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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. 251
    Jon Gradie says:

    Re: #242
    This concept has been studied in another form:
    Hurricane Tower Desalination System
    Client: National Science Foundation
    Project: Computational & Physical Modeling of the Hurricane Tower Desalination System

    Oceanit built a device and states, “The cost of water produced by the Hurricane Tower was comparable to that produced by existing condensation systems and reverse osmosis systems, but used only a small fraction of fossil fuel energy.”

  2. 252
    Rod B says:

    Barton (227), I was simply addressing Camus’ position as Ray provided in 188.

    JCH (231), Good. Now I see how we can do massive mitigation yet continue to support people’s standard of living. The climate guys simply do the defining of what is the satisfactory standard of living for them other guys. Neat and clean and no problem…..

    Also the Chinese et al, you say, (and concurred in by Jim Eager (249)) will gladly accept the hardships of mitigation because they’ve always lived with similar hardships and don’t know any better (which you attribute to “smarter”). ‘Nother nice neat plan. BTW, I would suggest that you not go on the stump for AGW and mitigation; your assertions are what would cause the aginers to drool all over the place because they could say convincingly to the public, “See! What did I tell you those guys really wanted??!!”

    Then Lynn says (233), “….would be a terrific economic boon to all countries rich and poor alike, so econ v. enviro is a total red herring here, and not even a consideration in the debate.”

    [sigh!] Lynn, would you tell me with guaranteed (by you) certainty which of the alt. energy enterprises will be a colossal success five years from now? I’ll make it easy: just guarantee me one of the current companies a five-fold increase in their stock price. But I still admire your zeal.

    Phillip Shaw (244): I’m assuming you are defining BAU in terms of trying or not trying to control carbon emissions. A novel definition going back to 1900, but I’ll go with it. You say “BAU” hasn’t gotten the 3rd world out of poverty [as an aside I think it actually is relative and not that bad, but I’ll go with this, too.] so not BAU is certain to do the trick. That logic flow is giving me a headache.

    Finally, raypierre says (235), “Now, getting back to the Cretaceous…”

    There’s a novel idea!

  3. 253
    Jerry Toman says:

    Thank you for the reference as well as your interest, Jon.

    Hawaii (Kona Coast, I assume) is a great place to desalinate sea water because it has warm surface water, plenty of direct sunshine to augment its temperature, and a cold undersea current that can be tapped to efficiently condense the fresh water that is evaporated in any device.

    The device you provide reference to is, at first blush, an interesting variation to standard mechanical methods of desalinating seawater such as what would be achieved by using a spray tower, in which pumps are used to provide brine to the nozzles, followed by recovery of the fresh water eaporated into the air by passing the humidified air stream through a condenser. In this case a “stirring device” seems to induce both air flow and water contact as well as to enhace heat and mass transfer coefficients, which represents an interesting variation on the standard theme.

    However, it is not an atmospheric vortex engine, which provides motive power through establishment of a tall (3-5 mile) buoyant vortex. This creates a “vacuum” at the surface below which induces air to converge (and be deflected tangentially) as it enters the base of the vortex. The humidity and enthalpy of the incoming air is enhanced by “warming towers” through which the air traverses (mostly) horizontally while being contacted with warmed water introduced by a spray or allowed to trickle down extended surfaces. A large one would normally be designed to export electricity as well as to produce desalinated water.

    In contrast to the Oceanit device (“hurricane tower” seems a bit O/T) the AVE would require no external source of power, since electricity to power the pumps could easily be generated internally.

    In my opinion, developing the AVE to accomplish these sorts of tasks weakens GW skeptics because it devalues the assets of their patrons, whether that be the technological “know how” of the nuclear industry or the fossil reserves of YKW. This low-tech form of power can be produced in a distributed fashion and owned by local municipalities. It is especially useful when combined with geothermal resources, which I understand to be plentiful in Hawaii, as well as most of the northwestern US.

  4. 254
    Jim Eager says:

    Re Rod B @ 252: “Also the Chinese et al, you say, (and concurred in by Jim Eager (249)) will gladly accept the hardships of mitigation because they’ve always lived with similar hardships and don’t know any better (which you attribute to “smarter”).”

    Nice mischaracterization of what Ray and I wrote, Rod.

    I’ll let Ray clarify his own words, but I was merely pointing out that if push comes to shove, whether it be due to environmental collapse or peak oil, the Chinese and Indians will be in a much better position to adapt than Americans will be.

    Preserving, or emulating, our current profligate, wasteful lifestyle is the antithesis of adaptation.

  5. 255

    Re #250 Where Steve wrote “I agree, but before you can seriously address that question with people, they have to admit that they do not already ‘know’ all the answers.”

    I admit that I do not already ‘know’ all the answers.

    Howver I do ‘know’ how the rapid warming that ended the Younger Dryas stadial happened. The sea ice which had spread out of the Arctic as far as Ireland suddenly melted. This case warming by changing the summer albedo, but it also allowed the water which had been below the ice to evaporate. Water vapour is the main greenhouse gas, and this intensified the warming causing more water vapour to be produced. What happened was a runaway warming when temperature rose by 10C within three years.

    Now the remaining ice in the Arctic is also about to disappear, and that will also cause a runaway warming. I don’t know how temperatures will rise. I don’t have all the answers. But it has the potential to seriously disrupt agriculture which will result in famine.

  6. 256
    SecularAnimist says:

    Lynn Vincentnathan wrote: “The Q should be, ‘How do you know we are NOT approaching tipping points, or that there are none?'”

    Steve Reynolds replied: “I agree, but before you can seriously address that question with people, they have to admit that they do not already ‘know’ all the answers.”

    What we do already know is that the observed anthropogenic increase in atmospheric concentrations of CO2, principally from the burning of fossil fuels aggravated by deforestation, is causing the observed heating of the Earth’s atmosphere and oceans as well as observed acidification of the oceans; that the anthropogenic heating is already causing the large-scale observed changes in the Earth’s climate, hydrosphere and biosphere; that these observed effects are far more rapid and extreme than predicted by our models; that the accumulated excess CO2 in the atmosphere will continue to cause such effects for many decades at least; and that our emissions are not only growing but accelerating; and that if we continue on this path the resulting unmitigated warming will have catastrophic effects for both human beings and the Earth’s biosphere itself.

    In short we know everything we need to know to understand that we must move quickly and aggressively to reduce carbon emissions by phasing out fossil fuels and replacing them with clean, renewable sources of energy, while simultaneously using large-scale reforestation and organic agriculture techniques to draw down the already excessive and dangerous CO2 levels by capturing carbon in soils and biomass.

    It is just because we know this, and because the public is at last awakening to the fact that we know this, that proponents of doing nothing are moving away from disputing the indisputable reality of anthropogenic warming and dangerous climate change, and offering instead spurious arguments that action will be “too expensive” or will “perpetuate poverty”.

  7. 257
    Chris Wagoner says:

    I find yoru information very interesting and informative. Could you answer a couple of questions I can’t get anyone else to answer on this topic though?

    1. What caused the last several Ice ages to end and the warming of the earth during those periods, before man was around?

    2. Has the Sun been getting warmer over the last few decades, in relation to the earths warming?

    These are questions I see some using as arguements against the Man made global wrming discussion and no one answers them. I would like to be able to do so with factual data, can you help?

  8. 258

    Chris Wagoner writes:

    [[1. What caused the last several Ice ages to end and the warming of the earth during those periods, before man was around?]]

    The Ice Ages are triggered by “Milankovic Cycles,” which are regular changes in the Earth’s orbit shape (“eccentricity”), axial tilt (“obliquity”), and precession. These alter the distribution of sunlight over the Earth’s surface on scales of tens of thousands of years. The temperature swings are amplified by greenhouse gases. In a natural glaciation, or deglaciation, temperature leads CO2, but that isn’t what is happening now. The fact that warming can take place naturally doesn’t mean it can’t happen artificially as well.

    [[2. Has the Sun been getting warmer over the last few decades, in relation to the earths warming?]]

    No. Solar output has been flat, on average, for about fifty years.

    [[These are questions I see some using as arguements against the Man made global wrming discussion and no one answers them. I would like to be able to do so with factual data, can you help?]]

    See above.

  9. 259
    Steve Reynolds says:

    SecularAnimist> In short we know everything we need to know…

    I doubt most scientists will agree with you. The IPCC does not.

  10. 260
    Ray Ladbury says:

    Steve Reynolds takes Secular’s quote out of context–It is certainly false to say that we know everything we need to know about climate. It is, however, quite true that whatever we learn is unlikely to overturn the knowledge that increased CO2 will cause temperatures to rise dramatically and probably dangerously over the next century. While we know pi is a transcendental number, this does not mean we can never work with circles. For most applications, pi~3.14 works just fine.

  11. 261
    Nick Gotts says:

    Re #230 [Walt Bennett] “What are your thoughts regarding hedging our bets with regard to emissions reduction and other “stop being bad” policies?”

    In principle it makes sense, in practice I fear the prospect of geoengineering solutions being used to delay action on emissions reduction. Since action of either kind requires an international agreement between at least the major emitters to have a good chance of success, I’d make the goal of reaching such an agreement top priority. Such an agreement could include an internationally-funded geoengineering research component, which I would welcome as long as I was confident it would not detract from emission reduction efforts, although I’m not sure exactly how this could be ensured.

    One more point: I’d be more willing to consider smaller-scale projects which could be tried out without excessive cost or risk. For example, New Scientist this week has an article on traditional methods of “growing glaciers” in the Hindu Kush and Karakorum areas. There is uncertainty about whether these really work, but it seems plausible there could be ways to encourage the growth/discourage shrinkage of glaciers, thus reducing AGW impacts at least temporarily.

  12. 262
    Steve Reynolds says:

    Ray, the context is available to anyone who wants to see it; just scroll up 3 messages. Here is a little more:

    Secular> In short we know everything we need to know to understand that we must move quickly and aggressively to reduce carbon emissions by phasing out fossil fuels…

    While most would probably agree that eventually phasing out fossil fuels is necessary, I don’t think we know enough to determine the cost/benefit balance of doing it quickly or gradually.

  13. 263
    John Mashey says:

    Well this has nothing to do with the thread topic, but…

    Read the Hirsch Report for the DOE, starting at

    and then going on to the full report linked there.

    Bottom line, we (USA) should start massive de-oiling our economy 20 years before Peak Oil … which turns out to be 2010 +/-4 years by most accounts, and we didn’t start in 1990. The Hirsch Report models the consequences. Kharecha & Hansen tell us that Peak Oil doesn’t come fast enough to stop AGW effects [i.e., we’re going to burn it all, the key issue is to transition so that we don’t end up burning a lot more unsequestered coal, tar sands, shale oil… of course, the coal companies really want oil&gas to burn up before renewables get widespread, because then there will be terrific pressure to burn more coal. All of this is quite straightforward short-term economic behavior and unsurprising.]

    1) Anyone who’s future prosperity is proportional to oil/gas profits knows that under no circumstances should there be any efforts to tax carbon noticeably, replace oil, or use it more efficiently, because that would cut into future profits. More efficient transformers should be inhibited [CA’s Jerry Brown has been suing the DOE on that one, less visible than the EPA suit.] We know we’ll use all the oil we can get, but if electrification/biofuels/conservation come faster, that will keep oil prices less high. This allows oil companies to obtain a higher percentage of GDP, because people with vehicle fleets and infrastructure will be desperate enough to pay. Fuel costs get embedded in other products, not just at the pump. ExxonMobil understands this well, which is why they made $40B profit in 2007.

    2) Anyone wealthy enough can take whatever position they want, without being much affected.

    3) Anyone else should be fighting very hard for rapid transition, and better hope they live in one of the areas that is trying very hard to de-oil, since it is going to take decades, and it will be bad enough in places (like CA) that actually try hard on efficiency.

    A lot of average wage-earners elsewhere in the US are going to be well-clobbered, and any such person arguing for delay has been effectively conned into arguing against their own (or their kids’) self-interest, for the benefit of a small set of people who will laugh all the way to the bank.

  14. 264
    Hank Roberts says:

    Steve, ocean pH. Regardless of temperature (atmospheric physics), the CO2 is going into the ocean at a rate calculable using simple physical chemistry, far better understood and much simpler science. No matter whether the sun quits spotting, the planet goes into a baby ice age, or the planet warms up — no matter, doesn’t make any difference in the chemistry. The chemistry will go along as predicted and the ocean food chain will change very greatly. Already overfished, with jellyfish becoming the top predator, and then we lose the commonest and most prolific organisms because the ocean starts dissolving their calcite and aragonite shells.

    And you don’t see anything to worry about?

    Apres moi le deluge?

  15. 265
    Ray Ladbury says:

    Steve Reyonolds–Phasing out fossil fuels quickly–hell, I’d settle for even reasonable movement in that direction! They are actually cutting back on research. There has been no effort to facilitate availability of energy-efficient technologies either domestically or in developing countries.

  16. 266
    Steve Reynolds says:

    Hank Roberts > ocean pH. Regardless of temperature (atmospheric physics), the CO2 is going into the ocean at a rate calculable using simple physical chemistry, far better understood and much simpler science.

    OK, but we know that there were times in the past when CO2 levels were likely much >1000ppm. There must be some info about what that did to ocean life. What does that data show?

  17. 267
    David B. Benson says:

    Steve Reynolds (266) — During PETM many marine organisms went extinct. Even Wikipedia has a little about it.

  18. 268
    Hank Roberts says:

    Steve, do you believe in evolution? I can find that answer for you. What sort of answer will you believe?

    Will you believe seabed fossils that show what was alive in the ocean during one of those times?

    Seriously — I’m sure I’ve answered this before, and I”m sure you can look it up. Since you don’t understand why it’s a problem, something about the easily available answers isn’t credible to you.

    How about you pick a time period from the past when you believe CO2 in the atmosphere was over 1,000ppm — name it — and then we look together at a geological record that you consider believable?

    I will say straight out that I do believe in evolution, and do rely on seabed drilling and other work in the scientific record to tell me what past CO2 levels were, and what was alive on Earth at the time.

    That work for you?

  19. 269
    Hank Roberts says:

    Further for Steve Reynolds, if you don’t have a preferred source of information you trust to suggest, start here, the ‘Supplementary Information’ PDF is downloadable as is the Abstract, and the various links to cites and references will get a good overview. Nature’s main article full text is paywalled of course.
    But they leave the edges accessible.

  20. 270

    Yes, Steve is right. Raypierre wrote “For example, estimates for the Eocene range from values similar to modern CO2 concentrations all the way up to 15 times pre-industrial CO2.”

    How was it that corals survived then, when the ocean must have been far more acid than today, or even tomorrow?

  21. 271
    Steve Reynolds says:

    Hank Roberts> start here, the ‘Supplementary Information’ PDF is downloadable as is the Abstract…

    Hank, I did look there, but did not find any direct links to useful data. I really did ask my question to see if anyone knew exactly where data was on what sea life survived the high CO2 levels of the past. Searching does take time.

    Some easily accessible data on CO2 is here:

    but that only shows that CO2 levels were very high any where from a few million to 100 million years ago, depending on which papers you believe.

    And yes, I do think evolution is the best explanation to origin of life. When have I ever given the impression that I did not accept most peer reviewed science as the best info that we have?

  22. 272
    Hank Roberts says:

    Which corals are you thinking of, Alastair?
    Don’t just assume what’s here now is the same animal that was there then.

    That’s why I asked about evolution. The calcite and aragonite shelled organisms are rather recent.

    Look at the strata. Black shale — no oxygen; white cliffs of Dover — oxygen.

    Kennett, J. P., and L. D. Stott, Abrupt deep-sea warming, paleoceanographic changes and benthic extinction at the end of the Paleocene, Nature, 353, 225–229, 1991.

  23. 273

    Alastair writes:

    [[Yes, Steve is right. Raypierre wrote “For example, estimates for the Eocene range from values similar to modern CO2 concentrations all the way up to 15 times pre-industrial CO2.”

    How was it that corals survived then, when the ocean must have been far more acid than today, or even tomorrow?]]

    There’s no reason to think corals then didn’t suffer when CO2 started going up, but that the few survivors were able to adapt to the changed environment. Natural selection in action. But in the Eocene we didn’t have a fishing industry feeding a sixth of the world and dependent on a healthy ocean ecosystem.

  24. 274
    Steve Reynolds says:


    That abstract does not convey much info to me about the effect of 1000ppm CO2 on ocean life.

  25. 275
    David B. Benson says:

    Steve Reynolds (271) — The origin of life is called abiogenisis. Biological evolution refers to the origin of species from previously existing life forms.

  26. 276
    Hank Roberts says:

    Steve, pick a geological time period, please, when you believe CO2 was at 1,000ppm. Then, assuming you believe in evolution, let’s look at what was living at the time and how things went during and after that time.

    Seriously — you pick. Let’s look. I can only talk about this if you do believe in evolution; if you don’t, I can point you to some sites with alternate explanations for everything.

    You might also have a look at Peter Ward’s recent book “Under a Green Sky” for more.

  27. 277
    John Mashey says:

    BPL: Steve R should be able to
    Google: eocene and then eocene coral
    as well as the rest of us, if he wanted to. says:

    “Marking the start of the Eocene, the planet heated up in one of the most rapid (in geologic terms) and extreme global warming events recorded in geologic history, called the Paleocene-Eocene Thermal Maximum or Initial Eocene Thermal Maximum (PETM or IETM). This was an episode of rapid and intense warming (up to 7°C at high latitudes) that lasted less than 100,000 years [2]. The Thermal Maximum provoked a sharp extinction event that distinguishes Eocene fauna from the ecosystems of the Paleocene.”

    7C? at high latitudes? in 100,000 years? Mother Nature is a wimp. We can do that in a few hundred years, no problem.

    The PETM lasted on the same order of time as the existence of modern humans, and then the Eocene lasted ~22M years, with lots of jiggles. Given 100,000 years to warm, corals may well have adapted, and certainly moved poleward and back, and evolved, and if even a tiny fraction survived somewhere, they could bounce back in some form or other.
    Reefs and coral rich deposits are comparatively rare in Eocene rocks from the Western Atlantic and Caribbean region

  28. 278
    Tim McDermott says:

    Hank (276),

    I think it is a tactical mistake to talk about ‘belief’ of scientific matters. [edit – no theology please]

    I think using the word ‘convinced’ is better in that it does not immediately bring false gods to mind. I think it is also better if, like me, you are convinced that the evidence to date supports a story that points in one direction, but would be willing to throw it all away given convincing evidence and an explanation that points in a different direction.

  29. 279
    Steve Reynolds says:

    Hank Roberts> pick a geological time period, please, when you believe CO2 was at 1,000ppm.

    According to the link I gave you, the Royer Compilation data show CO2>1000ppm for more than half of the last 250 million years. Did you look at it?

  30. 280
    CobblyWorlds says:

    Royer/CO2/Ocean Acidification “then & now”…

    CO2 may have been higher in the past, but the bottom line is that over the period current ecosystems have developed, CO2 has not been as high as 1000ppm. And given the speed of emissions it’s hard to see how such ecosystems will have time to adapt.

    As with the global warming caused by our CO2 emissions, it matters not whether life has prospered under the current likely “end result” conditions in the past. What matters is that we’ll be going through the transitional period!

    What arises from the explosive radiation that will follow the Anthropocene extinction event will arise too late to help us.

  31. 281
    Ray Ladbury says:

    Steve Reynolds said, “According to the link I gave you, the Royer Compilation data show CO2>1000ppm for more than half of the last 250 million years. Did you look at it?”
    Our restoration of Jurassic CO2 levels must come as a tremendous relief to any dinosaurs hiding away on remote islands.

  32. 282
    Alan Keller says:

    As a novice I wonder what the sources of greenhouse levels exceeding those presently driven by human activity were back in the Eocene and Cretaceous eras and what factors are thought to have ultimately led to lower greenhouse gas levels and lower temperatures at the end of those eras.

  33. 283
    max says:

    If this is the state of science that we cannot debate non-experts (or autodidactic experts) than science truly is no better than religion. I am not saying you should engage in a radio or TV debate, but what about one in a more eloquent form: Essays, written dialogue?

    I am sorry, but if you don’t even want to engage into a debate (if it not drops to a level of first class smears), then perhaps you shouldn’t also call you an expert and scientist on this matter.

    Most sceptics are not concerned about the science (although they don’t believe the “6°C” claim of so many environmentalists) but more about the economic possibilities and a risk and damage assessment, which incidentially is not any of climate scientists specific subjects…

    Max Schwing,
    Karlsruhe, Germany

    [Response: Where do you see us not engaging? What is this website? What are our public talks? I’ve even done multiple head-to-head ‘debates’. It is only through experience that one realises what is an effective use of ones time, and what isn’t. The important thing is too concentrate discussions on things that actually are debatable, and not on ‘faux’ debates which owe nothing to the scientific method, but everything to political rhetoric. Science is interesting to talk about, and you’ll not find any of us reticent on discussing that. – gavin]

  34. 284
    Ray Ladbury says:

    So, Max, exactly how would the sort of dog-and-pony show the skeptics are proposing advance anyone’s understanding of the science? It certainly has not done any good in the debate between creationism and evolution.

    Scientific debate is taking place exactly where it should be–in refereed journals and at conferences–where the opinions of experts are not drowned out by those of ignorant food tubes. And skeptics of course would be free to join in that debate…if they had anything scientific to add. Debate has moved beyond the science to the question of remediation and mitigation, and there the opinions of all are not only welcome, but essential. Scientists can further the debate too, by assessing credibility of the various threats climate change may pose. But all so-called skeptics accomplish by rejecting good science is ensure that their chairs will be empty at the negotiating table.

  35. 285
    Jeff says:

    This is a little off topic, but I hope you’ll indulge me. In the high school Physics course that I teach, my students use the Stefan Boltzmann equation to calculate the equilibrium temperature of the Earth using a simple box model. We then look at small perturbations in albedo, solar forcing, Milankovitch forcing and radiative forcings due to greenhouse gas emissions to calculate new equilibrium temperatures. I realize that some of these factors are related, but it is instructive for students to look at the temperature change due to each isolated variable. I have looked for an estimate of Earth’s albedo during past glaciations, but I can find no such estimate. Do GCMs calculate an overall albedo for the Earth, or do they use specific values for each type of terrain? Does anyone have an estimate for Earth’s albedo during the Pleistocene glaciation? I have read that the albedo was around 0.6 during the “Snowball Earth” hypothesis if you buy into this, but I have seen no other estimates.

  36. 286

    Alan Keller writes:

    [[As a novice I wonder what the sources of greenhouse levels exceeding those presently driven by human activity were back in the Eocene and Cretaceous eras and what factors are thought to have ultimately led to lower greenhouse gas levels and lower temperatures at the end of those eras.]]

    Excursions in volcanism are probably one source. CO2 from volcanoes and metamorphism are a very slow source on a human time scale, but over 100,000 years or so they can make large changes.

  37. 287

    Jeff —

    Here’s a quick and dirty model of the Earth’s albedo. A stands for albedo, f for fraction covered. I distinguish the albedo of the Earth’s surface (Asurf) from that of the planet (A) because of cloud cover, clouds being much brighter than ocean or land:

    ‘ Albedos:

    Ai = 0.60 ‘ ice
    An = 0.04 ‘ non-ice surface
    Ac = 0.45 ‘ cloud

    ‘ Fractional coverage:

    fi = 0.05 ‘ ice
    fc = 0.62 ‘ cloud

    fn = 1 – fi
    fsurf = 1 – fc

    ‘ Results:

    Asurf = fi * Ai + fn * An
    A = fc * Ac + fsurf * Asurf

    I wind up with Asurf = 0.068 and A = 0.305 for the present Earth.

    Now, double the ice cap coverage from 5% to 10%, and I get 0.096 for the surface albedo and 0.315 for the planetary albedo.

    It would take some good research to narrow down realistic figures for these parameters both for the present Earth and for the Earth during, say, glacial maximum 18,000 years ago. But I’m guessing the albedo was different by about 0.01 or 0.02 from its present value — enough to make a difference in the mean global annual surface temperature.

  38. 288
    CobblyWorlds says:

    #282 Alan Keller,

    On geological time-scales vulcanism alone would pump CO2 into the biosphere/atmosphere/ocean sinks. So given time this would increase CO2. CO2 is removed from those sinks by reaction with rocks in the ocean and on land, also by living organisms (sedimentary rocks). Since the development of life, CO2 has gradually been pumped out of the atmosphere and fixed in rock – that’s on a very long term trend.

    James Lovelock and others have proposed that the removal of CO2 and it’s long term reducing trend may have prevented increasing solar radiance causing a long term (billions of years) warming trend.

    Enhanced CO2 greenhouse to compensate for reduced solar luminosity on early Earth, Nature 1979.
    “We discuss here whether CO2−H2O in a weakly reducing atmosphere could have caused this change in the early Earth’s temperature by the so-called greenhouse effect.”

    #285 Jeff,
    Sorry I can’t find any albedo figures, although given the extent of the ice sheets and the angle of incidence I’d be surprised if it’s as low as 1-2% (But as I don’t know I ain’t arguin’ the point).

    Modern models will use localised albedo to be able to reflect land-use changes. NASA’s model E calculates albedo changes due to snow and vegetation…
    “The albedo of snow is a function of both depth and age. Fresh snow has an albedo of 0.85 and ages within 50 days to a lower limit of 0.5…
    The albedo of sea ice (snow-free) is independent of thickness and is assigned a value of 0.55 in the visible and 0.3 in the near infrared, for a spectrally weighted value of 0.45…
    Vegetation in the model plays a role in determining several surface and ground hydrology characteristics. Probably the most important of these is the surface albedo, which is divided into visible and near infrared components and is seasonally adjusted based on vegetation types.”

  39. 289
    Jim S says:

    Debates as a method of actually proving things is some kind of myth, I think. About 20 years ago a high school debate teacher assigned students to take a position on controversial topics. This is a common exercise. Two students were assigned to take the anti-abortion position. They did their research. They were convinced that it was the truth. The real deal. So they went out and fire-bombed a Planned Parenthood clinic that had nothing to do with abortions except that it was part of Planned Parenthood. True story. Ah, yes. Debate. That fount of logic.

  40. 290

    Jim —

    I’m not a Right-to-Lifer myself, but you’re talking anecdotal evidence there. I don’t think the usual member of a high school debate team indulges in terrorism on the basis of some issue they studied.

  41. 291
    Jeff says:

    Thanks Barton and CobblyWorlds for your comments.

  42. 292
    Joseph O'Sullivan says:

    I was glad to see a RealClimate post on the Antarctic ice in the cretaceous. I saw a summary of the paper and it seemed very interesting, but I was not able to read it. I understand the issue better now. The first half of the post on how issues are resolved in the scientific community is enlightening. I think explaining to lay people how scientists come to conclusions can be just as helpful as explaining the technical details of the science.

    CobblyWorlds, Hank Roberts, Steve Reynolds et al on the question about corals in the warmer climates of earlier geological eras, this question came up before on RC and Thibault gave this informative reply:

    [Response – Good question. Basically the loss of the symbionts by the corals (=bleaching) does not leave any track behind, although maybe altering the geochemistry of the corals (through the loss of photosynthetic activity). The other problem is that during the last 50 million years, both symbionts and scleractinians evolved. Because the long term trend of the last 50 or so million years was toward a cooling, the modern corals and symbionts seem to be better adapted to cool temperatures than warm ones – see for example the paper by Tchernov et PNAS . So even if we had some good ideas of how did the corals were reacting to warmer early Cenozoic temperatures, the difference of coral and symbiotic communities would make it tricky to apply to modern changes. (Browsing the references databases, I did not find anything on the coral reefs during the Paleocene thermal maximum, which could be useful.) -thibault]

    There have been two recent papers on the ecological effects of climate change on the oceans.

    Scripps Scientists Peg Wind as the Force Behind Fish Booms and Busts

    Abrupt climate change and collapse of deep-sea ecosystems

  43. 293
    Neil B. says:

    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 …

    No, the dilemma and the first half is false. The second half is definitely what you reap if you avoid. Not debating just makes the opponent look stronger and you look cowardly, unless they are so markedly horrible (Nazis, cannibals, whatever) that the normal psychology doesn’t work. Kerry thought he shouldn’t “dignify” the Swift Boaters with replies at first, and he paid the price. It is primal human psychology, don’t avoid the challenge. Debate them, and win if you can – that is the only viable response, please believe me.

  44. 294
    Ray Ladbury says:

    Neil B., Scientific debate is continual–but it has to be conducted by the rules of science. If the denialists want to debate all they have to do is do some actual science–get a paper accepted at a conference and go. Debates over evolution were the medium where Thomas Huxley earned the epithet “Darwin’s Bulldog”. Still, 49% of Americans believe in the biblical theory of creation. I don’t call that progress.

    There is no point in debating the ignorant. Or as Mark Twain said:
    “Never try to teach a pig to sing. It wastes time and annoys the pig.”

  45. 295
    scott everett says:

    Healthy debate in nearly all circumstances is a good thing – I have no idea why anyone would avoid it.

    If the facts are on your side then beat them up with them.

    [Response: I recommend reading the Ziman paper linked to above. This conference has very little to do with facts or healthy debate. – gavin]

  46. 296
    Martin Vermeer says:

    Re: #293 Neil B: It’s not about debating or not, but about the choice of arena. Alllowing the enemy to choose the battlefield is an elementary tactical error.
    As Ray L points out, a proper arena for scientific debate is the science literature; another one is this forum. The current article is widely read and linked to. Why do you think RC was created in the first place?
    Walking into enemy fire is just stupid.

  47. 297
    Kendall Jaye says:

    You gotta take advantage of the mainstream media.
    Science publications; Discover, Science, even periodicals like Mother Earth News might be wooed into sharing fascinating science such as this with their readers. Summarize the findings in layperson’s jargon without over simplification of the methodology.
    I totally agree that debating individuals that have had their brain chemistry altered by greed and/or fundamentalist enemas is a total waste of time. Even solidifying hard, fast, data that unequivocally substaniates that environmentally threatening industrialization and non-renewable energy sources are the root cause doesn’t change the zealot mantra.

  48. 298
    Ray Ladbury says:

    Scott Everett,
    Healthy debate is a continual feature of science. It takes place at (real) scientific conferences and in peer-reviewed journals. If the Heartland Institute wants to take part, all it would have to do is produce some real science. Of course, since there is no coherent theory that explains what is happening that doesn’t point the finger at anthropogenic CO2.
    Dog and pony shows accomplish nothing. You won’t convince ignorant ideologically blindered food tubes regardless of the facts. The best you can do is marginalize them.

  49. 299
    Indigo says:

    What Dr. Pierre doesn’t understand is that cloud cover over Antarctic will not cool but warm and any decent scientist would know this.

    Care to comment, anyone?

  50. 300

    Dear Ray,
    The data for this Cretaceous ice-sheet hypothesis can be explained another way. Oxygen isotopes become enriched in O-18 not only when ice sheets grow, but also when restricted seas in highly evaporative regions become partially cut off from the rest of the ocean. This is what happened to the Red Sea during the last glacial period, when it was nearly cut off from the Arabian Sea. By mass conservation, the strongly-restricted sea becomes one fractionation factor heavier than the open ocean, because evaporation is the only route by which water leaves. This would be 8 per mil. In less intensely restricted situations, such as where tidal flushing allows 16 times as much loss from the basin as net evaporation causes, then the isotopic enrichment would be 0.5 per mil, as seen in the Bornemann paper. There are in fact a number of independent lines of evidence suggesting that the tropical Atlantic at this time was highly restricted. Oxygen concentrations in bottom water were much lower than in the rest of the oceans, and the plate-tectonic opening of the south Atlantic was just beginning. So one hypothesis is that the 200,000 year long d18O anomaly represents a time when tectonics constricted the tidal/current flushing sufficiently that the basin became isotopically enriched. This would obviate the need for a large Cretaceous ice sheet, which doesn’t make physical sense.
    Another weakness in the data is that the inferred sea level low stands from Siberian platform data last much longer than the 200,000 year O-18 anomaly – several million years if I interpret their graph correctly. So this is a basic inconsistency in their argument – the sea level low stand and O-18 anomaly should last the same length of time.