# Global Warming for Dummies **URL:** \ **Category:** Great Debates\ **Created:** [January 30, 2012, 8:44am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172 "2012-01-30T08:44:22Z")\ **Posts on this page:** 20\ **Page:** 16
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [February 11, 2012, 8:18pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/301 "2012-02-11T20:18:42Z")
> [@GIGObuster](#): > > He already said that Dr. Alley is lying. Who is “he”? ´cuz in the whole sentence I was only talking 'bout Alley. > [@](#): > > And repeating this just makes you look more ridiculous (Fine with me) as many scientists, even conservative ones like Bickmore, link to SkS and recommend it. So that mean a NO, you’re not vouching for our gods at SkS. It is interesting thst you say it makes me look ridiculous, because it’s another page from your book. You’re always saying “he’s not a climate scientist” and apparently it’s only ridiculous when I ask you to vouch for your prefered source of knowledge. The same goes about **greenman3610** , why would I listen to generic guys with a youtube channel. Do you vouch for them? Why? What are their qualifications for deciding what’s good and what ain’t? Nice appeal to authority at the end,though. Still, you’re throwing your gods under the bus. It’s good to see that you can’t defend “your” isotope link, not becasue it’s false or wrongly done, but simply becasue it’s not an answer. Also, no news on your broken link. If you bring it, you gotta show it. ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [February 11, 2012, 9:31pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/302 "2012-02-11T21:31:33Z")
Gigobuster is fond of linking to Spencer Weart’s, “The Discovery of Global Warming”. It has been a few years since I read it, but there was one part I read that stopped me short and I saved it. [http://www.aip.org/history/climate/GCM.htm](http://www.aip.org/history/climate/GCM.htm) > [@](#): > > The IPCC pressed the modelers to work out a consensus on a specific range of possibilities to be published in the 2007 report. The work was grueling. After a group had invested so much of their time, energy, and careers in their model, they could become reluctant to admit its shortcomings to outsiders and perhaps even to themselves. A frequent result was “prolonged and acrimonious fights in which model developers defended their models and engaged in serious conflicts with colleagues” over whose approach was best.(111) Yet in the end they found common ground, working out a few numbers that all agreed were plausible. This makes it clear that ‘consensus’ on global climate models wasn’t a natural part of scientists actually a natural part of agreeing with each other, but a result of political pressure on the part of the the IPCC. I would also suggest reading the article linked in footnote 111. \*\*Seductive Simulations?:Uncertainty Distribution Around Climate Models \*\* [http://sciencepolicy.colorado.edu/admin/publication\_files/resource-1891-2005.49.pdf](http://sciencepolicy.colorado.edu/admin/publication_files/resource-1891-2005.49.pdf) ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [February 11, 2012, 9:35pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/303 "2012-02-11T21:35:41Z")
> [@GIGObuster](#): > > I and many others understand, Dr Alley is not lying, and does support all the items mentioned in the show and his points on water vapor are valid. And Forbes is a capitalist fool 🙂 for using that contributor. You are apparently willing to do anything to refute the Forbes article except actually read it. ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [February 11, 2012, 9:54pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/304 "2012-02-11T21:54:36Z")
> [@JoelUpchurch](#): > > You are apparently willing to do anything to refute the Forbes article except actually read it. But, IT’S A DENIER. He already knows everything they say because skepticalscience has all the answers. ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [February 11, 2012, 10:11pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/305 "2012-02-11T22:11:40Z")
> [@JoelUpchurch](#): > > You are apparently willing to do anything to refute the Forbes article except actually read it. Lol, probably that’s because there’s no rebuttal to the article on [skepticalscience.com](http://skepticalscience.com) or any other warmist web site. And by the way, Warren Meyer’s work on global warming is extremely logical and convincing if you take the time to read it carefully. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [February 11, 2012, 10:38pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/306 "2012-02-11T22:38:19Z")
> [@JoelUpchurch](#): > > You are apparently willing to do anything to refute the Forbes article except actually read it. > [@brazil84](#): > > Lol, probably that’s because there’s no rebuttal to the article on [skepticalscience.com](http://skepticalscience.com) or any other warmist web site. > > And by the way, Warren Meyer’s work on global warming is extremely logical and convincing if you take the time to read it carefully. And this was already dealt with, his was on opinion piece, nothing of substance really, making that you are making it to be is telling. ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [February 11, 2012, 10:41pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/307 "2012-02-11T22:41:20Z")
> [@brazil84](#): > > Lol, probably that’s because there’s no rebuttal to the article on [skepticalscience.com](http://skepticalscience.com) or any other warmist web site. If he had just reads the comments on the article in Forbes, he could have some intelligent rebuttal points to make. > [@](#): > > And by the way, Warren Meyer’s work on global warming is extremely logical and convincing if you take the time to read it carefully. Maybe I will get back to it, but I didn’t want to cite something without reading it in detail and the Forbes article was relevant to the **Global Warming for Dummies** OP. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [February 11, 2012, 10:41pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/308 "2012-02-11T22:41:35Z")
> [@Aji\_de\_Gallina](#): > > So that mean a NO, you’re not vouching for our gods at SkS. It is interesting thst you say it makes me look ridiculous, because it’s another page from your book. You’re always saying “he’s not a climate scientist” and apparently it’s only ridiculous when I ask you to vouch for your prefered source of knowledge. > > The same goes about **greenman3610** , why would I listen to generic guys with a youtube channel. Do you vouch for them? Why? What are their qualifications for deciding what’s good and what ain’t? He also links to the science, that you show others how incapable you are at looking the the main comment in the video is not my problem. > [@Aji\_de\_Gallina](#): > > Nice appeal to authority at the end,though. Still, you’re throwing your gods under the bus. > > It’s good to see that you can’t defend “your” isotope link, not becasue it’s false or wrongly done, but simply becasue it’s not an answer. > Also, no news on your broken link. If you bring it, you gotta show it. Meh, useless pap. ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [February 11, 2012, 10:43pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/309 "2012-02-11T22:43:59Z")
> [@GIGObuster](#): > > And this was already dealt with, his was on opinion piece, nothing of substance really, making that you are making it to be is telling. “It’s already been dealt with”, which transalted into English means “he said something I disagree with” + “he’s a denier” + “he says there’s been cooling in the last 10 years (like NOAA)”. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [February 11, 2012, 10:47pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/310 "2012-02-11T22:47:56Z")
> [@JoelUpchurch](#): > > Gigobuster is fond of linking to Spencer Weart’s, “The Discovery of Global Warming”. It has been a few years since I read it, but there was one part I read that stopped me short and I saved it. > > [http://www.aip.org/history/climate/GCM.htm](http://www.aip.org/history/climate/GCM.htm) > > This makes it clear that ‘consensus’ on global climate models wasn’t a natural part of scientists actually a natural part of agreeing with each other, but a result of political pressure on the part of the the IPCC. > > I would also suggest reading the article linked in footnote 111. > \*\*Seductive Simulations?:Uncertainty Distribution Around Climate Models \*\* > [http://sciencepolicy.colorado.edu/admin/publication\_files/resource-1891-2005.49.pdf](http://sciencepolicy.colorado.edu/admin/publication_files/resource-1891-2005.49.pdf) Of course the point was to deal with the idea that on the water vapor chart it is somehow misleading to not show the whole thing, it is clear there are reasons why you think that means something , but looking at history and the background I do not think it is as important as you want it to be. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [February 11, 2012, 11:15pm UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/311 "2012-02-11T23:15:49Z")
> [@Aji\_de\_Gallina](#): > > “It’s already been dealt with”, which transalted into English means “he said something I disagree with” + “he’s a denier” + “he says there’s been cooling in the last 10 years (like NOAA)”. He is trying to make it seem that he is in the middle, but me and others dismissed him before and that opinion piece just reinforces my views, he is just happy to raise a strawman of “catastrophic man-made global warming theory.” from the beginning, he uses just the worst estimations and acts like if that is what all proponents are into. That should be enough to dismiss him, what we will get is a lot of pain but not a catastrophe if we plan ahead and, of course, there are many that want to continue to say that nothing should be done as they claim this will not be serious enough, there is then a lot of self fulfillment on any future unrest and problems caused by not planning ahead, but this is not coming from the scientists but from the efforts of deniers and misguided skeptics. As for the Forbes contributor, his point is still that feedbacks are not important and the rise in temperature will remain low. Not sure where he is getting that. > **[Water Vapor Confirmed As Major Player In Climate Change](http://www.sciencedaily.com/releases/2008/11/081117193013.htm)** > > Water vapor is known to be Earth's most abundant greenhouse gas, but the extent of its contribution to global warming has been debated. Using recent NASA satellite data, researchers have estimated more precisely than ever the heat-trapping effect of... > [@](#): > > Climate models have estimated the strength of water vapor feedback, but until now the record of water vapor data was not sophisticated enough to provide a comprehensive view of at how water vapor responds to changes in Earth’s surface temperature. That’s because instruments on the ground and previous space-based could not measure water vapor at all altitudes in Earth’s troposphere – the layer of the atmosphere that extends from Earth’s surface to about 10 miles in altitude. > > AIRS is the first instrument to distinguish differences in the amount of water vapor at all altitudes within the troposphere. Using data from AIRS, the team observed how atmospheric water vapor reacted to shifts in surface temperatures between 2003 and 2008. By determining how humidity changed with surface temperature, the team could compute the average global strength of the water vapor feedback. > > “This new data set shows that as surface temperature increases, so does atmospheric humidity,” Dessler said. “Dumping greenhouse gases into the atmosphere makes the atmosphere more humid. And since water vapor is itself a greenhouse gas, the increase in humidity amplifies the warming from carbon dioxide.” > > Specifically, the team found that if Earth warms 1.8 degrees Fahrenheit, the associated increase in water vapor will trap an extra 2 Watts of energy per square meter (about 11 square feet). > > “That number may not sound like much, but add up all of that energy over the entire Earth surface and you find that water vapor is trapping a lot of energy,” Dessler said. “We now think the water vapor feedback is extraordinarily strong, capable of doubling the warming due to carbon dioxide alone.” > > Because the new precise observations agree with existing assessments of water vapor’s impact, researchers are more confident than ever in model predictions that Earth’s leading greenhouse gas will contribute to a temperature rise of a few degrees by the end of the century. > > “This study confirms that what was predicted by the models is really happening in the atmosphere,” said Eric Fetzer, an atmospheric scientist who works with AIRS data at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Water vapor is the big player in the atmosphere as far as climate is concerned.” ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [February 12, 2012, 12:56am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/312 "2012-02-12T00:56:53Z")
> [@GIGObuster](#): > > He is trying to make it seem that he is in the middle, but me and others dismissed him before and that opinion piece just reinforces my views, he is just happy to raise a strawman of “catastrophic man-made global warming theory.” from the beginning, he uses just the worst estimations and acts like if that is what all proponents are into. > > That should be enough to dismiss him, what we will get is a lot of pain but not a catastrophe if we plan ahead and, of course, there are many that want to continue to say that nothing should be done as they claim this will not be serious enough, there is then a lot of self fulfillment on any future unrest and problems caused by not planning ahead, but this is not coming from the scientists but from the efforts of deniers and misguided skeptics. > > As for the Forbes contributor, his point is still that feedbacks are not important and the rise in temperature will remain low. Not sure where he is getting that. > > [Water Vapor Confirmed As Major Player In Climate Change | ScienceDaily](http://www.sciencedaily.com/releases/2008/11/081117193013.htm) 1. It’s the same guy. It really shows that you’re reading. Worst estimations are par for the course for alarmists (even if it were true that he uses exclusively or primarily, but is isn’t; again you love to exagerate one point to obscure your defeat) 2. Catastrophe is par for the course for alarmists. 3. His whole point about feedbacks comes to one simple mathematical and physical point. High positive feedbacks point to a highly unstable system (this is very basic science), and climate isn’t an unstable sysyem. The secondary point is that high feebacks don’t work backwards when the model is compared to observations. 4. Mor water vapour traps more heat, but also reflects more heat. * * * And yeah, I haven’t forgtotten to tell you I’m still waiting for your defense of SkS’s and greenman3610’s experts. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [February 12, 2012, 1:11am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/313 "2012-02-12T01:11:16Z")
> [@Aji\_de\_Gallina](#): > > 1. It’s the same guy. It really shows that you’re reading. Worst estimations are par for the course for alarmists (even if it were true that he uses exclusively or primarily, but is isn’t; again you love to exagerate one point to obscure your defeat) And no evidence whatsoever to show he is wrong, or that others have not checked that. > [@Aji\_de\_Gallina](#): > > 1. Catastrophe is par for the course for alarmists. This is the problem with Warren, what does it make then about guys like Lovelock? Hyper uber cathastrophists? Really, the separations and divisions Warren is making are in the straw-man territory. > [@Aji\_de\_Gallina](#): > > 1. His whole point about feedbacks comes to one simple mathematical and physical point. High positive feedbacks point to a highly unstable system (this is very basic science), and climate isn’t an unstable sysyem. > The secondary point is that high feebacks don’t work backwards when the model is compared to observations. Well, lets see him publish in peer review journals and show all the ones supporting him at his University and NASA that they are wrong and convince others. Any moment now.. > [@Aji\_de\_Gallina](#): > > 1. Mor water vapour traps more heat, but also reflects more heat. And already I cited why that is based on an erroneous assumption. * * * > [@Aji\_de\_Gallina](#): > > And yeah, I haven’t forgtotten to tell you I’m still waiting for your defense of SkS’s and greenman3610’s experts. They site the science, for SKS the links to the scientific papers are in something that eye researchers call the color blue. For greenman3610 his scientific cites are under a tab that others know it is called “show more” in YouTube, I know it is so hard, but we hope you can manage. 🙂 ---
**Author:** ![Michael63129](https://avatars.discourse-cdn.com/v4/letter/m/3da27b/32.png) [@Michael63129](https://boards.straightdope.com/u/Michael63129)\ **Post date:** [February 12, 2012, 1:20am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/314 "2012-02-12T01:20:12Z")
> [@Aji\_de\_Gallina](#): > > 1. Mor water vapour traps more heat, but also reflects more heat. Do you have a cite for this? Maybe you mean clouds, [but if it gets warmer, then you need more moisture to saturate the air](http://www.engineeringtoolbox.com/water-vapor-saturation-pressure-air-d_689.html) (clouds are condensation). Also, the type of cloud matters; for example, thick low altitude clouds are very different from thin high altitude clouds (the latter cause warming) and clouds at night trap heat but clouds during the day reflect sunlight. There can also still be an overall warming even if both cloud cover (excluding cirrus) and water vapor increase if the water vapor feedback was stronger than the albedo feedback; [recent studies have found that the cloud feedback is likely positive, even for the past decade](http://www.nasa.gov/topics/earth/features/amplified-warming.html). ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [February 12, 2012, 1:43am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/315 "2012-02-12T01:43:25Z")
> [@Michael63129](#): > > Do you have a cite for this? Maybe you mean clouds, [but if it gets warmer, then you need more moisture to saturate the air](http://www.engineeringtoolbox.com/water-vapor-saturation-pressure-air-d_689.html) (clouds are condensation). Also, the type of cloud matters; for example, thick low altitude clouds are very different from thin high altitude clouds (the latter cause warming) and clouds at night trap heat but clouds during the day reflect sunlight. There can also still be an overall warming even if both cloud cover (excluding cirrus) and water vapor increase if the water vapor feedback was stronger than the albedo feedback; [recent studies have found that the cloud feedback is likely positive, even for the past decade](http://www.nasa.gov/topics/earth/features/amplified-warming.html). I think I’m right, but I could’ve confused with clouds. I’ll get back with a link. ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [February 12, 2012, 2:16am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/316 "2012-02-12T02:16:25Z")
This [pdf document (by NOAA)](http://www.gfdl.noaa.gov/bibliography/related_files/vr9801.pdf) talks about the abosrtion and reflection on near-ir radiation At the end of page 4 and the beginning of page 5 it says that clouds can’t absorb as much radiation because of above-cloud vapour. The interaction beteween clouds and vapor, and absorbtion and reflecting is much more complicated than a single sentence can summarise. ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [February 12, 2012, 2:46am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/317 "2012-02-12T02:46:05Z")
> [@GIGObuster](#): > > Of course the point was to deal with the idea that on the water vapor chart it is somehow misleading to not show the whole thing, it is clear there are reasons why you think that means something , but looking at history and the background I do not think it is as important as you want it to be. Actually this has nothing to do with that. I was talking about Global Climate Modelling, but if you want to continue to discuss it is because water vapor is a much stronger greenhouse gas than C02. I noticed that the graph not only cut of the water vapor, but part of the CO2 so he wouldn’t have to show the water vapor. [http://www.randombio.com/spectra.png](http://www.randombio.com/spectra.png) ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [February 12, 2012, 3:00am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/318 "2012-02-12T03:00:11Z")
> [@GIGObuster](#): > > As for the Forbes contributor, his point is still that feedbacks are not important and the rise in temperature will remain low. Not sure where he is getting that. Here is what Warren Meyer actually wrote in Forbes: > [@](#): > > Some skeptics have tried, relatively futilely I think, to deny that the world is warming at all. Certainly skeptics have a lot of evidence that this measured warming may be exaggerated — there are some serious flaws in our surface temperature measurement system today and almost certainly much worse flaws in the numbers from, say, 1900 to which we are comparing current readings. But radically new technologies, such as satellites, that are not susceptible to these same flaws and coverage gaps have still measured an upward drift in temperatures over the last 30 years. > > When looking at the historic temperature record, skeptics today tend to focus more on the fact that temperatures have leveled off over the last 10-15 years. Both sides of the debate play annoying games with cherry-picked end-points and graph scales to try to support their arguments, but most reasonable people look at the graph above of the last 15 years and will agree temperatures have been relatively flat. Even more important for scientists (since the oceans are a much larger heat reservoir than the atmosphere) is the fact that the new ARGO floating temperature stations have measured little or no increase in ocean heat content since they were put in service in 2003. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [February 12, 2012, 3:16am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/319 "2012-02-12T03:16:50Z")
This is still insisting on the it has “not cooled” misleading item mentioned and debunked before, not with the water vapor feedback and other reasons why a low estimate of a temperature increase is not well sourced, where he is missing it is when he still insists on just about a 1 degree rise in his linked explanation, he can only get that by ignoring a mess of other factors. > **[RealClimate: Calculating the greenhouse effect](https://www.realclimate.org/index.php/archives/2006/01/calculating-the-greenhouse-effect/)** > > RealClimate: In another forum (on a planet far, far away), the following quote recently came up: ....the combined effect of these greenhouse gases is to warm Earth's atmosphere by about 33 ºC, from a chilly -18 ºC in their absence to a pleasant +15... > [@](#): > > ``` > a temperature rise of 0.036 ºC”. More like 1-2.6 ºC actually, but although this gives numbers that are in the ballpark of the IPCC estimates (0.6 to 1.7 ºC warming for an increase of 30% in CO2 at equilibirum) this is not a sensible way to calculate climate sensitivty. > > ``` > > Why do I claim this is an irrelevant and not very sensible calculation? Firstly, it assumes linearity – all of the gases contributing according to their effects today when it is obvious that overlaps and saturation effects are large and important, and more importantly, it ignores feedbacks. The calculation above gives the impression that what you are calculating is the change of temperature that would result if you remove all the CO2. But since water vapour concentration is a feedback not a forcing, it can’t be assumed to remain constant as the planet cools. Water vapour does in fact change (roughly keeping relative humidity, as opposed to specific humidity, constant) and this has been shown in the real world as a function of volcanic cooling (Soden et al, 2002) and for longer term trends (Soden et al, 2005, discussed here), and is well reproduced in climate models. > > What then is an appropriate calculation? Well, it’s simply the estimate of climate sensitivity for the present climate – how much would you expect the planet to warm if you doubled CO2? We’ve discussed this numerous times before, and in my opinion the best answer so far comes from looking at the difference between the last glacial period and the modern era – this gives a number around 3 +/- 1 ºC at doubling. > > For the 30% rise in CO2 there has been so far, that would imply that would represent around 3% of the natural greenhouse effect – a good order of magnitude bigger than that suggested above. Of course, this is at equilibrium and not applicable to a transient change. If one takes into account the human-induced changes in the other GHGs (CH4, N2O, CFCs), you’d get something like double that. Given that even a 5 or 6 ºC cooling was associated with the huge ice sheets 20,000 years ago, and that 33 ºC cooling would reduce our planet to a near-snowball-like state, a potential increase of 5 to 6% of the natural greenhouse effect is not to be sniffed at… nor dismissed as irrelevent with highly misleading arithmetic. > > One could make the point that my calculations are ‘just another web page’ no more and no less authoritative than the links above. In some sense that is correct (though I’d argue my sourcing is a little better!). But you will never find a peer-reviewed rebuttal of such a bizarre line of reasoning as we are dealing with here – basically because such a line of reasoning is highly unlikely to make it past peer-review itself. There are innumerable ‘proper’ references to estimates of the climate sensitivity though, and one should indeed hesitate to accept calculations like this example over the mass of peer reviewed studies. ---
**Author:** ![Aji\_de\_Gallina](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aji_de_gallina/32/260_2.png) [@Aji\_de\_Gallina](https://boards.straightdope.com/u/Aji_de_Gallina)\ **Post date:** [February 12, 2012, 3:30am UTC](https://boards.straightdope.com/t/global-warming-for-dummies/611172/320 "2012-02-12T03:30:05Z")
> [@GIGObuster](#): > > This is still insisting on the it has “not cooled” misleading item mentioned and debunked before, not with the water vapor feedback and other reasons why a low estimate of a temperature increase is not well sourced, where he is missing it is when he still insists on just about a 1 degree rise in his linked explanation, he can only get that by ignoring a mess of other factors. > > [RealClimate: Calculating the greenhouse effect](http://www.realclimate.org/index.php/archives/2006/01/calculating-the-greenhouse-effect/) The 1°C is the effect of one CO2 doubling alone, without forcings, that’s what he says all the time, he doesn’t hide it. You need to read the article. > [@](#): > > The generally accepted value for \*\*direct greenhouse gas warming from CO2 \*\*is something like 1-1.2C per doubling of CO2 concentrations in the atmosphere, and most past IPCC reports have settled on a number in this range. > [@](#): > > The IPCC assumed that strong positive feedbacks dominated, and thus arrived at numbers that implied that feedbacks added an \*\*additional 2-4 degrees \*\*to the 1 degree from CO2 directly [Previous page](https://boards.straightdope.com/t/global-warming-for-dummies/611172.md?page=15) [Next page](https://boards.straightdope.com/t/global-warming-for-dummies/611172.md?page=17)