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This article may be too technical for most readers to understand.(September 2010) |
WMC, "come on" is not informative as to what is wrong with the following. [1] You've seen the source quotations. ( SEWilco 14:53, 20 May 2005 (UTC))
This is not true? How did models explain these things? ( SEWilco 03:04, 21 May 2005 (UTC))
"Coupled ocean-atmosphere GCMs are used to project/predict future temperature changes under various scenarios."
But the IPCC did not use that? ( SEWilco 04:17, 21 May 2005 (UTC))
( William M. Connolley 22:30, 21 May 2005 (UTC)) That was Silverbacks mistake, too. Read on. Its obvious that AOGCMs were used. See if you can work out the subtle distinction...
I just did, see below,
'The A2 scenario is characterized by a politically and socially diverse world that exhibits sustained economic growth but does not address the inequities between rich and poor nations, and takes no special actions to combat global warming or environmental change issues. This world in 2100 is characterized by large population (15 billion), high total energy use, and moderate levels of fossil fuel dependency (mostly coal). The A2 scenario is the most well-studied of the SRES scenarios that assume no attempt to address global warming.'
A near tripling of world population? Ever heard of Lutz? ref: Wolfgang Lutz, Warren Sanderson & Sergei Scherbov, 2001, The end of world population growth, Nature 412, 543-545, 2 aug 2001 [3]
I prefer, for climate model intercomparison, the pure mathematical 1% compound CO2 concentration rise over any SRES storyline. BTW the graph [4] is called Global_Warming_Predictions.png. I suggest to change it (and the graph title) to "Climate model intercomparison". Hans Erren 22:20, 4 January 2006 (UTC)
( William M. Connolley 13:16, 27 May 2005 (UTC)) SEW added some stuff, apparently because he thought I recommended it. I'm not sure exactly what he meant, but I regard most of what he added as badly phrased and pretty much POV pushing (the POV being anti-model). So I've removed it.
SEW wrote: many models are based on a flat planet. This is so bizarre that I don't know what he meant, but its wrong. William M. Connolley 09:23, 12 Jun 2005 (UTC).
I've removed:
Most of this is history of GCMs, which doesn't belong there.
Of the bits that *aren't* history but are current, its impossible to determine. Current models do (I think) conserve KE, so leaving it in is misleading. And... the refs in the AMIP table... don't mean that the exact Arakawa 1972 scheme is being used. People tend to ref the paper when doing a brief description and not ref local improvemnts.
Also, the AIP page is a bit... mystical in that section. I slightly wonder if Weart is a bit out of his field there.
Getting into this one a bit late. The AIP page is hopeless, a mish-mosh of allusions to aliasing (not named as such) and quadratic-conservative schemes. In the real world KE cascades from larger to smaller scales and eventually is dissipated at the scale of molecular viscosity, which of course is too small to represent in a GCM. The unresolvable part of the cascade is instead mimicked by viscosity-like terms that dissipate KE in the smallest resolvable scales. Raymond Arritt 04:51, 7 July 2006 (UTC)
I removed:
From the context, its clear that this statement isn't really about the *accuracy* of the models - its about the Hockey stick stuff. Also, the source is distinctly dubious: essentially propaganda.
There is a link to parametrization which redirects to Coordinate System which does not seem very relevant. I think linking Climate parameters, forcings and feedbacks is more relevant. However I am not happy with the quality of the page. Perhaps William Connolley could use his expertise to improve it then change the link.
I'm not sure how recent this China Daily article's information is, but it portends badly. Into Global Warming I inserted the paragraph "In December, 2005 it was revealed the reflectivity effect of airborne pollutants was about double that previously expected, and that therefore some global warming was being masked. This effect implies that pre-2006 models will underpredict future global warming. [10]" However, I feel that more detail is merited in this article. Does somebody get Nature? Simesa 20:56, 28 December 2005 (UTC)
Follow-up: I contacted a researcher (Jerry Meehl) at NCAR: He replied that, as WMC suggested, the new estimates are within the uncertainty bands for models being used ror the next IPCC report. (I wasn't aware that China had supercomputer-model capability.) Specifically, the researcher said:
The exact magnitude of various forcings is uncertain. The new estimates you refer to for aerosols are larger than what some models use (the magnitude of what models compute, for example, for sulfate aerosols varies depending on the nature of their sulfur cycle models or types of sulfate aerosol concentrations they use) but not out of the range of uncertainty for aerosol forcing used across all of the more than 20 models currently being assessed in the IPCC AR4. This accounts for some of the range of model responses to the simulation of 20th century climate. Even with this uncertainty in aerosols, the GHGs are still the largest forcing by far, and are the big driver for late 20th century warming and estimates of 21st century warming. The latest simulations will be assessed in the IPCC AR4, but many modeling groups are publishing their latest findings in the peer reviewed literature now (for example, from our group see: Meehl et al., 2005: How much more warming and sea level rise? Science, 307, 1769—1772).
Simesa 18:59, 29 December 2005 (UTC)
I've rm'd:
This para is somewhere between wrong and misleading. If models underestimate solar forcing, then they are likely to underestimate other forcing as well; so underestimating solar is just as likely to lead to underpredicting future change. It also (I think) rather misrepresents the D+A stuff. See-also http://www.realclimate.org/index.php?p=229 (and the comments) William M. Connolley 21:39, 28 December 2005 (UTC).
I've added the Technical template to this article largely because of the part under "A rather more complete discussion of climate models is provided by the IPCC TAR chapter 8, Model Evaluation (2001)." It really doesn't make much sense out of context, and needs cleaned up. Calion | Talk 06:41, 21 February 2006 (UTC)
Have there been examinations of the predictive value of climate models? I'm pretty sure that early models were around in 1990, say, so how well did their predictions accord with the change in climate over the past 15 years or so? "Postdiction" of facts known to the people who made the model isn't a terribly impressive achievement, I would say, and it surely isn't a good measure of how well the model will predict the future. — Simetrical ( talk • contribs) 20:45, 12 March 2006 (UTC)
Cleaned this part up a bit. Also removed the tangential comments on analog forecasting and such. That material could be appropriate for an article on history of weather forecasting but has no relevance to GCMs. Raymond Arritt 03:42, 8 May 2006 (UTC)
I've cut this to talk:
because I dont know what it means. There is some mixing of flux corr and clouds? William M. Connolley 19:24, 17 June 2006 (UTC)
I took out:
Its confusing as written (many people will interpret "fixed" and "constant" as meaning in time). Its also wrong, in implying that this exhausts the possibilities: as mentioned later, its perfectly possible to have a grid with any variation in latitude. What I think it means is that FD models tend to use constant-spacing and Spectral ones use gaussian... William M. Connolley 08:18, 21 September 2006 (UTC)
Anyone see this: New Study Increases Concerns About Climate Model Reliability. How does this get worked into the article and is the full paper out yet? DJ Creamity Oh Yeah! 20:45, 11 December 2007 (UTC)
I would like to add this new peer reviewed and published scientific paper concerning the predictive power of climate models. http://www.atypon-link.com/IAHS/doi/abs/10.1623/hysj.53.4.671
The data on page 9 is of particular importance. I know original interpretation is not allowed and I will find a credible source for that.
The data is very obvious, however, as the correlation numbers are absurd. —Preceding unsigned comment added by Mickeyklein ( talk • contribs) 19:45, 3 August 2008 (UTC)
Hello i have recently proposed the Wikiproject Earth. This Wikiproject`s scope includes this article. This wikiproject will overview the continents, oceans, atsmophere and global warming Please Voice your opinion by clicking anywhere on this comment except for my name. -- Iwilleditu Talk :) Contributions —Preceding comment was added at 15:34, 30 March 2008 (UTC)
This page should be titled 'General Circulation Model'. —Preceding unsigned comment added by 216.165.95.70 ( talk) 01:37, 10 January 2009 (UTC)
I've added this http://en.wikipedia.org/wiki/Global_climate_model#Weaknesses_of_Global_Climate_Models Needless to say, WMC reverted all my work without attempting to improve it. Please can people look at the text i added (try history if it's been axed again) and comment/improve on it. Andrewjlockley ( talk) 15:11, 6 April 2009 (UTC)
I think the problem is that you don't understand the material you are adding. Your "model" of the situation is, or appears to be from the outside, "fling stuff at the article and hope someone will fix it up". Our model is "if people add stuff that is wrong, remove it, and ask them to discuss on the talk page before they re-add it". You now have a solid repuation for failing to understand the references you add, so no-one trusts your refs to actually support what you say. Your task is to force us to revise this reputation William M. Connolley ( talk) 15:47, 6 April 2009 (UTC)
The entire thing was badly broken. This bit Carbon cycle modelling, notably the impact of climate change on methane clathrates and methane stored in permafrost.<ref>Harvey, L. D. D., and Z. Huang (1995), Evaluation of the potential impact of methane clathrate destabilization on future global warming, J. Geophys. Res., 100(D2), 2905–2926.</ref> is perhaps the most obvious - but please don't assume from that I mean the rest of reasonable. Most carbon cycle models do ocean carbon, and soil carbon, and some representation of vegetation. I don't think anyone does oceanic clathrates (probably because it would be dull: the ocean is too cold to release them, and will stay that way for a while) in GCMs and I don't think anyone does permafrost carbon but I could well be wrong about the latter. If anyone *is* doing it, it wont be in a ref from 1995. Without a doubt that ref (which I haven't read, any more than AJL has) says nothing about what happens when you add MC to GCMs William M. Connolley ( talk) 21:09, 6 April 2009 (UTC)
Might use http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VH6-50S8C4F-1&_user=870092&_coverDate=09%2F30%2F2010&_rdoc=4&_fmt=high&_orig=browse&_origin=browse&_zone=rslt_list_item&_srch=doc-info%28%23toc%236058%232010%23999589996%232436735%23FLA%23display%23Volume%29&_cdi=6058&_sort=d&_docanchor=&view=c&_ct=11&_acct=C000046800&_version=1&_urlVersion=0&_userid=870092&md5=44592835a9247366ae32ffba471562f6&searchtype=a someday William M. Connolley ( talk) 11:30, 5 October 2010 (UTC)
I've just noticed [11], which appears to "merge" (actually, copy - the original is still there) text from Climate model. I'm not at all convinced that made sense.
In the course of which, I notice that Climate models are systems of differential equations based on the basic laws of physics, fluid motion, and chemistry. To “run” a model, scientists divide the planet into a 3-dimensional grid, apply the basic equations, and evaluate the results. Atmospheric models calculate winds, heat transfer, radiation, relative humidity, and surface hydrology within each grid and evaluate interactions with neighboring points. is at http://celebrating200years.noaa.gov/breakthroughs/climate_model/welcome.html, though they may have copied us. That text came in [12].
William M. Connolley ( talk) 11:42, 5 October 2010 (UTC)
Referencing the above post, Gobal Climate Models do not "calculate" winds, etc. Those are affected by convection and other latent heat factors such as precipitation which are "estimated". The estimates are in turn applied to parameters, which in fact are not parameters of the real world at all, but only of the model. To actually "calculate" those factors would required computational ability in excess of what is available at this time, as although the phyusics is known, the grid sizes are much too large to accurately reflect reality, especially in terms of increased heat retained at the surface which would alter convection, precipitation, etc. Stevehhll ( talk) 16:20, 17 October 2010 (UTC)
Why do you object to indicating that the climate models begin from an artificial (i.e. human constructed even if they are based on data) set of initial conditions? -- The great sluggo ( talk) 21:09, 22 October 2010 (UTC)
{{edit semi-protected}}
In the phrase: "Atmospheric models calculate
winds,
heat transfer,
radiation,
relative humidity, and surface
hydrology within each grid and evaluate interactions with neighboring points.]]"
Please change "calculate" to "estimate" because grid sizes are too large to realistically calculate those factors, so they are parameterized or affected by parameters. The parameters are artificial inputs to the model. They are not calculations, so it is logically incorrect to say those factors are "calculated". They may be calculated in the model, but to say they are calculations of real world physical processes is inaccurate.
Thank You. Stevehhll ( talk) 10:12, 26 October 2010 (UTC)
Stevehhll ( talk) 10:12, 26 October 2010 (UTC)
{{
edit semi-protected}}
template. -
Atmoz (
talk)
16:51, 26 October 2010 (UTC)A history section was added, which was mostly from the recently-upgraded numerical weather prediction article. The section of GCM, within the GCM article, was giving the article the look of a nesting doll, so content from this section was subdivided between the history, computation, and accuracy sections. Thegreatdr ( talk) 01:12, 9 January 2011 (UTC)
Given that this article's title is "Global climate model", it's confusing to have the opening sentence of this article begin, "A General Circulation Model (GCM) is a mathematical model of the general circulation of a planetary atmosphere or ocean...". I would encourage someone familiar with the subject matter to rewrite the lead to introduce the term "Global climate model" before "General Circulation Model". - dcljr ( talk) 19:57, 21 June 2011 (UTC)
I removed the last sentence from the Accuracy section...
Forecasts of climate change are inevitably uncertain. Even the degree of uncertainty is uncertain, a problem that stems from the fact that these climate models do not necessarily span the full range of known climate system behavior. [13]
... with an edit summary of "Removed "...Even the degree of uncertainty is uncertain..." statement. Inhofe does not satisfy WP:RS on the topic" diff. This was reverted with an edit summary of "rv unexplained removal of text" diff. I'll bite. When did The Facts and Science of Climate Change by U.S. Senator James M. Inhofe become more than a WP:PRIMARY source for the political opinions of Inhofe? Without a better source the statement cannot remain. - ArtifexMayhem ( talk) 06:54, 27 August 2011 (UTC)
There is a wide spread pattern of deficiences, inconsistencies, and inaccuracies present in most existing citations of the IPCC AR reports. I have developed a replacement set of complete, verified citations, which can be seen at Global warming. If there are no objections I propose to appy them to this article. - J. Johnson (JJ) ( talk) 23:40, 12 September 2011 (UTC)
Anyone wanting to study this topic furhter might want to see "A Vast Machine" by Paul Edwards, reviewed in Science (14 Jan. 2011, p. 149). ISBN 9780262013925 ~ J. Johnson (JJ) ( talk) 21:44, 27 October 2011 (UTC)
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) 21:04, 30 January 2012 (UTC)
This article is confusing, because it uses the acronym GCM to mean both "General Circulation Model" and "Global Climate Model", and it is the article that is reached by searching for either term. I attempted to clarify this a little.
The structure is a little odd as well; it starts out with the most complicated models, and then after many screens of complicated models, without warming switches to discussing very basic models. I tried to clarify this by putting in a new heading "Simplified Models of Climate", and putting all the models that previously had their own headings as subheadings under this.
I will also note that as far as I can tell, the text here is cut-and-paste identical to the text in the Wikipedia Climate model article, even to the extent of including the same climate sensitivity error. Why do we have this material here? These aren't circulation models. Can't we just link to the Climate model article?
I would suggest renaming this article "General Circulation Model", and making the term "Global Climate Model" redirect to the Climate model article. Geoffrey.landis ( talk) 21:32, 30 January 2012 (UTC)
I did a google search, and found 1.15 million hits for the search term gcm "general circulation model", 307 thousand hits for the search term gcm "global climate model", and 329 thousand hits for the search term gcm "global circulation model." It seems pretty clear that GCM is used to mean "general circulation model" much more than that other uses of the phrase.
Therefore, I propose renaming this page "General Circulation Model," and redirecting "Global climate model", and "Global circulation model" here. Geoffrey.landis ( talk) 20:01, 2 February 2012 (UTC)
Overestimated global warming over the past 20 years, J C Fyfe et al, Nature Climate Change, vol 3, page 767 (2013) Their Figure one suggests that climate models dramatically overpredict temp rise; this is in contradiction to http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter8.pdf — Preceding unsigned comment added by 24.91.51.31 ( talk) 01:53, 14 October 2013 (UTC)
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Section on 'Model Accuracy' focuses on temperature - is there scope to include information on generally decent performance on large scale rainfall, but also to include info on rainfall error (e.g. double ITCZ) or circulation biases (e.g. latitudinal biases in subtropical jet)? Nzadi ( talk) 18:08, 12 May 2023 (UTC)