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The global cooling mole

By John Fleck and William Connolley

To veterans of the Climate Wars, the old 1970s global cooling canard – “How can we believe climate scientists about global warming today when back in the 1970s they told us an ice age was imminent?” – must seem like a never-ending game of Whack-a-mole. One of us (WMC) has devoted years to whacking down the mole (see here, here and here, for example), while the other of us (JF) sees the mole pop up anew in his in box every time he quotes contemporary scientific views regarding climate change in his newspaper stories.


The problem is that the argument has played out in competing anecdotes, without any comprehensive and rigorous picture of what was really going on in the scientific literature at the time. But if the argument is to have any relevance beyond talking points aimed at winning a debate, such a comprehensive understanding is needed. If, indeed, climate scientists predicted a coming ice age, it is worthwhile to take the next step and understand why they thought this, and what relevance it might have to today’s science-politics-policy discussions about climate change. If, on the other hand, scientists were not really predicting a coming ice age, then the argument needs to be retired.

The two of us, along with Tom Peterson of the National Climatic Data Center, undertook a literature review to try to move beyond the anecdotes and understand what scientists were really saying at the time regarding the various forces shaping climate on time human time scales. The results are currently in press at the Bulletin of the American Meteorological Society, and Doyle Rice has written a nice summary in USA Today, and an extended version based on a presentation made by Tom at the AMS meeting in January is on line.

During the period we analyzed, climate science was very different from what you see today. There was far less integration among the various sub-disciplines that make up the enterprise. Remote sensing, integrated global data collection and modeling were all in their infancy. But our analysis nevertheless showed clear trends in the focus and conclusions the researchers were making. Between 1965 and 1979 we found (see table 1 for details):

  • 7 articles predicting cooling
  • 44 predicting warming
  • 20 that were neutral

In other words, during the 1970s, when some would have you believe scientists were predicting a coming ice age, they were doing no such thing. The dominant view, even then, was that increasing levels of greenhouse gases were likely to dominate any changes we might see in climate on human time scales.

We do not expect that this work will stop the mole from popping its head back up in the future. But we do hope that when it does, this analysis will provide a foundation for a more thoughtful discussion about what climate scientists were and were not saying back in the 1970s.

Update: Full paper available here.


243 Responses to “The global cooling mole”

  1. 1
    Nick Gotts says:

    Excellent! A really heavy mallet to whack that mole with!

  2. 2

    This is a very important post and BAMS article — since the cooling nonsense remains the most common attack on climate scientists I get when speaking or writing on the subject. Kudos to your work on it.

    I blogged on your work here:
    http://climateprogress.org/2008/02/22/another-denier-talking-point-global-cooling-bites-the-dust/

    I also think you may want to address the other pieces of “cooling” nonsense — that we are now in a cooling trend, either since 1998 (!) or, more recently, since last January.

    I discuss that here:
    http://climateprogress.org/2008/03/02/media-enable-denier-spin-i-a-sort-of-cold-january-doesnt-mean-climate-stopped-warming/

    Hansen has also debunked it:
    http://climateprogress.org/2008/03/03/hansen-throws-cold-water-on-cooling-climate-claim/

    Keep up the great work!

  3. 3
    Tom says:

    Thanks for a great summary. I have been eagerly awaiting commentary on the recent hyping of a new sunspot minimum and ensuing Little Ice Age by the denial side. Any plans?

  4. 4
    Timo Hämeranta says:

    Well, for media only bad news are good news. Back in the 70s it was the just coming Next Ice Age, nowadays it’s the just coming disasterous GW.

    What about the study

    Miskolczi, Ferenc M., 2007. Greenhouse effect in semi-transparent planetary atmospheres. Idojaras Vol. 111, No 1, pp. 1-40, January 2007, online http://met.hu/doc/idojaras/vol111001_01.pdf

    Quote from DailyTech March 6:

    “Runaway greenhouse theories contradict energy balance equations,” Miskolczi states. Just as the theory of relativity sets an upper limit on velocity, his theory sets an upper limit on the greenhouse effect, a limit which prevents it from warming the Earth more than a certain amount.

    How did modern researchers make such a mistake? They relied upon equations derived over 80 years ago, equations which left off one term from the final solution….”

    [Response: Runaway Greenhouse is a strawman. I'm sure someone will take the paper to bits properly. The obvious problem for it is to explain the ice age cycle -William]

  5. 5
    Patrick Henry says:

    Instead of endlessly bringing up the past, how about concentrating on the failures of the current models?

  6. 6
    CobblyWorlds says:

    Woo Hoo!

    It’s GW Sceptic Bingo time again!
    http://timlambert.org/2005/04/gwsbingo/
    :) :)

  7. 7

    Someone should get Newsweek to revisit their 2006 revisit of their 1975 cooling prediction, defending it as an accurate depiction of the state of science at the time. RealClimate covered it once before:

    http://www.realclimate.org/index.php/archives/2006/10/global-cooling-again/#more-363

  8. 8
    Nick O. says:

    A useful and timely post.

    To sound a note of caution, however, stand by for the counter argument to shift to what scientists were ‘predicting’ in the 1950s and early 1960s. You may also kick off a ‘citation fight’, with people claiming certain articles are not in good enough journals, or some of the data or predictions in the published papers turned out to be suspect, or the paper was not reviewed properly, or there are plenty of papers you have not cited which put the cooling argument, and so on and so on.

    Well done, anyway, and I look forward to reading the paper!

  9. 9
    Pete Best says:

    Cool!!

    Like you say maybe now we can lay this one to rest.
    Maybe a article on the 1940 to 1970 cooling may be in order and the reasons as to why?

    In future decades for example as humans clean up their pollution act how much warmer will it be? How much more additional warming will eliminating aerosoles create in w/m2?

  10. 10

    William,

    Welcome back :-)

    Does this mean that we no longer have to worry about the THC stopping due to the melting of Arctic ice, and causing conditions to return to those of the Younger Dryas stadial?

    If so, then our British Government might like to know, since they are currently spending £10M on the RAPID project which is currently throwing hundreds of buoys into the Atlantic to measure the THC.

    Cheers, Alastair.

  11. 11
    Zane says:

    Why did those 7 article gain dominance over the 44 in school texts of the time?

    [Response: It would be nice to find a school textbook from the time, to see what it said -William]

  12. 12
    Spencer says:

    Congratulations on this important work. It would be interesting (but another and even harder job) to go through the popular-press accounts of the time. Many of the moles in need of a good whack are actually responding to what the magazines etc. are saying today, not what the scientists are saying.

    I am pretty sure that a study of the popular press in the 1970s (which I’ve only browsed through, not done up statistically) would find a substantial bias toward reporting predictions of cooling, since at the time “ice age coming!” would have been a lot more attention-grabbing than “warming.” Scientists of the time did worry that they were being misquoted. But I think such a study would also find that essentially all the journalistic accounts said it was all speculation and admitted that scientists had no consensus, indeed little understanding of climate, and were not making any kind of firm prediction–that is the most important difference from the current situation.

  13. 13
    Mark A. York says:

    Well done. The whole sceptic argument rides on often repeated canards of which this has to be the top prize winner. Hopefully this much needed accounting and my upcoming novel will cement dispelling the myth of global cooling into poular culture.

  14. 14
    Jason Cosford says:

    Keep in mind that the classic paper by Hayes et al (1976) showed that isotopic composition of forams in marine cores fluctuated on orbital time-scales in accordance with Milankovitch. This supported orbital forcing of the ice ages and led to speculation that another ice age was inevitable as the planet moved toward the corresponding configuration. Much of the talk about global cooling in the 70s related to these orbital time-scales and the cause of ice ages. So the science of the day was predicting cooling, but on a completely different time-scale.

  15. 15
    tico89 says:

    Those statistics make it look as if there’s actually more denial of warming going on now than there was then–when scientists were supposedly predicting an ice age!

    It’s always good to see that a typical denier argument has little or no basis. Although, by debunking this argument, you give it more strength. The response I always use is, basically, these days we’ve got an extra 30+ years of scientific investigation–surely the scientists have got a better chance of being right.

    As others have said, it would be interesting to see by what means the ‘ice age’ ‘prediction’ was the most noticed.

  16. 16
    jbroon says:

    RE: #5 Patrick Henry said:
    “Instead of endlessly bringing up the past, how about concentrating on the failures of the current models?”

    Which current models, in your estimation, have failed?

  17. 17
    Hank Roberts says:

    Alastair, see Peter Ward. Rearrangement, not halt, of the circulation looks likely to be what caused past anoxic events. The buoy system is appropriate to detect changes including rearrangement and to get a finer grained picture of a very complicated 4-dimensional process.

  18. 18
    SecularAnimist says:

    This is helpful to know. However, since a high proportion of misnamed “skeptics” are in fact deliberate liars, who endlessly repeat assertions that they well know have been repeatedly shown to be false, it will probably have little effect on the fake, phony, Exxon-Mobil sponsored “debate” about anthropogenic climate change.

  19. 19
    Bob North says:

    Spencer – Here is at least one group that has looked at the issue of media coverage. Regardless of what one may think of their purpose for this report or their likely position on AGW, I think there presentation of the wild swings in media coverage of changing climate is probably about right.

    http://www.businessandmedia.org/specialreports/2006/fireandice/fireandice.asp

    For most people who are not reading Science or Nature or other more specialized climatology journals on a routine basis, their understanding of the current state of the science comes from media coverage of the science. Therefore, even if many or most peer-reviewed articles were discussing climate warming in the 70s, what people remember is the coverage from the popular media.

  20. 20
    Steve L says:

    I think this was good work and I don’t mean to devalue it here. But I think the entire argument, even if true, would be specious. I mean, let’s say the AGW-deniers were right and the science (not just Newsweek) said we were coming to a new ice age. A mere 10 years later that was a minority opinion and it’s only become increasingly in the minority over the last decades. Do folks making the argument really prefer the science of the 70′s to the advances in understanding that have occurred since computers, satellites, 30 more years of data, etc have come to bear on the subject? I can’t think of anything that natural science ‘believed’ in the 70′s that is demonstrably more accurate than what natural science ‘believed’ in the 90′s.

  21. 21
    Winnebago says:

    RE: #19 The claims made in that ‘report’ about the popular press coverage have also been debunked. If you click through the links in the OP, you’ll quickly see that the newspaper coverage nearly always discussed the speculative nature of the science and was nearly always buried in the ‘filler’ sections of the paper. Applying denialist SOP, that report cherry-picks quotes and grossly misrepresnts the newspaper coverage.

  22. 22
    Steve Horstmeyer says:

    Bob North #19 has a point. I clearly remember, though I no longer have the book, discussions in an undergraduate climatology class regarding the “Snowblitz” theory of climate change as written about by Nigel Calder in his book “The Weather Machine”.

    This pre-dated the Newsweek article of April 28, 1975.

    Let us not forget others that lead the way to the idea that an ice age was just around the corner.

    The “Science” articles of 1956 and 1958 by Ewing and Donn about rapid climate change were popularized in a “Harper’s Magazine” article by Betty Friedan in 1958 titled “The Coming Ice Age”.

    John Gribbin concluded that in the next few hundred years an ice age would be upon us in his “Forecasts, Famines and Freezes” (1976).

    Don’t forget the book “Ice or Fire? Surviving Climate Change” (1978) by D. Halacy Jr.where the author suggests spreading soot to melt polar ice. Does that sound like seeding the ocean with iron filings?

    [Response: I hadn't seen the Science articles of 56/8. But the "ice age" scare is usually supposed to be the 70s - sometimes the 60s - I've never heard of it in the 50s before. And a quick scan of those articles doesn't show much hint of predicting an ice age, or talking about rapid change. Which bits did you have in mind? "Snowblitz", as I recall, only appeared in the book and never in a paper (Calder did have a paper in Nature, but I don't think it had the SB in it) -William]

  23. 23

    Hank,

    Nice to see that someone understood what I wrote :-)

    Is Peter Ward’s “Rearrangement” of the THC going to lead to a warmer or a cooler climate, and who is this Peter Ward anyway?

    OTOH, If you follow the link on the RAPID page to Will global warming make European winters colder? you will find that the oceanographers from the National Oceanography Centre at Southampton University are writing:

    “Luckily the new ice age from ‘The Day After Tomorrow’, is fiction, not future. But strange as it seems, global warming might bring colder winters to the UK and parts of North-West Europe. And if it happens, the change could take place over only a decade or so.”

    In other words, we could have an abrupt cooling in the next ten years!

    Cheers, Alastair.

  24. 24
    Hank Roberts says:

    Alastair, here:
    http://www.google.com/search?q=%2B%22Peter+Ward%22+%2Bclimate
    Worth serious reading.

    For others, don’t confuse local cooling (like ‘Medieval Warming’) with the current big denial theme: new ice age when the coal runs out on the Sun. Or something like that.

  25. 25
    Hank Roberts says:

    One more reference for Alastair:
    http://www.msnbc.msn.com/id/21468803/

    (Proceedings of the Royal Society B, haven’t found a link)

  26. 26

    Timo H. posts:

    [[“Runaway greenhouse theories contradict energy balance equations,” Miskolczi states. Just as the theory of relativity sets an upper limit on velocity, his theory sets an upper limit on the greenhouse effect, a limit which prevents it from warming the Earth more than a certain amount. ]]

    Yes, it can only warm a couple hundred more degrees if all the carbon in the carbonate rocks were to be released, which won’t happen for a billion years. But it doesn’t look like this guy actually understands what a “runaway greenhouse effect” is. He should look up the planetary astronomy data on the history of Venus, where it happened.

  27. 27

    Zane says:

    [[Why did those 7 article gain dominance over the 44 in school texts of the time?]]

    What school texts? Can you give a specific citation?

  28. 28
    J. Althauser says:

    #11 Zane writes:
    Why did those 7 article gain dominance over the 44 in school texts of the time?

    They didn’t. But the examples have been repeated for many years, often as a minor note to ‘confusionist’ editorials. Small bits of text are cherry-picked to ‘prove’ the points. George Will did this in 2006 with 3 famous papers. pdfs of articles that don’t require cheery-picking are stored, linked and reused by many.

    I hope William or someone can put copies of some of the other 64 articles on the web . . .

    The public remembers some of the puzzle (perhaps only Johnny Carson jokes). After encountering misinformation often enough, many people accept it uncritically as fact. Since it wasn’t, the difference is now ‘explained’ as scientists ‘tricking’ the public. Since that is a social taboo it causes the desired mistrust and rejection.

  29. 29
    mg says:

    do any of the current GCMs predict global cooling modes?

    what sort of near-term scenarios are outputted when short-term (eg 10 year) GWPs are used instead of the conventional 100 year GWPs?

  30. 30
    Hank Roberts says:

    mg, see the white rectangle, top right of each page?

    Good exercise here for how to answer your question:

    Pasting your question into it for Google.
    (Many of the hits you get are from PR sites, which are really emphasizing the notion of a new ice age this week, curiously)

    http://www.google.com/search?q=+current+GCMs+predict+global+cooling+modes%3F

    Now, try the same thing but use Google Scholar:

    http://scholar.google.com/scholar?num=100&hl=en&lr=&newwindow=1&safe=off&scoring=r&q=+current+GCMs+predict+global+cooling+modes%3F&as_ylo=2007&btnG=Search

    See the difference?

    Scholar finds you the modeling results, including the Hadley that describes a brief flat temperature period this year from La Nina; simple Google gets you a wonderful melange of PR, denial, opinion, witnessing, and believers along with some science sites.

    You have to make up your own mind.
    First, about which tool you use, faith or science.

    Where do you start?

  31. 31
    Ike Solem says:

    The history of the development of scientific knowledge vs. the misrepresentation of that history…

    In many ways, this is a strange argument for the last remaining denialists to raise. Would they also use “Back in the 1950s, scientists didn’t believe in plate tectonics” as a criticism of modern geological science?

    For the details about the history of the ice age theories, see http://www.aip.org/history/climate/cycles.htm.

    The chief culprit might have been Cesare Emiliani:

    Calculating how the cycle should continue in the future, in 1966 Emiliani predicted that “a new glaciation will begin within a few thousand years.” . . .

    In 1972, presenting more Caribbean cores, he again advised that “the present episode of amiable climate is coming to an end.” Thus “we may soon be confronted with… a runaway glaciation.” However, he added, greenhouse effect warming caused by human emissions might overwhelm the orbital shifts, so we might instead face “a runaway deglaciation.”

    Thus, the media articles about 1970s climate science should read “Scientists warned of runaway deglaciation in the early 1970s”, shouldn’t they? Or, maybe “Scientists were unsure of the direction of future climate change in the early 1970s”, perhaps?

    The modern picture seems to be that ice ages tend to end abruptly, but the onset of an ice age is gradual, driven by changes in sunlight across the northern land masses and decreasing atmospheric CO2 levels. So, we might have been past the warmest period of this most recent interglacial, and beginning a slow, multi-thousand year descent into a new ice age – until we changed the atmospheric composition.

    However, we’ve added so much fossilized carbon to the atmosphere that we’re now approaching double anything seen in the glacial CO2 record. The Mauna Loa record shows that we’re currently at 384 ppm, increasing at 2 ppm per year. This carbon may stay in the atmosphere for a very long time. This may very well put off the next ice age entirely:

    Next Ice Age Delayed By Rising Carbon Dioxide Levels

    Dr Tyrrell said: ‘Our research shows why atmospheric CO2 will not return to pre-industrial levels after we stop burning fossil fuels. It shows that it if we use up all known fossil fuels it doesn’t matter at what rate we burn them. The result would be the same if we burned them at present rates or at more moderate rates; we would still get the same eventual ice-age-prevention result.’

  32. 32
    John Mashey says:

    Ike, if you haven’t read Ruddiman’s ,“Plows, Plagues & Petroleum”, it’s been out in paperback fro a few months, and bears on this, i.e., evidence of start of lonnnnng glaciation process possibly aborted by early CO2& CH4.

  33. 33

    Thank you for the nice mole-whacker. I will put it to good use.

  34. 34
    Danny Bloom says:

    Important work, yes. Very good post. Let’s hope the mainstream media picks this research up and runs with it.

    In this regard, the newly-minted Vaclav Klaus Climate Joke Awards might be of interest to some of the posters here. Named after the right honorable CEO of the Czech Republic, who believes that “climate is a joke” to quote a recent AP story from the Heartland Con, the awards honor those on both sides of the aisle who make unsound remarks about global warming and climate change. See the carnage here, and feel free to nominate your nominees, with references and quote sources please:

    http://climatejokeawards.blogspot.com/

  35. 35
    erikG says:

    Browsing though file from my youth I cam across a junior-high school paper I was made to write in the early 1980′s. The premis given to the class was that industrial pollution might lead to another ice age, and we were supposed to describe how this might affect mankind.

    I had forgotten all about it, but it certainly explains why I always had that “vague impression” about impending cooling. Does anyone else here have school age memories about cooling vs warming?

  36. 36
    Chris Squire [UK] says:

    ‘ . . Inevitably June snowfall is a much rarer creature, but widespread sleet and snow showers did manage to affect the UK on 2nd June 1975, rudely and infamously affecting a cricket match between Derbyshire and Lancashire at Buxton where early afternoon snow covered the pitch with around an inch of snow (Markham, 1994, Eden 1995). Elsewhere, snow settled on hills just south of Birmingham (Eden 1995), whilst to the south and east Manley (1975) reports snow being observed in both Cambridge and London and another county cricket match, this time featuring Essex and Kent, being played in Colchester was interrupted by snow (Ogley et al. 1993). Meanwhile, sleet showers were observed in RAF Manston in eastern Kent, Hassocks, Sussex and Totton and Portsmouth in Hampshire (COL Bulletin 1975, Eden 1995, Ogley en al 1995).

    In his book Weatherwise, Philip Eden (1995) wonderfully describes this June snowfall as, “surely the most outrageous thing that June has ever done to us, meteorologically speaking”. It also seems that in recent times at least this is the latest in the season that such widespread snow has managed to affect southern Britain (Manley 1975, Eden 1995) and Manley (1975) suggests that the June 1975 snowfall was probably southern Britain’s latest snowfall since the turn of the nineteenth century.’ Snagged from: http://www.dandantheweatherman.com/Bereklauw/latesnow.html

    This freak event, observed by many, did much to fix the idea of a coming Ice Age in the popular mind in Britain in the late 70s. It was much more influential than any scientific papers published at the time.

  37. 37
    Robin Johnson says:

    I remember the cooling prediction but all I remember was a book (and some brief media attention). Before that I had read science fiction novels and seen a couple of movies that predicted warming and melting… But anyway, after the cooling hypothesis came out (it certainly wasn’t impossible given that ice ages were cyclic), I decided to naively think up a mitigation strategy. So I asked myself, what in retrospect was a decidedly stupid question: What if we detonated nuclear weapons to melt the ice? After a bit of research I realized that the amount of heat (while awesome) was pathetically small and that, by comparing it to volcanoes, instead of warming we would get cooling from the dust throw up (this was before Nuclear Winter was put forward as a compelling reason against limited nuclear war).

    So I remember it – but I certainly didn’t think it was “scientific consensus” – it seemed like a plausible hypothesis. But I mean, goodness gracious, the scientists weren’t entirely sure what the Great Red Spot on Jupiter was at that time (the leading theory was a big storm but that was far from proven).

  38. 38
    Ric Merritt says:

    In the AMS writeup linked in the post, page 3, I was amused to see CLIMAP decoded as the “Long-rage Investigation, Mapping, and Prediction project”. Freudian slip??

  39. 39
    William Astley says:

    The following is the by month NASA planetary land-ocean temperature anomaly data. The base for the table is 1951 to 1980.

    http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt

    Planetary temperatures were colder in the 1960s and early 1970s. I believe newspapers and magazines ran articles that stated that the planet was cooling and could enter an ice age because of the cold weather at the time.

    Planetary temperatures were also much colder in the 1800’s and early 20th century, as per the NASA data. Climate in the 1800’s and early 20th century must have been significantly different from 1980 to 2007.

  40. 40

    Chris Squire (#36) — a decade or two back, it snowed in Cape Town, South Africa in December. It generally does not snow in Cape Town, and December is summer there (usually hot and dry). Freak events can always occur. This is why you should be leery of anyone who looks out the window and says, “Aha! I’ve spotted climate change.” But of course the press will pick up on these things, and we should call them to account when it happens. (When they pay attention: The Australian for example very seldom prints factual corrections of climate denial for example.)

  41. 41
    Slioch says:

    re #22 Steve Horstmeyer.

    Thanks for reminding us that the “Snowblitz” theory of climate change was written about by Nigel Calder in his book “The Weather Machine”. This suggested that an ice age could be initiated within a few years by eg a volcanic eruption causing cooling that caused widespread snow cover, causing further cooling by reflecting sunlight etc.

    Nigel Calder is a prominent sceptic and made a pugnacious contribution to the Channel 4 “The Great Global Warming Swindle” film, just one year ago.

    So, one of those “scientists predicting a new ice-age in the 1970′s” that contrarians keep banging on about is himself now numbered amongst the contrarians!

  42. 42

    I should also note my considerable thanks to the authors of this paper for taking the time out of their busy schedules to do this comprehensively. That this should be necessary is a sad testimony to the effectiveness of the denialist disinformation campaign and the shabby standards of much of the press which reports this stuff without verification.

    Any plans to issue a press release when the paper is published?

  43. 43

    Re #20 Steve L

    Do folks making the argument really prefer the science of the 70’s to the advances in understanding that have occurred since computers, satellites, 30 more years of data, etc have come to bear on the subject?

    Don’t think so… the real gist of the argument is IIUC that the climate science of the 70s was already pretty good — the fundamentals were in place. Since then it has only gotten better still. Climatology as a science has a long history. Sure climatologists get things wrong all the time — but not this badly wrong, not this late in the game.

  44. 44
    Lawrence Coleman says:

    Good article…it would be interesting to see the same table 1 from 1980-2007 and see how it’s changed. Now infinitely more data has come to light from almost every earth science source. Were they using satellites in the 1970′s for climate study?

  45. 45
    MJ Sparrow says:

    The global cooling argument is hitting hard again right now due to the recent chill. The standard response is of course La Nina but I’ve had several skeptics e-mail me this NOAA paper:

    “Conversely, above normal ice cover was associated with La Nina conditions which are accompanied by the Aleutian low moving westward of normal allowing higher pressure and colder conditions to move over the Bering Sea. However, since the regime shift, this correlation of ice with both the Aleutian low movement and with the SOI has reversed.”

    I haven’t seen this pop up on climate audit but someone is obviously parading this around.

  46. 46
    Lawrence Coleman says:

    In regards to the possibilty of an ice age or period of noticable cooling for europe and north america I suppose that depends uopn the rate of slowdown of the north atlantic current. I saw the movie ‘The day after tomorrow’ two days ago..what a crock of #@$%!..I dont think anyone with half a brain or even quarter for that matter would believe the speed of the onset of the ice age portrayed there. Even if there was an sudden outflow of many gigalitres east of canada like there once was eons back..that still took up to a decade for that iceage to take effect. No one knows with any certainty what effect a moderate slowdown of the NAC would have..but I just cant see it triggering a snap ice age. The increasing rate of freshwater entering the atlantic from a greenland/arctic melt alone will no-doubt slow-down the NAC but to what degree?

  47. 47
    Thomas says:

    2: Thanks for the links. I keep getting hit with this cooling/new iceage #$%^ and could use a good mallet to do some wacking of my own.

  48. 48

    I’ve been fighting GW for nearly 20 years now, reducing my GHGs substantially at financial benefit to me, and trying to get others to do likewise. And I didn’t really know the science of climate change well (and still don’t) or where we stood in geological terms (so it doesn’t take a climate or rocket scientist to reduce GHGs).

    Until recently when I’ve come up against these “ice-age” denialists, I’ve only been able to answer them with, “well science does advance over time, and now the scientists have a lot better understanding….”

    Only this past year I’ve come to understand we are at a climate high point, a sort of plateau, in the glacial-interglacial cycle. And if there were no anthropogenic GHG forcing, we might expect over a long geological (in human terms) timeframe that we would be heading into an ice age….eventually. So the “ice-age” scientists back then were not necessarily wrong. But with our GHG forcing, we may be triggering positive feedbacks and tipping into a much greater warming period, as has happened several times in the past (251 mya, 55 mya), using this high warm plateau as our launching pad into hysteresis.

    So now I answer the “ice-age” denialist argument (denialists usually trot out ALL their inconsistent & contradictory arguments) this way: I draw a sine-wave in the air with my hand, saying, yes, that the normal fluctuation over a long geological timeframe is to alternate between cold ice ages and warm interglacial periods, and that now we are right here in a warm interglacial period (my hand raised at the top of the wave), and if there were no human GHGs, then we would expect that over a long time frame we’d be sliding down into an ice age. However, there have been times in the past when other factors have kicked in, such as extreme vulcanism or as now with our tremendous GHG emissions, when instead of going back down into an ice age, it has gone into hysteresis (raising my hand higher) in which the warming spirals way up, causing mass extinction of life on earth — 95% of life died out in such an event 251 years ago. And now we may be causing the climate, out of it’s normal cycle, to go into just such an event.

  49. 49

    RE #46, Lawrence, I think the creators of DAY AFTER TOMORROW made it clear somewhere (?in the film’s beginning?) that they were greatly speeding up the process for dramatic effect. But I was also put off, especially by the ice chasing the kids in the library — it popped out of my suspended disbelief.

    So the real problem is how to make great movies about global warming, that captivate audiences. The nuclear issue was easy (CHINA SYNDROME, ON THE BEACH, etc); these were nuke movies that shook the world. Global warming is also a grave threat, but how to make it photogenic with the necessary “ticking time bomb” so people will watch and get inspired to mitigate. I’m sort of up to my gills in global warming documentaries, quite frankly, though we need them to keep coming out.

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    Rando says:

    …..supposed to be +1C today in Yellowknife – Northern Canada. That beats the normal -17. I recall from my early science classes that ice melts at 0 degrees (well it was +32F when I learned it). So much for the impending ice-age around here.


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