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Examining Hansen's prediction about the West Side Highway

Posted on 10 March 2011 by ClimateHawk

One climate myth found on the internet, propagated by Anthony Watts, is that James Hansen erroneously predicted the West Side Highway would be underwater by 2008. James Hansen made his statement in response to a question by Bob Reiss, a journalist and author, in 1988.  A close examination of the interview reveals Hansen did not, in fact, predict that the West Side Highway would be underwater in 20 years. Bob Reiss reports the conversation as follows:

"When I interviewe­­d James Hansen I asked him to speculate on what the view outside his office window could look like in 40 years with doubled CO2. I'd been trying to think of a way to discuss the greenhouse effect in a way that would make sense to average readers. I wasn't asking for hard scientific studies. It wasn't an academic interview. It was a discussion with a kind and thoughtful man who answered the question. You can find the descriptio­­n in two of my books, most recently The Coming Storm."

James Hansen reports the conversation as follows:

"Reiss asked me to speculate on changes that might happen in New York City in 40 years assuming CO2 doubled in amount."

The book The Coming Storm and the article are different.  In The Coming Storm the question includes the conditions of doubled CO2 and 40 years, while the article which is quoted by skeptics does not mention doubled CO2, and involves only 20 years. 

To understand the discrepancy between these two published accounts, it helps to look at the timeline of events.  The original conversation was in 1988.  Ten years later, referring to his notes, Bob Reiss recounted the conversation in his book The Coming Storm.  James Hansen confirmed the conversation and said he would not change a thing he said.  After the book was published, Bob Reiss was talking to a journalist at about it.  As he puts it,

"although the book text is correct, in remembering our original conversation, during a casual phone interview with a Salon magazine reporter in 2001 I was off in years.”

We can check back in 2028, the 40 year mark, and also when and if we reach 560 ppm CO2 (a doubling from pre-industrial levels).  In the meantime, we can stop using this conversation from 1988 as a reason to be skeptical about the human origins of global warming.


The Coming Storm by Bob Reiss, copyright 2001

Book review in Salon. Com:

As reported by Anthony Watts:

Communication from James Hansen, January 26, 2011

Email from Bob Reiss, February 15, 2011

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Comments 51 to 100 out of 100:

  1. 45 Phila There is nothing I can do if you feel the climate science establishment shouldn't be held to scutiny. There is nowhere for our discussion to go from here. Again your appeal is that you want the discussion to be limited to what you think is relevant, you don't seem to be able to see that. There is plenty I disagree with on this site but I never(I think!) try to limit the scope of the discussion. Finally the title of the article is "Examining Hansen's prediction about the West Side Highway". That's what I'm trying to do, you seem to think the title is "Bash WUWT". Look if John wants to post an article with that title I'd be happy to join the conversation there if I thought I was going to get something from it.
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  2. HR @49, "If your data is correct then New York should be one of the spots on the earth were accelerating SLR should be showing up earliest." First off, they are not "my" data. Second, that is your interpretation of the paper which is talking about future GSL. Nice try though. That said, this satellite-derived map of GSL, does show a hot-spot for GSL rise (> 5 mm/yr) off the northeast coast of Canada for the period 1993-2009. [Source here]
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  3. HR: It's 17 years until Hansens speculation, but more generally the satellite data is still failling to show anything but a linear rise. Come on HR, you have been shown time and time again that Hansen did not put a time frame on the sea level rise. The reference was a doubling of CO2. There's not a single scientist on the planet speculating that a CO2 will double by 2028. What does it take for you to understand that?
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  4. HR @51, we absolutely believe the scientific community should be held up to scientific scrutiny. The first step in that process is to examine the predictions made in scientific articles or conference proceedings rather than equivalent predictions made of the cuff in interviews. It is very clear that the former will be more precise, and will more accurately reflect the considered views of the scientist. (If the of the cuff remarks widely differ from the considered views, that raises a separate issue, but no one has suggested that to be the case.) The second step is, where there is any ambiguity as to what was meant (which is certainly the case in this example) is to clarify with the author the actual intended meaning. Did Hansen mean 40 years regardless of CO2 levels? Did he mean 40 years, provided that CO2 levels had doubled? Or did he mean 40 years after CO2 levels had doubled? The exact interpretation makes a very large difference as to whether or not the prediction has been (or will be) falsified in 2018. Neither WUWT nor you have taken either of these steps. The notion that you are trying to hold Hansen up to scrutiny is therefore nonsense. In fact, what WUWT appears to be doing is to raise a straw man of Hansen's views in order to make him the subject of ridicule. Finally, if you want to subject Hansen's views to genuine scientific scrutiny, you need to remember that any prediction is based on multiple claims. Because the purpose of scientific scrutiny is to test those claims, where some of those claims are already modified, the prediction needs to be altered accordingly. Let's assume (contrary to what I believe is the most natural interpretation), that Hansen predicted that: "If CO2 levels double by 2028, the West Side Highway in New York will be under water." The theory underlying that prediction is based on Hansen's model work of that period. So it includes the sub-beliefs that: a) CO2 levels can plausibly to double by 2028; b) Climate sensitivity is 4.2 degrees C per doubling of CO2; and c) A 4.2 degree C rise of global temperatures above preindustrial levels will raise sea levels sufficiently to flood the West Side Highway. For scientific scrutiny, (b) is now irrelevant. The evidence, partly published by Hansen himself, shows the climate sensitivity is more probably 3 degrees C. Now, should we test Hansen's predictions without substituting for (b), (b') that climate sensitivity is 3 degrees C, and altering the prediction accordingly, then all we test in the prediction is the conjunction of (a), (b), and (c); which is boring because we already know (b) is probably false. In other words, if in fact the West Side Highway is not under water in 2028, all we learn is that either CO2 has not doubled, or climate sensitivity is lower than 4.2, or sea rise at 4.2 degrees C is not sufficient to flood the West Side Highway. As we are already fairly certain about the second of those possible conclusions, we learn virtually nothing. So, if you really want to examine Hansen's position: 1) Find, if possible, an equivalent prediction from the period in his primary literature; 2) Clarify any ambiguity if any; and 3) Adjust the prediction to allow for recent advances in knowledge. And if you are not prepared to do that, you are not holding Hansen up to scientific scrutiny - you are indulging a rather tawdry rhetorical ploy. Just don't expect us to be deluded by it.
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  5. This is getting more and more absurd. In a normal scientific review process, the 1998 interview would be long forgotten, as it was superseded by this more recent research brief. The two models suggest that ocean waters in this area could rise another 18 cm to 60 cm by mid-century, as the planet warms. By the 2080s, sea level could climb by 24 cm to nearly 110 cm ... As sea level rises, flood levels produced by the 100-year storm could reach 3 to 3.8 meters by the 2050s, and between 3.2 to 4.2 meters by the 2080s. --emphasis added So its not sea level rise alone, its the combination of sea level rise and the 100 year storm that floods the West Side. -- Figure 2 ... the current 100-year flood return period would shorten dramatically. By the 2080s, the likelihood of a flood engulfing the area in blue (Figure 2) would be once in 50 years, given present rates of sea level rise, and as often as once every 4 years, in the worst-case scenario. Given the huge percentage of NYC's infrastructure that is underground, this should be a serious concern, because there is no 3 meter sea wall around lower Manhattan. Instead its become a denialist playground. Go figure.
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  6. Muoncounter @55, interesting, but Hansen still consistently predicts greater sea level rises than the consensus position. It is, therefore, certainly justified to examine his independent predictions, so long as you actually do so rigorously (see 54). Of course, the deniers are simply taking rhetorical short cuts rather than actually examining Hansen's predictions.
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  7. Not to be pedantic Muoncounter, but this is about what was said in 1988, not 1998. But I agree with your point, it is absurd, and pathetic that people are having to debunk this nonsense being spread by WUWT and others. Hopefully concrete in cheap post 2050 to increase the height of the the sea walls-- hmm, but making concrete is CO2 intensive.....oh dear, another positive feedback loop.
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  8. Tom, When you don't have substance, go with the rhetorical shortcuts. Here's a more recent discussion of the same work, including a more detailed map of lower Manhattan: A Columbia University study concluded that as sea levels rise, large parts of Lower Manhattan including Battery Park City, part of the World Trade Center site, and the Seaport will experience 10-foot floods after large storms. 1988? Yup, that's what it says up top. For Watt$ to be combing over this is a joke.
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  9. Tomurray: Do you hold Lindzen and Spencer to the same standard you hold Hansen? Remember that in 1988 Lindzen was predicting it would get colder in the next decade. Why are you still listening to him?
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  10. HR: There is nothing I can do if you feel the climate science establishment shouldn't be held to scutiny. This is yet another strawman. I didn't say or imply this, and I don't believe it. Frankly, I don't think you're helping your credibility with this comment. Two other points come to mind. First, AGW has been under incredible scrutiny, as you know perfectly well. I've been following this issue pretty carefully since 1990 or so, so I know that there are few major claims from the consensus side that haven't been challenged, questioned, parsed, anatomized, checked and rechecked repeatedly. That process continues today -- despite efforts to defund or slander the relevant agencies -- and I'm pretty confident that when important adjustments are made to AGW, or its predicted outcomes, they'll come from competent scientists, rather than a flock of willfully ignorant ideologues. Second, "scrutiny" of a scientific theory is valuable laregly to the extent that it comes from informed, intelligent, honest people who are not simply parroting frivolous criticisms they heard on a site like WUWT. We probably don't agree on much, but I hope we can agree on that.
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  11. As a PS, Tom Curtis @54 has done a much better job than I of clarifying the difference between legitimate scrutiny and ideologically motivated ankle-biting.
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  12. Chrisd3, I haven't lived in NYC since the 1980's, so I'm not sure what changes have been made. Persistent flooding would seem to depend on a number of factors, including elevation and regional sea level rise (the global rise isn't distributed evenly). HR: "But what's more important speculation by an influential climate scientist who's helping to shape the IPCCs position or a blogger?" Watts is not shaping the IPCC position or the science. I think the blogger would argue that he's helping to shape public opinion, perhaps more so than the IPCC. He and others certainly want to be seen as credible sources, taken as seriously as the scientists. It would be nice if the public (and politicians for that matter) could distinguish between objective science and his brand.
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  13. 53 RickG Given that Hansen is answering one clear question with the answer to another question let's simplify this. RiskG do you think that the West Side Highway will be inundated by the sea in 2028? Does the evidence suggest it will?
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  14. 61 Phila We humans are complex beasts. We can take on many roles simultaneously, some of them contradictory. Is it possible that Hansen can be both a scientist and an ideologue? His activism certainly suggests so. Just for clarity I'm not trying to be disparging about him here, I quiet like somebody to take a clear position on things even when I disagree with them. I just think it's too easy to draw the boundaries the way you do. You present it as a clear black and white issue, science on one side, ideology on another. That's surely too simplistic. It's not the way I perceive it anyway. The skeptic argument contains "ideologically motivated ankle-biting" and some of it shows up on WUWT but the argument doesn't end there. There is a basis for scepticism from within the science based on the uncertainty and interpretative nature of the science. (apologies for going OT here)
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  15. HR: RiskG do you think that the West Side Highway will be inundated by the sea in 2028? Does the evidence suggest it will? Not in 2028, but it eventually will at some point in the future as sea level continues to rise at an accelerating rate as a doubling of pre-industrial CO2 is approached.
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  16. HR: Is it possible that Hansen can be both a scientist and an ideologue? His activism certainly suggests so. I think his "activism" only suggests this if you proceed dogmatically from the assumption that he's largely or entirely wrong. Otherwise, you could just as easily see it as a rational response to an actually existing problem. Hopefully, you're not so wedded to the a priori assumption that AGW is a hoax or an exaggeration that you can't acknowledge this point. And before you ask: Yes, I can imagine the consensus turning out to be wrong, just as I can imagine evolution turning out to be wrong. I just wouldn't care to bet anything valuable on it. You present it as a clear black and white issue, science on one side, ideology on another. No, I really don't. I say that there are people who tend to have a lot of relevant expertise on one side, and people who tend to have little or none on the other. Ideology enters into the equation primarily to the extent that it empowers the latter group to present their generally uninformed and paranoiac speculation as "scientific scrutiny." My position on this question is probably not that different from your position on aircraft mechanics versus pastry chefs: you'd probably prefer the former to service the airplanes you board. Of course, the people who tend to lack relevant expertise could turn out to be right, despite their errors and misrepresentations and demonstrable ignorance. But again, I wouldn't bet anything valuable on it. Especially if it weren't really mine to bet.
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  17. HR, "Is it possible that Hansen can be both a scientist and an ideologue?" Why not frame the question differently: Is it possible for a scientist to express a personal opinion? The ideologues are then those who seize those opinions and trumpet them for their own agenda.
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  18. This isn't permanent (yet), but likely to happen more often this century. Click here to see a photo of New York's West Side Highway under water. Another report from Wall St Journal Metropolis blog here: "Water is “flowing at great speed” from the West Side Highway into the Brooklyn-Battery Tunnel, he said, but it’s too early to say how much had entered the subway system."
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  19. Here is another photo - chest deep on the West Side Highway - during the Sandy superstorm.
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  20. In March 2011, perhaps in reaction to this March 10 SkS thread, Watts updated his original 2009 story to correct the record and concede that 40 years was the correct number. He wrote, “So I’m happy to make the correction for Dr. Hansen in my original article, since Mr. Reiss reports on his original error in conflating 40 years with 20 years.”

    See the updated first pages at:

    SkS should update its head post by mentioning Watts’s update. As-is, it can be read as implying that Watts is continuing to make a debunked claim. (It says, “One climate myth found on the internet, propagated by Anthony Watts, is that James Hansen erroneously predicted . . . .”) In addition, “previously” should be inserted before “propagated.”

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    Moderator Response:

    [JH] Your concerns have been duely noted.

  21. Roger,

    Have you gone to WUWT and asked them to correct al the other posts they have with errors?  It will be a long post since you will have to correct virtually everything they have.  Why are you so concerned that SkS is perfect when the bulk of WUWT is in error?

    In examining your link they still claim that Hansen is wrong.  Why should SkS change their article when WUWT has not changed their claim?  You need to correct WUWT before you try to get the post here changed.

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  22. Roger,

    Thanks for your definition.  We'll see if it survives moderation this time.

    You still have to  address the fact that you want SkS to correct their post when WUWT has not changed their false claim.  They now make their own projection for 25 years in the future.  Since Hurricane Sandy already submerged New York as Hansen suggested, Hansen has already been proved right while WUWT is incorrect.  Perhaps you want to dispute the damage to New York during Hurricnae Sandy?

    Since you appear to be a troll I will not respond to you again.   

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    Moderator Response:

    [JH] Please tone down the rhetoric.

  23. @Michael Sweet:
    In informal (inductive) logic, a Tu quoque accusation like yours is a fallacy. Here's Wikipedia's definition. (I don't provide the link because its improper formatting was apparently causing my comment to be moderated-out.)

    "Tu quoque (/tuːˈkwoʊkwiː/;[1] Latin for "you, too" or "you, also") or the appeal to hypocrisy is an informal logical fallacy that intends to discredit the opponent's position by asserting the opponent's failure to act consistently in accordance with that position. It attempts to show that a criticism or objection applies equally to the person making it. This attempts to dismiss opponent's position based on criticism of the opponent's inconsistency and not the position presented.[2] It is a special case of ad hominem fallacy, which is a category of fallacies in which a claim or argument is rejected on the basis of fact about the person presenting or supporting the claim or argument.[3] To clarify, although the person being attacked might indeed be acting inconsistently or hypocritically, such behavior does not invalidate the position presented."

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  24. Michael Sweet wrote, "Why are you so concerned that SkS is perfect when the bulk of WUWT is in error?"

    I have no over-riding, general concern about SkS’s accuracy. The motivation for my comment was a specific trigger: In the two-day-old WUWT thread "friday-funny-mann-overboard-at-agu14," newbie poster "kevinschmidtojai" commented (at December 19, 2014 at 9:21 pm) by reposting the entire head post of this SkS thread, followed by a link to it. He added nothing of his own (and hasn't yet responded to the four replies I made soon afterwards). (I provide the link to his comment in a separate comment below, because three of my prior comments were deleted because of link-format problems.)

    My replies pointed out to him that Watts had retracted his claim within three weeks of this SkS thread, so it was no longer operative; and that SkS should reword its head post so it no longer gave its readers the impression that Watts was still making that claim.

    I assumed that the moderators here at SkS were aware, or soon would be, of his comment and my responses, so I didn't feel the need to provide that background information. It was the moderators and/or the author of the head post I was mostly addressing.

    If I have spurred SkS to update its thread, it will be viewed as a more reliable and conscientious source. SkS readers who, like "kevinschmidtojai," cite this SkS thread in good faith and get rebutted will no longer find out that it has misled them, causing them to be warier of it in the future--as will lurking warmists at WUWT, who have read my rebuttal.

    I can easily imagine an SkS regular making this point too—that being forthright is the best policy. There's nothing necessarily nasty about saying so. Anyway, even had I been testy, "Your opponent is [or can be] your friend" (Burke)—by forcing you to up your game.

    Unfortunately, the change SkS has has made so far--adding a link to the WUWT thread containing Watt’s retraction--is insufficient. Most readers will not click on it, and so most will continue to be misled. Something like the following text should precede or follow that link:

    "In March 2011, perhaps in reaction to this March 10 SkS thread, Watts updated his original 2009 story to correct the record; he conceded that 40 years was the correct number."

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  25. As promised, here's the <a href="">link</a> to the comment on WUWT that triggered my replies.

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  26. Michael Sweet wrote, "Since Hurricane Sandy already submerged New York as Hansen suggested, Hansen has already been proved right . . . ."

    Hansen's prediction can't rationally be read as saying that there would be a one-time 14-foot flooding of NYC within 40 years. It was in response to a question about how much the everyday sea level would have risen by that time. He implied: at least ten feet.

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  27. Correction to the above: "It was in response to a question about how much the everyday sea level would have risen what NYC would look like by that time (40 years). Hansen responded that the West Side Highway (elev. 10 feet) would be underwater.

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  28. Correction to your correction... Hansen was asked about changes which would occur in 40 years (i.e. by 2028) if atmospheric CO2 levels doubled.

    Given that atmospheric CO2 levels haven't doubled, and are highly unlikely to do so before 2028, the entire 'debate' is staggeringly moot. It was an estimate based on a pre-defined set of conditions which haven't occurred. You might as well argue that saying, 'If you jump out of an airplane without a parachute you are likely to die' can be disproven by looking at cases of people jumping out of airplanes with parachutes.

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  29. CBDunkerson at 22:19 PM on 22 December, 2014:
    "Correction to your correction... Hansen was asked about changes which would occur in 40 years (i.e. by 2028) if atmospheric CO2 levels doubled."

    Er, you're right. I'd lost sight of that point.

    But it's strange that Hansen didn't bridle or quibble at the question for assuming too steep a rise in CO2 in too short a time. (In the unlikely event that he shared that assumption, it was a bad error.)

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  30. Roger Knights - Not really, the positing of a Gedankenexperiment, a 'what if' thought experiment, is entirely reasonable. Expecting Hansen to have thought through every possible misinterpretation of his words, and to phrase his speech accordingly, is not reasonable. 

    Looking at the WUWT article you mentioned, they are still misinterpreting the content of that Hansen interview, falsely posing a thought experiment for doubled CO2 (which has not happened) as a prediction for current, and quite different, CO2 levels. They are continuing to make a debunked claim. 

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  31. Roger Knights @various, I quote the most accurate account of the interview:

    "Reiss asked me to speculate on changes that might happen in New York City in 40 years assuming CO2 doubled in amount."

    The problem with that statement is that it is multiply amibuous.  It could mean Mann was asked to speculate on any of the following scenarios:

    1. Assume CO2 is 560 ppmv now (ie, in 1988), then what would the changes be in New York City in 2028;
    2. Assume CO2 levels rise to 560 ppmv by 2028, then what would the changes be in New York City in 2028; or
    3. Assume that at some time t, CO2 levels rise to 560 ppmv, then then what would the changes be in New York City in t + 40 years. 

    Because of that ambiguity, if you want to check Hansen's opinions on sea level rise, it is a ridiculous quote to do so on.  That is particularly the case as he has stated his position on sea level rise far more clearly elsewhere.  Thus, in the New Scientist, he writes:

    "As an example, let us say that ice sheet melting adds 1 centimetre to sea level for the decade 2005 to 2015, and that this doubles each decade until the West Antarctic ice sheet is largely depleted. This would yield a rise in sea level of more than 5 metres by 2095."

    Based on that scenario sea level rise in 2028 would be approximately 0.043 meters, not the three meters required for covering the WSH.

    It should be noted that Hansen does not consider the 5 meter sea level rise by 2100 the most likely scenario.  He does think sea level rise will be measured in meters, ie, that it will be significantly greater than that projected by the IPCC and considers 5 meters a plausible estimate in the upper range of possibility.  Even assuming that it is his actual estimate, however, clearly his more accurately stated views are inconsistent with the common interpretation of the WSH quote.

    Now, it is possible that Hansen is merely being inconsistent.  It is far more probable, however, that his critics (notably at WUWT) have merely misinterpreted his comments - and that ergo their criticism is still fraught with error.  Absent an explicit attempt by those critics to determine exactly what Hansen meant in his comment, either by directly asking him or by finding the original transcript of the interview so that the exact words used can be used to rule out possible interpretations, they are clearly indulging in an attempted "gotcha" where the purpose it is only rhetorical.  And because rhetorical, it is more important what they can persuade their audience to believe about what Hansen said, than what he actually said and meant.

    As a side note, absent specific clarrification by Hansen, and given his apparent recent reiteration that he stands by his comments, then consistency requires that Hansen actually to have intended his words to be a response to scenario 3 above.

    As a further note, I believe Hansen is wrong about sea level rise, even in his more clearly stated views.  I doubt sea level rise over this century will exceed 2 meters, and it may be as low as 0.6 meters.  That still represents a significant cause for concern.

    Finally, while it is appropriate for SkS to acknowledge (in a footnote) at least that Watts has slightly ammended his post to eliminate one error, while retaining many others.  That is so regardless of the standards of error correction at WUWT that, or other "skeptic" sites.  It is unreasonable, however, to expect continuous inspection of posts on which SkS comments in the off chance of a rare correction.  SkS authors are volunteers with many other demands on their time.  Therefore concluding that SkS is unreliable because they got the fact correct at the time of publication but failed to take note of a correction by Watts of which they had not been notified is unreasonable.  It suggests you are merely seeking a pretext to arrive at that conclusion - particularly given multiple egregious errors you seem prepared to over look at WUWT.

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  32. Tom Curtis wrote, in #81: “. . . it is appropriate for SkS to acknowledge (in a footnote) at least that Watts has slightly ammended his post to eliminate one error, while retaining many others. That is so regardless of the standards of error correction at WUWT that, or other "skeptic" sites.”

    Good. That agrees with what I said in #74, especially the last two paragraphs. I hope your opinion carries weight with the moderators here.

    Tom Curtis continued: “It is unreasonable, however, to expect continuous inspection of posts on which SkS comments in the off chance of a rare correction. SkS authors are volunteers with many other demands on their time.”

    (I presume the above refers to the comments I made on WUWT on Dec. 20, not here, where I haven’t suggested such a thing.) I didn’t think my expectation of SkS-awareness was unreasonable in this instance: 1) I had got the impression, from WUWT commenters who noticed rapid rebuttals here on SkS to recent WUWT material, and from SkS’s ongoing (I thought) long list of counterpoints to climate contrarians, that SkS-ers collectively, if informally, were on top of what happens on WUWT. 2) I also thought that Watt’s concession that he had been wrong about its “20”-year claim would be so juicy that it would have been reported here.

    As it happens, Watts’s concession was only a two-year-old “update” to his head post. So, within 2.5 hours, I realized, unprompted, that I had been wrong in assuming SkS should have been aware of Watt’s retraction. I then posted the following on WUWT: “I now realize that AW’s update to his thread would not have appeared as a new item in WUWT’s sidebar, so SkS probably was unaware of it. I’ve posted a comment on the SkS thread informing it of AW’s update and urging it to update its own thread too.”

    Tom Curtis continued: “Therefore concluding that SkS is unreliable because they got the fact correct at the time of publication but failed to take note of a correction by Watts of which they had not been notified is unreasonable.”

    Right. But I immediately corrected myself. You must have lost sight of my correction. (It’s easy to lose sight of such things. I acknowledged doing so myself in #79.)

    Tom Curtis continued: “It suggests you are merely seeking a pretext to arrive at that conclusion [of SkS’s unreliability]. . .”

    In light of my explanation above, I trust you will take that back. (For context, I do claim that if SkS fails to “add a footnote” to its link to Watts’s thread, it will be perceived, correctly, as implicitly misleading its readers.)

    Tom Curtis continued: “- particularly given multiple egregious errors you seem prepared to over look at WUWT.”

    We won’t know how deep WUWT is sunk in its Egyptian night until we have clarified Reiss’s ambiguous question. I’ve ordered Reisss’s book and, to establish a relationship with them, sent e-mails to Reiss and Hansen—and I have follow-ups in mind. I suggest that you contact Hansen and ask him to clarify which interpretation of Reiss’s ambiguous question he responded to. (I didn’t ask him that—I just posed three softball questions to get things started. Similarly, the only question I asked Reiss was the name of “the earlier book” in which he included his Q-and-A with Hansen.) Hansen’s e-mail is Reiss’s is When you and I (hopefully) get answers, we’ll have something we can get our teeth into.

    Tom Curtis wrote, earlier in his post: “Because of that ambiguity, if you want to check Hansen's opinions on sea level rise, it is a ridiculous quote to do so on. That is particularly the case as he has stated his position on sea level rise far more clearly elsewhere. Thus, in the New Scientist, he writes: . . . .”

    But that’s from 2007, and our argument is about his thinking about sea level rise in 1988. Here’s a quote from a 44-second 1988 Hansen video that seems consistent with Watt’s view that Hansen was foreseeing a huge SLR soon (e.g., within 40 years).

    (To view it, go to YouTube and search for “James Hansen speaks about Global Warming.” I’m afraid to post a link to it here, because SkS hasn’t properly processed the link I posted in #75. (Can someone please point to what’s wrong with it?) If you or anyone here knows how to post a link to it, please do so.)

    Hansen: “If we stay on with business as usual, I think for even a decade or so, then we are likely to get a temperature rise of several degrees Fahrenheit by the end of the century [2000], and that would be really a different planet. That would be the warmest it has been since the middle Pliocene—that’s about three million years ago—and at that time there was no ice in the arctic during the summer and fall and sea level was about 25 meters—that’s about 80 feet—higher than it is now. So that is a very different planet. About a half billion people live near the coastlines, which would be underwater if we got a sea level rise of 80 feet.”

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  33. I'm not sure that Hansen was advocating a several degree fahrenheit rise over the course of 12 years :p I imagine he meant the period of time from 1988-2088.

    He is not making a 'prediction' in any scientific sense, but suggesting the listener imagine a vastly different world from the one of 1988.

    I would probably have avoided the potential takeaway that 100 years of warming could result in a possible 25m sea-level rise.

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  34. Tristan @88, the video, SFAICT, was made as part of a 2007 documentary by inside out (click on Greenland).  Thus, when Hansen says, "... we are likely to get warming this century of several degrees fahrenheit"  he is reffering to the 21st century.  Further, and ironically, the video is concurent with his scientific statements about the possible rate of sea level rise I quoted above, and which Roger Knights rejected as "a recent view".

    On the dating of the video, the only thing tying it to 1988 is the mention the introduction to the video which says:

    "In 1988, he was one of the first prominent scientists to raise the alarm about the threat of global warming..."

    That, of course, is merely a historical reference, and is shown to be so by the continuation of the quote:

    "... and he continues to be one of the country's most outspoken scientists on this issue."

    Further, this is what Hansen looked like in 1988:

    You will probably notice distinctly less hair in the video.

    The crucial fact as the video and the article to which I linked are approximately concurrent, they do not represent different views, but different aspects of the same view.  Specifically, Hansen thought (and still thinks) that sea level rise will be rapid, measured in meters over the coming century, and plausibly as much as 5 meters over that century.  He also thinks that once the sea level stops rising, the total rise will be measured in tens of meters, and plausibly upward of 50 meters.  All of this assuming we keep on burning fossil fuels, and in particular, coal.

    As this response to you is an effective response to the later part of Roger Knights' comment @82, I will not repeat myself in responding to him.  I will note here, for his benefit, however, that lack of care in interpreting Hansen's comments, and in particular, failure to consult his more exact statements will lead to interpreting out of context such as interpreting a claim about ultimate sea level rise as (and frankly absurd) claim about sea level rise over this century.  That is why it is only done by those seeking rhetorical rather than scientific rebutal of Hansen's views

    I will also note that his recent views are entirely germain to his 1988 views in that in 2001, Reiss confirmed with Hansen that he still stood by his views as expressed in 1988 (he did).

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  35. Tristan,

    Hansen obviously meant several degrees by 2100.  That is the time frame for projections by the IPCC.  Comparing to the most recent IPCC report, that statement is still reasonable.  It is easy to make a projection look bad by changing the time frame from 110 years to 12 years.  The 2000 time frame added is incorrect.  A simple comparison to Hansen's testimony in 1988 to Congress shows Hansen estimated temperature increases close to a tenth of a degree by 2000.  Should we believe Hansen's testimony to Congress or an edited You-Tube video?  Roger is taking statements he reads at WUWT too seriously.

    Hansen and many other scientists have estimated equilibrium sea level rise of 20+ meters from 2-3 C increases in temperature.  This will take centuries to realize (the time estimated varies widely).  The IPCC projections only go out to 2100.  The sea will continue to rise after that for centuries and many meters.  The high end projections would result in complete loss of ice and 65 meters of sea level rise.  This rise would not be complete for perhaps 1-4 thousand years.  Imagine if we were still dealing with the consequences of pollution released by the Ancient Egyptians!

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  36. Here, below the line, is a comment I composed before reading the comments above. After reading them, I'm kicking myself for not noticing the clue in Hansen's hair. And for not realizing that the "1986" reference didn't necessarily apply to the date of the video.

    Anyway, this exchange has been valuable in clearing things up--and the answers I hope to get from my e-mails ought to make things even clearer. (Unless they make them muddier.)


    I’ve done some more Googling on this topic. It now seems unlikely to me that Hansen would have predicted a ten-foot rise in sea level within 40 years, regardless of how hot it got by the end of that period. There’s obviously, to any climatologist, way too much lag involved for that to happen.

    OTOH, I don’t see WUWT’s current skepticism as very blameworthy, for these two reasons:

    1) The video I cited is over-the-top—it’s a classic of alarmism. Watts and other contrarians could be forgiven for thinking, from seeing it (and probably from other alarmist statements of Hansen), that he might have gone even further off the rails and made a 10-feet-in-40-years prediction.

    2) Hansen’s qualification, “assuming CO2 doubled in amount,” was apparently not included in Reiss’s book. It certainly wasn’t in the e-mail he sent to Hansen that Hansen quoted. (Probably Hansen did make it though, IMO.) But Hansen’s say-so alone is insufficient to establish that as a fact. Reiss’s confirmation is needed. Without that confirmation—at a minimum—there’s nothing scandalous in Watts not yet conceding that he was wrong.

    I suspect, if it’s not in his book, that Reiss doesn’t recall it—although that doesn’t mean it didn’t happen. That is what I intend to ask him about. (If Reiss does recall it, and/or if it’s in his earlier book, I’ll mention it in WUWT’s Tips and Notes section.)

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  37. Roger Knights,

    Tom has provided documentation that your claims about Dr. Hansen are false.  You maintain above that Dr. Hansen has made "alarmist" statements.  I see only falsehoods like claiming estimates of sea level rise for 2100 are claims for 2000 and false claims of temperature projections by Dr. Hansen.  Please cite specific statements form the video that you consider alarmist.  Keep in mind that the video is from 2007 and not 1988 as you falsely claimed.  The only "alarmist" statements I see are your false claims from WUWT.

    You are claiming that Hansen has to provide documentation to prove the statements at WUWT are false.  You have the situation backwards.  WUWT is required to show that the wild claims they make are true, especially since you have provided evidence that their claims are false with two sterling examples. 

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  38. Roger Knights - WUWT is still misinterpreting a Gedankenexperiment for a prediction, a complete misinterpretation that they are using to attack Dr. Hansen. Blaming the victim is never appropriate - the responsibility lies with those making the misinterpretations, in this case with WUWT.

    Your personal opinion that Hansen 'might have gone even further off the rails' and made such foolish predictions anyway is wholly unsupported by any evidence (or IMO any sense), and is in my view just another case of attacking the man rather than considering the evidence. 

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  39. PS to #86: Here’s a third reason WUWT isn’t upbraid-worthy for not crying “mea culpa” on this issue. Its reason for being leery is expressed in this quote by TimG on the site:

    “Frankly, I don’t believe his [Hansen’s] recollection because it makes no sense that a reporter would ask a question on what would happen 40 years after CO2 doubles. It would either be what would happen in 40 years or what would happen when CO2 doubles.”

    I now believe Hansen’s recollection, because he wouldn’t have made a 10-feet-in-40-years prediction. He had to be speaking of when-CO2-doubles. Given that, here’s my guess as to what happened:

    Reiss posed two the questions TimG described above. Hansen gave an answer to the doubling of CO2 question. Reiss misremembered that answer as being to his 40-years question. When the Slate interview became a subject of controversy, Hansen chose to avoid embartrassing Reiss by saying that he’d garbled things. Instead, he tried to soften the blow by saying Reiss had asked a complex (double-barreled) question, hoping this would put the matter to rest with no hard feelings. Instead, it aroused suspicions in contrarians like TimG—and perhaps in Watts, at least unconsciously.

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    Moderator Response:

    [JH] Case closed. Time to move on.

  40. Michael Sweet wrote, in #89: “Please cite specific statements from the video that you consider alarmist. Keep in mind that the video is from 2007 . . . .”

    Adjusting for my mistake about the year of the video and my resulting wrong implied end-of-century date, Hansen, in #82, implied that by 2017 under continuing rising CO2 we’ll likely be locked-in to a global temperature that will be the hottest in 3 million years by 2100. That was alarmism—it was an attempt to stampede people into ACTION NOW action now with an UNlikely unlikely scenario.

    (It’s unlikely mainly because Hansen (per a quote I read somewhere) estimates the climate sensitivity to be 3.0. That’s within IGPOCC’s IPCC's range, but it’s much higher than the latest estimates in the literature—and because the temperature has barely risen in the past seven years.)

    Michael Sweet wrote: “You are claiming that Hansen has to provide documentation to prove the statements at WUWT are false.”

    Strawman. I said that, lacking confirmation from the other party to Hansen’s interview, Watts is not “very blameworthy” (see item “2” of #86) for not accepting Hansen’s “assuming a doubling of CO2” to be an unquestionable fact.

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    [JH] The use of "all caps" constitutes shouting and is therefore prohibited by the SkS Comments Policy. In addition, you are now skating on the thin ice of sloganeering - which is also prohibited by the SkS Comments Policy.

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  41. Rodger,

    This reference provides temperature data going back 800,000 years.  The temperatures over the previous two million years were similar.  We are currently within a couple of degrees of the hottest in the past three million years.  IPCC RPC 8.5 shows 5C by 2100 and more after that.  If CO2 continues to rise we will exceed the temperature of the past three million years as Hansen states.    Your claim that Hansen was alarmist is baseless and uninformed.  Please provide a citation to support your wild claim that Hansen is incorrect.  In the absence of a scientific citation your claim must be presumed false.  

    Hansen's estimate of 3C per doubling is the middle of the IPCC range.  The latest IPCC report has a best estimate of 3C per doubling.  Your claim that the Hansen's value is too high is incorrect.  Please read the literature and try to become up to date.  You are uncritically accepting false information from WUWT.  This article addresses some of your misconceptions.  You should keep in mind that you are talking about the climate sensitivity.  The earth system sensitivity is much higher (like double the climate sensitivity).  It includes slow feedbacks like ice sheets melting.  You must determine if Hansen was referring to the climate sensitivity or the earth system sensitivity (he is likely to be  refering to the earth system sensivity).  If you do not know what the earth system sensivity is you can ask here and people will try to educate you.

    Watts is completely blameworthy for publishing false information like the post you have cited.  It has been documented in this thread that the WUWT post is filled with false and misleading information.  You yourself were uninformed about the basis of your argument untill the facts were presented to you on this thread.

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  42. Roger Knights @90, michael sweet has more than adequetly addressed the point about temperatures over the last few million years.

    What I wish to note is the shere unreasonableness of your suggestion that Hansen was alarmist because, in 2007, he failed to take into account climate sensitivity determinations that would not be made for another five years at the time of his speaking.  In 2007, a climate sensitivity of 3 was not just within the IPCC range.  It was the IPCC central estimate of climate sensitivity, of the then just released (or just to be released) AR4.  Further, the fifteen year temperature trend to 2007 (ie, 1993-2007) using Gistemp was 0.263 C per decade.  Therefore there was no "pause" in evidence, so again you are condemning Hansen as "alarmist" because he did not predict, and was not aware of the effect on the short term global temperature record of two very large La Nina events (2008, and 2011/12) that postdate his comments. 

    So, quite apart from the fact that there have been a number of climate sensitivity estimates in recent years, spanning a range of values (not just the low value estimates exclusively reported at WUWT); and that the "pause" is an artifact of one of the two strongest El Ninos in the twentieth century at the start of the "pause" and two very strong (including possibly the strongest on record, and certainly the strongest since 1974/5 La Ninas at the end of the period, your criticism is anachronistic.  It amounts to criticizing a scientist as "alarmist" for publicly reporting the best science at the time; which clearly shows it comes from a desire to criticise rather than a desire to fairly assess what Hansen has said.

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  43. One of the problems with the Climate crisis is that slow motion that it occurs.  Watching glaciers move is positively speedy.

    In watching my own attitudes to things, for many things if it's more than 3 years to a consequence it doesn't exist.

    This changes for individuals at certain times.  E.g. when you have kids, then 20 years for certain topics of interest is normal.

    One of the questions to ask people:  "How far in the future should we plan?  And then guide them through a few scenarios:  

    • Should cities buy up right of way for mass transit and freeways that won't be needed for 50 years.  How about 10 years?
    • Your town is a mining town.  At the present technology the mine will run out of ore in 15 years.  As city counselor and as a business man with various inventments what do you think your city should be doing regarding things that are beyond the end of your 3 year term?
    • A new medical treatment for obesity comes out.  It works *really* well for about half the population.  The other half it kills over the span of 5 years.  There is no certain way to tell the people apart until symptoms show.  What are the implications for your town?

    This is training in taking the long view.  Most people feel far more connected, more able to affect decisions, to the local comunity than to the nation.

    Initially all the scenarios should NOT work in the field of climate.  Much of the scenario development stresses what the research has found out.  Get them to make decisions based on 'best guess' of what's going on now.

    After a time of this summarize the methods used.  Talk to the people who should know. Talk about how to trust what they say.  If there are numbers, crank the numbers.  Make the best decision you can, based on the current knowledge.  Start to act on that decision. 

    Now bring in one that has definite pre-set attititudes.  Point out where they depart from the decision model they just used.

    At this point don't try to convince them they are wrong.  Try to convince them to use the model that seems to work so well.

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  44. Tom,

    I noticed on review that I left out some adjustments in my data on temperature.

    1) The temperature data is from Antarctia and the IPCC estimate is global.  Antarctic temperatures are expected to raise at least double the global average so 10C instead of 5C.

    2) The IPCC data is calculated using the Climate Sensitivity not the Earth system sensitivity.  This adds another 50-100% to the rise.  This makes the expected final rise 15-20C.  It would be several hundred years (or thousand) to equilibrum of the Earth System Sensivity.  Current temperatures are probably slightly below the highest spike in the record (the temperature scale is 0-4C to compare to 15C increase expected).  Hansen's estimate was certainly reasonable.  Jason Box's estimates of sea level rise are comparable to this fingernail calculation (sea level rise is proportional to temperature).  Perhaps Roger can find a 2,000% error in my calculations or Dr. Box's (and supply a citation).  RPC 2.6 is only a little higher than the past 3 million year estimate.

    When you do this calculation the change is unbelievable!  How can we even be discussing such a change?  Ditto with Box's sea level rise of 23 meters from CO2 already in the atmosphere!!

    It might be interesting to have a dedicated thread for poetry.  I am sure others could write interesting odes.  I don't think we need an OP.

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  45. michael sweet @94, a couple of points.

    First, on see level rise it is well worth looking at the blog posts by Aslak Grinsted, particularly

    his view in 2009, his update of that view in 2013 in light of three recent papers; and his view on the rate of sea level rise.  From those pages, his 2009 graph is very interesting and does not require major modification in light of the later papers:

    This plots expected sea level rise relative to projected long term global temperature anomalies.  As we are already committed to somewhere between 6 and 25 meters of sea level rise, with a mean estimate of about 12 meters (values judged by eye from the graph).

    All three recent papers suggest the increase in sea level with temperature will be fairly flat for a given temperature range, and then ramp up suddenly.  The disagree, however, about the temperature range.  The empirical data suggests greater than 20 meters of sea level rise even for a 2 C rise in temperature.  The model based data suggests we will not reach 20 meters even at about 5 C.  Grinsted's take is that:

    "At 2°C (383 ppm) we will lose the Greenland ice sheet. We do not really know how strongly the West Antarctic will respond. There is evidence of a large response during the last interglacial though (e.g. this).
    At 4°C (525 ppm) then we are pretty much committed to an eventual complete deglaciation of both the West Antarctic ice sheet and the Greenland ice sheet.
    At 6°C (720 ppm) we may be committed to an ice free planet."

    On short term sea level rise, these are his semi-empirical predictions, with uncertainties:

    The second point is that projecting Earth System Sensitivity, or even Equilibrium Climate Sensitivity on current CO2 levels is ill advised as the CO2 levels will reduce if we eliminate all net greenhouse emissions.  That is big if, as even 5% of emissions is likely to maintain levels at a constant value, and any higher than that (and certainly if higher than 10%) will result in an ongoing increase.  I suspect, however, that if we can transition to a renewable energy economy, zero net emissions is feasible provided we keep in mind that it is necessary to avoid the worst consequences of climate change.

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  46. [JH] Moderator's Comment

    Roger Knights: 

    Your most recent posts constituted sloganeering and were deleted. In addition, I have recommended that your posting privilege be rescinded. 

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  47. Roger Knights drew attention to this video in which Hansen says (among other things) that "If we allow emissions to continue at a high rate ...":

    "On the long run, if that really happened, ... over centuries we could actually get a runaway greenhouse effect"(1:16)

    He later says:

    "But with continued rapid increase in greenhouse gases, you could melt the ice sheets in less than a century"(3:40)

    With regard to the later claim, it is implicit in his view that the rate of sea level rise due to melting ice sheets could double every decade (from which comes his claim of a potential 5 meter sea level rise this century (see my comment @81).  If that doubling of sea level rise due to melting ice continued to 2135, you would have a melting of over 70 meters of sea level - something requiring the melting of all major ice sheets.  Even switching to a linear melt in 2110 results in a complete melting of the (then remaining) ice sheets within 100 years, ie, by 2210.  So, the claim is not new, and is not a claim about what could happen in this century.  It is, however, a claim about what could happen in some not to distantly future century.

    Nor is his claim about the potential (not certainty) of a runaway greenhouse effect new to him.  Furthermore, unlike the claims about ice melt, it is a claim he is entitled to make in one respect in that he certainly has the relevent expertise to have an opinion on the subject.  Nearly half of his pre-1981 publications are on aspects of the greenhouse effect on Venus.

    Like Roger Knights, however, I do consider these claims to be alarmist.

    Before progressing, I should define my terms.  By "alarmist" I mean a view on the pessimistic side of the scientific concensus.  The scientific concensus, in turn, is that view held by 90% plus of scientists with the relevant expertise.  Note that the consensus need not be a singular view.  Thus on climate sensitivity, the consensus is not that the (central estimate of the) ECS is 3, but that it lies between approximately 1.5 and 4.5.  The range is given by the likely range of the IPCC (ie, the 66% confidence interval) because the conjoint uncertainty estimate must extend beyond range of the central estimates.  Therefore the concensus range is less than the 90% uncertainty interval given by the IPCC (or in the case of ECS, not actually given).  

    The range of the concensus position need not be reducible to a simple numerical range, as is the case with ECS.  The consensus view on clathrates (as I understand it) centers around two views - one that clathrates are, and one that they are not a serious threat.  The former is associated with certain experts on methane in the Arctic, and the latter in particular with modellers of the carbon cycle.  It follows that the concensus position on clathrates is a diffuse position consisting in what is agreed by both sides of the dispute rather than a more precise statement such as could be obtained from one side or the other.

    So, having thus defined alarmism (and the concensus), what of Hansen's views.

    On runaway greenhouse, there is no doubt.  The concensus position is that it is not possible given the current amount of radiation recieved from the Sun.  Note that that is not absolutely certain.  If the Earth's albedo was 0.05, for instance, the Sun would provide enough energy for a runaway greenhouse effect on Earth.  Consistent with this, Hansen considers the presumed large reduction in albedo from a melting of the ice sheets a necessary precondition for runaway greenhouse.  Further, there is uncertainty about the strength of the combined water vapour feedback (water vapour plus lapse rate feedbacks).  If it is in the upper end of the consensus range, a higher albedo is consistent with a runaway greenhouse effect - though not an albedo equivalent to the current value.  Therefore it is not self evident that Hansen's view is unreasonable, and certainly not that it is pseudo-scientific.  It is, however, on the extreme margin of scientific thinking and "alarmist".

    Likewise his opinion about the doubling every decade of the sea level rise due to ice sheet melt is clearly in disagreement with the scientific concensus.  That consensus is that even with ongoing emissions sufficient to melt the entire Antarctic ice sheet (which itself would take centuries), the actual melting of the ice sheet would take many centuries and likely several thousand years.  A time to melt all the ice sheets of 500 years would not be clearly outside the consensus, nor yet a time of 10 thousand years.  But 100 years is clearly so.

    So, Hansen on at least two points, is alarmist.  As it happens, SFAIK, he is only alarmist on those two points and the potential effect of the Alberta tar sands.  On other points he tends to be very close to the scientific concensus.  

    What is interesting, however, is what is implicit in the criticism of his views as "alarmist".  Absent a clear comparison with consensus positions it is mere name calling.  With that comparison, it suggests that scientist should restrict themselve in public communication to the consensus position - or at least indicate where they disagree with the consensus position, and why.  The later should include a clear indication as to why the consensus position is reasonable, followed by discussion of why it is disagreed with.  Further, there is not scientific difference between disagreeing with the concensus on the plus or minus side.  So, criticism of Hansen as "alarmist" is mere name calling if it is not paired with criticism of Lindzen, and of Spencer and Christy for being (even further) outside the scientific consensus.  (Indeed, I would go further in their cases in that they have ventured into the realm of pseudo-science on several occasions, with the possible exception of Spencer.)

    I do not expect Roger Knights to criticize the leading "skeptical" scientists as pseudo-scientists.  As he pushes the "alarmist" line, however, I do expect him to criticize them (and Watts) for not being within the consensus.

    Or are we to understand by his criticisms that they are mere name calling.

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  48. Far be it for me to even attempt to amplify on Tom's rigorous comments, but I would like to expand on this brief point:

    "On runaway greenhouse, there is no doubt. The concensus position is that it is not possible given the current amount of radiation recieved from the Sun."

    Hansen himself has repudiated that earlier position of his (WRT a Venus-style runaway):

    "With the more realistic physics in the Russell model the runaway water vapor feedback that exists with idealized concepts does not occur. However, the high climate sensitivity has implications for the habitability of the planet, should all fossil fuels actually be burned.

    Furthermore, we show that the calculated climate sensitivity is consistent with global temperature and CO2 amounts that are estimated to have existed at earlier times in Earth's history when the planet was ice-free.

    One implication is that if we should "succeed" in digging up and burning all fossil fuels, some parts of the planet would become literally uninhabitable, with some time in the year having wet bulb temperature exceeding 35°C.

    At such temperatures, for reasons of physiology and physics, humans cannot survive, because even under ideal conditions of rest and ventilation, it is physically impossible for the environment to carry away the 100 W of metabolic heat that a human body generates when it is at rest. Thus even a person lying quietly naked in hurricane force winds would be unable to survive.

    Temperatures even several degrees below this extreme limit would be sufficient to make a region practically uninhabitable for living and working.

    The picture that emerges for Earth sometime in the distant future, if we should dig up and burn every fossil fuel, is thus consistent with that depicted in "Storms" — an ice-free Antarctica and a desolate planet without human inhabitants"

    [Source LINK]

    So no runaway. But Hansen notes that it won't take a runaway to basically completely eradicate civilization as we know it.

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  49. It pains me to read that a scientist of any qualification could imagine a regular doubling of a rate of sea level rise i.e. a faster than exponential rate of change!

     No wonder he corrected himself.. (He did correct himself, didn't he!??!)

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  50. Willis Eschenbach on WTF just repeated this myth about James Hansen's "prediction" of the West Side Highway being covered by now.

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