The Intersection

Ice Age Predictions in Context

For reasons that will remain obscure, I was recently reading a 1978 volume of the journal Oceanus, published by the Woods Hole Oceanographic Institution. And in light of the tripe we often hear about how in the 1970s scientists were worried about a New Ice Age, one passage in particular stuck out to me. It’s from a paper by one John Imbrie, a Brown University oceanographer, entitled “Global Perspectives on our Changing Climate” (p. 65-70, Number 4, Fall Issue 1978, “Oceans and Climate”). Here’s what it had to say about this subject:

…there is no doubt that the 40 year cooling trend exhibited by the hemispheric average is real, and demands an explanation. Unfortunately, this phenomenon–like so many other characteristics of climate–is not fully understood.

Despite this uncertainty, some journalists and other writers–eager to dramatize a blizzard or draw attention to a prolonged cold snap–publish interpretations each winter based on the observed 40-year cooling trend. The logic of these prognostications is simple: having persisted for many decades, the trend can be expected to continue indefinitely, until the Earth enters another ice age. It is even possible to calculate when this new ice age will occur; given a 0.6 degree Celsius decline every 40 years, it would take 400 years to reach a temperature level characteristic of the last major ice age, some 6 degrees Celsius cooler than today.

However, before those readers of Oceanus who live in New England rush to put their homes up for sale and move to the Sunbelt, they should remember that making predictions based on trends of unknown origin is a risky business indeed–a principle that many investors in the stock market will confirm. In fact, many modern prophets of climatic doom have no more justification than the soothsayers of old, who, on observing a three-month cooling trend each autumn, built mid-winter bonfires to encourage the god of the sun.

Um, it doesn’t seem like this scientist was very worried about a “new Ice Age” back in 1978, even if perhaps the popular press was….


  1. #1 John McKay
    June 28, 2006

    You should probably mention that John Imbrie is probably the scientist most responsible for articulating the current concensus model on what causes ice ages.

  2. #2 Chris D.
    June 28, 2006

    I remember, as a kid, watching the Ice Age episode of In Search Of with the spooky narration by Leonard Nimoy. As soon as it was over, I ran out to my dad, who was doing something in the garage. “An Ice Age is coming! We’ve got to do something,” I declared. He said something to the effect of “Uh-huh.” Then I remember wandering back inside wondering how he could be so dismissive in the face of such a threat. Same thing with killer bees. Anyhow, I recently read Doug MacDougall’s book Frozen Earth and really enjoyed it. I definitely recommend it for the layman wanting to know more on the subject.

  3. #3 Steve Reuland
    June 28, 2006

    “And in light of the tripe we often hear about how in the 1970s scientists were worried about a New Ice Age…”

    No, the great worry back in the 70s was the not the New Ice Age, it was the New Age. Global warming denialists have simply gotten the phrase mixed up, though they are correct that it had scientists in a state of near panic.

  4. #4 laurence jewett
    June 28, 2006

    Just goes to show that whenever one reads in the popular (think-tank-enamoured) press that “Scientists said …”, one should first ask, “Which scientist?” (singular) immediately followed “What did he/she ACTUALLY say?”

    The reason for the latter question is made obvious by quoting Brown University oceanographer John Imbrie (above), out of context:

    “There is no doubt that the 40 year cooling trend exhibited by the hemispheric average is real… having persisted for many decades, the trend can be expected to continue indefinitely, until the Earth enters another ice age.”

  5. #5 Lance Harting
    June 28, 2006

    I think the following quote from Imbrie’s journal article is very sanguine to the current debate over global warming.

    “…making predictions based on trends of unknown origin is a risky business”

    This is the point that Lindzen and other “denialists” are trying to make about the current doomsday predictions of AL Gore and others. The Scientific consensus is not that we are headed for an apocalyptic meltdown, but that there has been a less than one degree rise in global mean temperature over the last century and that anthropogenic sources are probably at least partially responsible.

    In contrast Al gore, while on NPR’s “Fresh Air” stated that we were facing a “global emergency” that threatened the “existence of civilization”. I don’t think that calling these statements “alarmist” is an overstaement. I guess he could have been a bit more Cassandra-like by declaring a “galactic emergency”.

    I am a scientist (physicist) and take no umbrage at being called a “skeptic”. Indeed skepticism is the root of all scientific endeavor. You seem to think that the key to good science is to take a poll and then shout down and ridicule anyone that is outside the “consensus”. Especially if you can make political hay from the public panic that may ensue.

    You are a “progressive” political blogger and wouldn’t have the slightest interest in climate science if you didn’t smell a political angle that you could exploit.

    Your use of words like “Senator Crank” and “denialist” show that you aren’t even an evenhanded journalist. A quick review of your “credentials” shows your true interests are in advancing “progressive” ideological positions.

    Before you label me a republican stooge let me say that I share many of your political opinions. I’m just not willing to whore science to forward my political goals.

  6. #6 Jon Winsor
    June 28, 2006

    Mr. Harting:

    What radical agenda has Chris come out for? Most of what I’ve seen him advocate is pretty science-specific, like reinstating the Office of Technology Assessment and wanting the Bush administration to refrain from staffing non-experts in government positions requiring scientific expertise. Fire-breathing radical, that Chris Mooney.

    As for “Senator Crank”, do you, Mr. Harting, believe that climate change is the “greatest hoax ever perpetrated on the American people?” How do you feel about Inahofe’s latest press release? Talk about “whoring science.” That press release is just a minefield of inaccuracies and misleading statements–and it’s written by someone who in the past has really not been too friendly to scientists.

    When considering things like this, as an opinion journalist, Chris is well within his rights to exersize a bit of humor when describing the Senator’s behavior.

  7. #7 Johnny Vector
    June 28, 2006

    Hmph. Well speaking as a physicist, I apologize for the comment by Lance Harting. Not all of we physicists presume to be automatic experts in all fields of physics. Given that at this point essentially all atmospheric scientists agree that the data points unambiguously to anthropogenic climate change, well me personally that’s where I defer to their years of training, and expertise in the area.

  8. #8 laurence jewett
    June 28, 2006

    I don’t know about interviews of Al Gore on NPR’s Fresh Aire (not my first [or even 100th] choice for accurate information on science-related issues), but I HAVE heard from reputable, informed sources (actual climate scientists) who are in a good position to judge that Al Gore’s movie basically “got the science right” on global warming — something the denialists still seem to be having a very difficult time doing.

    For example, University of Washington isotope geochemist said the following on the Real Climate website:

    “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.”

    Then, there is also this:

    WASHINGTON – The nation’s top climate scientists are giving “An Inconvenient Truth,”Al Gore’s documentary on global warming, five stars for accuracy. — By SETH BORENSTEIN, AP;

    Yes, I know. I know. Senator Inhofe has attacked the above article but that is addressed by Tim Lambert here:

    Besides, why address the science in a rational, adult manner when we can engage in calling each other names like “whore” (or what is far worse, “Progressive”. Ouch!)

    All the physicists I know are far more interested in debating science than in engaging in childish name-calling, but then again, perhaps that is just because, like myself, they were educated in the years before the “The General Theory of Name-calling” became a required part of the physics curriculum.

  9. #9 Lance Harting
    June 29, 2006

    My comments on “whoring science” were not aimed specifically at Chris Mooney. Also my criticism of Mr. Mooney is not an endorsement of Senator Inahofe. While I wouldn’t use the words hoax to describe the current media hysteria over “global warming” I would point out that the level of doom saying is disproportional to the actual evidence. Even the worst-case scenarios of climate modelers don’t justify the claims that sea level rise will inundate Manhattan and that drought, famine, and killer storms will decimate the world.

    While I appreciate Mr. Mooney’s right to hurl invective towards the blustery senator Inahofe I note he gives Al Gore a pass on his fear mongering and exaggeration. As I said in my previous post Al has painted the bleakest possible picture. He claims that we have “at most a ten year window” to take massive steps to prevent a “catastrophe”. Perhaps you could show me the evidence for this count down to Armageddon. This is “whoring” science for political purposes. Mr. Gore, and from what I can tell Mr. Mooney, have taken a moralizing political stance that only massive government actions and punitive sanctions can “save the world”. The science supports no such proselytizing.

    As far as apologizing for my comments is concerned please don’t bother. Since when does one scientist have to apologize for the differing opinion of another? Isn’t skeptical criticism the very forge that produces resilient scientific theory? This is the kind of ad hominem assault that is typical when the “faithful” feel that the sanctity of the “global warming” gospel is being threatened by an infidel. I have tossed my alms into the plate and acknowledged the accepted facts: an approximate one degree increase in global mean temperature over the last century, substantially due to anthropogenic CO2. Like it or not those are the only real facts on the table. The rest is conjecture based on computer models trying to analyze nonlinear systems involving literally hundreds (if not thousands) of independent and interdependent variables.

    Now I readily admit that I am not a climate scientist, but I have tried my hand at analyzing multi-dimensional nonlinear systems. I wouldn’t bet my lunch money on the accuracy of such models let alone the economic well being of millions if not billions of people. Such chaotic systems are largely unpredictable by definition.

    I suppose that blaspheming the prophecies of saint Al was the transgression that drew the rebuke. I would just like to see a clear-headed discourse that leaves behind partisan political hyperbole and moralizing condemnation. Perhaps my “whoring science” remark was a bit emotional, but I feel it is accurate when applied to much of the political discourse that is masquerading as scientific debate on the subject of climate science.

  10. #10 Jon Winsor
    June 29, 2006

    Incidentally, in case you want a rundown on what was wrong with Sen. Inhofe’s press release, Tim Lambert has a post on it:

  11. #11 Lance harting
    June 29, 2006

    Again the ad hominem attacks. I called no one a name. I only pointed out that distorting science to promote one’s politics is abusing the principles upon which science is founded. I also acknowledged that the verb “whoring” was a bit emotional.

    I thought the word “progressive” was the currently preferred term of folks that write for environmental advocacy journals in which Mr. Mooney’s work has been featured (i.e. Grist, Mother Jones, etc.) No offense was intended; indeed many of my own political opinions are often described as “progressive”.

    I assume no one is laboring under the delusion that this website is politically neutral. I don’t expect everyone to converse in monotone declaratives, “Spock-like” in their absence of personal emotion.

    What I would hope for is the acknowledgement that one need not be labeled a knuckle-dragging “denialist” for having the temerity to infer that global warming may not bring about the extinction of our species or that there is scientific unanimity on the validity of sensationalized predictions of doom based on computer climate models.

  12. #12 Jon Winsor
    June 29, 2006

    Well, I’m looking at the index of the Republican War on Science and Al Gore is only mentioned twice, and both only in passing. And as far as this blog goes, the one recent post of where Chris mentions Gore, he’s saying that he liked his movie but had some concerns that it may mislead people into believing that climate change caused particular storms.

    So I think you’re going to have some trouble making the case that Chris writes hagiography for Al Gore.

    And I believe the “ten year window” remark originated with James Hansen. Gore is just quoting him, I believe.

    Hmm, there seems to be an awful lot of interest in personalizing this issue so that it’s all about Al Gore. To me that smacks of political strategy rather than reflection on the science and the risks that scientists are describing.

    Incidentally, we’re getting off topic. This is a thread about the Ice Age brouhaha back in the 70’s. Do you have anything to add on that subject?

  13. #13 Laurence Jewett
    June 29, 2006

    Mr. Harting, you posted above that “I readily admit that I am not a climate scientist”.

    Sites like Real Climate
    provide good explanations/discussions of many of these issues for those who are not climate scientists — or even scientists, for that matter.

    If you read what some of the climate scientists have posted there, you may learn something about climate science and climate modeling about which you are currently unaware.

    At Real Climate, one can also find point by point analyses of the positions taken by Lindzen, Gray, Senator Inhofe, and others (even an anlysis of the “science” in Michael Chrichton’s book “State Of Fear”)

  14. #14 Scott Church
    June 29, 2006

    Mr. Harting,
    “This is the point that Lindzen and other ‘denialists’ are trying to make about the current doomsday predictions of Al Gore and others. The Scientific consensus is not that we are headed for an apocalyptic meltdown, but that there has been a less than one degree rise in global mean temperature over the last century and that anthropogenic sources are probably at least partially responsible.
    In contrast Al Gore, while on NPR’s ‘Fresh Air’ stated that we were facing a ‘global emergency’ that threatened the ‘existence of civilization’. I don’t think that calling these statements ‘alarmist’ is an overstatement. I guess he could have been a bit more Cassandra-like by declaring a ‘galactic emergency’.”

    Without stepping into the whole ad-hominem debate, there’s at least two fundamental differences between Lindzen’s brand of “skepticism” and Al Gore’s “alarmism” as far as this subject is concerned. Science and money.
    The original investigations into “global cooling” during the 70’s centered mainly around a 1975 report by the National Academy of Sciences on cooling trends and one or two other papers, the most notable of which was probably Hays et al. (Science, 1975). Those discussions revolved around what was then known, and what might possibly be expected from natural and man-made aerosols (discussions mind you… not predictions), and the Milankovich effect. The latter involves shifts in climate due to gravitational perturbations in the orbit of the earth or its nutation that happen on timescales far longer than anything relevant to the next few centuries (the time constant for such cycles is generally on the order of millennia). In other words, none of this ever was, or currently is, relevant to discussions of manmade global warming. But this doesn’t keep global warming skeptics from bringing it up every chance they get as “proof” of “alarmism”.
    As for there being “less than a degree” of global temperature rise in the last century (a deg. C that is, not F), that’s a fairly significant rise. A degree of global temperature rise is very different from a one degree rise in your bathtub. It carries with it a great deal of regional change that can have (and in fact, has had) all sorts of impacts. In the coming century for instance, the sea-level rise expected from those few insignificant degrees of warming that we shouldn’t be worried about is expected to completely flood the entire nations of Tuvalu and Kiribati. This may mean nothing to you, but I assure you that is will be a big deal to the people of those nations! I have friends in Kiribati. Believe it or not, they actually matter to me, and I don’t relish the thought of them losing their homes, their livelihoods, and their heritage, even though my home and personal wealth are less likely to be impacted by this.
    Furthermore, as a physicist you of all people should be aware of the fact that systems respond differently to being forced than components, and there’s a phase lag involved that varies inversely as the system’s “capacitance”–a fact well known to any undergraduate differential equations student. Though the atmosphere can be thought of as a “soft” thermal “spring”, the oceans constitute a huge thermal mass, and there is a corresponding increase in the time constant for system response–almost a century. Before the 70’s we were seeing temperature trends due mostly to various combinations of solar, volcanic, natural and manmade aerosols, and other effects (rises early in the century, declines during the middle). Now is when we’re beginning to see the warming that our CO2 inputs have held “in the pipe” during this period, and from here on out the response is not going to be similar to the past–in speed or magnitude. Bear in mind that the same physics that says is hard to get a wagon full of bowling balls moving with a slinky also says that it’s even more difficult to stop it once it’s in full motion.
    We “alarmists” tend to worry about very heavy things that are difficult to stop–especially when things we care about are in the way.
    The other piece is money. Nearly every one of the publicly prominent skeptic “scientists” like Lindzen who are loudly decrying “Cassandra’s” like me are being paid exorbitant fees for doing so by Exxon/Mobil, Western Fuels, Unocal, Shell, GM, and other polluting industry interests. Lindzen is a case in point. As of the late 90’s his industry consulting fee was $2500 per day. He loves to wax eloquent about how “alarmist” scientists are only in it for the funding he thinks they’ll get from producing alarmist research. Needless to say, he carefully avoids any discussion of why they should expect funding for alarmist research from a Far-Right presidential administration and Republican controlled Congress. That discussion might prove somewhat uncomfortable. And it’s not like these money-grubbing scientists have deep industry pockets to fall back on like he does!
    Though I’m not a research scientist, I’m one of the “alarmists” he loves to rant about. His consulting fee from polluting industries alone, apart from his MIT salary, would pay more than my entire annual income by mid September if he only worked 2 or 3 days a week. Do you really expect me to believe that this doesn’t impact his objectivity? If so, what exactly do you think is impacting mine and that of the publishing scientific community in general? I assure you that I don’t get paid what he does. In fact, I don’t get jack from anyone about anything I’ve written on this subject.
    Unless of course, you count hate-mail from skeptics.
    All the best.

  15. #15 laurence Jewett
    June 29, 2006

    It has been said by many others before, but it can not be overemphasized, that humans are performing a mammoth experiment on the earth’s atmosphere/climate that may very well be irreversible.

    It may have effects that we can forsee (sea level rise and consequent indundation of lowlying areas) and it may also have deleterious effects that we do not now forsee. (One characteristic of nonlinear systems is that they can respond in qualitativeley different ways when pushed beyond certain bounds and seemingly insignificant changes in inputs can produce quite significant outcomes).

    If we (or more likely our children and grandchildren) do not like the results of our experiment, we (or they) may simply be “out of luck.” Due to the long time lags referred to above (lag between drop in atmopheric CO2 and drop in temperature), there may very well be no second chances, for all intents.

    If ever there was a good argument for the “precautionary principle”, this is it. If some consider it “alarmist” to be (possibly overly) cautious about what we do to the earth’s atmosphere and other life support systems, so be it.

    Though it is the proverbial “elephant in the room,” the most critical element of all (by far) is that the earth is only liveable planet we have (or are even aware of) and we owe it to future generations to act wisely — and cautiously now.

  16. #16 Barry
    June 29, 2006

    Lance, I’m not a physicist, so please forgive me if I’m unfamiliar with physics culture. But in some other fields, walking in and immediately showing that you don’t know what you’re talking about *decreases* your credibility.

  17. #17 Lance Harting
    June 29, 2006

    Well I certainly appreciate the well-reasoned and thoughtful responses (with the possible exception of Barry’s snide comments).

    To Jon Winsor, I have no personal axe to grind with Al Gore. He just happens to be the current focus of the debate, in this blog and else where, due to the recent release of his movie.

    I just pointed out that his remarks could hardly be more sensational or emotionally charged. Being new to this site I observed that Chris made no mention of his over the top predictions and doom saying. I took this as an indication that perhaps he shared Mr. Gore’s opinions on the subject.

    To Laurence Jewett, though I have acknowledged that climate science is not my venue I have read the literature extensively. I have been to realclimate many times. I am not too impressed with Mr. Mann’s work. His site is largely a vehicle for him and a few colleagues to exchange self-affirming pats on the back.

    His statistical methods, among other deficiencies in his work, have been rightly challenged. Stephen McIntyre and Ross McKitrick have created a website largely dedicated to their work showing the many problems with MBH98, one of the main studies used by the IPCC, of which Mann was a contributing author, to justify its global warming conclusions.

    The site is Unlike RealClimate it encourages criticism and openly displays the data sets and methods the authors use to do their work. It isn’t a very slick production but it is gratifyingly accessible.

    To Scott Church, your post is an eloquent summation of the position held by many people that are convinced that the climate models are based on sound science and that their dire predictions should be accepted.

    Thanks for the well written, if a bit condescending, refresher. Yes I do remember Hook’s Law and the concept of inertia.

    I just don’t share your confidence in the certainty of the conclusions reached by these climate models. When it is pointed out that current climate conditions do not reflect the predictions made in the early 1990’s a variety of explanations (excuses?) are brought forward, such as aerosols moderated the expected effects.

    Well that is just the point, if negative feedbacks like aerosols have been overlooked in past iterations of these models than what confidence should we have that current parameters and algorithms are any more prescient?

    As for impugning Mr. Lindzen’s motives I would hasten to remind you that his qualification are somewhat unimpeachable. He is the Alfred P. Sloan professor of Meteorology and Earth Science at MIT. He is a member of the National Academy Of Sciences and was a lead author in the IPCC report on Global Warming.

    He continues to produce respected work in climate science and even his critics in the scientific community don’t claim he is a shill for the oil industry as you have. This is representative of the kind of ad hominem mudslinging to which the debate has degenerated.

    Also the frequently made argument that the consequenses of inaction are so potentially bad that it justifies accepting the conclusions “just in case” is not only bad science but bad logic. It also ignores the fact that these alleged remedies have very real costs and consequences for individuals and society.

    It is also akin to the same argument my fundementalist Christian parents make to accept “Pascal’s wager”. “If we’re wrong what’s the harm? If we’re right your going to hell!” I reject it’s use in both cases.

    I have no dog in this fight. I just would like an honest scientific discussion that doesn’t attempt to paint me as an unknowledgeable cretin or heartless moneygrubber if my take on the evidence isn’t in lock step with the acerbic leftist editorials in Grist.

    It is making me miss the quiet and tepid discussions of spin-lattice relaxation rates in my field of ESR research. Well OK this is more fun.

  18. #18 Scott Church
    June 30, 2006

    Mr. Harting,
    My apologies if I seemed condescending. It wasn’t my intention. This issue is one I care about, and I’ve spent a lot of time lately confronting some folks who are even more bellicose than they are ignorant. It’s starting to wear on me. Yes, I’m well aware of Lindzen’s credentials and his work with the IPCC. I actually have a section at my own web site that discusses some of his more recent work on negative feedbacks. You are right that he is one of the more truly accomplished scientifically of the skeptic community, and has in fact done much good work. This includes (in my mind anyway) his role as a published skeptic in that even if he end up being wrong, he has provided a much needed check that keeps the more mainstream community on their toes (in fairness, my reference to him as a “scientist”–in quotes–was made largely in irritation).
    But unfortunately, he has tainted himself in recent years. He has devoted over a decade now to finding some kind of negative feedback mechanism–any kind at all–that will blunt the end of global warming and restore status quo. To some extent, fine. But this has become a personal crusade for him–a holy grail that he’s been after for over a decade now, all the while loudly insisting that such a mechanism exists despite his ongoing failure to demonstrate one. While his recent “iris effect” work is some of his best to date, other researchers have not been able to reproduce his numbers, and it now appears that his satellite data and conclusions were contaminated by other effects he hadn’t considered (there’s more about this is at my global warming science page).
    The less successful the man is at proving any of this, the louder he insists that anyone who dares to dispute him on it is an idiot. Add to that the fact that he’s begun chronically repeating many of the same misconceptions paraded about by industry funded mouthpieces who have little or no scientific acumen, and you do not get a picture of objectivity. Fer Gawd’s sake, even Michael Chrichton, who ain’t going to win any awards for his climate science literacy, fashioned the “hero” of his own global warming “conspiracy” potboiler after the guy!
    It’s been some time now since I’ve seen Lindzen offer anything other than polemics, and as you’ve rightly pointed out, polemics aren’t what we need these days.
    All the best.
    PS – Actually, your “tepid” discussions of spin-lattice relaxation rates sound pretty interesting to me. My own masters is in applied physics too. I did my thesis on larmor coupled optical pumping in alkali metals, and that brings back some good memories!…

  19. #19 ZF
    July 9, 2006

    Speaking from the outside world, it’s funny to see scientists and other academics turn so rapidly to hurling their certificates at each other and questioning each other’s motives and reputations. If you guys were at all serious you would see that this just trashes any influence you might have had beyond the campus.

    The most remarkable feature of the climate change debate is precisely the way it illustrates how little influence academics have left (and yes I know you’ll all instantly blame this on everyone else’s ignorance, but it’s not so).

    It’s apparent to outsiders that you’re all entranced by the idea of at last exerting some sort of influence in the real world, but fall at the first fence because you collectively have no idea how to go about it.

  20. #20 non fear mongerer
    October 15, 2007

    those that want to blow off the fact that some scientists say it is cyclical, what makes your scientists the right ones? Just as back then, we still don’t know. True we should do what we can to help the environment, but I will not live like tomorrow the earth will burn up because none of us know. Unless you yourself are a scientist can you argue with me and then I wouldn’t believe your argument unless you gave me factually convincing arguments, otherwise I will believe you to be one that wants to continue making a living by grants. For all we know – it could be cyclical which only makes sense. The salt content gets too high for ocean life then more fresh water is needed to lower the levels. How would that happen if we didn’t have periods of cooling and periods of warming? We honestly only have a little of a hundred years of actual factual data to be able to figure out what is going on and when we haven’t the factual data from the many hundreds of thousands of years the earth has been around.

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