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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. 201
    Walt Bennett says:

    I have taken the bull by the horns, and created a blog at blogspot: Engineering Climate.

    I have dedicated my opening post to continuing this discussion. Please feel free to join me there. I hope you will.

  2. 202
    Walt Bennett says:

    Re: #198


    You have completely mis-read me. My answer is “No!” followed by “…and we’d better learn how to!”

    We have already tacitly accepted such responsibility, as alluded to bt Ray.

    We must get better at what we are already doing.

  3. 203
    SecularAnimist says:

    Walt Bennett wrote: “We must get better at what we are already doing.”

    Why “must” we get better at “what we are already doing” when “what we are already doing” is clearly destructive? Why do you rule out, with the use of the word “must”, the alternative of stopping “what we are already doing” and doing something different instead?

    Should a tobacco smoker “get better at smoking”, or quit? Perhaps the smoker’s problem is that he needs to learn how to “manage his lungs” so he can continue smoking with impunity. Surely there are “engineering solutions”, perhaps genetic engineering, that could be applied to modify the functioning of his lungs so that he can continue smoking. Perhaps his lungs could be replaced with synthetic organs that would not be vulnerable to carcinogens.

    The hubris of imagining that human beings have the knowledge, understanding or ability to “manage” the Earth’s climate is exactly the root cause of the present crisis.

  4. 204
  5. 205

    One of the best on this subject so far is “Warm Words:
    How are we telling the climate story and can we tell it better?” Coming out of the British Institute for Public Policy Research.

  6. 206
    Rod B says:

    Ray, Walt, et al. Just an opinion and observation regarding getting people to do stuff. In a nutshell, I agree with Rays quote (188) of Camus, “…but when it becomes clear that the way to survival is to cooperate, they do so, even if the cooperation involves increased hardship or even risk to the individual…” The problem is that this is not a realistic expectation until the danger is directly in front of them and they have physically seen its potential. That isn’t about to happen any time soon. I see no reason to expect the people of India, China, any other developing state to jump on the AGW bandwagon and bite off a bunch of serious personal hardships to cooperatively solve it for mankind. It might be really nice if they did, but wishing for it is not going to help. As the movie line said, “you can wish in one hand and crap in the other and see which fills up first.”

  7. 207
    Rod B says:

    SecularAnimist (192): An erudite post, that has some valid assertions but your overall assessment is grossly sanguine. It sounds like you are, in this case, believing and espousing what you like and hope for. It’s odd that nobody, with any degree of agreement or consensus, knows for certain how to get 3rd world states out of poverty — except, it seems, climate scientists.

    [Response: Is your argument that you know for certain that any economic/technological change that might reduce emissions must increase that poverty? That would seem similarly ill-posed. – gavin]

  8. 208
    Rod B says:

    SecularAnimist (195, 203…): These are an interesting point of view — worth pondering.

  9. 209
    Rod B says:

    ps to my 207: correction — I should have said some climate scientists, and not pigeon-holed the whole lot.

  10. 210
    Steve Reynolds says:

    Ray Ladbury> I also know that we are not far away from various tipping points–loss of arctic sea ice, increased natural sources of CO2 and CH4, depletion of the oceans ability to absorb CO2, ocean acidification.

    How do you ‘know’ these things (both how far away we are and whether they are ‘tipping points’) or not? And whether these effects are worse than the effects of reducing emissions? Even the IPCC does not claim to know.

  11. 211
    Hank Roberts says:

    No, Rod, the climate scientists know some options are ‘free lunch’ bogus choices. Cheap coal, for example.

    How about paying 2 percent per year to solve the problem — sound affordable?

    Yes, one of these three is a climate scientist — Stephen Schneider, of Stanford. You know his work?

    “… we need to cut roughly 2% of current emission levels a year for the next forty years.”

    The other two are people who’ve done the economics and business plan work.
    Conservation _is_ conservative — of resources. It’s liberal in letting most people get a little better off, instead of a few get much richer. You know the income distribution trends, I’m sure.

    Which kind of world are you working on?

  12. 212
    Hank Roberts says:

    That link, I think it didn’t get in:

    Stanford University climate scientist Stephen Schneider,
    sustainability expert Hunter Lovins, and
    green jobs pioneer Van Jones

  13. 213
    Ray Ladbury says:

    Rod B., Obviously we will have to offer something to China, and I’m thinking that subsidized advanced energy generation technology, energy-efficient technology, etc. might be a reasonable incentive. After all, we were willing to send fuel oil to N. Korea. As I’ve said, we have to stop viewing this as a zero-sum game.
    As to development, the biggest challenge is to keep it from being a corporate welfare program and facilitate building of wealth in the target country. We’ve seen takeoff in our lifetimes in India and China, so we know it is possible. The time is particularly good to be contemplating green technology. Much of the world is just now building its infrastructure, and at the same time, we’re nearing and era of increasing fossil fuel prices. If we can get the developing countries to opt for green technologies it will pay dividends for generations to come.

  14. 214
    Steve Reynolds says:

    SecularAnimist> With all due respect, Steve Reynolds raised a scripted talking point…

    I guess that you don’t think much respect is due. What I say here are my own opinions, not influenced by special interest lobbies or conflicts of interest. You do not win arguments with sincere people by telling them that they are not sincere.

    SecularAnimist> …it is demonstrably bogus, and has repeatedly been aired-out and shown to be without merit in discussion threads on this very site.

    A standard of scientific evidence must be pretty low if having a majority of commenters here agree is enough to prove a point.

  15. 215
    Walt Bennett says:

    Re: #203 and the other posts by SA,

    I held the belief, briefly, that all we need to do to “fix” global warming is to stop doing the things that caused it. You evidently still hold that belief.

    I believe that we are beyond that point both as a practical matter (it will take 10 to 20 years before we see an actual annual reduction in ghg emissions, and that is a best-case scenario) and from the standpoint of what’s feasible (getting the world to agree on this strategy sounds good until the world has to agree on how to do it).

    You and some others seem to have missed my point completely, which is this: we cannot put all our eggs in the “stop being bad” basket, because the very real possibility is that we’ve already been too bad, or will reach that point before we can stop it. Therefore we must – and I mean, must – get better at engineering the climate system, in particular the atmosphere.

    As Hank and Ray acknowledge, we are already doing it (engineering climate). We have to move from doing it unconsciously to doing it consciously.

    Although perhaps you cannot envision it, it is clear to me: we must, and we will engineer our way forward.

    I am approaching this from the standpoint of realistic optimism (or, if you prefer, optimistic realism).

  16. 216

    Re #212


    You are correct that “we’ve already been too bad” and the only hope is geoengineering. But that seems as unlikely as us cutting back on our CO2 emissions :-(

    You claim to be a realistic optimist but that term is is an oxymoron. Optimists are not realistic and a realistic person is not an optimist. What we need is realism not optimism. We have spent too long behaving like Mr Micawber believing something would turn up to save us. Unless we panic, and take action immediately then we are all doomed!

    Cheers, Alastair.

  17. 217
    Ray Ladbury says:

    Steve Reynolds, Published research has shown that oceans are becoming more acidic and are less able to absorb CO2. Other research has shown that we are starting to see outgassing of CO2 and CH4 from thawing permafrost. And to know the precarious state of Arctic Sea Ice, opening up a newspaper ought to do just fine (OK, well maybe not the Wall Street Urinal, but a real paper.).
    That these are potential tipping points–well we can surmise those from the paleoclimatological record. At some point in past warming trends, natural sources of CO2 kicked in–presumably the oceans and permafrost, etc.. Moreover, I would contend that the fact that we do not know how close we had perhaps better not take comfort in our ignorance of how close we are to various tipping points. An undefined risk is a more serious risk than a high risk.

  18. 218

    #200 David can you tell were the South Pole is on those charts?

  19. 219
    Hank Roberts says:

    > where the South Pole is
    There’s a spherical projection map for the Late Jurassic, which is “close”

  20. 220
    Steve Reynolds says:

    Ray Ladbury> Published research has shown that oceans are becoming more acidic and are less able to absorb CO2. Other research has shown that we are starting to see outgassing of CO2 and CH4 from thawing permafrost. And to know the precarious state of Arctic Sea Ice, opening up a newspaper…

    Yes, research has shown that these effects exist, which I did not dispute. What I dispute is that anyone ‘knows’ we are getting close to tipping points.

  21. 221
    Jerry Toman says:

    I am pleased to invite all contributors, readers and posters at RC to review the brilliant presentation by Louis M. Michaud, P. Eng. on the qualities of the Atmospheric Vortex Engine at the Wayne State University Nuclear Physics Forum on Jan. 28, 2008.

    Both the slides and notes are located at in the Presentations section.

    In summary, Mr. Michaud (The Wizard of On) states:

    “The energy production potential of the atmospheric vortex engine is far greater than that to other solar energy technologies because the solar collector is the earth’s surface in its unaltered state; there is no need for a huge solar collector. A vortex engine increases the efficiency of thermal power plants by reducing cold source (sink) temperature. The AVE could alleviate global warming by reducing the quantity of fuel required to meet energy needs. The AVE could remediate global warming by lifting heat above greenhouse gases so that the heat can more easily radiate back to space.”

    I will be looking forward to reading any comments you might have on the presentation.

    Given the implications of Mr. Michaud’s statement, isn’t it about time everyone gets past the “first they ignore you” (Gandhi) stage?

  22. 222
  23. 223
    Ken Feldman says:

    Off topic, but I’m wondering if something unusual is going on in the Bering and Chuckchi Sea right now. Cryosphere Today’s image for January 29, 2008 shows a large open area in those two seas. I read an article earlier this month about larger than normal leads in the sea ice in the Beaufort Sea and how the new thin ice was easily blown about by the winds. Is this happening in the Bering Sea too?

  24. 224
    Rod B says:

    Gavin (per 207), No, I definitely am not saying that I “….know for certain that any economic/technological change that might reduce emissions must increase that poverty…” If I were to guess (thoroughly uneducated) I might say it is likely — which is probably worth nothing. My criticism was the “certainty” part. I absolutely do not know “for certain” that reducing emissions will increase that poverty. My point was that the folks who claim “for certain” that reducing emissions will increase everybody’s standard of living have no justification for their belief or assertions.

    re Hank, et al — same topic: I don’t doubt that isolated individuals can point to cases, maybe their own, where they have seen or effected significant emission reductions at no “noticeable” degradation of their living standards. Some here have claimed such (though they didn’t claim significant improvement). Nor do I dispute that scholars with PhDs and experience in economics can create erudite studies that show, with some of credibility, cutting emissions, and maintaining status quo or even getting economic improvements is possible (though the scope of those studies, as a rule, is limited.) Nor do I dispute some enterprises have made economic improvements in their business through selective conservation (though those sometimes count money that is a little funny, like carbon credits.)

    I’m just simply saying that probably nothing can be projected as a slam dunk, the least of which, by far, are economic projections. Those climate folks and AGW proponents who claim otherwise ought to knock it off.

    Ray (213) I generally agree with your thought here. But “…have to offer something to China, and I’m thinking that subsidized advanced energy generation technology, energy-efficient technology, etc. might be a reasonable incentive….” is not exactly people in developing states clamoring all over themselves to get hardships so they can cooperatively help save us all from the throes of AGW — which was my original point.

  25. 225
    Gareth says:

    Steve Reynolds said:

    What I dispute is that anyone ‘knows’ we are getting close to tipping points.

    And you “know” we aren’t?

    As Alastair MacDonald said, it’s time for realism, not foolish optimism.

  26. 226

    I’ve been through all this. Twice. The tobacco isn’t bad for you war and in, South Africa, the HIV doesn’t cause AIDS war. It does seem that you can’t win but the thing is, it’s trench warfare, not a matter of flicking a switch. The sorry thing is that the denialists are willing to risk killing millions of people to satisfy their egos (or their desire for profit) — as happened with the delays they caused in stopping the tobacco epidemic.

    Thanks for the hothouse stuff. I’ve been looking up paleoclimatic evidence to support what’s going on now and in my opinion it’s an underdeveloped field, even if there are significant difficulties e.g. in accuracy of long-range proxy-based measurement, and changes in continental configurations.

    My experience is that rather than high-profile debates where someone is meant to land a killer blow, grass-roots work (for which realclimate is a great resource) like letters to the press and responding on blogs and forums is the way to go.

    It’s depressing that even engineers seem to be incapable of scientific reasoning as e.g. in the comments on a recent article on greenhouse gas trends (IEEE Spectrum Jan 2008

    My own contribution is to write lots of letters to the press, maintain my own blog (e.g. and I wrote a novel (No Tomorrow which people who’ve read claim has helped them understand the science. And I’m trying to fit in the odd climate related paper alongside my computer architecture interest.

    If everyone who is concerned about the faux debate pitches in with little contributions like this, we will win in the end. Even the French have banned smoking to a greater extent than you could have imagined a few years ago, and a recent survey in Australia reported something like 80% of business leaders thought they should be doing more about climate change (but didn’t know what to do).

  27. 227

    Rod B posts:

    [[I see no reason to expect the people of India, China, any other developing state to jump on the AGW bandwagon and bite off a bunch of serious personal hardships to cooperatively solve it for mankind.]]

    I see no reason that they would need to embrace “serious personal hardships” in order to stop AGW. The solve-poverty/solve-global-warming dichotomy is a false one.

  28. 228
    Juola (Joe) A. Haga says:

    Well, at least I think we can agree that there will arise no hero(ine) on a white horse to lead us out of our discussion ( or dithering, if you will) until we settle on a feasible action which promises an extension of our species’ life. The extreme snows of China may fruitfully extend the conversation. Many will dismiss the supposition that nearly seven billion of us will chatter like Iroquois in the long house to reach consensus, so irritating to the 18th Century developers in Philadelphia that they broke the frontier’s peace which Friends had established for two generations. But we have the advantage of the internet and, I hope, patience and experience.

  29. 229
    Nick Gotts says:

    Re #215 (Walt Bennett) “As Hank and Ray acknowledge, we are already doing it (engineering climate). We have to move from doing it unconsciously to doing it consciously.

    Although perhaps you cannot envision it, it is clear to me: we must, and we will engineer our way forward.”

    Who is this “we”, Walt? If geoengineering is undertaken, who decides what is to be done? Who decides what the goal is? A climatic regime that suits China might not suit the USA and vice versa. So, if we are to avoid some self-selected group deciding on the goal for everyone, or more likely “climate wars” between rival geoengineers, we will need global or near-global agreement. It is also likely that much geoengineering research would have direct military applications – suppose you could block out the sun over a “rogue state” using giant mirrors for example? So unless it is preceded by a very high degree of international agreement and performed under UN or similar auspices, research on geoengineering could trigger a new arms race; and if we can achieve that degree of international agreement, why not use it to cut emissions?

  30. 230
    Walt Bennett says:

    Re: #228,


    You raise good points and they all need further discussion, don’t you agree?

    What are your thoughts regarding hedging our bets with regard to emissions reduction and other “stop being bad” policies?

  31. 231
    JCH says:

    The peoples of India and China are actually more likely to embrace mitigation. That is how they have lived for centuries. They know how to ride bicycles to work. They aren’t horrified by living in close quarters. They don’t mind taking the train. What Americans cannot apparently get, is that just like we had a high standard of living in the 19th century, when we walked most of the places to which we wanted to go.

    Long commutes and huge houses in the suburbs with four cars in the garage are not your standard of living. The standard of living is defined mostly by hope for the future. I don’t care if my kids have to live in efficient skyscrapers and that they might have to walk to work. That’s how I live now. It’s great. With the money I don;t waste on that stupid lifestyle in the burbs, I have a great time.

    [[I see no reason to expect the people of India, China, any other developing state to jump on the AGW bandwagon and bite off a bunch of serious personal hardships to cooperatively solve it for mankind.]]

    They are a lot smarter than that. They can make responsible decisions; given their familiarity with living on a low energy budget, they could easily make far more responsible decisions than us.

    Three cars in the garage and a huge house in the suburbs and overseas vacations are not necessary to have a high standard of living.

  32. 232
    Hank Roberts says:


    Yup. Walt, rhetoric is in use there when you claim the unintended and widely denied consequences of our over-draft of fossil carbon count as “engineering.”

    By that argument I’m an engineer any time I eat the seed corn, paint myself into a corner, flood the basement while trying to fix the plumbing, or build a fire in the fireplace with the damper closed.

    Causing a problem isn’t “engineering” — solving one might be.
    Being able to cause a problem — in a culture widely in denial — isn’t engineering.

    Sure, I read about the HAARP ionosphere heating experiments and can mumble to myself that maybe there’s a way to beam up microwaves and nudge CO2 molecules to emit photons, up there where the odds are good they’ll leave, tickling the ones that haven’t quite absorbed enough energy from the rare bump and grind event to do it on their own. I’d love to see an engineering answer. Heck, I’d love to find out the ‘red dwarf’ stars cluttering the galaxy are all outer shells of Dyson spheres methodically getting rid of vast amounts of excess heat while containing huge albeit inward-turning civilizations.

    But the Ringworld _is_ unstable.

    Not getting there _is_ often the best idea to cross one’s mind, when contemplating the journey.

    Reread _Overshoot_. ISBN 0252009886. Read it in the illumination provided by today’s financial news.


    To see where we are now headed, when our destiny has departed so radically from our aspirations, we must examine some historic indices that point to the conclusion that even the concept of succession (as explored in previous chapters) understates the ultimate consequences of our own exuberance. We can begin by taking a fresh look at the Great Depression of the 1930s, an episode people saw largely in the shallower terms of eco-nom-ics and politics when they were living through it. [1] From an ecologically informed perspective, what else can we now see in it?

    The Great Depression, looked at ecologically, was a preview of the fate toward which mankind has been drawn by the kinds of progress that have depended on consuming exhaustible resources. We need to see why it was not recognized for the preview it was; this will help us to grasp at last the meaning missed earlier.

    We did not know we were watching a preview because, when the world economy fell apart in 1929-32, it was not from exhaustion of essential fuels or materials. From the very definition of carrying capacity—the maximum indefinitely supportable ecological load—we can now see that non-renewable resources provide no real carrying capacity; they provide only phantom carrying capacity. If coming to depend on phantom carrying capacity is a Faustian bargain that mort-ga-ges the future of Homo colossus as the price of an exuberant present, that mort-gage was not yet being fore-closed in the Great Depression. Even so, much of the suffering that befell so much of mankind in the 1930s does need to be seen as the result of a carrying capacity de-fi-cit. The fact that the de-fi-cit did not stem from res-ource exhaustion in that instance makes it no less indicative of the kinds of grief entailed by resource depletion. Accordingly, we need to understand what did bring on a carrying capacity def-i-cit in the 1930s…..

    —–end excerpt——- from

  33. 233

    RE #210 & “How do you ‘know’ these things (both how far away we are and whether they are ‘tipping points’) or not?”

    This is the wrong question for laypersons living in the world (tho it might be the right one for scientists from Mars studying Earth).

    The Q should be, “How do you know we are NOT approaching tipping points, or that there are none?”

    People concerned with survival on earth want to avoid the false negative; they’re not so interested in avoiding the false positive.

    And as mentioned, reducing GHGs through energy/resource conservation/efficiency and alt energy 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. (Hint: it’s a fallacy the fossil fuel industry perpetuates, and they are doomed to die out like the very dinosaurs from which they get their product.)

  34. 234
    SecularAnimist says:

    Walt Bennett wrote: “I held the belief, briefly, that all we need to do to “fix” global warming is to stop doing the things that caused it. You evidently still hold that belief …”

    No, in fact I agree with Australian scientist Tim Flannery that the excess CO2 we have put into the atmosphere over the last century or so has already created dangerous levels of CO2, and is already causing dangerous warming, and will continue to cause even more dangerous warming for decades or centuries due to its longevity in the atmosphere, and that we must therefore not only stop adding CO2 to the atmosphere, but also find ways to remove CO2 from the atmosphere to reduce CO2 concentrations to safe (eg. pre-industrial) levels.

    I also agree with Flannery’s proposals that this can best be accomplished through large-scale reforestation projects as well as through organic agricultural techniques that capture carbon in the soil — both of which have numerous other benefits, and none of the risks of “geoengineering” schemes that involve tinkering with the chemistry of the atmosphere and oceans by adding huge amounts of additional pollutants to try to counteract the pollutants that we have already added and continue to add.

    Walt Bennet wrote: “I believe that we are beyond that point both as a practical matter (it will take 10 to 20 years before we see an actual annual reduction in ghg emissions, and that is a best-case scenario) and from the standpoint of what’s feasible (getting the world to agree on this strategy sounds good until the world has to agree on how to do it).”

    And yet you appear to believe that complex, potentially dangerous “geoengineering” schemes, using technology that doesn’t exist and relying on scientific understanding that we don’t have, can be implemented more quickly than reductions in CO2 emissions (which we know very well how to achieve) and are more feasible because it will be easier to get “the world” to agree on such risky schemes than it will to get agreement on reducing emissions (agreement which, with the exception of the fossil fuel corporations and a couple of national governments, we already have). That doesn’t make a lot of sense to me.

    Walt Bennett wrote: “Therefore we must – and I mean, must – get better at engineering the climate system, in particular the atmosphere […] we are already doing it (engineering climate). We have to move from doing it unconsciously to doing it consciously.”

    We are not “engineering climate”. We are wrecking the climate. Saying that we are already engineering the climate and must get better at it is like saying that someone who has just smashed up a computer with a sledgehammer is “engineering computers” and just needs to get better at it in order to produce a better computer.

    Walt Bennett: “Although perhaps you cannot envision it, it is clear to me: we must, and we will engineer our way forward.”

    I have no doubt that engineering clean, renewable energy and efficiency technologies that will provide ample energy for a prosperous and sustainable human civilization able to thrive while living within the carrying capacity of the Earth’s biosphere will play a major role in our way forward. And we already know how to accomplish that. The barriers are political, not technical or economic barriers.

  35. 235
    raypierre says:

    Now, getting back to the Cretaceous…

    From time to time on this thread, people have expressed an interest in seeing more about what the geography looked like at various times in Earth’s past. I think many have already found their way to Scotese’s wonderful sight, which has some spectacular animations:

    I’d like to point out another site that has beautiful maps, probably the best I’ve seen. That’s at:

    You have your choice of seeing things in any of a variety of different map projections. If you have access to a poster printer, these make terrific wall decorations and birthday presents.

  36. 236
    John Wegner says:

    You cannot talk about paleoclimate without taking into account paleogeography.

    For example, 150 million years ago, there were NO continental landmasses near the poles. So there were no continental glaciers and all there would have been was polar seaice during the winters (when there would have been 24 hours of darkness just like today.)

    No polar glaciers means warmer world.

  37. 237
    David B. Benson says:

    wayne davidson (218) — The south pole is at the bottom.

  38. 238

    Isn’t it time we move past debating and into solutions?

  39. 239
    Karl says:

    I think it’s a shame this has turned into yet another debate on AGW, emissions, skeptics etc. The original topic is a very interesting one, but sadly it has drowned in the torrent of AGW-quarrels.

    I think it was Hank Roberts who (early on) suggested a seperate thread for that kind of discussion – an idea I think should have been taken further.

    [Response: Well, it’s largely my own fault for coupling the two issues in my article, but I knew there was that risk. I went ahead and did it anyway, because some discussion on how scientific issues are thrashed out (and how different that is from a “debate”) is needed. At the same time, I thought it would be more productive to discuss those issues with a concrete example of an ongoing scientific controversy before us. Carrying out the discussion in a vacuum would be more likely to lead up a garden path. It’s a variant on the legal principle that “bad cases make bad law” (and conversely good cases at least have a chance to make good law). –raypierre]

  40. 240
    David B. Benson says:

    The following link to an abstract might help in settling dates and paleo-Antarctic geology related to the main topic of this thread:

  41. 241
    Ray Ladbury says:

    Raypierre–thanks. That is a really cool site. In particular it is very interesting to see the epochs of glaciation and orogenesis.

  42. 242
    Jerry Toman says:

    All is well, all problems solved–no need for further debate regarding the best way forward with respect to energy/AGW issues.

    Read Mr. Louis M. Michaud’s presentation (slides and notes) to the Wayne State University Nuclear Physics Forum on Jan. 28. Go to and click on Presentations/AVE, and report back as to whether you are in agreement, or not.

    [Response: OK, it’s an interesting device, and it’s not manifestly a perpetuum mobile. This is a very analyzable device and makes an interesting GFD problem. You ought to get hooked up with a decent GFD rotating fluids person and actually do some calculations. Then go out and build and test. If it only takes 30m, it’s not a huge investment of venture capital, but enough that the calculations have to be done first. Let us know when there’s either been a field test or some numerical simulations. Meanwhile, this isn’t really the right place to be discussing the AVE. Thanks for noting its existence, though. –raypierre]

  43. 243
    Martin Vermeer says:

    Walt Bennett:

    What are your thoughts regarding hedging our bets with regard to
    emissions reduction and other “stop being bad” policies?

    The problem of pulling down CO2 from the atmosphere consists of two sub-problems: a big one and a small one. The big one is, that pulling a unit of CO2 down costs the same amount of energy as what was generated when it was released: both useful energy and waste heat that was disposed of. That’s a lot of energy.

    If you have a realistic recipe for CO2 pull-down on a large scale, you must have access to a source of (relatively) inexpensive, C-neutral energy. You know what I would do if I had that? I would start substituting existing GHG-emitting generating capacity with it. There is a long way to go before you run out of capacity to substitute.

    Only after that does the issue of CO2 pull-down come up, if substitution turns out — or is foreseen — not to be sufficient. Which I personally expect to happen; full disclosure. Only then do we need to address the smaller sub-problem. In that order. It will not be cheap, but it will be straightforward, once you have that energy source.

    (BTW if you are thinking about using biological processes to do it, consider that we will also have some 9B mouths to feed within an ecosystem under severe environmental and climatic stress. You don’t want to compete with that.)

    Same for stratospheric aerosol engineering. Again, two sub-problems, the big one and the small one. The small one is doing it: we did it accidentally from 1945-1970, and the Chinese are working on doing it again. The big problem is understanding it before even considering doing it. And that requires no special effort, just what the climate science community is already doing generally, year in, year out: understanding the workings of the climate system. As for doing it, we’ll cross that bridge when, and if, we get to it.

    What about doing something on the critical path, rather?

  44. 244
    Phillip Shaw says:

    I have an open question for those who claim that reducing carbon emissions will doom millions to poverty:

    How is it that a full century of BAU failed to eliminate poverty? In fact one can make a good case that BAU exacerbated the gulf between the haves and have-nots. The technology level of agrarian America in 1908, say in per-capita carbon emissions or however you care to define it, was a lot closer to that of India in 1908 than 2008 America is to 2008 India.

    It is completely hypocritical to claim that we have to keep wasting vast amounts of energy in order to ease poverty in the undeveloped world. BAU didn’t ease poverty yesterday, it’s not helping today, and our wasting limited resources certainly won’t help tomorrow.

  45. 245
    Walt Bennett says:

    Re: #233

    I consider all of your suggestions to fall under the heading “geo-engineering”.

    I never said “seed the atmosphere”, although we must look at such things as that. However, the best ideas will win, and that’s what matters.

    As regards my belief that we can accomplish that feat much more quickly and reliably than we can achieve emissions REDUCTIONS, you read me 100% correctly.

    And, I believe, it is imperative that we do so. You seem to agree with that.

  46. 246
    David B. Benson says:

    Shortly, later today or at latest tomorrow, there will have been

    5,000,000 visits

    to Real Climate. My enthusiastic approval to the real climatologists who have produced and maintained this most useful site!

  47. 247
    Hank Roberts says:

    Walt, beliefs can be proclaimed endlessly, it’s the science we’re trying to understand. Proclamation if anything discourages the scientists who might post. A break, please?

  48. 248
    Rod B says:

    Philip Machanick (225): hmmmm… do I dare jump back into the tobacco pool?? Nah! Everyone just goes bonkers; and it would hijack this good thread even more.

    But to point out one discrepency with your comparison. Tobacco, right or wrong, generated a tremendous oder of big big big bucks for government. That’s why the attack was sucessful. So far AGW does not have that potential, so your comparison falls apart.

    None-the-less, I would agree that your post offers some credible advice.

  49. 249
    Jim Eager says:

    Re JCH @ 231: “The peoples of India and China are actually more likely to embrace mitigation. That is how they have lived for centuries. They know how to ride bicycles to work. They aren’t horrified by living in close quarters. They don’t mind taking the train.”

    Moreover, having only recently reached their current state of development, they have not yet forgotten, either individually or collectively, how to live without the trappings that we ourselves now deem to be so utterly necessary, meaning they are in a much better position to adapt and thrive under conditions without those trappings than we are.

  50. 250
    Steve Reynolds says:

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

    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.