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Gray and Muddy Thinking about Global Warming

Filed under: — group @ 26 April 2006

Anybody who has followed press reporting on global warming, and particularly on its effects on hurricanes, has surely encountered various contrarian pronouncements by William Gray, of Colorado State University. A meeting paper that Gray provided in advance of the 2006 27th Conference on Hurricanes and Tropical Meteorology (taking place this week in Monterey California, and covered here by CNN), provides an illuminating window into Gray’s thinking on the subject. Our discussion is not a point-by-point rebuttal of Gray’s claims; there is far more wrong with the paper than we have the patience to detail. Gray will have plenty of opportunities to hear more about the work’s shortcomings if it is ever subjected to the rigors of peer review. Here we will only highlight a few key points which illustrate the fundamental misconceptions on the physics of climate that underlie most of Gray’s pronouncements on climate change and its causes.

Gray’s paper begins with a quote from Senator Inhofe calling global warming a hoax perpetrated on the American people, and ends with a quote by a representive of the Society of Petroleum Geologists stating that Crichton’s State of Fear has "the absolute ring of truth." It is the gaping flaws in the scientific argument sandwiched between these two statements that are our major concern.

Claim: The Thermohaline Circulation causes Global Warming, Hurricane Cycles, etc

For years, perhaps decades, Gray has been ascribing all sorts of climate changes and hurricane cycles to fluctuations in the Thermohaline Circulation (THC), an overturning circulation in the Atlantic ocean associated with formation of deep water in the North Atlantic. None of the assertions are based on rigorous statistical associations, oceanographic observations or physically based simulations; it is all seat-of -the-pants stuff of a sort that was common in the early days of climate studies, but which is difficult to evaluate when viewed as a scientific hypothesis. The THC is undoubtedly important to climate, because it transports heat from one place to another. However it cannot do magical things. It cannot created energy out of thin air (or thick water), nor can it make energy mysteriously disappear. Thus, Gray’s statement that "The average THC circulation cools the ocean by about 3 W/m2" is a scientific absurdity. In the paper Gray makes many extravagant claims about how supposed changes in the THC accounted for various 20th century climate changes ("I judge our present global ocean circulation conditions to be similar to that of the period of the early 1940s when the globe had shown great warming since 1910, and there was concern as to whether this 1910-1940 global warming would continue. But beginning about 15 years following the onset of a strong THC circulation in 1926, in the early 1940s, the warming began to abate. A weak global cooling began from the mid-1940s to the mid-1970s.") but the reader would never guess that he in fact has no direct oceanographic evidence that the THC was doing anything of the sort. These are all subjective estimates based on Gray’s conception of the relation of Atlantic temperatures to the THC state. In fact, it is exceedingly difficult to directly monitor the THC, and reliable results have only recently been obtained. We have reported recently on the "Decrease in Atlantic Circulation". For years prior to the publication of evidence that the THC was slowing down, Gray was testifying in Congress and writing widely that hurricane increases were due to Atlantic warming arising from a speed-up of the THC (see our article for some typical quotes). Confronted with evidence that the THC was in fact behaving in the opposite way to what he had been assuming, Gray did a flip-flop and came up with a new story that yields the same conclusions. There’s no shame in a scientist changing his or her mind, or in seeking new theories in the face of new observations. However, if Gray’s old theory was really testable, where were the tests to show that it was wrong in the years he was touting it? How is one to put any confidence in the new theory? The fact is that neither of Gray’s story lines about the THC is sufficiently well formulated to allow any clear-cut test. Nonetheless, insofar as it can be understood at all, some aspects of Gray’s new story line about the THC are demonstrably wrong.

The heart of the problem with Gray’s new version of the THC story is that he labors under the misconception that the THC primarily upwells in the tropics, so that any reduction in the THC cools the North Atlantic but warms the tropics. This conception is at least 50 years out of date. The tropical upwelling is a shallow wind-driven cell that does not connect to the THC. It is almost impossible for cold deep water to upwell in the tropics, because it takes too much energy to bring it up; the main THC connection is with the Southern Ocean, as described by Marotzke and references therein (for more general background, see also There are only a few very limited regions where moderately deep water can upwell in the Tropics. Simulations by Vellinga and Wood (Climatic Change, 2002) in fact show that a THC shutdown causes a cooling right into the Northern Subtropical Atlantic (the birthplace of hurricanes), and in fact only very weak warming in a few spots elsewhere in the tropics. On a longer time scale, the classic study of Manabe and Stouffer (Paleoceanography 1997) shows virtually no impact of THC shutdown in the tropics, but a considerable remote impact in the Southern Ocean. No doubt, Gray would object that these are only models, but why should we believe that Gray’s drawing of circles and arrows on a map yields a better prediction than a simulation embodying the best of what we know about the underlying physics?

Note that Gray does not merely claim that THC changes are responsible for the observed hurricane cycles. He in fact claims that the entire 20th century warming signal is due to a slowdown of the THC, and that CO2 has nothing to do with it. He claims flatly and without supporting evidence that models cannot simulate the THC properly, neglecting the fact that the models employed in the IPCC reports yield a rather wide variety of different possible THC behaviors, and none of them, including ones known to have a sensitive THC, spontaneously generate a warming of the sort Gray claims. Insofar as we can follow Gray’s reasoning, he appears to think of the THC as burying heat in the deep ocean, as if the heat were some kind of solid nuclear waste. Thus, weak THC = less heat removal = warming, in Gray’s world view. In reality, everything known about the physics of the THC’s effect on climate suggests the opposite. For example, Vellinga and Wood find that, owing to certain nonlinearities like sea ice formation, a shutdown of the THC leads to a reduction in the Northern Hemisphere mean temperature, and very little multidecadal scale effect on the Southern Hemisphere mean temperature.

The other reasons Gray thinks that the THC could cause global warming are tied up with a number of additional misconceptions he has about the physics of climate.

Claim: Evaporation changes cause global warming, hurricane cycles, etc.

Gray’s grand answer to the riddle of global warming is evaporation, presumably modulated by changes in the THC. Again, Gray simply doesn’t seem to understand energy conservation. Evaporation does not create heat; it does not add any heat to the climate system or take it away. It is an energy transfer that moves heat from a moist surface (like the ocean’s) into the atmosphere. That severely constrains what evaporation changes can do to climate. In contrast, changes in CO2 concentration affect the top of atmosphere radiation budget directly, and change the rate at which the whole climate system loses energy.

Let’s start with an atmosphere that is in equilibrium, both at the surface and top-of-atmosphere. Now reduce the evaporation (you could do it by reducing the surface wind). The surface is now receiving more energy than it loses, so it will begin to warm. However, the atmosphere is no longer receiving all the energy it used to obtain from the surface as evaporative heat transfer; hence the atmosphere will begin to cool. This adjustment will continue until balance is restored. The precise way the adjustment is divvied up between atmospheric cooling and surface warming depends on details like the net atmospheric infrared opacity, boundary layer relative humidity,and so forth. However that all shakes out, the net result is nothing at all like the observed pattern of warming, in which both troposphere and surface warm up. This reasoning can be confirmed in the simplest radiative-convective model, of the sort introduced by Manabe and Strickler in the 1960’s.

A more serious problem is that Gray doesn’t even understand that the greenhouse effect works primarily through the effect of greenhouse gases on the top of atmosphere radiation budget, and only very indirectly through the surface budget (as explained in A busy week for water vapor). This compromises almost all of his analysis. For example, many of the supposed changes in surface budget he describes could in fact be due indirectly to changes in greenhouse gases, via their affect on low level atmospheric temperature. By balancing a 4 W/m2 (top of atmosphere) CO2 radiative forcing against changes in evaporation, Gray concludes that the warming from doubling CO2 would be a mere two tenths of a degree C.. He ascribes the weak warming to the lack of water vapor feedback in his calculation, but in fact it is simply due to an incorrect calculation of the energy balance. Standard radiative physics based on a correct treatment of the top-of-atmosphere balance– physics going back at least to Arrhenius– yields a surface warming of about 1C in response to a doubling of CO2, when water vapor feedback is neglected. Gray has committed the major blunder of applying that 4 W/m2 top of atmosphere forcing at the surface. In reality, when that radiative forcing is properly applied at the top of the atmosphere, it leads to a warming of the entire atmospheric column which, at the surface, yields a far larger perturbation in the surface energy budget, as we have explained in the above-referenced article.

By the way, Gray discounts water vapor feedback, based on what seems to be a gut feeling on weather systems, plus some unspecified analysis of the NCEP reanalysis dataset (which is completely unsuitable for studying trends in mid tropospheric water vapor); more reliable satellite based studies (e.g. Soden’s study described in A busy week for water vapor ) support a positive water vapor feedback, and even Lindzen seems to be no longer arguing against this feedback.

Claim: Ocean heat storage is inconsistent with CO2 as a cause of warming

Gray also made a mess of an attempt to analyze the mid-twentieth century ocean heat storage. "… the globe underwent a weak cooling between 1950 and 1975 during which CO2 amounts were rising and causing a continuous mean energy gain over this 25 year period of about 0.4 W/m2. If all of this energy went into an accumulation of temperature in the upper 100 m of the global oceans, we would see an upper mean 100 m global ocean temperature increase of 1.1oC. " We are not sure where Gray gets the 0.4 W/m2 radiative forcing figure; the total radiative forcing increase from pre-industrial times to 1975 would be more like .95 W/m2 and it is not a trivial matter to figure out how much to subtract from that to account for the part compensated by ocean warming before 1950; the CO2 radiative forcing increase between 1950 to 1975, on the other hand, would be only .45 W/m2 and the mean new forcing over the period would be about half that. Be that as it may, Gray has not even done the arithmetic right, since .4 W/m2 going into a 100m mixed layer having specific heat of 4200 J/kg and density of about 1000 kg/m3 would only yield a warming of .75C . That’s far from the worst flaw in his calculation, since his two biggest blunders are the neglect of the radiative cooling due to sulfate aerosols (known to be a critical factor in the period in question) and his neglect of the many links in the chain of physical effects needed to translate a top of atmosphere radiative imbalance to a change in net surface energy flux imbalance. In fact, the calculation has been done very carefully by Hansen and co-workers, taking all factors into consideration, and when compared with observations of ocean heat storage over a period long enough for the observed changes to be reliably assessed, models and observations agree extremely well (see this article and this article.).

Concluding remarks

The Wall Street Journal has insinuated that there is some ageism involved in the reaction to Gray’s work ("Hurricane debate shatters civility of weather science," by Valerie Bauerlein, Feb.2, 2006). The problem is not Gray’s age — we all revered Henry Stommel who did some of his finest work in his seventies. The problem is Gray’s failure to adapt to a modern era of meteorology, which demands hypotheses soundly grounded in quantitative and consistent physical formulations, not seat-of-the-pants flying. The WSJ also made much of the withdrawal of an invitation for Gray to join a debate on hurricane trends at an Atlanta tropical meteorology conference. We can’t speak for the organizers, but we find it easy to believe that their decision was guided more by the invalidity of Gray’s scientific reasoning than by any political or personal considerations.

144 Responses to “Gray and Muddy Thinking about Global Warming”

  1. 101
    Urs Neu says:

    Re 89,90

    After a look at the Klotzbach paper, I can’t see anything new or anything contradictory to Emanuel (2005) and Webster et al. (2005)

    Just examining the graphs of Emanuel and Webster et al. it is not difficult to estimate the results that Klotzbach got for the decades 1986-1995 and 1996-2005 (see and you see hardly any trend for the PDI and about a 10% increase for category 4/5 hurricanes. Thus there isn’t any apparent contradiction to what Klotzbach found.

    Neither Emanuel nor Webster et al. have claimed a steady increase. A steady increase cannot be expected, given the interannual variability and the different SST variability in the different basins. Thus the presumption of Klotzbach that the trend in the period he examined should be the same as in the periods calculated by Emanuel and Webster is inadequate. His results match more or less the results of the other studies.

    It looks very much like just another attempt to shorten the period until one finds only small or negative trends (like the negative trend in global temperature after 1998).

    Of course it is important to look closely at the correlation between SSTs and hurricane intensity. It is well known that other factors are important for hurricane development, and therefore the correlation to SSTs is not expected to be very high (and also depends on the time scale examined). However, Klotzbach finds, that in both basins with a significant TC trend (North Atlantic and Northeast Pacific) there is a significant correlation (even with trends of the opposite sign), a conclusion not far from what Hoyos et al. have found…

  2. 102
    Urs Neu says:

    Re comment to 99

    Mike, thanks for your comment.
    I do not at all dispute that there is a 50-70 year cycle in the instrumental data. Your analyses seem convincing, especially the similarity of the patterns.
    However, Knight et al found also a similar pattern in their model, but in the 70-120 year range. Why that?
    And there still remains the problem that external forcing produces a nice oscillation in the 50-70 year range at least from 1860-2000. It would be interesting to look at the patterns of this pseudo-oscillation.

  3. 103
    william says:

    Thanks a lot for your discussion on global warming and its effects. U have removed all the misconceptions on the physics of climate, how its changes and its causes. Its time we should do something about this global warming otherwise it would be too late.

  4. 104
    Eachran says:

    Post 103. William is that you just getting fed up or what?

  5. 105
    da silva says:

    Beg pardon if this has already been called to your attention, but Nature has a news item related to the debate: Tempers Flare at Hurricane Meeting. Unfortunately, I don’t have a subscription. Anyone else read it?

  6. 106
    Steve Bloom says:

    Published online: 3 May 2006

    Tempers flare at hurricane meeting
    Researchers debate effects of climate change.
    Alexandra Witze

    Monterey, California –

    Hurricane Wilma helped to make 2005 a record hurricane year, but is global warming to blame?

    Last week, meteorologists gathered in Monterey, California – the meeting was to have been held in New Orleans – to hear new evidence supporting the proposed link between rising sea surface temperatures and more-powerful hurricanes. The fresh crop of research was triggered by two papers arguing for that connection, published by coincidence during the height of the devastating Atlantic hurricane season of 2005 (K. Emanuel Nature 436, 686-688; 2005; P. Webster et al. Science 309, 1844-1846; 2005).

    The effects of global warming, many say, are already in evidence. “It’s not going to happen in the future – it is actually happening now,” says Greg Holland of the National Center for Atmospheric Research in Boulder, Colorado.

    But not all are convinced, and there were raised voices in the hallway discussions at the American Meteorological Society meeting. At a lively panel discussion on 25 April, the moderator accepted audience questions only on written cards, and admonished the speakers not to indulge in personal attacks. This prompted Christopher Landsea, of the National Hurricane Center in Miami, to quip: “I get along personally with everyone in the field, and I want to continue that – even if they’re wrong.”

    At issue is whether the historical record of cyclones is complete enough for accurate conclusions to be drawn about changes from past patterns. Many researchers called for the databases to be brought up to date by including modern assessments of past storms, including their intensities. It is a daunting task that, for now, is being done only for the Atlantic basin by Landsea and his colleagues.

    Even given the gaps in the database, several new studies suggested that rising sea surface temperatures are having a noticeable effect on cyclones. Peter Webster of the Georgia Institute of Technology in Atlanta, co-author of one of last year’s papers, presented data hinting that not only are hurricanes growing more intense over time, but that the length of the storm season has increased as well. Starting from 1950, he told the meeting, the storm season has grown longer in the Atlantic by about five days per decade, in the northeastern Pacific by eight days per decade, and in the northwestern Pacific by ten days per decade.

    In Britain, researchers at the Benfield Hazard Research Centre in Surrey have run climate simulations suggesting that half the recent rise in hurricane activity in the North Atlantic can be explained by the observed increase in sea surface temperature in the region where these hurricanes develop. A warmer ocean would, in theory, provide more fuel for hurricanes to intensify.

    And in Japan, a team has used the Earth Simulator supercomputer to run high-resolution simulations of global climate, both in today’s conditions and in a world warmed by higher levels of atmospheric carbon dioxide. Preliminary results suggest that, in the latter scenario, the number of tropical cyclones would drop by about 30% worldwide. But the number would rise in the Atlantic, and storm intensity would increase worldwide (K. Oouchi et al. J. Meteorol. Soc. Jap. 84, 259â??276; 2006).

    Kerry Emanuel, a hurricane expert at the Massachusetts Institute of Technology, and author of the other paper published last year, says that many of these models need more work before firm conclusions can be drawn. But he spent his time as a panellist demolishing another popular tenet of climate research: that a natural temperature cycle known as the Atlantic Multi-Decadal Oscillation (AMO) controls the formation of Atlantic storms during the peak of the hurricane season. Removing the oscillation would remove one of the last arguments that hurricane patterns are driven by a natural cycle.

    “There may be such a thing as an AMO, but it’s not affecting the sea surface temperature in the North Atlantic in the late summer,” says Emanuel.

    Few of these studies have appeared in peer-reviewed journals yet, and not everyone is persuaded by the conclusions. Johnny Chan, of the City University of Hong Kong, presented data suggesting that in the northwestern Pacific, numbers of typhoons do not track with rising sea surface temperatures.

    One major critic is William Gray, a longtime forecaster at Colorado State University, Fort Collins, whose climate theories have been criticized by many researchers. He continued to insist that hurricanes are driven more by natural patterns of ocean circulation than by human-induced global warming. “I don’t care what anyone says – in the end the data will prove this to be true,” he says. “Why try to read all these demonic influences into the system?”

    Forecasters, including Gray, are predicting that a busier-than-usual Atlantic hurricane season will start on 1 June.

  7. 107
    Mark says:

    You might start by getting the name of the organization right. It is American Association of Petroleum Geologists. I am a member. The geology community is far from unanimous in supporting the notion of manmade global warming. The earth has a very long history of warming and cooling, mostly related to the sun. Check out Newsweek’s article (4/28/1975) “The Cooling World”, complete with very dire predictions. Global warming is mostly about politics and left-wing solutions to problems.

    [Response: Before you put your ignorance too much on display, why don’t you check out the various RealClimate articles about the supposed global cooling scare. So far you’re not impressing me very much. I have met many petroleum geologists whose scientific judgement is quite respectable, and I’m happy to say you are far from typical. –raypierre]

  8. 108
    Grant says:

    Re: #107

    The geology community is far from unanimous in supporting the notion of manmade global warming.

    But the climatologist community is very near to unanimous.

    Check out Newsweek’s article (4/28/1975)

    Honestly, I don’t mean to be flippant, but around here, “Newsweek 1975” isn’t exactly an impressive reference.

  9. 109
    Hank Roberts says:

    You live in Minnesota. What have you noticed? Any of this will be familiar if you hunt, camp, canoe, or read any science outside your immediate profession. Does this surprise you?
    Do you find it incredible?

    [Response: Note: I deleted a comment by Mark in which he made some inflammatory accusations, but also mentioned he lived in Minnesota and would like to see some global warming. That’s what this refers to. –raypierre]

    Minnesota, 2006

    “…. there may be no greater poster child for what’s happening on the planet than the Minnesota moose.

    “Scientists have known for a very long time, they’re quite sensitive to temperature.

    “Mike Schrage, with the annual moose census in Minnesota says the animal will actually pant when the temperature gets above 67 degrees Fahrenheit. Schrage and his colleagues have spent years counting moose here.

    “… There were four-thousand moose here in the late eighties. Today there are 250. The rate of pregnancy here is low – half of what’s normal. And moose are dying here – faster – than normal.

    “Scientists tell us it’s not that “heat” is the direct cause of these deaths. But increased temperatures do cause a lot of extra stress on the animal.

    “Specifically, these moose are dying from parasites: brain worms and liver flukes. Mark Lenarz with the State Department of Natural Resources says it appeared the parasites “caused those individual moose to starve to death.”

    “Lenarz says that’s “really contrary to what parasites are supposed to do.” Parasites are not supposed to kill the animal.

    “In trying to figure out – why – this is happening, scientists have become focused on ‘temperature’. Lenarz says, “If you’re a moose, and it’s the middle of summer, and you’re panting, you just have a lot less time for eating.” In the end, he says, many of these moose cannot cope with the added stress. Lenarz says the moose are dying in greatest numbers â�� within a year of a very hot summer.

    “…. in Northwest Minnesota, where the moose are dying, the growing season has increased 39 days in the last 41 years. Record dew-points make it feel even hotter than it is.

    “Mark Seeley, a climatologist from the University of Minnesota, told us “in the summer of 2005 we had dew points in the 80’s. This is like Bombay, India. It’s not like Minneapolis/St Paul!” In fact, we’ve seen dew points in the 80’s here seven of the last eight summers.

    “That kind of air can spur greater storms. Precipitation is up here 20 percent in the last century.

    “… Even Minnesota’s great pine forest is at risk. Not just because of the blow-down, but because of the kinds of trees scientists see coming up underneath it. They are the type of trees usually found growing much farther south.

    “Wildlife biologist Bill Berg says, “They’re finding maple basswoods coming up in some of the blow-down area at least 50 years ahead of the predicted timelines.”

    “Berg has been living and working in northern Minnesota for decades. He’s seen the earlier mating season of the grouse, and the expanding range of wild turkeys, raccoons, opossums and skunks. He says they are animals that could not survive so far north before.

    “The realization of climate as a factor in all this, he says, is relatively new. “Before we were kind of like why is this happening,” he said. “And then people, myself included, started putting temperature changes into this. We added it as a variable. And it’s probably the most important variable right now.”

    “Fisheries scientists can see the impact of warming lakes, more toward the central and southern parts of the state. In winter it’s obvious with thinner ice.

    “And in the summer on Lake Pepin they’ve already begun to measure the impact on the walleye population. They believe warmer water is causing larger walleye to grow more slowly. It is also believed to be impacting reproduction.

    “Don Pereira, a scientist with the state Department of Natural Resources says, “What we saw in those Pepin data, in those summers when they (walleye) didn’t grow very well because it was really warm, the following spring there was reduced production of young walleyes on Lake Pepin.”

    “On Lake Mille Lacs, Pereira says the warmer water has resulted in a serious blow to the tullibee population. Tullibee is a feeder fish for walleye and northern pike. It had a strong presence on Mille Lacs for a number of years. But after the scorching heat of 2002 fisheries staff failed to net a single one.

    “There can be a number of factors that have contributed to that, but we know we’ve had very warm summers since the late eighties and we know that this species die when we have really warm summers,” Pereira said.”

  10. 110
    Mark A. York says:

    Wow. That’s weird because Maine moose have increased.

    [Response: Forgive me if one-liners like this leave me a little unimpressed. Perhaps you’d like to let us know something about the data on the Maine moose population, how it relates to the regional climate change to date in the area, and what will happen in the out years as climate continues to warm and the areas that escape substantial warming are reduced. The point of the preceding post wasn’t that Moose are supposed to be indicators of global warming, but rather that warming has known deleterious effects on natural ecosystems. –raypierrre]

  11. 111
    Gareth says:

    SOHF, ray?

    [Sense Of Humour Failure]

    [Response: Nah, just too much coffee all at one go. Sorry, Mark (York) if I got grumpy. Happy moose watching, or even hunting. –raypierre]

  12. 112
    Hank Roberts says:

    More, I think, a request for Mark to expand beyond ‘weird’ to ‘science’ — he knows how to dig for details and can backtrack for cites. People in other states may well want to look at what’s happened in Minnesota for cautionary information.

    One could for example compare summertime temperatures in the animals’ ranges — northern and central Minnesota and Maine (is the coastal state’s summer weather cooler than the midwestern state’s, below the temp. at which moose have to spend time panting to reduce body temp?) Is the Maine moose herd known different than the two herds in Minnesota (read the original page I excerpted from; there’s a regional difference between Minnesota herds too); are there different kinds of parasite loads in the two states? Are the parasites moving farther north in the Midwest?

    Short answer is, our petroleum geologist visitor hadn’t noticed any of the many changes documented by biologists in his own home range.

    How scientists observe and inquire is the focus of discussion here (and helping us to think scientifically before making decisions about what to do next).

    Of course one could assume that Minnesota has left-wing moose ecologists and Maine has right-thinking moose ecologists. But that would be wrong.

  13. 113
    Mark A. York says:

    Well all it was is an observation not an all-encompassing conclusion. Since I would be considered left-wing of sorts there is no correlation there either. I was just surprised is all. Other than that I don’t know about the implications. Maine has a lottery hunting system now and has for a number of years. I grew up there and moose have always been plentiful in my lifetime. I would wonder if they have declined in Maine as well?

  14. 114
    Mark A. York says:

    No problem Ray. It says there are around 29,000 animals in the Maine population as of 2001.

  15. 115
    Hank Roberts says:

    Maybe what we’re finding out is that global warming has no immediate and observable effect on petroleum geology (I suppose erosion rates and acidification of lakes based on surrounding rock typep ought to come within a geologist’s ambit, more generally, and be noticeable).

  16. 116
    Mark says:

    A quote from AAPG, “Our concern is that the geologic perspective generally has been missing from the debate on global warming. Geoscientists have a perspective that is important to this issue, especially the understanding of ancient climates and climate changes in relation to geologic time. AAPG recognizes that that we have members on both sides of this debate and we respect their opinions and encourage them to be part of the scientific process and discussion.” I think this is a very reaasonable statement.

    Newsweek (4-28-1975) was reporting the prevailing notion in the “scientific community” at that time. I remember the talk in the late 70’s that the ices ages were returning. Many of us are old enough to remember that.

    What about talk of global warming on Mars? How do you explain that one? There is one common denominator–the sun.

    The fact is that the climate scientists are far from unanimous on global warming. Perhaps the believers just get a lot more favorable press form “mainstream” outlets.

    Please don’t make this site a subsidiary of the dailykos.

  17. 117
    Mark A. York says:

    Why is it these people just keep recycling debunked myths?

    “There are lots and lots of climitologists [sic]that subscribe to the Global Warming meme. There are also lots and lots of skeptics over this issue. One thing that is absolutely true is that according to many, only 0.278 % of the green house gases are man made. These gases include C02 (less than 3%) and water vapor which alone accounts for 95+% of the total green house gas. In fact, the two combined account for 99.44% of the total. Interestingly enough, the Department of Energy does not list water vapor as a green house gas even though it is the largest single green house gas. Of course, I will present both sides, there is argument to Hieb here Who is right? Probably a little of both, it is warming a bit, tales of catastrophe belong in the round file cabinet. Skeptics are absolutely correct to be skeptical, it is the scientific principle in research. True believers are people that demand that you see things their way…kind of like lefties huh?”
    They use this same site and counter with this one:

    False dilemma fallacy in full play. Unfortunately newspapers do the same thing. One commenter said this about being referred to RC: “why do people from the left always refer us to RealClimate, as if the people there were credible?”

    Because they are.

  18. 118
    Grant says:

    A quote from AAPG, “Our concern is that the geologic perspective generally has been missing from the debate on global warming. Geoscientists have a perspective that is important to this issue, especially the understanding of ancient climates and climate changes in relation to geologic time. AAPG recognizes that that we have members on both sides of this debate and we respect their opinions and encourage them to be part of the scientific process and discussion.” I think this is a very reaasonable statement.

    I agree, it’s a very reasonable statement. I disagree that the geologic perspective is “missing,” rather that climate scientists have a very good perspective on paleoclimate.

    Newsweek (4-28-1975) was reporting the prevailing notion in the “scientific community” at that time. I remember the talk in the late 70’s that the ices ages were returning. Many of us are old enough to remember that.

    Definitely check out posts on this site about the “ice age” scare.

    What about talk of global warming on Mars? How do you explain that one? There is one common denominator–the sun.

    There’s another common denominator: carbon dioxide. And, what about global super-warming on Venus?

    The fact is that the climate scientists are far from unanimous on global warming. Perhaps the believers just get a lot more favorable press form “mainstream” outlets.

    I believe you’re mistaken. In fact it’s the deniers who get vastly disproportionate press coverage. Bear in mind that the IPCC reports represent the combined effort of about 2000 climate researchers. Most of them never get any press. But a small number of denialists get regular op-eds in the Wall Street Journal.

  19. 119
    Hank Roberts says:

    Mark, at least read the threads here discussing the frequent skeptic claims, before you restate them. (Preferably, tell us where you read them, and why you trust the source where you found them, and whether they were provided to you with any cites/footnotes/references that you could check for yourself.)

    Many of the skeptic claims are PR from industry sites and have no basis in the scientific literature.

    Trolls and PR people don’t footnote (because they’re making this stuff up, or repeating baseless claims).

    You can check many of the skeptic claims easily. For your latest:


    Was an imminent Ice Age predicted in the ’70’s?
    Google Results: about 1,270,000 for 1970s claim ice age.

    Skeptic Claims Generally, with science cites:

    Libertarian perspective:

    Look for the footnotes when you see claims made, and read the science. Tell us what the basis is for what you assert. The above links are examples of claims with sources cited so you can check what’s said yourself. As you would do in any scientific study, do here.

  20. 120

    #116, “Perhaps the believers just get a lot more favorable press form “mainstream” outlets.”
    Nonsense. I took a look at my Countries weather today, almost all major cities are having above normal temperatures, that is what is driving some journalists. They are seeking answers about this warming which is occurring now, they are doing their jobs.

    [Response: If journalists are stimulated by above normal temperatures to look into the broader climate change issues that’s a good thing. Of course, no short term period of above (or below) average temperature tells you much one way or another about climate change. A string of several years of new records does begin to hint at something, and an increase in the occurence of extreme events tells you something, but it takes a good many years of statistics before the picture becomes clear. I like the way the studies of the last European heat wave put it — this kind of event is expected to become more probable in a doubled CO2 world, but there is no attribute any one particular event to global warming. Same situation for, say, Katrina. –raypierrre]

  21. 121

    #120, Raypierre, I believe that Chaos with respect to temperature variations is not so prominent anymore, that is catching the attention of many. When nearly every big city
    is above normal almost simultaneously, questions arise, immediate answers are sought. May be GW GCM’s have projected this for sometime in the future, it is nevertheless a great phenomenon.

  22. 122
    raypierre says:

    To amplify on the response to Mark in Comment #118, it is utterly unjustified to say that a geological perspective is missing from climate change studies. Usually this is taken by some of the less thoughtful petroleum geologists to mean that “global warming believers” don’t realize that “climate changes all the time” (whatever that latter is supposed to mean). In fact, the study of past climate changes is at the very heart of the way climate research operates. There is a whole journal devoted to it (Paleoceanography),and almost any issue of JGR-Atmospheres has something about paleoclimate in it. The best of this work combines modeling with geological studies of the proxy record. A lot of my own recent work is on Neoproterozoic climate, and without careful geological studies by Paul Hoffman and others (ironically, the same kind of field studies that petroleum geologists use to spot promising formations) my whole subject would be toast, for lack of data to help constrain the models. Going more recent, the record of the Pleistocene (relying on both ice core and marine sediments) is a big part of our understanding about how the climate system responds to CO2 and other forcings. The LGM is in fact a major test of the model sensitivity to CO2, as has been discussed in a number of places on RealClimate. In between you have hothouse climates like the Cretaceous, which cannot be explained without the greenhouse effect of elevated CO2 (and so far have not even been completely explained with it, though the gap may be more due to data than the theory). Let’s not get into the claim that Veizer showed it’s all cosmic rays and not CO2, since that’s been thoroughly debunked.

    I won’t tar the whole petroleum industry with the same brush handed to us by the spokesman for the S.A.P.G. who lauded Crichton’s book. As an indication of the extent to which the petroleum industry accepts the very same climate physics used in understanding global warming, at least one major oil company is using climate simulations of the Cretaceous (based on CO2 induced warming on top of geography changes) to spot promising oil formations. In fact, one of Paul Valdes’ industry-funded Cretaceous simulations was more or less embargoed from publication for five years because of its potential value to exploration. I hasten to add that Paul is one of the most respected climate modellers in the business, and his case shows that it is entirely possible to get some funding from the fossil fuel industry without compromising one’s research. The paleogeographic atlas project at U. of Chicago has also gotten funding from the oil industry from time to time.

    That’s not to deny that some industry groups do indeed fund work for hire whose intent is to spread confusion about the state of climate science.

  23. 123
    Blair Dowden says:

    Hi, raypierre. My impression is that models of the Cretaceous climate have a hard time reproducing the amount of warmth in the polar regions and continental interiors. In particular, there are very large (more than 10 watts per square meter) uncertainties about forcings from cloud cover. I am surprised that a general circulation model (if that is what they used) could achieve regional accuracy sufficient to predict the formation of oil. I wonder if you can point me to some references to help me understand this better?

    [Response: You are right about the nature of the problems with Cretaceous simulations. They are too cold in the winter in continental interiors, and when CO2 is turned up enough to make the poles warm enough to melt ice, the tropics tend to be too warm (though that latter may be a data problem, not a model problem). I don’t know much about petroleum geology, but my recollection is that the organic precursors to oil are in high-productivity marine environments, and those are less affected by the continental interior problem. For the gradient problem, I believe the idea was to set the CO2 level at something that achieved a reasonable match to the available Cretaceous data, even if it somewhat overestimated the gradient, in the hopes that the oceans would still be close enough to the real thing to provide some guidance as to high productivity regions. I have sent Paul some email to see if there is any work in the petroleum exploration literature which explains how this is done — for all I know, the details may be proprietary. I am also checking up on the publication status of the specific Cretaceous simulations I referred to, and will post the references once I hear from Paul. –raypierrre]

  24. 124
    raypierre says:

    Apropos of Blair’s query:

    I’m still waiting to hear from Paul Valdes, but a quick check of Science Citation index tells me that his “best” Cretaceous simulation (which I have seen!) has not appeared in print yet. To get an example of the state of the art in Cretaceous model-data comparison, insofar as it’s reached publication, you can take a look at the following from the NCAR group:

    Title: Late cretaceous ocean: coupled simulations with the national center for atmospheric research climate system model
    Author(s): Otto-Bliesner BL, Brady EC, Shields C
    Document Type: Article
    Language: English
    Cited References: 52 Times Cited: 12
    Abstract: [1] Deep-ocean circulation may be a significant factor in determining climate. Here, we describe two long, fully coupled atmosphere-ocean simulations with the National Center for Atmospheric Research Climate System Model for the Late Cretaceous (80 Ma). Our results suggest that higher levels of atmospheric CO2 and the altered paleogeography of the Late Cretaceous resulted in a surface ocean state, temperature, salinity, and circulation, significantly different than at present. This, in turn, resulted in deepwater features that, although formed by mechanisms similar to the present, were quite different from the present. The simulations exhibit large overturning cells in both hemispheres extending from the surface to the ocean bottom and with intensity comparable to the present-day North Atlantic simulated overturning. In the Northern Hemisphere the sinking takes place in the Pacific due to cooling of the much warmer and saltier waters compared to the present day. In the Southern Hemisphere the sinking occurs primarily in the southern Atlantic and Indian Oceans. For a simulation with atmospheric CO2 reduced from 6 times to 4 times preindustrial concentrations, the southern branch is reduced by 35% due to less poleward transport of salty waters in the South Atlantic Ocean. Warm waters inferred from proxy data in deep-sea cores can be explained by the high-latitude sites of overturning. These results contradict the traditional hypothesis that warm Cretaceous ocean bottom waters must have formed by sinking in shallow low-latitude seas.

  25. 125
    Hank Roberts says:


    So — is it the same oil companies that are in public dismissing modeling and climate change as wacky science, while at the same time, without publishing the work, using climate modeling to locate oil?

    Or are these different companies, the Exxon-Mobil group that funds Tech Central Station and so many of the other denial industry outlets opposing modeling, and — who, favoring it?

    I imagine the oil industry can afford to hire very good people, taking them and their work out of the public discourse entirely.

    If I’m deciding on my retirement funds, I’d sure like to know which company, if there is one, both believes in modeling and publicly supports scientists who are doing modeling — and lets them publish, eventually, for the public good.

    This is eerily reminiscent of the history of tobacco science, isn’t it?

    [Response: I wouldn’t say it’s necessarily the SAME oil companies; that wasn’t relevant to my point, which was only that the petroleum industry is not uniformly skeptical about the strong link between CO2 and climate, or about the value of climate models. Also, it wouldn’t be fair at all to characterize Paul Valdes as having been “taken out of circulation,” if that’s what you had in mind. He’s continued to be very active in publishing climate simulations, both on things relevant to the LGM and to anthropogenic climate change. It’s just this one Cretaceous paper that seems to have been delayed, and Paul no doubt has as big or bigger a backlog of papers to write up as I have, so I wouldn’t jump to conclusions about the reasons for the delay. –raypierre]

  26. 126
    Hank Roberts says:

    Thanks, Ray. I’ll hope the stockholders’ groups clarify which oil companies are completely in denial, which are hypocritical (if any are publicly denying while internally using models) and which — if any –have models or understand yours and are thinking about the future as well as the past.

    Time will tell, if there’s time, and if climate isn’t a ‘tragedy of the commons’ in the short run.

    It worries me to imagine how many not-yet-written papers are no doubt awaiting drafting.

  27. 127
  28. 128
    Stephen Berg says:

    Re: #127,

    That makes little sense to me, especially with studies by Emanuel, Curry, et al. which say the opposite. Again, the contrarian crowd is throwing out obfuscations and misinformation to confuse the general public.

  29. 129
    Joel Shore says:

    Re #125 and 126: I’ll start the list for you:

    Oil companies in denial: Exxon/Mobil

    Oil companies accepting the science: BP, Shell

    I’m not sure about the rest. [And, I think coal companies, like Western Fuels Association, tend to be heavily denialist since coal is even more carbon-intensive than oil.]

    BP has been particularly good on the issue as they made Kyoto-size cuts in their own greenhouse gas emissions, completing them like 8 years ahead of schedule and noting that they are actually saving hundreds of millions of dollars (i.e., the net cost of these emissions reductions was negative). I think they are now starting to consider the issue of end-use emissions from the products they sell (i.e., the greenhouse gases emitted when you buy your gasoline at BP and run your car on it), which is, of course, dicier for them.

  30. 130
    Joel Shore says:

    Just to follow-up on what I wrote, here is a link to BP’s web pages on climate change:

  31. 131
    Hank Roberts says:

    The paper mentioned here
    is now available to AGU subscribers. The AGU abstract is here

    From the abstract they agree with Dr. Cheliah and Dr. Webster (if I read them right in the earlier thread) that there’s more than one thing going on. Anyone read the full text? I’m still hoping we hear more from Drs. C. and W. and the others about the earlier papers — that discussion was going to happen elsewhere and appear eventually, presumably in a journal article. Patience ….

  32. 132
    Bryn Hughes says:

    Re Raypierre’s response to post 100
    Antarctic Cooling “because of the thermal inertia of the massive Southern ocean.”
    Gavin wrote a paper attributing Antarctic Cooling to the effects of decreasing ozone in the upper atmosphere.
    Which of these reasons is Scientifically most probable ?

    [Response: There’s more than one thing going on in the Southern Hemisphere. My point about thermal inertia is just to explain why the global warming signal is less pronounced so far in the Southern Hemisphere. That does work together with the subtle ozone effects on Antarctic interior climate, though, since subtle cooling forcings have less general Southern Hemisphere warming to fight against. –raypierre]

    [Response: I’ll try and clarify. Overall the southern hemisphere will not warm as quickly as the north because of the larger thermal capacity of the oceans. This of course does not predict any actual cooling! However, in the presence of a very mild expected GW signal, local dyanamics can make an important difference. Mainly because of the ozone hole, winds around Antarctica have sped up and this pattern is associated with cooling in the Antarctic interior – consistent with the observations. – gavin]

  33. 133
    Hank Roberts says:

    For Mark the petroleum geologist from Minnesota — still with us? — your state senate held hearings on state climate change in 2005. Here’s a link to one presenter’s video:

  34. 134
    Bryn Hughes says:

    Re 132
    So there are two processes causing this Antartic cooling.
    I find it interesting that the only places on earth that are cooling are probably the only one’s to have no air routes across them.

  35. 135

    […] In fact in my search to find out just what was behind William Gray’s thinking what I did find was a critical article on the web site entitled Gray and Muddy Thinking about Global Warming. […]

  36. 136

    […] quoted as a tropical expert, Gray’s actual prediction record is unimpressive. Read more at RealClimate. This entry was posted on October 14, 2007 at 6:56 pm. You can bookmark the permalink. Comments […]

  37. 137

    […] was presented with glee in a right-wing denier paper is just the ice on the cake, as it were…. RealClimate Gray and Muddy Thinking about Global Warming William M. Gray – Wikipedia, the free encyclopedia The Sydney Morning Herald – Wikipedia, the […]

  38. 138

    Re: Gore Wins Nobel Peace Prize…

    Although Gray arguments seem complex, his theories are full of holes..


  39. 139

    […] ad hominem attacks. But Dr. Gray also makes scientific arguments, flawed though they are. Read a rebuttal of his recent efforts. It begins: Anybody who has followed press reporting on global warming, and particularly on its […]

  40. 140

    […] Fox News Uses Not-So-Expert-on Global-Warming Expert to Try to Discredit Al Gore – Dr. William Gray, who argues that humans are not responsible for the warming of the earth, and says that salinity determines the temperature of the oceans’ waters, was cited on the Fox and Friends show as proof that Al Gore is all wrong. However, The Washington Post reports: Gray’s crusade against global warming “hysteria” began in the early 1990s, when he saw enormous sums of federal research money going toward computer modeling rather than his kind of science, the old-fashioned stuff based on direct observation. Gray often cites the ascendancy of Gore to the vice presidency as the start of his own problems with federal funding. The National Oceanic and Atmospheric Administration (NOAA) stopped giving him research grants. So did NASA. All the money was going to computer models. The field was going off on this wild tangent. […]

  41. 141

    […] Gray and Muddy Thinking about Global Warming A look at William Gray’s contrarian arguments […]

  42. 142

    […] much all quarters of the atmospheric science community the last few years. Here’s a good summary: RealClimate Since all those debunkings a couple of years ago, Gray has largely stopped trying to argue and has […]

  43. 143

    […] Gray and Muddy Thinking about Global Warming A look at William Gray’s contrarian arguments […]

  44. 144

    […] Gray and Muddy Thinking about Global Warming A look at William Gray’s contrarian arguments […]