# Need proof of Global Warming **URL:** \ **Category:** Great Debates\ **Created:** [April 4, 2008, 2:39am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879 "2008-04-04T02:39:53Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [April 6, 2008, 9:36pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/41 "2008-04-06T21:36:01Z")
[QUOTE=SentientMeat] Well, a _commitment to take the issue seriously_ would be a start, [/quote] That’s a bit vague. What if Congress passes a law stating “We hereby take the issue of global warming seriously”? > [@](#): > > From then on, simply institute policies which offer the best cost-benefit ratio, emissions wise. Who exactly would be instituting these policies? ---
**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\ **Post date:** [April 6, 2008, 9:43pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/42 "2008-04-06T21:43:04Z")
> [@brazil84](#): > > if temperature of ice increases from 41 below to 39 below, it will not melt. But a _global_ temperature rise (since the IR-absorbing gases mix well) would mean that _some_ places would rise from -1 to +1 Celsius. > [@](#): > > Did you know that ice coverage in Antartica recently hit an all time high? Funny, I’ve heard [differently](http://www.independent.co.uk/environment/climate-change/loss-of-antarctic-ice-has-soared-by-75-per-cent-in-just-10-years-769894.html). > [@](#): > > Please show me peer-reviewed evidence that CO2 emissions will cause a rise in sea levels of a magnitude and rate sufficient to be a significant threat to the lives of billions of people. If the concentration of IR absorbing gases continues to rise without a mitigation mechanism kicking in, the resultant warming will cause [sea levels to rise](http://www.realclimate.org/index.php?p=427) enough to submerge many of the worlds most populous river deltas and coastal plains, especially when storm surges are considered. ---
**Author:** ![jshore](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@jshore](https://boards.straightdope.com/u/jshore)\ **Post date:** [April 6, 2008, 9:46pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/43 "2008-04-06T21:46:03Z")
[QUOTE=brazil84] For the record, this depends. For example, if temperature of ice increases from 41 below to 39 below, it will not melt. At the same, a temperature increase might cause increased precipitation over cold places like Antarctica, increasing the ice coverage. Did you know that ice coverage in Antartica recently hit an all time high? (since the late 70s when measurements began). So it’s not clear that an increase in tempearture would cause sea levels to rise by means of melting ice. [/quote] From the IPCC summary for policymakers: > [@](#): > > New data since the TAR now show that losses from the ice sheets of Greenland and Antarctica have very likely contributed to sea level rise over 1993 to 2003. It is also important to note that much of the expected sea level rise is simply due to the thermal expansion of sea water…and, in fact, IPCC estimates of sea level rise by 2100 explicitly exclude the possibility of the sort of dynamical effects that could cause ice sheets to break up at an accelerated rate…and that there is increased evidence are already beginning to happen. (The IPCC chose to exclude these effects because they felt the science wasn’t yet advanced enough to allow them to make a good estimate of how much they could contribute to sea level rise. However, as a result, many scientists believe that the IPCC forecasts in this regard are too conservative.) It is also important to note that sea level rises will continue for hundreds to thousand of years (even after greenhouse gas levels are stabilized) because it takes a long time for the oceans and the ice to “catch up”). > [@](#): > > That obviously depends on the rate and magnitude of the rise. > > Please show me peer-reviewed evidence that CO2 emissions will cause a rise in sea levels of a magnitude and rate sufficient to be a significant threat to the lives of billions of people. Well, “billions” may well be too large an estimate…at least for the next hundred years (assuming that the scientists who believe sea level rise will significantly exceed IPCC estimates are incorrect), but there are certainly many millions…probably even hundreds of millions…who live very close (within a meter or so) of sea level. In fact, a significant fraction of Bangladesh falls into that category. > [@](#): > > Could you please quote the section and references you are referring to? I gave you the IPCC estimates of the effect of mitigation on the economy (which can be found in Tables SPM.4 and SPM.6 of the Summary for Policymakers for Working Group III). As for the various effects of climate change, I will allow you to look at what Working Group II has to say in that regard. ---
**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\ **Post date:** [April 6, 2008, 9:52pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/44 "2008-04-06T21:52:35Z")
> [@brazil84](#): > > That’s a bit vague. What if Congress passes a law stating “We hereby take the issue of global warming seriously”? Then voters could judge whether or not their government was lying in future. > [@](#): > > Who exactly would be instituting these policies? Governments. I happen to live in a democracy, so I advocate the policies which I would like to see my goverment both institute and pressure other governments (who I can’t influence directly) _to_ institute. Like I said, it might be bashing my head against a brick wall, but so be it. ---
**Author:** ![jshore](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@jshore](https://boards.straightdope.com/u/jshore)\ **Post date:** [April 6, 2008, 9:54pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/45 "2008-04-06T21:54:29Z")
[QUOTE=Sam Stone] I have yet to hear a practical plan from advocates that we ‘do something’ that will A) significantly ease the problem, B) has a chance of actually being adhered to on a scale that will make a difference, and C) won’t wreck the global economy. Have you got one? If so, let’s debate it. [/QUOTE] **Sam** : This is a big problem and not one that can be solved overnight. However, the basic idea is to move toward a carbon-constrained economy using flexible market approaches such as carbon taxes or cap-and-trade and allow the markets to come up with the solutions that are the most cost-effective. As I am sure you would agree, government is generally not very good at picking winning technologies, so rather than having the government do that, we need to have government set the constraints and the free market find the solutions (although government can certainly help by funding some research and such). As for not wrecking the global economy, I have noted in previous posts what the estimates are for GDP reductions for the mitigation efforts going out as far as 50 years for the most stringent scenario (of aiming to stabilize emissions at 445-535 ppm CO2 equivalent). It is a bit curious that most conservatives argue that the market is a wonderful tool for dealing with scarcity but freak out when there is any attempt to actually regulate the use of a resource. So, why don’t you just pretend that we are running out of coal, oil, and natural gas faster than we otherwise would and that we are just reacting to this scarcity? (In fact, it is not as bad as that since we can use these resources as long as we sequester the CO2 that is emitted.) ---
**Author:** ![intention](https://avatars.discourse-cdn.com/v4/letter/i/e95f7d/32.png) [@intention](https://boards.straightdope.com/u/intention)\ **Post date:** [April 6, 2008, 9:55pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/46 "2008-04-06T21:55:26Z")
[QUOTE=SentientMeat] …[ul] [li]CO2 concentrations have increased over 30% in mere generations from humans digging up carbon stores and burning them.[/li][li]CO2 absorbs IR wavelengths.[/li][li]Higher temperatures cause land-based ice to melt into the sea, and the sea itself to expand.[/li][li]Sea level rise threatens the lives and homes of the billions of people who live at sea level.[/li][li]Unless the warming effect of the IR absorption is mitigated by some mechanism or other, rising CO2 concentrations will pose a significant threat to the lives and homes of anyone living at sea level.[/ul][/li]Which of these premises, which are founded not merely in peer-reviewed science but the _two-century old_ science of the greenhouse effect, do you deny?.. [/QUOTE] SentientMeat, thanks for the question. Me, I’d take exception to a couple of these. First, we have no evidence at all that the rate of sea level rise has changed in the slightest. None. Zero. Second, the sea level rise of say eight inches to a foot per century (which we had last century) did not (IIRC) kill scads of people. In any case, the claim that some unspecified sea level rise will threaten someone’s life somewhere is not a scientific claim (lack of specificity) because it is not falsifiable. To claim that this premise is “founded in peer-reviewed science” reveals a profound lack of understanding of the nature of science. Third, I know of no peer-reviewed science that shows that CO2 poses a “significant threat” to anything. I do see lots of scientists claiming that in the media. The underlying problem, which you have perhaps overlooked, is that while we can say with pretty good scientific certainty that increasing the CO2 will very likely increase the global temperature, we have very, very little evidence that would tell us _how much_ it will increase. If doubling CO2 will increase the temperature by say six degrees, we have a problem. If, on the other hand, it will increase temperatures by a quarter of a degree, we have no problem at all, no Regarding the OP, as others have pointed out, your question is poorly posed. You are not really asking for proof of “global warming”, you are asking for proof that humans are causing increased global warming. In this, I fear you will be disappointed. If such proof existed, the debate would be over … but it rages on, both in and out of scientific papers. w. ---
**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\ **Post date:** [April 6, 2008, 10:04pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/47 "2008-04-06T22:04:06Z")
> [@intention](#): > > First, we have no evidence at all that the rate of sea level rise has changed in the slightest. None. Zero. But you accept the premise that higher temperatures cause water to expand, yes? > [@](#): > > Second, the sea level rise of say eight inches to a foot per century (which we had last century) did not (IIRC) kill scads of people. But you accept the premise that rising sea levels _threatens_ sea level homes, yes? > [@](#): > > Third, I know of no peer-reviewed science that shows that CO2 poses a “significant threat” to anything. But _without a mitigating mechanism_, a rising CO2 concentration will **eventually** pose a threat, yes? I don’t think I’ve ever heard you suggest that concentrations of 1000ppm plus would not be dangerously high, only that there _is_ some mitigating mechanism which will stop it getting so high. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [April 6, 2008, 11:13pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/48 "2008-04-06T23:13:35Z")
[QUOTE=jshore] As **Sam Stone** noted, there is no such thing as “proof” outside the realm of deductive reasoning (i.e., mathematics). In science, there is just the preponderance of the evidence or, as you say, “beyond a reasonable doubt”. [/QUOTE] I believe we’ve been through this before, but this statement is simply not true. For instance, if we oxidise Hydrogen, we get water and maybe some peroxide as well. If we apply sufficient heat to a volume of water to raise it above 100 degrees at sea level, it will all convert to steam. A pure diamond is made of carbon. Hydrogen will fuse to form helium. Certain minerals have certain chemical compositions. These are all known facts. Sure they’re simple facts, but from basic blocks like these we can eventually do things like build the Milau Bridge. You can’t do something like that on ‘the preponderance of the evidence’. Everything has to work. It’s pure science working from pure facts. ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [April 6, 2008, 11:25pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/49 "2008-04-06T23:25:18Z")
[QUOTE=SentientMeat] But a _global_ temperature rise (since the IR-absorbing gases mix well) would mean that _some_ places would rise from -1 to +1 Celsius. [/quote] So what? The question is whether a rise in temperature of a few degrees necessarily means that sea levels will rise due to melting ice. The answer is that it’s not clear. > [@](#): > > Funny, I’ve heard [differently](http://www.independent.co.uk/environment/climate-change/loss-of-antarctic-ice-has-soared-by-75-per-cent-in-just-10-years-769894.html). :shrug: That article says nothing about total coverage. [here’s a graph](http://www.climatechangefacts.info/ClimateChangeImages/current.area.southbig.jpg) that purports to show that ice coverage is at an all time high. Oops, I just noticed it is talking about sea ice not land ice. Anyway, my basic point stands, which is that warmer temps doesn’t necessarily mean less ice. > [@](#): > > If the concentration of IR absorbing gases continues to rise without a mitigation mechanism kicking in, the resultant warming will cause I guess we’re not speaking the same language here, because I keep asking for the “peer-reviewed evidence” that **jshore** has been trumpeting, and you keep not supplying it. Look, you’re free to use speculation and logic to argue that the worst case scenario of AGW would be terrible. But if you’re going to do that, I’m going to point out that the worst case scenario of aggressive mitigation would also be a disaster. ---
**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\ **Post date:** [April 6, 2008, 11:28pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/50 "2008-04-06T23:28:56Z")
> [@Quartz](#): > > I believe we’ve been through this before, but this statement is simply not true. No, he’s right. Induction is as good as it gets in science. You provide examples in which the evidence constitutes many millions or billions of observations over centuries, and I’d agree that that the evidence for those statements is beyond reasonable doubt (which you might paraphrase as “proof” using rather sloppy language), but it’s still induction, not deduction. ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [April 6, 2008, 11:35pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/51 "2008-04-06T23:35:45Z")
[QUOTE=jshore] Well, “billions” may well be too large an estimate…at least for the next hundred years (assuming that the scientists who believe sea level rise will significantly exceed IPCC estimates are incorrect), but there are certainly many millions…probably even hundreds of millions…who live very close (within a meter or so) of sea level. In fact, a significant fraction of Bangladesh falls into that category. I gave you the IPCC estimates of the effect of mitigation on the economy (which can be found in Tables SPM.4 and SPM.6 of the Summary for Policymakers for Working Group III). As for the various effects of climate change, I will allow you to look at what Working Group II has to say in that regard. [/QUOTE] Ok, then I’ll get to the point: As far as I can tell, there is NO “peer-reviewed evidence” that CO2 emissions pose a significant threat to the lives of billions of people. It’s just a speculative fantasy that **sentient meat** cooked up for rhetorical purposes. A worst case scenario. And if he or she is going to do that, then it’s reasonable for me to point out the worst case scenario the other way. ---
**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\ **Post date:** [April 6, 2008, 11:41pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/52 "2008-04-06T23:41:41Z")
[QUOTE=brazil84] So what? The question is whether a rise in temperature of a few degrees necessarily means that sea levels will rise due to melting ice. The answer is that it’s not clear. [/quote] I contend that there are places on Earth where ice exists at -1C for some part of the year, such that if global temperatures rise such rise by \>1 degree, that ice will melt. I look forward to your rebuttal. > [@](#): > > [here’s a graph](http://www.climatechangefacts.info/ClimateChangeImages/current.area.southbig.jpg) that purports to show that ice coverage is at an all time high. Oops, I just noticed it is talking about sea ice not land ice. Which would be entirely understandable if land-based ice (like the ice shelves _attached_ to the land) are falling into the sea at an increasing rate. Thank you for supporting my point. > [@](#): > > I guess we’re not speaking the same language here, because I keep asking for the “peer-reviewed evidence” that **jshore** has been trumpeting, and you keep not supplying it. What?? Which studies referenced in the [article](http://www.realclimate.org/index.php?p=427) I cited weren’t peer reviewed? > [@](#): > > Look, you’re free to use speculation and logic to argue that the worst case scenario of AGW would be terrible. > > But if you’re going to do that, I’m going to point out that the worst case scenario of aggressive mitigation would also be a disaster. And our audience can judge whose position is based on two-century old science and whose is mere attention-seeking reactionary myopia. ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [April 6, 2008, 11:54pm UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/53 "2008-04-06T23:54:09Z")
Great post, **intention** I want to amplify one point you made: > [@](#): > > Second, the sea level rise of say eight inches to a foot per century (which we had last century) did not (IIRC) kill scads of people. Not only that, but deaths due to weather have dropped dramatically over the past 100 years, even as temperatures have risen and CO2 emissions have increased. Why? Because the world has improved dramatically in wealth and technology. > [@](#): > > On September 28, 1955, a Category 5 hurricane named Janet slammed into Chetumal, on Mexico’s Yucatan Peninsula, killing over 600 people. > > Hurricane Dean, another Category 5, and the third-strongest storm ever measured at landfall, hit in exactly the same place earlier this week (Tuesday, August 21,2007) and killed no one. Maximum winds in both storms were indistinguishable. The hurricane-hunter pilot who flew through the eyewall of the storm Tuesday reported severe turbulence, which is a temporary loss of aircraft control. Probably for the first time in human history, a Category 5 storm hit a populated area and everyone lived. > > . . . > > Similar storms, huge storms, very different results. What’s happening here? > > Since then, people in the Yucatan have learned to adapt. While storms like these used to kill hundreds, even thousands, we now have the technology to forecast their tracks, at least for the critical last 24 hours, with reasonable confidence. > > . . . > > Adaptation includes technology, infrastructure, and response. National Hurricane Center forecasts and data are available to everyone. But the infrastructure to respond to a forecast hurricane costs money, and poor nations don’t have it. Among other things, it requires good roads for evacuation. > > Perhaps even more important, adaptation to hurricanes or other natural disasters is political. No elected official wants to be blamed for hundreds of preventable deaths, so the nations that can afford it develop evacuation plans, open shelters, and deliver people from danger. In formulating policy, we need to remember that economic and technological growth saves lives. ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [April 7, 2008, 12:01am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/54 "2008-04-07T00:01:23Z")
[QUOTE=SentientMeat] I contend that there are places on Earth where ice exists at -1C for some part of the year, such that if global temperatures rise such rise by \>1 degree, that ice will melt. I look forward to your rebuttal. [/quote] There’s no need to rebut that since it does not contradict my point. If you can’t understand why, it’s too bad. > [@](#): > > Which would be entirely understandable if land-based ice (like the ice shelves _attached_ to the land) are falling into the sea at an increasing rate. Thank you for supporting my point. I’m a little confused . . . are you saying that when ice shelves fall into the sea, they don’t drift off and melt somewhere? > [@](#): > > What?? Which studies referenced in the [article](http://www.realclimate.org/index.php?p=427) I cited weren’t peer reviewed? I have no idea. The blog article itself is not peer-reviewed. And it does not say anything about billions of human lives being significantly threatened. This is the last time I will ask you: Please cite a peer-reviewed article that says that CO2 emissions pose a significant threat to the lives of billions of human beings due to rising sea levels. ---
**Author:** ![jshore](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@jshore](https://boards.straightdope.com/u/jshore)\ **Post date:** [April 7, 2008, 12:46am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/55 "2008-04-07T00:46:05Z")
[QUOTE=Quartz] I believe we’ve been through this before, but this statement is simply not true. … These are all known facts. Sure they’re simple facts, but from basic blocks like these we can eventually do things like build the Milau Bridge. You can’t do something like that on ‘the preponderance of the evidence’. Everything has to work. It’s pure science working from pure facts. [/QUOTE] You are wrong. All science is inductive and therefore cannot be proven. Yes, there is sure a hell of a lot of evidence that you fuse hydrogen together to get helium and that there is this force called “gravity” that causes an apple to fall toward the ground when I let go of it. But, all of this is inductively-determined “facts” and we have no way of **proving** that the next time I drop the apple, it will fall. And, of course, we actually find evidence that in some limits, the physical laws that we know break down. Hence, while we believed Newtonian physics was correct, we now understand that it is only a very good approximation for relative speeds of objects that are not too close to the speed of light. And, if we had used it to predict something outside this realm, like how a particle in a particle accelerator would behave, we would have been woefully mistaken. I am not saying that there are not different degrees of certainty in science based on the amount of evidence that we have acquired. But, all knowledge is tentative because nothing can ever be proven to be true. You can argue otherwise until you are blue in the face but you are wrong, as any philosopher of science will tell you. ---
**Author:** ![Key\_Lime\_Guy](https://avatars.discourse-cdn.com/v4/letter/k/48db29/32.png) [@Key\_Lime\_Guy](https://boards.straightdope.com/u/Key_Lime_Guy)\ **Post date:** [April 7, 2008, 12:50am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/56 "2008-04-07T00:50:31Z")
[QUOTE=brazil84] Anyway, my basic point stands, which is that warmer temps doesn’t necessarily mean less ice. [/QUOTE] Do you have access to some alternative theory of thermodynamics we should all be aware of? ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [April 7, 2008, 12:56am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/57 "2008-04-07T00:56:23Z")
[QUOTE=Key Lime Guy] Do you have access to some alternative theory of thermodynamics we should all be aware of? [/QUOTE] No. ---
**Author:** ![jshore](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@jshore](https://boards.straightdope.com/u/jshore)\ **Post date:** [April 7, 2008, 1:02am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/58 "2008-04-07T01:02:58Z")
[QUOTE=brazil84] This is the last time I will ask you: Please cite a peer-reviewed article that says that CO2 emissions pose a significant threat to the lives of billions of human beings due to rising sea levels. [/QUOTE] [Here](http://pubs.giss.nasa.gov/docs/2006/2006_Hansen_etal_1.pdf) is an article by Jim Hansen and co. in the Proceedings of the National Academy of Sciences that talks about the possibilities of extremely large sea level rises: > [@](#): > > Sea level rise could be substantial even in the AS, ~1m per century, and cause problems for humanity due to high population in coastal areas (10). However, AS problems would be dwarfed by the disastrous BAU, which could yield sea level rise of several meters per century with eventual rise of tens of meters, enough to transform global coastlines. Here, “BAU” means business-as-usual scenario whereas “AS” is the alternative emissions scenario that Hansen proposes we aim for. You can go on to read about the plant and animal extinctions, which would likely also have widespread impacts on us. Is Hansen right? Who knows…He is certainly more pessimistic than many scientists. But so far he has had a pretty good track record. > [@](#): > > In formulating policy, we need to remember that economic and technological growth saves lives. That is true when you harness them well. However, when you blindly refuse to adopt the policies that will lead to the economic and technological growth that we need to overcome a serious problem because you would rather remain beholden to a few of the least progressive fossil fuel companies (one can’t even blame that whole industry anymore since it is really only a part of it that is still holding out), then you will unfortunately not allow such growth to occur in the ways that we need. ---
**Author:** ![intention](https://avatars.discourse-cdn.com/v4/letter/i/e95f7d/32.png) [@intention](https://boards.straightdope.com/u/intention)\ **Post date:** [April 7, 2008, 1:05am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/59 "2008-04-07T01:05:22Z")
[QUOTE=jshore] … If I had to review the basic scientific argument for AGW, it would go something like this: We know beyond a shadow of a doubt that since the industrial revolution, the levels of greenhouse gases have been rising significantly. In particular, CO2 levels have gone up from about 280 to 380 ppm, which is well outside the range of ~180-300 ppm that they have varied in over the last 750,000 years (as ice core data shows). We also know quite accurately the radiative effects of this, i.e., for example that the “radiative forcing” depends logarithmically on the CO2 level and increases by ~3.8 W/m^2 when CO2 levels in the atmosphere double. … [/QUOTE] **jshore** , good to hear from you as always. You have made a claim which illustrates clearly a recurring problem with climate science. This involves the citation of previous claims as “facts”. For example, you say we know “quite accurately” that the effect of doubling CO2 is approximately 3.8 watts/square metre change in forcing. My questions are: 1. If we know the CO2 forcing “quite accurately”, why do you say that the “~3.8” w/m2 figure is only approximate? 2. Where did this “~3.8 w/m2” figure come from? (Not who cited it, everyone cites it, but who showed scientifically that this is the correct figure, and how did they calculate it?). The IPCC TAR gives three different formulas for CO2 forcing (one of which uses 3.7 instead of 3.8 as you do), but all they say is that they are “similar in form to” or “based on” or “with a form similar to” earlier studies. They don’t say why they are different from the earlier studies. They don’t say why they were changed. They don’t say who changed them. They don’t say why they were based on those studies rather than other studies. The main “earlier study” referred to is James Hansen’s study of forcings using a very early GISS model … color me unimpressed. Results from an early climate model don’t give … what was your term … “quite accurate” scientific results. Yes, they give results, but those results cannot be simply assumed to be “quite accurate” as you are assuming. 3. Why is the radiative forcing of CO2 claimed to change in a simple logarithmic manner, while the forcing of the other GHGs (CH4, N2O, etc) are calculated using very arcane heuristic formulas with no known source? In the IPCC formulation, CHC forcing is said to be linear with increasing concentration. Why? CH4 forcing is said to be linear, but also depends logarithmically on N2O forcing, presumably because their bands overlap, but no derivation of the formula is given. Their formula is CH4 Forcing = alpha \* (sqrt(M) - sqrt(M0)) -f(M,N0) - f(M0,N0) where M, N = current concentrations of CH4 and N20 respectively M0, N0 = pre-industrial concentrations of CH4 and N20 respectively f(M,N) = 0.47 ln[1+2.01x10-5 (MN)0.75+5.31x10-15 M(MN)1.52] Now, you might claim that this CH4 forcing calculation is scientifically based. To me, it is just a heuristic calculation with no known antecedents. When you come back with answers to those questions, when you can identify the source of the CH4 calculations and all the rest, we can see how scientifically solid your claims are. w. PS - Many of these wonderful, “quite accurate” things come out of the IPCC. There’s a good discussion of the so-called “review process” of the IPCC [here,](http://www.climateaudit.org/?p=2960) so you can see just exactly how well reviewed this stuff actually is. The IPCC reports are supposed to be among the most carefully reviewed documents in existence … but in truth, the review is pathetic, salient points are glossed over, and opposing views are simply ignored. ---
**Author:** ![jshore](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@jshore](https://boards.straightdope.com/u/jshore)\ **Post date:** [April 7, 2008, 1:20am UTC](https://boards.straightdope.com/t/need-proof-of-global-warming/443879/60 "2008-04-07T01:20:41Z")
[QUOTE=intention] Third, I know of no peer-reviewed science that shows that CO2 poses a “significant threat” to anything. I do see lots of scientists claiming that in the media. [/quote] Plenty of scientists claim this not only in the media but in their peer-reviewed papers. > [@](#): > > In this, I fear you will be disappointed. If such proof existed, the debate would be over … but it rages on, both in and out of scientific papers. > > w. Just like the debate supposedly raged on about smoking being harmful for you long after most scientists believed it was settled. And, in fact, some of the same interests (e.g., [Steven Milloy of JunkScience.com](http://sourcewatch.org/index.php?title=Steven_J._Milloy) and [Fred Singer](http://sourcewatch.org/index.php?title=S._Fred_Singer)) are involved in prolonging the appearance of a significant scientific debate. This isn’t to say that some significant uncertainties don’t exist. However, there is a whole industry out there dedicated to exaggerating the uncertainties, exaggerating the extent of disagreement in the peer-reviewed literature, etc. [Previous page](https://boards.straightdope.com/t/need-proof-of-global-warming/443879.md?page=2) [Next page](https://boards.straightdope.com/t/need-proof-of-global-warming/443879.md?page=4)