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Al Gore’s movie

Filed under: — eric @ 10 May 2006 - (Français)

by Eric Steig

Along with various Seattle business and community leaders, city planners and politicians, a large group of scientists from the University of Washington got a chance to preview the new film, An Inconvenient Truth, last week. The film is about Al Gore’s efforts to educate the public about global warming, with the goal of creating the political will necessary for the United States to take the lead in efforts to lower global carbon emissions. It is an inspiring film, and is decidedly non-partisan in its outlook (though there are a few subtle references to the Bush administration’s lack of leadership on this and other environmental issues).

Since Gore is rumored to be a fan of RealClimate, we thought it appropriate to give our first impressions.

Much of the footage in Inconvenient Truth is of Al Gore giving a slideshow on the science of global warming. Sound boring? Well, yes, a little. But it is a very good slide show, in the vein of Carl Sagan (lots of beautiful imagery, and some very slick graphics and digital animation). And it is interspersed with personal reflections from Gore that add a very nice human element. Gore in the classroom in 1968, listening to the great geochemist Roger Revelle describe the first few years of data on carbon dioxide increases in the atmosphere. Gore on the family farm, talking about his father’s tobacco business, and how he shut it down when his daughter (Al Gore’s sister) got lung cancer. Gore on the campaign trail, and his disappointment at the Supreme Court decision. This isn’t the “wooden” Gore of the 2000 campgain; he is clearly in his element here, talking about something he has cared deeply about for over 30 years.

How well does the film handle the science? Admirably, I thought. It is remarkably up to date, with reference to some of the very latest research. Discussion of recent changes in Antarctica and Greenland are expertly laid out. He also does a very good job in talking about the relationship between sea surface temperature and hurricane intensity. As one might expect, he uses the Katrina disaster to underscore the point that climate change may have serious impacts on society, but he doesn’t highlight the connection any more than is appropriate (see our post on this, here).

There are a few scientific errors that are important in the film. At one point Gore claims that you can see the aerosol concentrations in Antarctic ice cores change “in just two years”, due to the U.S. Clean Air Act. You can’t see dust and aerosols at all in Antarctic cores — not with the naked eye — and I’m skeptical you can definitively point to the influence of the Clean Air Act. I was left wondering whether Gore got this notion, and I hope he’ll correct it in future versions of his slideshow. Another complaint is the juxtaposition of an image relating to CO2 emissions and an image illustrating invasive plant species. This is misleading; the problem of invasive species is predominantly due to land use change and importation, not to “global warming”. Still, these are rather minor errors. It is true that the effect of reduced leaded gasoline use in the U.S. does clearly show up in Greenland ice cores; and it is also certainly true that climate change could exacerbate the problem of invasive species.

Several of my colleagues complained that a more significant error is Gore’s use of the long ice core records of CO2 and temperature (from oxygen isotope measurements) in Antarctic ice cores to illustrate the correlation between the two. The complaint is that the correlation is somewhat misleading, because a number of other climate forcings besides CO2 contribute to the change in Antarctic temperature between glacial and interglacial climate. Simply extrapolating this correlation forward in time puts the temperature in 2100 A.D. somewhere upwards of 10 C warmer than present — rather at the extreme end of the vast majority of projections (as we have discussed here). However, I don’t really agree with my colleagues’ criticism on this point. Gore is careful not to state what the temperature/CO2 scaling is. He is making a qualitative point, which is entirely accurate. The fact is that it would be difficult or impossible to explain past changes in temperature during the ice age cycles without CO2 changes (as we have discussed here). In that sense, the ice core CO2-temperature correlation remains an appropriate demonstration of the influence of CO2 on climate.

For the most part, I think Gore gets the science right, just as he did in Earth in the Balance. The small errors don’t detract from Gore’s main point, which is that we in the United States have the technological and institutional ability to have a significant impact on the future trajectory of climate change. This is not entirely a scientific issue — indeed, Gore repeatedly makes the point that it is a moral issue — but Gore draws heavily on Pacala and Socolow’s recent work to show that the technology is there (see Science 305, p. 968 Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies).

I’ll admit that I have been a bit of a skeptic about our ability to take any substantive action, especially here in the U.S.
Gore’s aim is to change that viewpoint, and the colleagues I saw the movie with all seem to agree that he is successful.

In short: this film is worth seeing. It opens in early June.

245 Responses to “Al Gore’s movie”

  1. 51
    Simon Donner says:

    Re: Pacala and Socolow

    The Pacala and Socolow wedges approach does aim for stabilization at 500 ppm. The idea is that the technology exists today to keep emissions, not GHG concentrations, at today’s level for the next 50 years. That would be a big improvement from the IPCC “business-as-usual” estimates but would not be stabilizing GHG concentrations. They assume by making this initial effort, the world will then be driven to develop the breakthrough technologies necessary to substantially reduce emissions beyond 2050 and achieve stablization of concentrations at 500 ppm.

    Whether or not one agrees with those assumptions, it is an interesting and pragmatic take on what they call the “carbon problem”.

  2. 52
    Hank Roberts says:

    Pat, the posting software here chokes and dies over URLs with commas like the one you posted.

    That link is to an Australian paper that cites the IPCC draft — which anyone who’s had a look at has agreed not to quote or distribute until the final version is released.

    We have a topic for not discussing that draft, here; let’s use it.

  3. 53
    david Iles says:

    Regarding #30, #36, #40 and others

    Whether Al Gore is the right messenger for Global warming or not, there seems to be no one else on his level of political popularity with the courage to raise his or her heads above the surface on the issue.

    As far as the public is concerned according to the polls (as I have posted a number of times. see ), the public recognizes the importance of a healthy environment and the need for a much larger governmental response to global climate change. I have no doubt that Mr. Gore is fully aware of this.

    I know four people who have met Mr. Gore and all of these, intelligent and discriminating people, were completely impressed by him and remarked on what a sincere person he was. He did, after all win the popular vote in 2001 even after a disastrously stupid (sorry Al) campaign in which he contorted himself into a bizarre political puppet, when what the public clearly was looking for was someone who was sincere. I think if he is willing to leave his handlers in the closet and show the people the person my friends met he has good chance of advancing this preeminently important issue.

    Re: #46
    Thank you Tony for your directness. I think evolution is pretty clear on the issue, species that do not show the correct adaptations to a changing environment die, regardless of the eloquence of their last words.

    Re: 45 and Jim Reddons random thought.

    Any leader in any sector that is willing to advocate intelligent adaptation to changing conditions would be a welcome change. However our current business leaders appear to have their heads firmly wedged into next quarters profits and apparently the view of the future is not to clear from that particular position.

    Due to sickness and chance I happened to be watching PBS on Sunday an interview with the head of Southwest airlines and the founder of Valero Inc a major oil refinery. These are two business leaders that are know for their for far-sightedness and compassion towards their employees. They seemed to vigorously endorse the notion of more of the same along with a heaping helping of denial. Naturally peak oil, green house gases and changing climate never came up. Both were hard hit by Katrina but seemed to have no plans to adapt to changing times or even a willingness to recognize that we are in them.

    I suppose I am one of those progressives that don’t have a particularly warm feeling about the corporate culture. My wariness is generated from reading history and an observation of current times. The corporate world has actively tried to promote their profit margins at the expense of the environment and the population’s health and welfare -often including their own workers – since the start of the industrial revolution. From the eight hour day and five day work week to seatbelts and safe handling of toxins, corporate structure has been violently opposed to even the most basic of precautions and they have tended to hold onto their positions until the last possible moment. I suppose appealing to their greed is a winning strategy, but I fear it will just keep us lurching from one crisis to another. I do agree any kind of forward motion is better then none.

  4. 54
    Mike Salem says:

    I think the questions of post 48 are important ones for the contributors to Real Climate to answer. As the proponderance of evidence against the ideas of the naysayers becomes more publically available and well known, I suspect the naysayers will switch their tactics from denying anthropogenic global warming, to claiming that global warming isn’t a big deal, or that there is too much uncertainty in predicting the dangerous effects of global warming to justify action.

    I think the contributors to Real Climate will do much to advance their mission if they take the initiative to begin addressing this line of argument before it gains too much momentum in the mainstream debate.

  5. 55
    John P says:

    I’m a scientist. Would someone please add “GHG” (Global Hydrocarbon Glut?) and “AGW” (Accelerated Global Warming? Atlantic Geostrophic Wind?) to the glossary page ( Thanks.

    [Response: GHG= Greenhouse Gas, and AGW = Anthropogenic Global Warming… But your point is well taken! – gavin]

  6. 56
    pat neuman says:

    re 52. 48. 47.


    I found that Australian link at RC’s thread on ipcc-draft-no-comment.

    My previous comment (48) was in reply to points made by Alain (47) of this thread dealing with emissions and GHG concentrations, therefore, your comment (52) that … We have a topic for not discussing that draft, here; let’s use it. seems inappropriate to me.

    Another comment you made in 52, about agreeing to not quote or distribute info from the draft until the final version is released, does not apply to all of us.

    Open U.S. review of IPCC draft report is a good thing, despite criticism — Part 1, posted at climatesciencewatch on May 09, 2006:

  7. 57
    Doug Percival says:

    There is a very good interview with Al Gore here:

    “At Some Point, Reality Has Its Day”
    By Eleanor Clift
    28 April 2006

    Note that it is a Newsweek/MSNBC interview, but the above link is to a copy posted at

  8. 58
    Doug Percival says:

    Mike Salem wrote in comment #54:

    As the proponderance of evidence against the ideas of the naysayers becomes more publically available and well known, I suspect the naysayers will switch their tactics from denying anthropogenic global warming, to claiming that global warming isn’t a big deal, or that there is too much uncertainty in predicting the dangerous effects of global warming to justify action.

    I am reminded of something that electrical engineer and parapsychologist Dean Radin wrote in his book The Conscious Universe. He was writing about attitudes towards laboratory research on parapsychology but I think his comment has some resonance with “skeptical” attitudes towards antrhopogenic global warming and climate change:

    In science, the acceptance of new ideas follows a predictable, four-stage sequence. In Stage 1, skeptics confidently proclaim that the idea is impossible because it violates the Laws of Science. This stage can last from years to centuries, depending on how much the idea challenges conventional wisdom. In Stage 2, skeptics reluctantly concede that the idea is possible, but it is not very interesting and the claimed effects are extremely weak. Stage 3 begins when the mainstream realizes that the idea is not only important, but its effects are much stronger and more pervasive than previously imagined. Stage 4 is achieved when the same critics who used to disavow any interest in the idea begin to proclaim that they thought of it first. Eventually, no one remembers that the idea was once considered a dangerous heresy.

    Here’s hoping that AGW is beginning to reach Stage 4 now.

  9. 59
    ninin says:

    I notice has done a global warming “fact sheet” in response to news of Al Gores movie: (

    I can spot a little cherrypicking, strawman erecting and obvious omission of relevant facts in it, but it would be great to read a one-off article on realclimate that thoroughly reviewed one such skeptical website piece to demonstrate the wide difference between armchair science and the actual science.

    Just a suggestion, not an order

  10. 60
    Hank Roberts says:

    It’s bafflegab, stuff like “… emission … at lower energy [longer wavelength] radiation than the energy previously absorbed … since the absorbed energy has been transformed it cannot be said to be “reradiated”

    They’re aiming to confuse the part of the voting population that doesn’t understand physics.

    Oh, wait ….

  11. 61

    I hope Gore’s movie will help the lay person distinguish between credible scientific conclusions and think-tank ideology on the issue of climate change.

    Journalists are already beginning to grasp the difference. In today’s Wall Street Journal, Sharon Begley writes “Scientists Explain How They Attribute Climate-Change Data” (May 12, 2006; Page A15). Begley explains how climate scientists attribute increasing global average temperatures to increasing levels of greenhouse gases, rather than natural variations in climate.

    Remarkably, (considering the history of the editorial page), this Wall Street Journal article explains the science of climate change without the phony “balance” provided by professional global warming skeptics, faking science with discredited think-tank talking points and advocacy-driven cherry picking. No Fred Singer claiming “satellites show no warming”, no Richard Lindzen complaining about alarmist scientists competing for research funds by spinning scary scenarios, nothing but credible, accomplished scientists clearly and dispassionately explaining the results of hard won research. I hope Gore’s movie will help the public understand the credibility of this approach.

    Comments (#30) that Gore is “patronizing and insincere” reflect the success of an agenda-driven smear campaign against the man, rather than character of the man himself. I think Gore’s sincerity and his integrity are self-evident. Given his long commitment to global warming issues, and his apparent concern for getting the science right, he should be commended for his honesty and his passion, not condemned as “wooden” and self-serving.

  12. 62
    Randolph Fritz says:

    “Assuming someone from Mr. Gore’s program is reading — please, the citations, the footnotes.”

    He already has them out; *Earth in the Balance* has a somewhat dated collection of them. But for the best cites and footnotes you can (I’m a broken record) do no better than to look in the IPCC report, which has more, probably, than even experts in the field can read in their lives.

  13. 63
    S Molnar says:

    I wouldn’t read too much into the Wall Street Journal article: they have a well-deserved reputation for keeping a firewall between their (generally accurate) reporting and their (generally nonsensical) editorial page.

    And a belated pile-on to the post at #30: I agree that unpopular people shouldn’t go around publicizing their beliefs, but the rule should apply to people I don’t like, not people A. Fortner doesn’t like. (And, by the way, it isn’t Al Gore’s movie.)

  14. 64
    dave says:

    what do you think of this link? It is from “junkscience”…which is supposed to refer to the science that it is debunking. however…is this JUNK?

    check out

    the guys makes strong arguments to sway the lay person and potentially politicians. thoughts????

  15. 65
    Hank Roberts says:

    Randolph, I’m aware of the book and the IPCC reports. But for purposes of supporting, and responding to questions and misrepresentations point by point when people are reacting to the movie of the slide show Mr. Gore is presenting — the references _for_each_point_in_each_slide_ could be presented.

    We tell people who come in with grab-bag denial and disinformation talking points to please tell us where they got those ideas, specifically. “Scientists say” or “many would argue” isn’t sufficient reference to defend ideas, true or not.

    Take the point raised above as just one example — if there’s a reference for invasive plants and warming _on_which_Mr._Gore’s_slide_is_based_ (not just “if there’s one somewhere anyone can find by hunting” for the topic) — it’d be helpful to know the cite, the exact one.

    A slide show is a very boiled-down presentation. Just saying look in the old book or the IPCC for support is not effective argument.

    Yes, I’m sure I can find support — but I’m not sure what I find is what his slide is based on, so I can’t argue in support of his point as effectively.

    Have I been any clearer here? I’m asking for cites for the actual points in the actual slides because it’s actually educational and good practice when arguing a scientific issue to provide them, and be willing to adjust the discussion as research goes on.

  16. 66
    david Iles says:

    This is off thread but, i could not find a email address for Realclimate so i am writting here with asuggestion for an article.i would really like to know more on the implications of these findings
    It is somewhat dated (2004) but this has got to be very significant to our climate. I tried a search of your site to find past articles and found nothing.

    Thanks for all of your efforts to inform us on what is probally the most important topic to humanity and all the other critters stuck with us as the current dominant species.

  17. 67
    Grant says:

    Re: #64

    I agree. IPCC has lots of references (so does RC) for us — but we’re interested enough to go digging.

    I’m hoping that Gore’s book (same title as the movie) will contain the desired references.

  18. 68
  19. 69
    Joel Shore says:

    Re #61 (and #63): We can indeed be thankful for the “firewall” that exists between the WSJ editorial page and news reporting. Nonetheless, I think it is important to encourage such good reporting so I sent an e-mail to the author of that article, Sharon Begley, thanking her for it and noting that it is a refreshing change from the sort of junk-science editorials and op-eds that we see on the editorial page of the WSJ.

    [Response: I also think Begley’s article was excellent — very accurate and to the point. It was on the front page of the Marketplace section, and so should have have attracted a lot of readership. Though the reporting sections of the WSJ are not as biased as the editorial pages, they are by no means uniformly good either — recall the front page “Global Warming is a Myth” article they carried a few years back. One can hope that Begley’s article will set a new standard, but time will tell. I toyed with the idea of doing a “job well done” article on Begley (like the piece on Kristof a little while back), but decided there wasn’t enough to comment on. Nevertheless, I am very happy to declare here that it is indeed a job well done. As for that famous firewall between the editorial page and the reporting pages, in this instance one could wish it were just a little more leaky — at least in one direction (guess which one). –raypierre]

  20. 70
    Hank Roberts says:

    David, the ‘Contact’ email is under the ‘About’ link (top of each page)

  21. 71
    Stormy says:


    See the movie. Stop confusing the presenter with the message. Nit pick at the movie, if you will. But address the message.

    Why do we always have to tangle with those who look at fluff, who want a warm fuzzy feeling? Even responding to this makes me queasy. And queasy I was when I watched the editors here respond to it. Stooping.

    The long and short of it: I suspect you do not think much of the science and less of Gore because he ran against your guy Bushâ?¦.and prefer to snip away at the messenger.

    I, like you, am a novice in climatology. How hard it is to have an open mind. And it is hard, for all of us. Take politics elsewhere, please, where the media is the message.

  22. 72
    Blair Dowden says:

    Re #64: The Junk Science take on Greenhouse Warming.

    There is a lot of good information here, and it starts off well. The explanation of the greenhouse effect leaves out the Stefan-Boltzmann law, which is rather fundamental to it. If found the following statement interesting, and I think it is valid:

    Theoretically, if the planet’s surface cooled by radiation alone, then the greenhouse-induced surface temperature would be much warmer, about 350 degrees K (77 °degrees C), but atmospheric motion (convective towers carrying latent and sensible heat upwards and large scale circulation carrying it both upwards and polewards) significantly increase the “escape” of energy to space, leaving Earth’s surface more than 60 degrees C cooler than a static atmosphere would do.

    [Response: Actually, even this statement is garbage. It takes the atmosphere as observed, which is already influenced by the redistribution of surface heating by convection, keeps it fixed, and then computes what the surface temperature would be if convection and surface turbulent heat fluxes were turned off. This is not a possible equilibrium state of the atmosphere. If you were to completely turn off the turbulent heat flux out of the surface and suppress convection, the atmosphere would be much colder than it is, and the vertical temperature gradient would be considerably weaker. It’s simply not correct to say that the convection increases the escape of energy to space. Another inconsistency is that if you shut off convection and surface turbulent fluxes, the atmosphere would be dry, which would make the planet still colder. All in all, the above is a pointless and misleading statement — unless the point is to mislead. –raypierre]

    The trouble begins a little later:

    Water accounts for about 90% of the Earth’s greenhouse effect — perhaps 70% is due to water vapor and about 20% due to clouds (mostly water droplets), some estimates put water as high as 95% of Earth’s total greenhouse effect. The remaining portion comes from carbon dioxide, nitrous oxide, methane, ozone and miscellaneous other “minor greenhouse gases.” As an example of the relative importance of water it should be noted that changes in the relative humidity on the order of 1.3-4% are equivalent to the effect of doubling CO2.

    The usual figure is 65% water vapor compared to other greenhouse gases. Adding in clouds at this point is not valid, because they also reflect incoming radiation and should be handled separately. The implication (not explicitly stated) is that only 10% of the greenhouse effect is from gases other than water vapor, which is false, it is 35%. This is dishonest accounting. Adding that some [invalid] “estimates” claim 95% water vapor is even more dishonest.

    As for the statement about water vapor, it is ambiguous. If it means 4% relative to present levels (as it implies) it is false. If it means an absolute value of 4%, compared to the 1% level it is today, then it is true, but exactly what is going to make water vapor rise? Water vapor levels correspond to atmospheric temperature, so water vapor is a feedback to other climate forcings.

    It gets worse. This is a very sleazy statement:

    If we consider the warming effect of the pre-Industrial Revolution atmospheric carbon dioxide (about 280 parts per million by volume or ppmv) as 1, then the first half of that heating was delivered by about 20ppmv (0.002% of atmosphere) while the second half required an additional 260ppmv (0.026%). To double the pre-Industrial Revolution warming from CO2 alone would require about 90,000ppmv.

    He is talking about the total effect of carbon dioxide, starting from zero. Doubling pre-Industrial Revolution warming means doubling from 33 degrees, which might well take 90,000 ppmv. This is deliberately intended to be confused with doubling carbon dioxide from pre-Industrial levels, which gives about 1.2 degress C in direct forcing, and about 3 degrees after feedbacks.

    Maybe some other readers here can add to these observations.

  23. 73
    joel Hammer says:

    Is this true?

    This comes from junkscience.

    Readers should be aware that the temperature effect of atmospheric carbon dioxide is logarithmic (that means there is a diminishing response as you keep adding more, like the additional window shade example, above). If we consider the warming effect of the pre-Industrial Revolution atmospheric carbon dioxide (about 280 parts per million by volume or ppmv) as 1, then the first half of that heating was delivered by about 20ppmv (0.002% of atmosphere) while the second half required an additional 260ppmv (0.026%). To double the pre-Industrial Revolution warming from CO2 alone would require about 90,000ppmv (9%) but we’d never see it – CO2 becomes toxic at around 6,000ppmv (0.6%, although humans have absolutely no prospect of achieving such concentrations).

    [Response: The only part of this statement that’s true is the first sentence, the statement of toxicity, and the statement that humans have no prospect of increasing CO2 to 90000ppmv. The radiative forcing is indeed logarithmic, this is incorporated in the standard radiation physics used in every model, and it has been taken into account in every mainstream estimate of global warming going back to Arrhenius. The rest is a deception wrapped in pseudoscientific gobbledegook. Blair explained it well in his comment above. I actually do work on very high CO2 atmospheres, for dealing with the Early Earth and Snowball Earth problems, and based on the radiation codes I use, here are some numbers: Keeping the temperature and water vapor fixed at typical modern values, increasing CO2 from 280 ppm to 90000ppm would give you about 50 W/m**2 of additional radiative forcing. That’s actually a lot larger than the 30 W/m**2 CO2 radiative forcing you get going from none to 280 ppm with water vapor fixed. Evidently, the junk science writer didn’t take into account the fact that the radiative forcing becomes somewhat steeper than logarithmic at large CO2 values, when formerly weak bands start to become important. That 30 W/m**2, added to about 80 W/m**2 from water vapor, warms the Earth from about 255K (no greenhouse effect) to about 285K. Now, the 50 W/m**2 additional CO2 radiative forcing going to 90000ppmv would warm the Earth by an additional 25K, if we applied the same water vapor feedback coefficient from the present climate. In reality, the warming would be considerably greater, since water vapor feedback becomes more effective at high temperatures. –raypierre]

    [Response: I’ve been thinking some more about what kind of deception the writer was trying to pull off here. My reading is that he is setting up the false premise that people are concerned about doubling CO2 because they think that doubling CO2 would double the total radiative forcing — then he debunks that hypothetical belief, leaving the reader with the feeling that doubling CO2 is no big deal so far as radiative forcing goes. That’s a false impression to leave the reader with, because in fact doubling the radiative forcing of CO2 would be a huge deal. If the radiative forcing of CO2 were actually linear in concentration, then when contemplating doubling CO2 we’d be talking not just about the risk of exterminating polar bears, but about extinguishing everything less hardy than a thermophilic bacterium. Because the climate change from a doubling of total CO2 radiative forcing is so incredibly massive, it doesn’t provide an appropriate frame of reference for thinking about the radiative forcing that would actually be caused by a doubling of CO2. It’s a darn good thing that radiative forcing is only logarithmic in CO2 — otherwise, climate would have undergone such massive fluctuations in the past that it’s unlikely that any multicellular life would be around today to think about things like radiative transfer. ]

  24. 74
    bibliothécaire says:

    For the record, Mr. Gore does not claim to have been sitting in Dr. Revelle’s class in 1958. He simply says that Revelle began his C02 studies about that time. Mr. Gore merely states that Revelle was one of his most admired professors. When exactly he studied with him remains unclear, at least to the rest of us.

  25. 75
    pat neuman says:

    re 69. 61.

    I also sent an email to the WSJ for the article by Sharon Begley. I said … Comment 41. at RC (below) shows part of why I think the public needs help to understand how scientists attribute climate-change data. Your article will help. I have done work that shows other signatures of global warming, including some related to polar (and mod-high latitude) amplification, and some on increasing overnight low temperatures and winter-spring temperature averages in the Upper Midwest. … ref to TOWN MEETING:
    … Thanks for doing your article.

    There was some positive discussion on the al gore movie at the TOWN MEETING. Presentations included Explorer Will Steger on Anarctica-Arctic (great discussion of Will’s experience crossing two mile thick Greenland ice sheet), State Representative Keith Ellison (on global warming concerns and alternative energy), Lynn Hinkle, UAW 879 (â??Ford Green Proposalâ?? to stay in St. Paul… reasons for failure), Chad Kister (author of Arctic Melting: How Climate Change Is Destroying One of the Worldâ??s Largest Wilderness Areas), Phyllis Walker, President AFSCME Local 3800 & Former New Orleans resident (failure of federal government to help out New Orleans), Professor Mark Davis, Macalester College Biology Department (told the group not to exaggerate global warming consequences (his perspective) and Christine Franks (planned the meeting and arranged for reading of letters from a few of the mayors in the Twin Cities area. I gave my power point presentation on Climate Change in the Red River Valley (full page op-ed in the Grand Forks Herald, May 4, 2006). My power point presentation for the TOWN MEETING is now at my photos link, …
    … (click Mighty Mouse).

  26. 76
    Mark A. York says:

    Milloy is just setting up a classic straw man fallacy Ray if I read your comments correctly. I’m just a biologist and the context of these numbers and elements is critical. I have to work my butt off just to keep track of all the shellgaming going on with the sceptic mercenaries. To the regular scientifically illiterate citizenery Milloy can be convincing. He’s a political tool. That’s a crime in my view. Get yur snake oil here, step right up!

    [Response: It’s easy for somebody like Milloy to make the effect of CO2 look small to the naive reader. A 4 watt/m**2 change in the radiation budget is only something like 1% of the Earth’s energy budget, right? So maybe we get a 1% change in temperature, sort of, right? But what the naive reader, used to degrees C or degrees F (measured relative to freezing) doesn’t realize is that in all the physics, what counts is degrees KELVIN — i.e. measured relative to absolute zero. Life occupies a small operating range of temperature, measured relative to absolute zero, and multicellular life a still smaller range. Hence, a 1% change of temperature is in fact a big deal to us. 1% of a 285K temperature is 2.85K. –raypierre]

  27. 77
    Eli Rabett says:

    I don’t think it was Milloy. The argument was too sophisticated. It must have been written by someone with a fair grasp of the underlying science. The normal names come to mind.

  28. 78
    Matt says:

    The bioshpere and co2 levels would have evolved together, cooperatively, to get the temperature just right for maximum work. Even geologicaly, over time, evolution would have naturally buried enough excess carbon to get it right, in a sense all those mass extinctions served a long term goal.

    Reading real climate, wikopedia and google scholar gives me the willies. Evolution seems intelligent, effecting global change to maximize biological output.

    I wonder, how many extinctions evolution normally poduces at this stage of recent glacial cycles. I wonder if the evolution of mammals over time tended to increase their effect on noticable co2 levels.

  29. 79
    jhm says:


    Fox’ “Journal Editorial Report” had this report Saturday. The link doesn’t have the complete transcript [yet? I don’t know what their policy is] so, you don’t get to read the comments by the panel, but maybe one can get the video (I have a dial-up connection, and can’t be bothered to spend that much effort to see something that agrivating for a second time). One comment that sticks inmy mind, and my craw, was something like ‘Even if GW is a fact, the best responce is business as usual, stay rich and adapt.’ Wow.

  30. 80
    Blair Dowden says:

    The following is from Milloy’s explanation of the greenhouse effect. I realize it fails to deal with the importance of the temperature at which a greenhouse gas radiates into space. But I am still having trouble understanding how it works at a basic molecular level, so I am not sure which parts of this are correct. In particular, it is true that a greenhouse gas must “re-radiate” (to use the forbidden term) at a longer wavelength? If so, I would think very little energy with the right wavelength would ever reach the top of the troposphere.

    Greenhouse gases, therefore, do not “trap heat,” but could be fairly described as delaying the energy transfer from Earth to space. “Trapping heat” implies that the energy is stuck in the system forever — this is a false notion. Greenhouse gases do not emit energy in the same bandwidth that they absorb energy, and thus emissions from carbon dioxide are not absorbed by carbon dioxide. While energy may be delayed on its inevitable journey back to space, it will eventually be emitted regardless of the number of intervening stages.

    Do greenhouse gases ‘reradiate’ the infrared radiation they absorb?

    This is an unfortunate expression that is all too common. Absorbed radiation is transformed to either kinetic or potential energy and, as such, no longer exists in its original form — hence, it cannot be “reradiated.” When molecules absorb infrared radiation they are said to become excited (“hot”). Such molecules can release energy usually in one of three ways: by chemical reaction (uncommon, since greenhouse gases are pretty stable and non-reactive); quenching (transferring energy to cooler molecules, increasing their temperature) and; emission (usually at lower energy [longer wavelength] radiation than the energy previously absorbed). Once more, since the absorbed energy has been transformed it cannot be said to be “reradiated”.

    [Response: Some of this is incorrect, and other bits are technically correct but basically just nitpicking about terminology. There are many levels at which the greenhouse effect can be understood, and a rather basic notion of energy balance suffices for most purposes. The point of statements like the one above is to persuade people that the whole thing is so complicated that they can’t possibly understand it, and by implication that people like Gore are clueless when they talk about the system. In fact, the basics are very, very simple and should be readily comprehensible to anybody who has ever spent a night under a down comforter or in a sleeping bag. There is only one way a planet loses heat, and that’s by infrared radiation to space. Greenhouse gases insulate the planet against this energy loss,thus allowing the planet to say warmer with the same energy input. In this sense, they work in just the same way as a blanket or sleeping bag — not generating heat, but “keeping heat in” so that you can maintain the same temperature difference between your body and the great outdoors while expending less energy. Would you say that “trapping heat” is a fundamentally flawed explanation of how a blanket works? Does anybody think a blanket traps heat forever, so that you’d be burned to crisp by morning? Lots of the rest of the discussion of absorption and reradiation is also just a matter of semantics, and some is just plain wrong. It’s true that you can’t tag and trace an individual photon after it’s been absorbed, but no physicist thinks of it this way, and I doubt that the lay audience thinks at that microscopic level when thinking about a statement like “absorption and reradiation.” Though energy is transformed, it is never lost, and if you simply think in terms of energy fluxes, you won’t go too far wrong. Greenhouse gases high up absorb a great deal of the infrared flux coming from below. The net energy balance (which includes absorption,emission and convective heat transport) keeps the upper levels colder than the lower levels. Since colder levels radiate infrared more feebly than warmer levels, the cold levels have essentially intercepted the infrared from below, and replaced it with new infrared radiated at a colder temperature. It’s not so terribly bad a description of this to simply say that these levels absorb infrared and reradiate it at a lower temperature — it’s just a matter of what you mean by “it,” and I doubt that anybody but radiation physicists thinks too much about that. By the way, about the business of emission and absorption being at different wavelengths: Lot’s of the description is wrong. The upward infrared into the upper troposphere is compounded of emission from the surface and emission from clouds and greenhouse gases. This emission is indeed partly or largely absorbed by the same greenhouse gases that contribute to the emission from below. The re-radiation (or “replacement radiation,” if you will) from the colder upper layer does indeed have a different spectrum from the incident radiation, but the shift in wavelength with temperature is a relatively small contribution to this. The main contribution comes from the fact that the upward infrared is already “depleted” in those wavelengths which greenhouse gases absorb well. However, by Kirchoff’s law, the emission is strongest in those bands where the greenhouse gas is the best absorber. That means that the CO2 in the cold upper troposphere is radiating mainly around the 15 micron band, whereas the absorption is more or less occurring in the complement of this band, or at least on its fringes. This is what allows the tropopause temperature to be substantially below the skin temperature. From the standpoint of the way the greenhouse effect works, the spectral niceties are more or less irrelevant — the net effect is still that the GHG reduces the rate at which infrared is lost to space, for any given surface temperature. Oh, and of course, all this physics, including the spectral niceties, is fully incorporated in climate models. It’s just a matter of how much of it the informed public needs to understand in order to make informed decision about carbon emissions and energy policy. For that, the blanket analogy works perfectly well. What’s much more consequential from the policy perspective are things like the nature of cloud uncertainties, the geographic distribution of climate change, the way precipitation might change in critical areas, and the chemical oceanographic stuff that determines the lifetime of CO2 in the atmosphere. –raypierre]

  31. 81
    dave says:

    thanks to all above for the comments on the “junk” science article. The name is fitting huh? These often appear in fox news(go figure!!!) and for those not involved in heavy duty climate modelling, it is hard to really understand what is going on. Their arguments muddy up the waters of understanding these highly complex radiative non-linear processes. i have learned a lot. thanks all!

  32. 82
    dave says:

    one more comment….has anyone noticed the continuing anomalously low arctic sea ice extent? It has been running very low since last fall’s record minimum….except for a brief period in November. In fact I believe it has been near or at record low levels (since 1979) almost every month. check out….

    This is scary because it seems that each year it is getting lower and lower faster(feedbacks kicking in now?). I hope this pace of ice loss is just a natural trend that will reverse to some extent soon…but overall in the long run it will probably continue to drop. Also the satellite MSU temp records are really showing some warming of which I believe are fairly accurate. If we continue to warm at the pace of the last few years (which hopefully will slow down or temporarily reverse), 10 years from now the climate will be noticeably different for many more people than just those that live in the arctic… any comments or thoughts would be appreciated?? thanks

  33. 83
  34. 84
    Hank Roberts says:

    #72, Blair Dowden — you start off by saying you thought the junkscience page as having ‘good’ information.

    Raypierre responds debunking what you quoted from junkscience, point by point.

    Your posting started by saying you thought the junkscience page
    “…. leaves out the Stefan-Boltzmann law, … If [I?] found the following statement interesting, and I think it is valid …” and quoted something without a source.

    Ray pointed out that too was wrong.

    Where did find that statement you quoted? Why did you trust that source, and does it have any cites or footnotes? (I can’t find what you quoted searching online.)

    [Response: I don’t think this is entirely fair to Blair. I read his comment as, for the most part, saying that key parts of the junkscience article (those which invite the reader to draw a conclusion) are deceptive. Blair happened to think the first passage he quoted was reasonable, and indeed it sounds reasonable unless you have worked a lot on the climate system and know how it works. I know many professional climate researchers who still are somewhat confused about the different roles of the surface and top-of-atmosphere energy budgets. The junkscience statement on this was an especially egregious blunder, but still not one I’d expect a non-professional to spot the problems with. That’s just the problem with junkscience — they manage to sound like the high-minded sober professionals, whereas a lot of what you find there is a pseudoscientific equivalent of the ink a squid jets out to confuse its enemies –raypierre]

  35. 85
    Hank Roberts says:

    Thanks Ray, I didn’t mean to criticize Blair — I didn’t see the holes in that statement either.

    Blair, I was asking what your source was for that first statement — you said it wasn’t from junkscience, and can’t find it anywhere. Was it from a book or other offline source? I wanted to understand where it came from.

  36. 86
    Hank Roberts says:

    Argh. My mistake, Blair’s first statement is also from the same junkscience page as the rest — the paragraph that begins “[Edited for clarity, April 24]”

  37. 87
    Treehugger says:

    RealClimate Reviews the Science of An Inconvenient Truth
    The climate scientists are have posted a short review of the science in the upcoming Al Gore movie about global warming: An Inconvenient Truth. The verdict? “For the most part, I think Gore gets the science right, just as he did in Eart…

  38. 88

    #80, the underlying reason for sea ice change may be sea surface salinity (sss), there should be significantly more of it during winter. The overlying reason is of course warmer tropospheric temperatures, that we know is happening. This said it is hard to confirm because there are very few (if any) permanent sss websites dedicated for
    displaying salinity concentrations.

  39. 89
    pat neuman says:

    re 81. 75.


    At the Town Meeting in Minneapolis yesterday (75), Will Steger showed a sequence of slides on areal ice loss within the Arctic. Will Steger was very serious in his concern about slippage of the ice fields on Greenland into the sea, which could happen suddenly and produce a 20-30 ft rise in sea level. I think there is great uncertainty about when that might happen. On May 19th, Will Steger will be receiving the Lindberg Award for his explorations and “his deep understanding of the environment and his efforts to raise awareness of current environmental threats, especially climate change.”

  40. 90

    Re #72 and Ray’s comment, “[Response: Actually, even this statement is garbage. It takes the atmosphere as observed, which is already influenced by the redistribution of surface heating by convection, keeps it fixed, and then computes what the surface temperature would be if convection and surface turbulent heat fluxes were turned off. This is not a possible equilibrium state of the atmosphere. If you were to completely turn off the turbulent heat flux out of the surface and suppress convection, the atmosphere would be much colder than it is, and the vertical temperature gradient would be considerably weaker. It’s simply not correct to say that the convection increases the escape of energy to space. Another inconsistency is that if you shut off convection and surface turbulent fluxes, the atmosphere would be dry, which would make the planet still colder. All in all, the above is a pointless and misleading statement — unless the point is to mislead. –raypierre]”

    I think the contrast called for is that between an atmosphere in pure radiative equilibrium, which really does produce a surface temperature of 330-350 K, and the same atmosphere with a convective adjustment, which brings down Ts to c. 290 K. Check chapters 2 and 4 of Houghton’s “The Physics of Atmospheres,” or Goody and Yung on the use of the convective adjustment. Yes, the atmosphere in pure radiative equilibrium is unrealistic; but it’s often used anyway to start off examining heating of a planet’s surface and atmosphere by Solar radiation.

    [Response: See my comment #109 below. –raypierre]

  41. 91

    I don’t know if it would help things or not, but I’m thinking about writing a short paper which would use a gray approximation to explain the greenhouse effect. I am not, repeat not, a professional scientist, so maybe I don’t have the standing to post an article on RealClimate. Could y’all let me know if 1) such a post would be a good idea, and 2) if I would be allowed to do it? Thanks.


  42. 92
    Blair Dowden says:

    Re #91: I would welcome a consise (and accurate) explanation of the greenhouse effect, even if I do not know what a gray approximation is. It seems most information is at one of two levels – a simplistic explanation for people with little knowledge, or scientists in the field communicating with each other. It is hard to find anything aimed at levels in between.

    Ray suggested that the blanket analogy is sufficient for most people. The problem is when they find out there is about 30 times more water vapor than carbon dioxide, and water vapor absorbs over a wider spectrum, then carbon dioxide must be a trivial component of the system, so why worry about it? While I think I now understand why this is not the case (thanks mainly to Ray), I have not seen any single place where it is explained properly at a level I can understand. When trying to explain this to others, I can’t give a reference so I am essentially asking them to take my word for it.

    [Response: You might check our post on water vapor, here]

  43. 93
    Blair Dowden says:

    Re #89: After doing my part to debunk the skeptics, I am now going to be one. The statement that “slippage of the ice fields on Greenland into the sea, which could happen suddenly and produce a 20-30 ft rise in sea level” is at least as misleading and irresponsible as anything Milloy the Junkman has said. The complete melting of the Greenland ice cap would cause sea levels to rise 6.6 meters, or about 21 feet. That is not going to happen “suddenly”. Greenland is not a table with a hunk of ice on it. It is mostly surrounded by mountains along both coasts, so it is better thought of as an overflowing bowl. It will take many hundreds (some say thousands) of years to melt that under any climate scenario.

    There is no question that rising temperatures will cause melting in Greenland and elsewhere. But let us be realistic about the timescale this will happen in.

  44. 94
    cwmagee says:

    Getting back to the movie, although Al Gore’s comments on hurricanes and CO2 may be nuanced, isn’t the movie poster a bit on the alarmist side?

  45. 95
    Wonderin' aimlessly says:

    A few loosely related thoughts:

    But the question is whether there is any measureable impact in Antarctica from changes in aerosol emissions from the U.S. The answer is, no, there is not

    While not Co2, the Clean Air Act has had a definite impact on other pollutants. Check out this page from USGS:

    Significant decreases in total mercury observed in the last 15-20 years of the ice-core record indicate reductions in emissions that correspond to the time period when the Clean Air Act and other emission reduction strategies became prominent“.

    On another note, anecdotal evidence, I am a hiker, have been for many years. The last five years or so I have noticed an aggravating change here in California. Ticks, long the bane of summer hiking, are now infesting our woodlands year round, even in wintertime when we have some hot days.

    Lastly a proposition (if simplistic) to reduce Co2 in the atmosphere. I’m picturing tall, narrow air filters (solar powered) along the lines of Seattle’s Space Needle near all of our large cities continuously filtering the air.

  46. 96
    Alain Henry says:

    To reply to a question of post 48:

    What would a global rise in temperatures of 3C mean for the inhabitants of the world? – by 2050? by 2100? What about if the rate of increase in CO2 and global temperatures is even more rapid?

    The Exeter conference in 2005 produced three summary of global warming impacts at various levels of temperature change: On the page:, see the three topics:

    – Impacts of level/rate of temperature change on ecosystems (PDF, 117 kb)
    – Impacts on human systems due to temperature rise, precipitation change, increases in extreme events and sea level rise (PDF, 136 kb)
    – Major impacts of climate change on the earth system (PDF, 93 kb)

  47. 97
    Andrew Dodds says:

    Re: 93

    I believe that you are correct; if you want something more realistic to worry about, I’d investigate the West Antartic Ice sheet. This is not enclosed by mountains, and is additionally grounded below sea level. Off the top of my head, that’s a 5-6 meter sea level rise which has happened during some previous interglacials.

  48. 98
    pat neuman says:

    re 97 93 89 75

    Will Steger has led teams of scientists across Antarctic, the Arctic and Greenland (by dogsled) for the last few decades. Will has presented his findings for many years to groups of students and scientists. At other times, he lives in a back woods cabin in northern Minnesota, an area which has been smoothed over by moving ice many times during interglacial periods.

    I believe Will Steger, an explorer and scientist, understands the way ice and water moves, and that once a large ice sheet begin to slip, the weight of ice and water and their forces cannot be stopped by anything.

    May 15, 2006, The Guardian, excerpts:
    Walt Meier, a researcher at the US National Snow and Ice Data Centre
    in Colorado, …
    … Experts at the US Naval Postgraduate School in California think the
    situation could be even worse. They are about to publish the results
    of computer simulations that show the current rate of melting,
    combined with increased access for warmer Pacific water, could make
    the summertime Arctic ice-free within a decade. Dr Meier said: “For
    800,000 to a million years, at least some of the Arctic has been
    covered by ice throughout the year. That’s an indication that, if we
    are heading for an ice-free Arctic, it’s a really dramatic change and
    something that is unprecedented almost within the entire record of
    human species.”,,329480158-117780,00.html

  49. 99
    Hank Roberts says:

    Decent abstract here for techniques of determining mass balance of ice sheets, this one “melting from the bottom” == good source of well written abstracts generally:

  50. 100

    As an American in the UK, I often feel like I’m looking at an alternative universe when I get news & opinions from the states. But here in Britain, the Conservative candidate is touting “Go Green, Vote Blue [Conservative].” I couldn’t imagine a Republican in the US, esp a leading candidate advocating anything like that!

    I anxiously await the “reviews” of this film from the likes of Ann Coulter, Rush Limbaugh, Cato Institute, Myron Ebell, etc! I imagine it will be more of the “gee, Al Gore is so stiff & wooden & scientific, you don’t want to just hang out with him at TGIF like you would with George Bush!”

    At the very best, there will be making big things out of the motes missed or slightly wrong in the film (as some here are pointing out), whilst ignoring the “beams” that the right-wingers conveniently miss!