet to the cosmic background. A direction is a dimension. That is what makes this a one-dimensional equation. This is absolutely correct from a heat transfer engineer's standpoint. An example of a zero-D model would be one without spatial dimension such as one which calculates the proportions of products based on the proportions of the reactants. I am unsure where the disagreement begins. What I am saying is that a general model is 3-D. Collapse along the latitudes you get 2-D. Collapse along the longitudes and you get the remaining 1-D which, since we are ignoring the temperature gradient in the atmosphere, is from the planet to the cosmic background. If climatologists call this a zero-D model (what's in a name) maybe they should be aware that they are using terminology that is different from the terminology that is used in radiation heat transfer. Dan Pangburn 23:59, 2 July 2007 (UTC)[reply]

I'm a physicist, calling this 0-D is normal usage for me. Think of it this way. All you need to do the problem is the total power delivered by the sun and the equilibrium constraint that outgoing energy must equal incoming. It doesn't matter where it goes. That is immaterial to the model and not at all something that anyone I know would count as a "dimension". In order to have a dimension there must be some variable that is calculated as a function of that dimension. T is only ever calculated for a single point. Maybe its just you that has strange perception of dimensionality. Dragons flight 00:52, 3 July 2007 (UTC)[reply]

In radiation heat transfer it certainly does matter where the energy goes and this may be key to the discussion. In this case the energy goes to a place that can accept it which is a black body at (nearly) absolute zero. If the cosmic background were at the same temperature as the earth there would be no net heat transfer to the cosmic background. I don't think that there is any question that a 'general model' is 3-D. If you collapse one dimension does that not result in 2-D? And if you collapse one more dimension does that not result in 1-D? Or, to go the opposite direction, start with this model. Add north-south variation. It becomes a 2-D model because it is still averaged along latitude lines. Add variation along latitude lines and the result is a general 3-D model. I have been unable to find any credible reference that refers to this as anything other than a one-D model. Perhaps the issue could be avoided by expressing it another way e.g. simple model. Dan Pangburn 02:20, 3 July 2007 (UTC)[reply]

Examples of zero dimensional models. Dragons flight 02:44, 3 July 2007 (UTC)[reply]

Suddenly (?) the light comes on! The main problem (my error) was the assumption that the most general radiation heat transfer model for a spherical body in a black enclosure is 3-D. Since it is only 2-D, the two collapses gets to zero-D as you have been trying to get across. Sorry for the frustration but thanks for hanging in there. Dan Pangburn 08:00, 3 July 2007 (UTC)[reply]

You're still wrong I'm afraid. The most general radiation *is* 3D (or 4D with time...). Why do you have a problem with the idea that there can be 3 collapses into 0-D rather than only 2 into 1-D? William M. Connolley 08:40, 3 July 2007 (UTC)[reply]

Of course radiating bodies or configurations can be 3-D. But besides the S-B constant, radiation exchange calculation between two surfaces (in a non-participating medium) only requires temperatures, areas and dimensionless shape factors (dimensionless radiosity if any surfaces aren't black). I have no problem with a 3-D GCM being collapsed 3 times to get to zero-D or a (smooth) spherical body with a radiating surface any point on which can be specified by two dimensions (e.g. latitude and longitude) being collapsed two times to zero-D. Dan Pangburn 10:47, 3 July 2007 (UTC)[reply]

What do current state-of-the-art climate models include?

From a discussion here it became apparent that some people are not aware that current state-of-the-art climate models include fully interactive clouds.[15] and use that ignorance as an argument against climate models. I thought of adding that information here, but I'm not sure what the best context is. Ideally, it would be part of a list of all things that have been considered in current climate models. — Sebastian 22:26, 1 June 2007 (UTC)[reply]

What do current state-of-the-art climate models not include?

Watching a recent video, I was surprised to learn that some models do not include what I consider basic components, like heat and temperature variations. With that as a backdrop is there any relevance to identifying the (prevailing) components to such equations, even from a list with explanations for their omissions/inclusions. And if you really want to spice up the gumbo add a section for the elaboration of various self interest groups and the potential flaws of their interpretation of climate change?

Really belongs at Global climate model William M. Connolley 17:28, 2 June 2007 (UTC)[reply]

Perfer no merging of pages

This page on climate models provides a suitable length 'start-page' about climate models. Much better to keep it separated from more advanced pages, the existing links being suitable for those looking for more depth.

David B. Benson (talk) 16:54, 5 April 2008 (UTC)[reply]

The correct solution is to rename the "Global climate model" page to "General Circulation Model" and restrict that page to the technical description of circulation models, as opposed to climate models (of which AOGCMs are a component). Eric Salathe (talk) 18:39, 23 January 2009 (UTC)[reply]

I agree with this!! Why hasn't this been done? Geoffrey.landis (talk) 21:41, 30 January 2012 (UTC)[reply]

The current article is a bit weak on other climate system components such as vegetation modeling and carbon modelling. I think that the prev. comment is s a sensible move, but i'd prefer the expanded aogcm as a title. Andrewjlockley (talk) 21:59, 22 May 2009 (UTC)[reply]

ClimateModels wow!!!! —Preceding unsigned comment added by 90.215.241.56 (talk) 17:35, 15 March 2010 (UTC)[reply]

Independence of Zero D model Albedo and Emissivity

In the current article there is the following statement:
Using the simple formula, the percent change of the average amount of each parameter, considered independently, to cause a one degree Celsius change in steady-state average earth temperature is.. I have a problem considering albedo and emissivity as independent variables, as they both measure a similiar thing; relatively how black or white a surface (in this case a point sphere) is.
Please show me why $(1-a)$ is independent of emissivity, and therefore why they can be considered independently? --94.197.131.166 (talk) 18:25, 20 March 2010 (UTC)[reply]

Albedo is SW; emissivity is LW. But I'm rather dubious about the asserion that the avg emisivity is 0.6. I'd say it is ~1 William M. Connolley (talk) 22:13, 20 March 2010 (UTC)[reply]

radiative heat loss from full surface

Since the irradiance depends on T⁴, more accuracy could be obtained by integration over the surface temperature.

Last, the amount of light energy per unit area goes as the cosine of the tangent angle. Integration over the hemisphere of the cosine would give a better result for the energy input.

The geometric integrations are reasonably easy with a calculus book in hand. But even without integration, correcting for emission over the full sphere will get one in the ballpark. More problematic is the surface temperature integration of the T⁴ law since this requires real data. — Preceding unsigned comment added by 67.182.205.2 (talk) 18:56, 23 December 2011 (UTC)[reply]

equilibrium temperature

I have put in some wording to justify the existence of a redirect from the phrase 'equilibrium temperature', which till now was redirected to Thermodynamic equilibrium#thermal equilibrium which wasn't a suitable redirect, I think. Logically it can be argued that it was a suitable redirect, and that my new redirect is not suitable, but I think it is a matter of balance of suitabilities, and my new version may perhaps be on balance an improvement, though a still better one might soon be found.Chjoaygame (talk) 21:12, 24 December 2011 (UTC)[reply]

Error in climate sensitivity

I am baffled by the results listed under zero-dimensional models. How in the world could the temperature be twice as sensitive to albedo as it is to incident intensity? This is clearly an error. Geoffrey.landis (talk) 21:43, 30 January 2012 (UTC)[reply]

Good point, I think. The source seems to have been DP ages ago [16] and he definitely isn't a good source. Part of it might be that it is (1-a)S, so if a were 0.98 it would make sense. But it isn't, its about 0.3, so it doesn't make sense William M. Connolley (talk) 22:08, 30 January 2012 (UTC)[reply]

The numbers in that ancient file are correct. Check them yourself. Hint, the starting temperature is 288.15 K and each of the changes separately gets to 288.7 K KDan Pangburn (talk) 02:32, 13 August 2015 (UTC) (AKA DP)[reply]

Propose adding section on U.S. National Research Council report

Hi, I'd like to add the following text to the end of the Research and Development section:

A 2012 National Research Council report discussed how the large and diverse U.S. climate modeling enterprise could evolve to become more unified.^[1] Efficiencies could be gained by developing a common software infrastructure shared by all U.S. climate researchers, and holding an annual climate modeling forum, the report found.^[2]

I'd also like to add information about a new website that explains climate modeling to the external links section. The website is Climate Modeling 101 http://nas-sites.org/climatemodeling/. Any feedback would be great! Best wishes, Earlgrey101 (talk) 18:49, 27 September 2012 (UTC)[reply]

References

Climate models vs. Reality discussion?

Not discussed here & I'm not finding it at, eg, Index_of_climate_change_articles. Where is the discussion? Help? --Pete Tillman (talk) 21:21, 28 February 2015 (UTC)[reply]

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[1] ttp://dels.nas.edu/Report/National-Strategy-Advancing-Climate/13430

[2] ttp://dels.nas.edu/Materials/Report-In-Brief/4291-Climate-Modeling

[1]

[2]