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The debate is just beginning — on the Cretaceous!

Filed under: — raypierre @ 23 January 2008

Most of us who are involved in research related to climate change have been asked at one time or another to participate in public debates against skeptics of one sort or another. Some of us have even been cajoled into accepting. In the pre-YouTube days, I did one against the then-head of the American Petroleum institute at the U. of Chicago law school. Gavin did an infamous one against Crichton and company. People are always demanding that Al Gore debate somebody or other. Both Dave Archer and I have been asked to debate Dennis Avery (of “Unstoppable Global Warming” fame) on TV or radio more than once — and declined. It’s a no win situation. If you accept you give the appearance that these skeptics have something to say that’s actually worth debating about — and give their bogus ideas more publicity. If you decline there are all sorts of squawks that “X won’t debate!” or implications that scientists have declared “the debate” (whatever that is supposed to mean) prematurely closed when in fact it is “just beginning.”

Scientists tend to react badly to demands like this in part because the word “debate” is a rather poor description of the way disagreements get hashed out in science. John Ziman has a good discussion of the extent to which scientific questions are ‘debatable’ here (pdf). In a lawyerly debate, it is fair game for each side to pick and choose whatever argument has the most persuasive force with the audience, jury or judge, without any obligation to consider the force of counter-arguments except insofar as they affect one’s defense against the opponent. Science, in contrast, is a deliberative, cooperative, yet still competitive enterprise, where each side is duty bound to fairly consider all arguments and data that bear on the matter at hand. This is not to say that scientific disputes are necessarily dispassionate or orderly. Indeed, I’ve seen near-fistfights break out over things like the Snowball Earth and the interpretation of Neoproterozoic carbon isotope excursions.

The repeated challenges to debate are probably meant to imply that scientists — and their supporters, including Al Gore — are fixed in their ideas, unreceptive to the new and challenging, and unwilling to defend their ideas in public. This picture is hard to square with how scientists actually behave among themselves. It is not that scientists don’t debate, dispute, disagree about matters related to climate. All those things happen, but not on the subjects that skeptics like Inhofe or Fred Singer or Dennis Avery would like to debate (like whether global warming is mainly caused by CO2 or solar variability, or whether the IPCC warming forecasts represent a credible threat.). Those sorts of things are indeed considered settled science by serious climate scientists. Then, too, scientists are justifiably wary of being drawn into staged debates on such diffuse, ill-defined and largely meaningless topics as whether global warming counts as a “crisis.” In the war of the sound bites, the people who feel free to lie and distort can always win. David Mamet made this point eloquently in Bambi vs. Godzilla. A debate like that is not any kind of debate in the sense understood by scientists.

In fact scientists are probing theories and conceptions all the time, trying to break them. The best way to become famous is to overturn established wisdom, so scientists look hard all the time for opportunities to do this. The problem of Hothouse climate states like the Cretaceous and Eocene is a case in point.

The Cretaceous is the time period from 145 million years ago up to the demise of the dinosaurs about 65 million years ago. The Eocene is a more recent period, from 56 million years ago to 34 million years ago. In between is the Paleocene, which is generally somewhat cooler than the late Cretaceous or mid Eocene. It has long been known that the polar climate — particularly the Arctic climate — was very different from today’s. Many lines of evidence indicate temperatures well above freezing, with little or no permanent land ice and infrequent or absent sea ice. Lemurs could live in Spitzbergen, and crocodiles on Hudson Bay, to name a few examples. Most evidence also points to an absence of ice in Antarctica as well. These Hothouse (or Super Greenhouse) climates have much warmer polar regions than is the case for today’s climate, and winters were evidently very mild. These hothouse climates are idealized as having been almost completely free of significant ice sheets on land and sea ice cover in the ocean. Hothouse climates pose a challenge to our understanding of climate in general, but more particularly they serve as a critical clue as to what surprises a high-CO2 world might have in store for us.

This is so because, at present, the only viable theory for Hothouse climates is that they come about as a result of elevated CO2 concentrations, which in turn are due to long term changes in the Earth’s carbon cycle. The CO2 theory has many problems, some of which I’ll discuss below, but no theory without elevated CO2 has been able to even come close to accounting for the Hothouse states. These climates would be just dandy as a natural test of the Earth’s sensitivity to long lived greenhouse gas concentrations were it not for one nasty fact: it is very, very difficult to get an accurate idea of how high the CO2 concentrations were so far back in time (see Crowley and Berner or Broadly Misleading on RC). For example, estimates for the Eocene range from values similar to modern CO2 concentrations all the way up to 15 times pre-industrial CO2. This unpleasantly large range represents uncertainties in the proxies used to estimate CO2 in the distant past. Various general circulation models can achieve largely ice-free polar conditions with CO2 between 4 and 8 times present concentrations, though even at those levels there are difficulties in accounting for the mildness of the winters. And up until recently it was thought that the tropical temperatures in such simulations were far warmer than reality — but more about that anon.

In the past few years there has been a real shake-up in the conception of what hothouse climates are like. First, it was found that the Tropical regions in hothouse climates are not tightly thermostatted as had been previously thought. Prior indications of a cool tropics turned out to be an artifact of alteration of the chemistry of marine sediments after they were deposited — a nightmare known as diagenesis to paleoceanographers. The tropics are actually quite a bit warmer than today’s tropics. For example, the Eocene tropical ocean may have been as warm as 35C, as compared to about 29C today. The upward revision of tropical temperatures is quite a good thing for the CO2 theory, since it removes a good part of the “low gradient” problem, wherein models were thought to systematically exaggerate the pole to equator temperature gradient.

So far, so good. But then, just last year through heroic efforts involving a nuclear icebreaker, a conventional icebreaker and an icebreaking drill-ship. a deep-time sediment core was recovered from the Arctic ocean. The results, which came out in a series of papers in Nature (here,here and here) were startling. At times the Arctic was practically a freshwater lake, indicating some quite dramatic changes in the hydrological cycle. And more germane to the matter at hand, in the early Eocene, the Arctic was much warmer than previously thought. According to Sluijs et al ocean temperatures were as high as 23C — rather like Key West today. These temperatures come to you courtesy of a novel biochemical proxy known as Tex86, derived from certain lipids produced by tiny plankton called Crenarchaeota. Tex86 is the new wunderkind of paleoceanography.

Will wonders never cease? Evidently not. Just when the hothouse starts looking really, really hot, along comes a new Science article by Bornemann et al, dealing with climatic conditions in the Turonian (93.5 to 89.3 million years ago). The principal result of this paper is that there appears to have been a 200,000 year period right smack in the middle of one of the warmest periods of the past half billion years, when there were ice sheets (presumably in Antarctica) that were up to 60% the volume of today’s Antarctic ice sheets. How in the world do you get such large ice sheets in a high CO2 climate warm enough for crocodiles to survive in the Arctic at the other side of the planet? And this apparent glaciation is not the result of a global cold snap. As in the Eocene results quoted earlier, the tropical ocean surface temperatures are again on the order of 35C — courtesy once more of the wondrous Tex86 proxy.

How was the ice volume inferred? Primarily by an especially meticulous application of an old technique. When a glacier forms on land, the water it is made of is enriched in the lighter form of oxygen, 16O, which leaves the ocean enriched in the heavy form, 18O. Single-celled shelly creatures called foraminifera (“forams” for short) record this composition, but they are very subject to diagenesis. The key to the new estimate was to take samples from pristine glassy portions of exceptionally well-preserved foram shells. The sample was taken from a core in the Tropical Western Atlantic, so the investigators are able to determine tropical surface temperatures, making use of Tex86 proxies from organisms living near the surface. The ocean water isotopic composition is estimated using both surface-dwelling and deep-dwelling forams.

Since the oxygen isotope composition of forams depends on temperature as well as ocean water composition, the Tex86 proxy was used to correct for the temperature effect in forams living near the surface. There is no independent temperature proxy for the deep ocean, but the investigators assumed (a bit questionably) that deep ocean temperature did not change much over the time period. Be that as it may, the deep ocean oxygen isotope shift (uncorrected for any temperature effect) was similar in magnitude to the estimate from surface forams. Once you have the oxygen isotopic composition of sea water, you can translate that into ice volume by making an estimate of the isotopic composition of glacier ice. All this is easier said than done, but they did it. The glacial interval corresponds to the excursion of delta-18O toward positive values in the figure below, taken from the paper:

There is a useful commentary by Richard Kerr One must exercise the usual caution we urge in connection with radical results, and await confirmation before taking it to the bank. As Kerr points out, there is other data from this time period that doesn’t show the isotope shift.

There are two additional things I myself noticed, which seem inconsistent. The first is that in order to get reasonable numbers for ice volume, the investigators needed to assume that Antarctic ice in the Cretaceous period had the same isotopic lightness as Antarctic ice today. Most theories of fractionation would have Antarctic ice being less fractionated in a warm climate, however. Perhaps the high Equator to Antarctic gradient helps keep the Antarctic ice light, but this is something that needs to be checked. What’s even more troubling to me is that the bottom-dwelling forams (uncorrected for temperature) indicate the same ocean water isotopic shift as the temperature-corrected surface dwelling forams. However, if Antarctica glaciates, the deep ocean should be filled with cold Antarctic bottom water, which should produce an additional positive isotopic shift in the uncorrected bottom dwelling forams. That this shift isn’t seen suggests that something is amiss to me.

Still, this paper already has a lot of modelers scratching their heads. To give an example of the magnitude of the problem, I reproduce below a figure from one of Rob DeConto’s old simulations (Nature 421, (2003) ), showing the glacier distribution in Antarctica as a function of CO2, as CO2 is steadily decreased. These are done for orbital parameters favorable to Antarctic glaciation; the simulations don’t use Late Cretaceous geography, but they do give a good idea of how hard it is to get a big glacier in Antarctica with anything much above twice the preindustrial CO2.

It is salutary to keep in mind that in many past cases where data conflicted with robust modeling results, it turned out to be the models that were right and the data that was wrong. This was the case for the early satellite reconstructions of twentieth century lower tropospheric temperature, which showed a spurious cooling. It was also the case for early reconstructions of tropical climate during the Last Glacial Maximum, which failed to show the cooling we now know to prevail in that region during glacial times.

So, what does all this mean for CO2 and anthropogenic global warming? Does it mean we don’t know beans about climate, so let’s have a party and why worry? No, actually. All this hothouse strangeness gives us a great deal more to worry about. The tropics is not strongly thermostatted, and there appear to be feedbacks in the system that can amplify polar warming more than previously thought possible. Perhaps due to clouds? Matt Huber, one of the foremost Eocene modellers, stated in a recent seminar at the University of Chicago that he could get closest to reproducing the Eocene hothouse by assuming that the Earth’s real climate sensitivity is at the high end of the IPCC range — around 4C per doubling of CO2. Or, perhaps there are mode switches in the climate system we know nothing about, which we are risking triggering by increasing CO2. Without understanding the Hothouse climates, it’s impossible to say how close we are to the danger zone.

But what of this new riddle of Cretaceous ice? An optimist might say that the result shows that you can keep a lot of ice in Antarctica even in a very warm climate. On the other hand, the conditions allowing the ice to exist in a warm climate are evidently very fragile, since it was there (assuming the result holds up) for only 200,000 years — the wink of an eye, in geological terms. That could mean that the factors governing whether Antarctic ice stays or goes in a warm climate are more subtle than we thought, offering more possibilities for surprise transitions. Or it may turn out that Cretaceous CO2 is really only twice the pre-industrial level, but that there’s some whopping positive feedback which bumps up tropical temperatures to 35C. In a scenario like that, the strange and unexplained resistance of Antarctica to warming might save some Antarctic ice, but that would be cold comfort, since the rest of the world would be toast.

Or, it may turn out that the processes determining the glaciation and deglaciation of a partly ice covered Antarctica have nothing to tell us about the present situation starting with a large Antarctic ice sheet. I’d be surprised if this turned out to be the case, but it could happen. One thing is for sure — if the result survives, it will provide an important and challenging test for the next generation of ice sheet models.

Could it be that the glaciation is telling us that we are completely barking up the wrong tree with the CO2 theory of hothouse climates? Perhaps, but somebody will have to pony up a quantifiable alternative before that avenue can be pursued. And whatever the alternative is, the challenge of simultaneously explaining the coexistence of a super-hot tropics with Antarctic glaciation — and also explaining why this happened for only 200,000 years — is apt to be as big as any challenge posed to the CO2 theory. One could probably get a climate something like the suggested one by combining moderately elevated CO2 with making a lot of low clouds over Antarctica while making the rest of the world essentially cloud free (or somehow making the high cloud greenhouse effect dominant in the rest of the world), but that’s quite a stretch. If somebody comes up with a way of doing that which can be expressed in a sound mathematical formulation, I’ll be the first to want to have a look at it. Cosmic ray enthusiasts could have a field day with this, but I doubt they’d have much success.

However you slice it, it starts to look like the Eocene and Cretaceous are tugging at our sleeve, whispering to us “There are things going on with climate you don’t begin to understand. Proceed with caution.”

We already knew hothouse climates were interesting, but darned if they don’t just keep getting more and more interesting. It puts me somewhat in mind of the old Yiddish curse– “May you live in interesting times.” But, to paraphrase Maurice Sendak — Let the Wild Rumpus Continue!


308 Responses to “The debate is just beginning — on the Cretaceous!”

  1. 51

    re 46
    Mark, I wish I were making this up, but it is a measure of the bipartisan weirdness of the Climate Wars that the Captain Nemo theory of a toasty abyss has been championed not by the WSJ, but its political nemesis, The Nation magazine:

    http://adamant.typepad.com/seitz/2007/05/nation_denounce.html

  2. 52
    Jim Eager says:

    Re JB @ 45: “There are a large number of solar variables and they should all be taken into account; not dismissed and ignored.”

    They need to be proven first, and then quantified, and then demonstrated to have a measurable affect on climate before they can be taken into account.

    What are you waiting for? You have much work to do.

  3. 53
    C. W. Magee says:

    Great post.
    I was wondering, though. Can you get sulphate aerosols from a Southern Hemisphere source like the Ontong-Java to cool that hemisphere? 200k is not a bad timescale for flood basalt volcanism. Also, if you have East-African style uplift associated with the rifting of India and/or Australia from Antactica, then you only need to glaciate a 2-3km plateau, and not a sea level continent. And a high altitude glacier need not necessarily interfere with the southern ocean circulation.

  4. 54
    David B. Benson says:

    C. W. Magee (53) — Flood basalts may well have occured in the land masses to be asembled to form West Antarctica. See my earlier post and also the following link to see that Java appears to be too far away for such a (presumably) local effect:

    http://www.scotese.com/cretaceo.htm

  5. 55
    Mark A. York says:

    Russell,

    Thanks! That worked wonderfully for what I was trying to say. These libertarian types will believe anything but scientists who work for NASA! Well I detest people who talk behind others’ backs which is the stuff of cowards where I come from up in Maine so here’s the message hand delivered as sad as it is.

    I predict that within a decade we’ll wonder why we paid any attention to the Gores and Hansens and Manns and Schmidts of the world.
    Ken C., Jan 24, 2008, 7:58pm EST

  6. 56
    Paul Inglis says:

    re 46

    Mark, tell “Captain Nemo” that it’s more like 0.04% of the atmosphere not 0.4%. 0.4% which would be 4000 pppm. At least I assume the percentage quoted refers to C02 concentration and not just the level of hot air emitted by AGW skeptics!

    Excellent post, raypierre. I’m a long time reader but first time poster.

  7. 57
    Ray Ladbury says:

    Mark, Perhaps you might suggest to the good captain that if submerged volcanos were in fact responsible for warming that it would have to be the oceans (and the deep oceans, at that) that warmed up first. It never ceases to amaze me how many guys there are out there who are utterly convinced that on the basis of the one semester of algebra-based physics, the understand everything better than people who study the subject in depth for decades. There is a word for such people: morons.

  8. 58

    re4

    I think there is a consensus that we won’t be seeing any optical depths of 20 in Toon’s Nuclear Whatever model.

    I am prepared to entertain the hypothesis that the Soviets threw in the towel in despair at how far behind they were in GCM’s. Still, it was very bad form of them to liquidate Alexandrov for failing to get with the program.

    To paraphrase Goudschmidt on Heisenberg, climatologists should not shoot other climatologists.

    [Response: Who'm I shooting? Certainly not Sagan. Regarding your comment on Soviet GCM's I recall back when I was at GFDL, when all the Russians who could travel were apparatchiks of some sort or another, running into one who had a sense of humor. Sitting in the back of a car on Route 1 he remarked that at his institute they used (what I heard as) a "CDC 100." I remarked in surprise, a CDC 1000! (at the time a pretty big supercomputer, the thing you'd design TsarBomba with), and he clarified "No, iz CDC one hundredth. Is almost exactly one hundred times slower than CDC." --raypierre]

  9. 59
    Hank Roberts says:

    Ray, can you compare the amount of water involved when

    > the Arctic was practically a freshwater lake

    compared to the amount frozen in the Antarctic ice?

    Just thinking, the Antarctic is a freshwater lake right now, frozen to the bottom and piled higher and deeper.

  10. 60
    JB says:

    Re: Jim, #52

    I, and anyone else who cares for the pursuit of truth, do have a lot of work to do. Life is much easier for those that have already made up their minds.

  11. 61

    The Bornemann paper is fascinating. I reviewed it for Science and agree with most of what you say. But you seem to lack perspective on the development of this idea. The Bornemann paper provides data supporting the Matthews-Stoll-Miller hypothesis. Matthews was scorned. Stoll and Schrag were ignored. And we (Miller et al., 1999, 2003, 2005a, b) finally convinced the community to look.

    The hypothesis is that large (>25 m), rapid (

    [Response: Ken, use & l t ; (no spaces) for a less-than symbol. Otherwise the software eats the comment... - gavin]

  12. 62
    spilgard says:

    The Capt. Nemo theory is only the beginning. Keep in mind that it’s just *one* of his theories, and that’s just starting with the pet ones.

  13. 63
    Mark A. York says:

    RE: 56, yeah that was my typo. He said 0.04. Good point Ray L. That crossed my mind too but for once I was trying to be diplomatic.

  14. 64

    RayPierre

    This has just reached me in Boston-it seems that such as wish to discuss Roy Spencer’s views will have a capital opportunity tomorrow evening at the Cosmos Club’s auditorium.

    I do hope there is a good turn out for Roy certainly deserves to be heard:

    The Philosophical Society of Washington is pleased to announce its 2232nd meeting will feature as guest speaker:

    Dr. Roy W. Spencer, University of Alabama in Huntsville

    “Manmade Global Warming: A Pending Catastrophe, or False Alarm?”

    Friday; January 25, 2008 at 8:15pm

    Public Invited

    The John Wesley Powell Auditorium; 2170 Florida Avenue NW, Washington DC
    (Attached to the Cosmos Club) No reservations required

    [Response: Interesting to note that Roy is only the second speaker on climate change that the Philosophical Society has hosted since 1990 -- and the one before him was Fred Singer, speaking on "Hot talk, cold science." Strange, that. --raypierre]

  15. 65

    #28 Robert, And then the intriguing evidence presented by Raypierre here shows substantial ice when CO2 levels were much higher than 2 X pre industrial levels. I can conceive +20 C in darkness near or at the North Pole, because it happened before as Axel Heiberg lonely sentinels of the past attest; mummified cedar tree stumps and leaves along with Ellesmere primitive Alligator skull. But there should always be some ice at higher elevations in darkness especially at latitudes 80 to 90 degrees South when a critical sun elevation angle, about 30 degrees, is not reached during summer. I’ve observed many a springs when the sun has no effect on snow until the sun exceeds that threshold. Now a few questions arise from this, since there was potentially Antarctic ice beyond Vostok’s 600,000 years, is there any possibility of finding ice millions of years old (not knowing how many drill sites were done)?

  16. 66
    Francois Marchand says:

    I know this is a bit outside the purview of a discussion on the extent of ice caps during a very hot period, but such a change in Antarctica during a rather limited period of time should have left some evidence in the fossil records of -at the very least- the adjacent areas(quite apart from the foraminifers). I am not thinking about a mass extinction or a sudden blooming of biodiversity, but what about pre- or proto-mammals for instance? Any known confirmation of a sudden change?

  17. 67

    re 58
    Raypierre

    VV Alexandrov was the GCM jockey who was hustled into Le Machine Bleu a white van actually) outside the Soviet embassy in madrid in 1985, after failing to toe the party line on large optical depths, and the identity X NATO cruise missiles = N Extinctions of H.sapiens; where N is an integer equal to or greater than one.

    I’ll spare you the corny particulars, but Alexandrov is still missing,and after 22 years, presumed very dead. Andropov was running things at the time,and the wear and tear on scientific mavericks considerable.

  18. 68
    Dodo says:

    Ray, don’t you see by now that, you spoiled a great piece with the first three paragraphs. Most of the commentators are not talking about the cretaceous at all, but the current warm period instead.

    And Crichton for one, has never made any claims to be an expert on the cretaceous. His specialty is the jurassic;-)

    [Response: To some extent, the debate on the debate has taken over the discussion, but actually I think that's important, too. One of the things I was hoping to bring out was the way ideas are churned over by scientists, and how disputes are resolved. There is an important question here, too, about how to bring science to the public. Is a public debate an effective way to communicate the flaws in, say Avery and Singer's book? Or does the public just come away with the idea that two sides are arguing about this so there must be disagreement? And debates also rely on the real-time facts at the debaters' disposal. If somebody claims "there's global warming on Mars" and among the hundreds of skeptics arguments you happen not to know the answer to this one, what do you do? Science as carried out in journals and scientific meetings is an extended deliberation, offering lots of time to think about responses, get new data, and do new calculations. This works fine among scientists, but the general voting public does not read the scientific literature or go to AGU meetings. So what do you do when skeptics take the argument outside the usual scientific venue? What is in fact the best way to get junk science (again, Avery and Singer is a prime example) out of the public discourse? I'm bringing this up because in fact I'm not certain that my persistent refusal to appear on talk shows with Avery actually is the best decision. It's something that is worth discussing. --raypierre]

  19. 69
    Ray Ladbury says:

    So, JB, since you think everything can be explained by the Sun, perhaps you’d care to posit a mechanism. I say this because nobody has yet come close to positing such a mechanism that even gets you in the ballpark. Just to be sure, maybe we ought to be looking at the phase of the moon and wheter it is in the 7th house and all that, too?

  20. 70

    JB writes:

    [[“It does, but it has very little impact on recent climate change.”

    That is a huge assumption. You are assuming that solar irradiance is the only variable we should be looking at with regards to the sun. Assumptions like this are exactly the problem. There are a large number of solar variables and they should all be taken into account; not dismissed and ignored.]]

    Nearly all those variables correlate with TSI. They’ve been examined; no connection was found. Your assumption that they are “dismissed and ignored” is ignorant and wrong.

  21. 71

    Mark York quotes some denier:

    [[“One of my pet theories is that there is much more coupling between the hot core and the oceans that cover 71% of the earth’s surface (particularly the deep parts of the ocean where the crust is thinnest) than is accounted for in the GCMs. If someone offered me grant money, this is what I’d look into. I read that volcanic activity in Greenland (in areas where, again, the crust is thin) might be partially responsible for its glaciers receding…”]]

    The core is separated from the surface by the mantle and the crust. The average heat flow at the surface from the Earth’s interior is well known; it’s about 0.087 watts per square meter. Compare that to the 237 watts per square meter of sunlight absorbed by the climate system.

  22. 72
    Ray Ladbury says:

    Russell,
    I have to say I find little value in taking public debate of science, precisely because the public are not interested and are mostly ignorant of science. True scientific debate takes place between the pages of refereed science journals and at conferences–that is between experts. It works because the participants share a common culture and have agreed to be bound by the rules of evidence. I think it is naive to expect nonscientists–or those like Lindzen who have given up on science–to play by those same rules. And when you factor in the audience–50% of whom (if they’re Americans) believe in the Biblical account of creation(!), it all smacks a bit too much of trying to teach a pig to sing. Do you really think that Captain Nemo (referred to above by Mark York) is will be persuaded by rational argument?

  23. 73
    Appy Sluijs says:

    Dear Ray Pierrehumbert, others,

    Great article.
    One additional point that may be worth adding to the discussion regarding the gradient problem are temperature records from a rapid greenhouse warming phase, 55 million years ago, called the Paleocene-Eocene thermal maximum (PETM). This phase occurred superimposed on already warm conditions, with (largely?) ice-free polar regions and low equator-to-pole temperature gradients. Warming during at the onset of the PETM comprised 5 to 8 degrees C in the tropics, mid latitudes, as well as in polar regions and the deep ocean. Hence, the temperature gradient did not increase during global warming during the PETM, in the absence of ice-albedo feedbacks. Whatever mechanism caused the reduced the reduced gradients, it was pretty much saturated during the early Eocene.

    [Response: Thanks for stopping by, Appy. Hope to meet you sometime. Indeed the PETM deserves a post of it's own. Are you guys going back to drill the Arctic again anytime soon or do the Russians have their icebreakers tied up with their territorial claims on the Lomonosov ridge? --raypierre]

  24. 74
    Meltwater says:

    In comment #21 Hank Roberts asked:

    `Gavin, could you open a “Friday” thread (top of page) to intercept driveby/naive/elementary questions, so this can stay focused?’

    In #34 Walt Bennett said:

    `We need more frequent posts; regular unthreaded posts or a forum; more editing of comments to keep them semi-focused and to whittle out ad-hom or rhetorical arguments.’

    Now I add that I too hope for a recurring RealClimate feature under which questions and comments that would otherwise be off-topic or miscellaneous can regularly be collected, with responses when appropriate from the climate scientists blogging here. I expect this practice would have much the same benefits that Roberts and Bennett have suggested. Unlike your occasional Friday Roundup, however, the feature need not require any of you to compose a starting post. You could instead merely enter the `Unthreaded’ headline and the date.

  25. 75

    re64 raypierre
    Timing is interesting- the last one was on the heels of:

    R.W. Spencer and J. R. Christy’s declaration that satellites were not seeing a significant AGW signal “”Precise Monitoring of Global Temperature Trends from Satellites , “Science 247 (March 30, 1990): 1558

    which many took as gospel ,not realizing they were looking at an orbital model of where and when radiometers were supposed to be asigning measurements –
    http://adamant.typepad.com/seitz/2006/09/stone_me_a_crow.html

  26. 76
    Joel Shore says:

    re (#51): Russell, I think it is a misstatement to say that the theory is championed by The Nation Magazine. It is championed by one columnist in The Nation magazine. The Nation seems to give their columnists very free reign and Cockburn has some very nutty ideas (such as his ones on global warming) that don’t seem to be shared at all by the editors in their editorials (or by any other contributing writers to the magazine that I know of).

  27. 77
    Chris Colose says:

    #68 raypierre’s response

    Unfortunately, I do not feel that the scientific community has done a good job at all when it comes to translating the issues to the laymen, and getting quality information out to laymen venus (realclimate being a good exception). Maybe I am the only one who thinks this way, but there is a large disconnect between how scientists and laymen are thinking of the issue, where the actual debates are, and what the implications mean. Al Gore should be commended in this regard, because despite “errors” or the simplicity in his presentation, he is getting people to think about it.

    But people still say to me “what is 6 degrees…that is nothing” or “if sea levels rise a half a meter, where is the concern?” or “only 0.8 C, doesn’t sound like a trend to me, and the weather man can’t even get next week right, I’m supposed to accept ‘by 2100′ projections?” In my meteorolgoy class last year, we ended up getting in a debate on anthropogenic global warming, and one fellow remarked that it was a natural cycle, and I asked him which natural cycle, and he said “the natural cycle the earth goes through.” Round and round we go.

    The problem is people read too many wingnut sites, and scientists need to be a bit more aware that the average joe decides to watch a youtube video, and check out Inhofe’s blog, when making a decision on “if it is real or not.” The fact is you are not going to stop that. And when average joe sees that raypierre declined a debate on Inhofe’s blog, he isn’t going to think “raypierre knows these people aren’t worth debating,” he is going to think “raypierre cannot defend his ideas.” Unfortunately, you are left with not too many options.

    “The hydrostatic paradox of controversy. Don’t you know what that means? Well, I will tell you. You know that, if you had a bent tube, one arm of which was of the size of a pipe-stem, and the other big enough to hold the ocean, water would stand at the same height in one as in the other. Controversy equalizes fools and wise men in the same way. And the fools know it.”– Oliver Wendell Holmes

  28. 78
    Bryan S says:

    Re: #66; One problem is that there are very few Cretaceous rocks exposed on the Antarctic continent. The only real exposures occur on James Ross, and Seymour Islands (Antarctic Peninsula) (the Fossil Bluff Group, Albian, and Campanian-Maastrichtian Marambio Group).

    From a modern view, the reason that the subject of this post has importance, is that glacio-eustacy is the dominant component of sea level rise, and thus what we may learn in the ancient record may give us some inkling of how tricky it is to forecast how sea level might respond during a very warm global climate.

    The idea that there might have been ice sheets on Antarctica during the Cretaceous, challenges recent assumptions, but is not new in the literature. Matthews and Poore (1980) suggested such nearly 30 years ago. There is also more than a little evidence that ice sheets on East Antarctica may have been present during the superhothouse climate of the Middle/Late Eocene. For anyone wanting to gain a better or broader perspective of this evidence, I advise those interested to find these:

    Matthews, R. K., and R. Z. Poore, 1980, Tertiary d18O record and glacio-eustatic sea-level fluctuations: Geology, v. 8, p. 501–504.

    Barron, E. J., B. Larsen, and J. G. Baldauf, 1991, Evidence for late Eocene to early Oligocene Antarctic glaciation and observations on late Neogene glacial history of Antarctica: results from Leg 119: Proceedings of the Ocean Drilling Program Scientific Results, v. 119, p. 869–894.

    Hambrey, M. J., W. U. Ehrmann, and B. Larsen, 1991, The
    Cenozoic glacial record from the Prydz Bay continental shelf,East Antarctica: Proceedings of the Ocean Drilling Program Scientific Results, v. 119, p. 77–132.

    Eittreim, S. L., A. K. Cooper, and J. Wanneson, 1995, Seismic stratigraphic evidence of ice sheet advances on the Wilkes Land margin of Antarctica: Sedimentary Geology, v. 96, p. 131–156.

    Birkenmajer, K., 1991, Tertiary glaciation in the South Shetland Islands, West Antarctica: evaluation of data, in M. R. A. Thomson, J. A. Crame, and J. W. Thomson, eds., Geological evolution of Antarctica: Cambridge, Cambridge University Press, p. 629–632.

    Ray says: “However you slice it, it starts to look like the Eocene and Cretaceous are tugging at our sleeve, whispering to us “There are things going on with climate you don’t begin to understand. Proceed with caution”. Ray, we actually completely agree on this!

  29. 79

    Re;37- Thank you ,Raypierre, for your response. I’m relieved that sincere naive questions aren’t verboten(at least not altogether). I didn’t connect the long lifetime of CO2 to it’s well mixed distribution in the atmosphere. It seems intuitive now that I know, yet a number things that often seem to be intuitive turn out not to be so,e.g. that,if we are moving relative to one another, we all carry our own time and space around with us.

  30. 80
    Kevin Stanley says:

    @68, raypierre’s inline response about the debate on the debate:

    I just posted on another some thoughts I was having that, upon reflection, fit better on this thread, so I’ll excerpt the relevant part of it here:

    “[when trying, as a layman, to evaluate the arguments]…here’s what I do. I think of the hierarchy of evidence I learned in college: true experiment>correlational study>case study>anecdote>expert opinion>personal opinion. Lab experiments verify the properties of CO2 that lead to it functioning as a greenhouse gas, as well as a lot of (all?) the other physics in the models. The balance of experimental and correlational research leads to a pretty coherant picture of what’s going on, summarized by the IPCC. There are margins of error around all the terms, but things are constrained enough to make it seem profoundly unlikely that some new finding will fundamentally disrupt the big picture. People regularly tell stories about being able to grow certain plants in zones where they formerly wouldn’t grow, spring coming earlier, winters being milder, etc. News reports about changes in the Arctic are frequent, I’ll also count that as anecdote. You can find “professional” opinion going either way, but when bodies of scientists have issued official positions, it has AFAIK always been to endorse the IPCC synthesis. The only place where I encounter as much support for the position that the current warming isn’t anthropogenic (or has stopped, or whatever) is at the lowest tier of evidence: personal opinion. However, there are several very vocal “experts” of the non-anthropogenic position, so I’ll grant that there is some debate at the lowest two tiers of evidence.

    But my impression is that many if not most people put expert opinion much higher in the hierarchy, and then weight expert opinions differentially according to how closely the various experts match their own preexisting beliefs. So in effect, the determining factor in how many laypeople evaluate the evidence is…how well it accords with what they already believe, or want to.

    Here’s where I’m going with all this–the professional and amateur climate scientists here, and at Tamino’s place, and Eli’s, etc. often recommend that we laypersons educate ourselves about climate physics so we can grasp the significance of the evidence. I agree. But given that we know, or at least strongly suspect, that for most people that will never happen, I recommend that the climate folks also educate themselves about another professional field: social psychology, particularly persuasion and attitude change. I think it’s important. And I think those who have set themselves up as your idealogical opponents are ahead of you on this. I’m not suggesting that you use any of the “dirty tricks” of marketing that the other side is already using–going over to the dark side would ruin your credibility with us idealistic people. But I really, really do think you should get more savvy about the social psychology of attitude change.”

  31. 81
    pat n says:

    In #47 Gareth wrote “until we can refine the models so that they can cope with the observed rates of Arctic warming,” …

    Increasing cloudiness in winter in mid-high latitudes, and less cloudiness in summer in low-mid latitudes, are only part of the reason for more rapid thawing happening, than modeled, in the Arctic (#38).

    Another factor is latent heat being released from condensation on ice and cool ground as humidity increases with warmer temperatures in the mid-high latitude regions.

    Increasing winter humidity (dewpoints in Jan-Mar) at four stations in the Upper Midwest (Fargo ND, Duluth MN, Minneapolis MN, Eau Claire WI) are shown for the 1950s-2003 period at:

    http://www.mnforsustain.org/climate_snowmelt_dewpoints_minnesota_neuman.htm

    Furthermore, increasing winter dewpoints are indicative of increasing winter cloudiness.

  32. 82
    Hank Roberts says:

    Ray, Chris Colose’s OWH quote seems quite apt.

    Religion or history can be debated; finding a flaw at the root causes the whole thing to fall down.

    Science can’t be debated, it grows like kudzu — patches don’t thrive, but new growth happens wherever an idea reaches a place to root.

    The thing missing in attempts to debate science is any attempt to teach people how to look things up for themselves.

    Who teaches that? Librarians.

    Suggestion — if you feel you must respond, challenge a two-column side by side written debate under the supervision of a public library reference desk, where the rule is something like

    2 column-inches per day, and cite your sources. A print/audio/video version could provide the links, but the link should be to the reference librarian’s page hosting the _source_ material, and satisfy the reference librarian’s professional judgment.

    At the end of the week or month publish it as a series of side-by-side ‘debate’ pages, on each topic raised — with a link to a reference librarian’s help desk to look up new information.

    http://www.ipl.org/div/about/edinit.html perhaps?
    Not much there about climate change now, but it’s promising.

    Debate is prescientific discourse. Don’t go back there.

    Bottom line — we either keep the enlightenment or lose it.
    David Brin’s eloquent about this.
    http://davidbrin.blogspot.com/
    Right now he’s recommending this; I do too: http://www.youtube.com/watch?v=wt_mluFK7xk

  33. 83
    Mark A. York says:

    I think scientists are going to have to put on public face and debate not only the crackpots, but the handful of credentialed sceptics like Lindzen and Christy and Spencer. And somehow make the point that only looking at scientific issues through a political filter is a fool’s errand. That was my point in the Gather.com thread.

    http://www.gather.com/viewArticle.jsp?articleId=281474977235302#comments

    The sceptic questions are the ones the public sees. I’m hoping my upcoming novel answering Crichton will help spark meaningful discussion and hopefully prominent exposure. We’ll see. I know who I’m gonna call to chime in.

  34. 84
    Kevin Stanley says:

    @82 Hank Roberts

    “The thing missing in attempts to debate science is any attempt to teach people how to look things up for themselves.”

    This is important, but I think the first step has to be persuading people to be open minded enough to evaluate the evidence fairly and update their beliefs accordingly. I know some people who are quite capable of looking things up, and they use that skill only to find things that support their preexisting beliefs.

    [Response: Something to keep in mind is that only a tiny fraction of people will ever get to a live public debate or public lecture. In line with your comment about people seeking out material that consolidates their pre-existing beliefs, one need only think about the fragmentation in audiences of talk radio and TV. There are lots of people who get all their information on global warming from Glen Beck's Headline News and similar shows. You could also say that there are people who get all their information about global warming from Al Gore and similar expositors. I don't mean to put these two in the same class -- having looked at both sources as a scientist, I am firmly convinced that people who get all their information from Gore (whatever his minor transgressions) are living in something closer to the reality-based community than people who get all their information from Beck. But all that aside, the essential problem in public discourse today is how to get all people to seriously consider a variety of different sources of information. And also, how to teach them ways to decide between conflicting viewpoints, either by learning what constitutes a worthy authority, or by directly understanding the arguments. --raypierre]

  35. 85

    Raypierre writes that:

    “the essential problem in public discourse today is how to get all people to seriously consider a variety of different sources of information. And also, how to teach them ways to decide between conflicting viewpoints, either by learning what constitutes a worthy authority, or by directly understanding the arguments.”

    Perhaps more fundamental is to inoculate society with a more healthy skepticism. On all sides of this issue we have a dangerous tendency to search out information that supports our preconceptions, something exacerbated by the sheer volume of information available on the internet (where it is all too easy to see what we want to see).

    We need to emphasize a neutral approach to knowledge in our scientific education, where we can cast aside our preconceptions for a moment to objectively evaluate the evidence on any given issue. But as with many things, it is far easier said than done.

  36. 86
    Martin Vermeer says:

    raypierre:

    …in fact I’m not certain that my persistent refusal to appear on talk
    shows with Avery actually is the best decision. It’s something that is
    worth discussing.

    Still I think refusal is right; but we should sell it better. What about the dueling code? “The challenged has the right to choose his own weapon … The challenged chooses his ground”. So there is no refusal to debate, but rather the right to choose the peer reviewed literature as the “ground” and the “weapon” ;-)

    [Response: I think this is a very good analogy. My choice of weapons is the peer reviewed literature. Their choice is the oral single-session debate. They can say "raypierre won't debate," but I can say "Avery won't publish " (in the peer-reviewed literature. But not only does that look like a stalemate, it still leaves us with the problem that anything settled in the peer-reviewed literature needs to be communicated somehow to the larger public. Nonetheless, when cleaning Mark Morano's clock over at DotEarth, I've tried to emphasize that most of the Inhofe 400 can't be taken seriously, because the ideas that qualify them as skeptics have not been subjected in any way to peer review. --raypierre]

  37. 87
    tharanga says:

    “what constitutes a worthy authority”. This is the part that really dismays me: the unhelpful role played by some scientists and engineers in other disciplines – people who really ought to know better.

    There are just enough of them who, after a moment’s reflection or a simple calculation, are sure that they’ve found the key that overturns decades of research in another field. Don’t get me wrong; interdisciplinary work can be very productive, but not in this manner.

    Can you blame the laymen for having trouble sorting it out?

  38. 88
    Hank Roberts says:

    More Brin, found here:
    http://lifeboat.com/ex/singularities.and.nightmares

    This info and pointer:

    For a rather intense look at how “truth” is determined in science, democracy, courts and markets, see the lead article in the American Bar Association’s Journal on Dispute Resolution (Ohio State University), v.15, N.3, pp 597-618, Aug. 2000, Disputation Arenas: Harnessing Conflict and Competition for Society’s Benefit.
    http://www.davidbrin.com/disputationarticle1.html

  39. 89
    Martin Vermeer says:

    …it still leaves us with the problem that anything
    settled in the peer-reviewed literature needs to be communicated somehow
    to the larger public.

    Sigh, true. But that’s education, not debate.

    I have sometimes responded to ultimative demands that I prove the reality of evolution with “Read the textbooks. This is textbook stuff. I am a teacher; teaching is what I do for a living. Why should I teach for free someone unwilling to learn?”

    Which is what RC does, though much of the audience here — the intended audience — is willing to learn. Never forget that the appropriate format for textbook science is teaching, not debating!

  40. 90
    Daniel C. Goodwin says:

    Re: 85 “We need to emphasize a neutral approach to knowledge in our scientific education, where we can cast aside our preconceptions for a moment to objectively evaluate the evidence on any given issue.”

    Surely, your suggestion is the only way out of our cultural difficulty with the concept of truth. My experience as a goldfish in this American bowl is that your remedy will be almost impossible to administer. It would be hard enough to upgrade from legal to scientific standards of “debate” or discussion, a dichotomy Raypierre points out in his post. But even the word “debate” has been degraded (as have a plethora of other words) to near meaninglessness. Consider the political pageants we refer to as “debates.” Nothing resembling reasonable discussion can get a word in edgewise, aside the soundbytes. One of the candidates may say something incoherent, like “there you go again,” after which all consent manufacturing machinery declares such a statement a master-stroke which “won” the debate.

    Raypierre is well-advised to avoid lending any legitimacy to these stupid games we call debates. For the most part, people in our culture have lost the very concept of truth as something non-fungible. The truth is whatever we want it to be. You only need to believe, and to clap, in order for Tinkerbelle to revive.

  41. 91
    Kjell Arne Rekaa says:

    This is very interresting subjects, and a good article from you, Raypierre!
    I can see there are some questions around how the temperature could be as high as 23C in the Artic. I wonder if we could explain it with some of todays observations?

    For us nordic (norwegian) people, we are quite used to experience that our warm (T-shirt and shorts) summer, in average starts in June. On the other end, august is sometimes even the hottest summer month, while may, which give us the same elevation to the sun (and radiation) as august, seldom are. The reason are the vast amounts of snow and ice still covering big areas of the mountains in Scandinavia, cooling the air when the wind flows over this surface.
    Ice and snow is giving an tremendous cooling effect, as long it is there. Beside fairly high radiation from the sun in summertime, we are also receiving enormous amount of hot Golf stream water. Especially the latest years, we are experiencing «indian summer» (above 20C for at least 24 hours) more frequently and even further north. Try to imagine the needed energy to melt the amount of disintegrated ice in the Artic during the short summer season? When you know the amount of ice melted, think about a future with all ice melted in the Artic around july/august? The same amount of hot Golf stream water still sweaping north, will fast give such conditions above 20C, when the basic temperature is 35C from the tropical area.

    About doing panel discussions aboute Global Warming:
    I would love to see the following demonstation from the beginning of such a talk, where you or anyone doing that, starts out with the following setup/actions:
    - Two one liter glass-bowls with 0C water, and a termometer attached
    - Both of them are added a equal hot warming element.
    - After 10 minutes or so, ONE is BOILING (100C), while the other still holds 0C!
    - Oh… I forgot to say that this bowl still holding 0C, still has some ice cubes left which has not melted…
    - This will REALLY demonstrate the vaste amount of energy needed to simply MELT the same amount of 1 Kg ice (0C), compared to rise the temperature with 100C in 1 Kg water.

    So it makes it easier to understand the important refrigiator effect the Artic ice is giving us

    Kjell Arne

  42. 92
    Thomas says:

    Raypierre good debate. A couple of (possibly naive) geochemical questions, which if they haven’t been asked perhaps should be. Is there any hope of estimating ancient CO2 concentrations via the effect of CO2 on ocean acidity? I.e. could there be missed proxies for ocean PH which might shed light on CO2 concentration?
    The second question has to do with plate tectonics, which to my understanding sometimes varies in speed. Speed of the tectonic conveyor belt can effect (I think it’s been a very long while) the distribution of water between the oceans, and the mantle, as water is incorporated into descending slabs, and liberated via vulcanism. Could this process lead to long term changes of Oxygen isotope ratios, independent of surface conditions? Also the speed of tectonic motion effects the average depth of the ocean (faster means younger warner less dense seafloor), and presumably the ratio of land to water as well. I think the time scale of these process changes is larger than the 200Ky glacial-by-proxy interval, but perhaps many proxies could be effected together.

    [Response: When it comes to geochemistry, I'm as naive as the best. I have a good handle on O-18, but I'm still feeling my way through the various things that affect carbon isotopes and other isotopes. Dave Archer could answer your question about ocean pH better than I can, but my understanding is that the Boron isotope proxy is basically a pH proxy, turned into CO2 proxy via the chemistry you have in mind. Tectonics has no significant effect on oxygen isotopes on these time scales, and probably not on any other time scales. There's just too much ocean water relative to the water vapor outgassed from the interior of the Earth. --raypierre]

  43. 93
    Thomas says:

    Thanks for the response. Do the Boron PH proxies provide much of a constraint on the CO2 concentrations? I’m not convinced about the O isotopes. I had the impression that the total amount of water in the mantle is quite large. IIRC downgoing slabs may contain 1-2% water, and the volume is huge. At least that seems consistent with the claims of exobiologists that a planet must have working tectonics to be suitable for life -the theory being that the recycling of certain chemical constituents (and effective buffering of surface concentrations) being critical. I suspect the time spans involved may be hundreds of millions of years.

  44. 94
    Dodo says:

    #77. Chris, you are not alone in your frustration. As a journalist with a degree in science (way back), I have noticed that the public at large is simply not able to move beyond the first round of arguments. They just adopt whatever feels good and right in their own immediate reference group, and then pick what they read in order to get their chosen opinions confirmed – if they read at all.

    It is very likely that this will never change. Even among journalists, there is the same unwillingness to have one’s views seriously challenged. So we get the same outlets churning out the same message over and over again, partly because journalists want to prove to themselves and their peers that they were right all along.

    In economics there used to be a schism between Keynesians who favor fiscal policy and Friedmannian monetarists who prefer monetary policy. The former was identified with Yale, the latter with Chicago, and a very serious joke was that economics would begin its journey towards being a science when Yale produces a study emphasizing monetary policy or Chicago publishes something pointing to the importance of government spending.

    Well, economics has moved somewhat into the right direction – there is less tribal bickering and outcomes of many studies are truly surprising. Let’s hope climate science goes the same way. But for the time being, the results of climate studies are completely predictable: just look at the name of the lead author and you know whether the conclusions are mainstream or heretical.

    Sooner or later the layman may begin to question the whole point of research: why all these studies, if you already know everything?

  45. 95
    Nick Barnes says:

    Thomas@93: suppose your number of 1-2% is correct. The lithosphere is ~100km thick, and moves at speeds up to about 5cm per year, and there’s a total subduction front of maybe 10000km. So my back of the envelope suggests that maybe one cubic kilometre of water is subducted every year, compared to some billions of cubic kilometres in the oceans.

  46. 96

    RE #4, I know what is meant by “toast.” One might have to live in a place like the Rio Grande Valley of TX during the Canicula (mid-July-August heatwave) to understand. Or (elsewhere) wait around a few decades or a century or two for GW to really kick in.

    Of course, no one in the RGV actually gets toasted bec no one is crazy enough to sun bath during the Canicula. We just struggle to make it from our airconditioned cars to the airconditioned stores or workplaces without fainting from the heat…or getting toasted.

  47. 97

    Re the Antarctic glaciers during this hothouse period. Maybe some synthetic approach, maybe many different factors converging, each giving a slight nudge toward glacier formation.

    Some orbital or wobble thing that gives less solar irradiation to the Antactic. (Or clouds, as suggested.) A big ozone hole over the area caused by something or other. Ocean currents not bringing warmer waters. Etc, etc. And then that large land area of Antarctica gets blanketed with snow one day due to all that WV held up in a GW world and some freak cold snap (weather can fluctuate wildly). Maybe a spring cold snap. Then the albedo effect kicks in, making it colder, and more snowfall on through the summer.

    Also (this is stupid, I’m sure) but the land there is not going as fast as the tropical area as the earth makes its 24 hr spin, so less friction, less heat.

  48. 98
    Rod B says:

    Just an observation and a maybe helpful comment of the topic of public debate. I think your assessment is quite accurate (and you should know!), but none-the-less you have an obligation to enter into the public discourse, unless your scientific pursuits are purely academic — which I get no indication that they are. Plus I think the public discourse (debate to be sure sometimes) has to include all topics; no topics are off-limits; you can’t successfully pick and choose what science is completely settled and not up for debate. It has to be viewed as a sales process, assuming you are hoping to get some action done. The aginers, skeptics (like me), politicos, and the general public are your customers. You can never tell a customer that his question or concern is out of bounds and expect to close the sale — even if their questions or assertions are really off the wall and abominably stupid.

    The problem is, of course, that typical scientists are usually not highly skilled in salesmanship (with notable exceptions), find it distasteful and foreign to the way they like to operate, and are not very good at spin and sound bites (as many from our side are.) They work much better making strong definitive claims and carrying out the heated scientific debates as you describe with people of the same ilk who understand the rules. This is appropriate, in some sense, IMO, because the mental processes required for public debate and sales are frankly not conducive and tend to diminish scientific skills. But it has to be done if you want societal success. And done on their turf. You almost can’t win for losing, but that’s the way the world turns.

  49. 99
    Thomas says:

    Nick@95:
    Lets assume that over the relevant time period cycling of Oxygen atoms between the oceans/atmosphere/cryosphere and rock reservoirs is 10%. We are using isotopic differences of a few ppm as significant proxies. If the isotopic compostion of the rock reservoir is significantly different than the ocean reservoir and/or the cycling process has significant isotopic selectivity the rate of drift might be significant on that time scales of a hundred million years. We shouldn’t take the modern values as relevant to the distant past without first asking the experts (I am not one) what rate of drift is possible over these sorts of time spans. Unfortunately, if the result is that such drift could be significant it would make the job of paleclimate reconstruction much more difficult.

  50. 100
    Hank Roberts says:

    > Texas

    And courtesy of the Texas Department of Health, this advice on working outdoors during the heat — adaptation!

    ——excerpt—–

    Forty-seven workers in the United States died from environmental heat exposure in 2005, according to the Bureau of Labor Statistics. In the same year, 2,610 workers missed at least one day of work because of heat-related illness.

    The Occupational Safety and Health Administration does not regulate the number of hours people work in the heat, a representative said. A catch-all clause in a 1970 act proscribes “recognized hazards that are causing or are likely to cause death or serious physical harm,” according to the OSHA Web site.

    Yara Doyle, safety coordinator for a construction company, trains workers on how to stay cool and visits job sites to check for heat exhaustion.

    “They’re so used to (the heat),” said Doyle, from Cris Equipment Company Inc. “They just go about it like it’s a normal day.”

    Cris employs about 90 workers, who are outside for 10-hour shifts….

    People who work outside physically adapt to the heat, said Dr. Brian Smith, regional director of the Texas Department of Health.

    “They change the electrolytes that are in their sweat,” Smith said. “It takes about two weeks to get accustomed to not being in air conditioning.”

    —–end excerpt———

    Isn’t that reassuring? Of course, Mr. Smith is referring to the kind of people he sees working outside at manual labor in the Texas sun. They adapt. I doubt he adapts. Bet he has air conditioning?

    http://www.themonitor.com/onset?id=4042&template=article.html


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