Talk:Climate model

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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.

Contents 1 Rv Ed re Singer 2 Talk talk not edit war 3 Typo 4 Michael McElroy etc... 5 Satellite data discrepancy 6 The paleo bit 7 SEWilco vs. IPCC Figure 4 8 Ed again 9 simple models enhancements

[edit] 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.

[edit] 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?

[edit] 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)

[edit] 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.

[edit] 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.

[edit] 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!

[edit] 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)

[edit] 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).

[edit] 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)