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Richard Lindzen’s HoL testimony

Filed under: — gavin @ 14 February 2006

Prof. Richard Lindzen (MIT) is often described as the most respectable of the climate ‘sceptics’ and is frequently cited in discussions here and elsewhere. Lindzen clearly has many fundamentally important papers under his belt (work on the QBO and basic atmospheric dynamics), and a number of papers that have been much less well received by the community (the ‘Iris’ effect etc.). Last year, he gave evidence to and answered questions from, a UK House of Lords Committee investigating the economics of climate change, in which he discoursed freely on the science. I’ll try here to sort out what he said.

Firstly, it is clear that Lindzen only signs up to the first point of the basic ‘consensus’ as outlined here previously, that the planet has indeed warmed significantly over the 20th century. While he accepts that CO2 and other greenhouse gases have increased due to human activities, and that this should warm the planet, he does not accept that it is necessarily an important component in the 20th century rise. His preferred option (by process of elimination) appears to be intrinsic variability, but he provides no support for this contention.

In terms of scientific content, his testimony covers a few basic topics: the greenhouse effect, climate sensitivity, aerosol forcing and water vapour feedbacks. We have discussed these topics previously (here, here and here), and so my critique of Lindzen’s comments will come as no surprise. He intersperses his comments with references to ‘alarmism’ which I will get to at the end.

Greenhouse Effect

Lindzen accepts the main principle of the greenhouse effect, that increasing greenhouse gases (like CO2) will cause a radiative forcing that, all other things being equal, will cause the surface to warm. He uses an odd measure of its effectiveness though, claiming that a doubling of CO2 will lead to a ‘2%’ increase in the greenhouse effect. How has he defined the greenhouse effect here? Well, a doubling of CO2 is about a 4 W/m2 forcing at the tropopause, which is roughly 2% of the total upward longwave (LW) (~240 W/m2). But does that even make sense as a definition of the greenhouse effect? Not really. On a planet with no greenhouse effect (but similar albedo) the upward LW would also be 240 W/m2, but the absorbed LW in the atmosphere would be zero, so it would make much more sense to define the greenhouse effect as the amount of LW absorbed (~150 W/m2). In which case, doubling of CO2 is initially slightly more*, but as soon as any feedbacks (particularly water vapour or ice albedo changes) kick in, that would increase. Due to the non-linearities in the system, you certainly can’t multiply the total greenhouse effect of ~33 C by 2% to get any sensible estimate of the climate sensitivity. So it’s not clear what relevance the ‘2%’ number has except to make the human additions to the greenhouse effect seem negligible.

*Update: The initial post had an arithmetic error which I have excised (see comment 76 below).

Climate sensitivity

That leads in to Lindzen’s main theme in his evidence – how sensitive climate will be to increasing CO2. He starts off by giving the standard Stefan-Boltzmann no-feedback value for the climate sensitivity: “A doubling of CO2 should lead (if the major greenhouse substances, water vapour and clouds remain fixed), on the basis of straightforward physics, to a globally averaged warming of about 1°C”. But he couples this with an extremely misleading statement: “The current increase in forcing relative to the late 19th Century due to man’s activities [by which he means greenhouse gases alone] should lead to a warming of about 0.76°C, which is already more than has been observed, but is nonetheless much less than current climate models predict.” He repeats this point in the Q&A session as well. However, Lindzen is undoubtedly well aware (having written papers on the subject i.e. Lindzen, GRL, 2002) that lags in the surface temperature due to ocean thermal inertia imply that the transient response is always smaller than the equilibrium response, and that additionally, there are other forcings in the system (specifically land-use change and aerosols) that counteract the forcing from greenhouse gases alone. Since he does not mention these two factors in connection with this statement, a listener could be left with a rather misleading impression. He combines this with a (deliberate?) overstatement (Q130) of the ‘consensus’ value for the sensitivity as being 4 to 5°C (while the actual consensus is between 1.5 to 4.5°C, best guess around 3°C), misleadingly giving the impression that the mainstream is way off. Similarly, his claim that models overpredict the 20th Century temperature rise is easily shown to be false.

Later he states: “Attempts to assess climate sensitivity by direct observation of cloud processes, and other means, which avoid dependence on models, support the conclusion that the sensitivity is low. More precisely, what is known points to the conclusion that a doubling of CO2 would lead to about 0.5°C warming”. One wonders which attempts he is referring to, since it can’t be Lorius et al (1991), or Forrest et al (2004) or Andronova and Schlesinger (2002), given that they give ranges that are all significantly higher than this, and indeed, Gregory et al (2002) specifically rules out anything less than 1.6°C. A more recent estimate (Annan and Hargreaves, in press) using multiple lines of observational constraints places the sensitivity well within the value estimated by the models (i.e. around 2 to 4°C).

Actually, I think it is quite easy to rule out a sensitivity as low as 0.5°C by considering the last glacial period about 20,000 years ago. At that time the temperatures were globally around 5 or 6°C colder than the pre-industrial, and the forcings (from ice sheets, vegetation, greenhouse gases and dust) are estimated to be around 6 to 11 W/m2 (a slightly broader range than I previously quoted, updated from some of the PMIP2 results). This implies a sensitivity of between 1.8 and 4°C for a doubling of CO2, with a most likely value of around 3°C. If however, the sensitivity really was as low as 0.5°C, that would imply that either the forcings estimates are 3 to 8 times too low, or the temperature changes are 3 to 8 times too high. Since around 3 W/m2 of the ice age forcing is directly related to greenhouse gases and is well accepted (even by Lindzen), it would require the ice sheets to impart an enormous forcing even to get anywhere near a level consistent with his sensitivity estimate. That does not appear even remotely plasuible. On the other hand, it is unlikely that we have mis-interpreted the proxy evidence for temperature since it comes from very many different sources – snow lines, foraminefera, alkenones, Mg/Ca, pollen records, ice core isotopes, speleothems, faunal assemblages etc. To be sure, some of these data do not completely agree, but none would imply that global temperatures were only 1.5°C cooler (which is the minimum that would be required).

In summary, Lindzen’s testimony regarding on climate sensitivity is idiosyncratic at best, and certainly not supported by the literature.


He goes on to describe the attribution study of Stott et al. (2000) who showed that both natural (solar and volcanic) and human-related forcings (GHGs and aerosols) were necessary for a climate model to match the 20th Century temperature changes. This is seen in every model (for instance) and so is not the result of some individual model quirk. Lindzen goes on to claim that uncertainty in the forcings (particular solar and aerosols) imply that the result is somehow ‘fixed’ to give the observed result. Since we all agree that there are uncertainties in the forcings (which preclude strong statements about climate sensitivity being derived from the 20th century records for instance), is this criticism valid?

In the absence of any other constraints on either of these forcings and if their value was being defined a posteriori then he may have had a point. However, timeseries for solar forcing have been produced by groups unaffiliated with any modelling group, and the modellers have simply taken the values from the literature (Lean et al, 1995;2000;2005, Hoyt and Schatten, 1998) – any ‘fudging’ to produce the ‘correct’ answer would be immediately obvious. For aerosols, models are needed to produce the 3-dimensional distribution based on independently-derived emission data sets, but the validation is based not on the transient studies over the last 100 years, but on the satellite data and observations over the last 25 years. Once the various unknown parameters have been constrained as much as possible, they are fixed before the transient runs are started. However, aerosol modelling is indeed fraught with uncertainty, and so no group can claim that their resultant transient forcing is the unique best representation of the value found in the real world. Thus in papers such as Hansen et al (2005), it is clearly stated that the results are merely consistent simulations that match the surface temperature response and ocean heat content changes (as well as many other observations) but that this does not rule out a different combination of climate sensitivity and aerosol forcing having as good a match (see this post for more details). The point that needs to be emphasised is that all of these forcings are all very close to the ‘best guesses’ of the aerosol and solar communities.

Water Vapour

In the question session (Q143), Lindzen goes into more detail on the reason why he feels that climate sensitivity is so low – specifically, he believes that water vapour feedbacks are not only less positive than models suggest, but actually negative. That is he feels that the amount of longwave aborbtion by water vapour will go down as the planet warms due to increasing GHGs. This implies that actual water vapour amounts will decrease with increasing temperature. On the face of it this is a rather odd claim to make in general – the amount of water vapour that can exist in the atmosphere depends on the Clausius-Clapyeron equation that goes up with temperature. However, it is conceivable that convective processes might cause more extensive drying due to increased areas of subsidence (the basis of the so-called Iris effect), but this applies mainly to the upper troposphere and in the tropics only. As a general effect, reductions in water vapour as temperature increases in general seem rather unlikely.

But we can do better than simply speculating on the issue – we can look at the data and compare that to the models. The best examples to test this idea come from large and relatively rapid changes in the climate such as El Nino events, the eruption of Mt Pinatubo and the trends over the last few decades. In each case (Soden 1997; Soden et al 2002; Soden et al 2005), water vapour increases with warming, and decreases with cooling. There is some uncertainty about exactly how much it increases in the very uppermost troposphere (Misnchwaner and Dessler, 2004), but even those results show a positive feedback. So in summary, the data and the models both agree that not only is the water vapour feedback positive, it is quite close to the value suggested by the models – Lindzen’s insistence on the converse (while it has generated increased attention on the subject) seems increasingly perverse.

In general, I think it is incumbent on scientists when speaking to non-specialists to clearly deliniate what one’s personal opinion is, and what is generally accepted. That is not to say one should not state one’s opinion, but when a panelist specifically asks ‘how far your view of the role of water vapour is shared by other scientists?’ (Q144), one cannot honestly answer ‘That is shared universally’ when no other scientist in the field has made a case for a negative water vapour feedback. This is probably the most egregious mis-statement in the whole testimony and is deeply misleading.


Throughout his testimony, Lindzen refers to the global warming ‘alarmists’. In my dictionary an ‘alarmist’ is defined as ‘a person who alarms others needlessly’. However, Lindzen appears to define as ‘alarmism’ anything that links human activities to climate change. For instance, when discussing the statement from the NRC (2001) report (which he co-authored): The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability., he states that “To be sure, this statement is leaning over backwards to encourage the alarmists”. To my mind, this statement is actually a fair assessment of both the NRC report, and IPCC report to which it was referring. To claim that this is ‘alarmist’ is such a gross overuse of the term as to make it useless except as a rhetorical device.

Lindzen has frequently claimed that within the scientific community “alarm is felt to be essential to the maintenance of funding”. I have yet to see any empirical evidence of this and a brief perusal of active NSF grants related to climate change reveals a lot of interesting projects but none that jump out as being ‘alarmist’. Having sat on panels that decide on funding allocations and as a reviewer of proposals for both US and international agencies, my experience has been that these panels actually do a very good job at deciding which proposals are interesting, tractable and achievable. I have not seen even one example of where the degree of ‘alarmism’ was ever a criteria in whether funding was given. (NB. I don’t regard my own grants (viewable here) as remotely ‘alarmist’ and I don’t have too much trouble getting funding (fingers crossed!)).


In some ways Lindzen’s thinking on the climate change issue has not changed much since 1999, as can be seen in an older rebuttal of his position by Jim Hansen (scroll down to Table 1). However, he does seem to have become convinced that the 20th Century warming is real. What is interesting about the comparison between then and now, is that Hansen made two appeals to the data gathering community to test a) whether water vapour feedbacks can be observed, and b) whether the ocean heat content is increasing in line with the model predictions. It is quite telling that both of these data analyses have since been made and they confirm Hansen’s contentions, not Lindzen’s.

85 Responses to “Richard Lindzen’s HoL testimony”

  1. 1
    Matt says:

    I read the article, though I am not an expert.

    Query? The greenhouse melting was bound to occur, with or without man? Am I interpreting the ice core data wrong? It seems the glacial cycle is lengthening mainly because each cycle sequesters more carbon into the crust, and this net fixing of carbon from cycle to cycle lengthened by 10,000 years the period of last two cycles. (Is this my theory alone?)

    We all complain about oil burning because oil is sequestered carbon.

    Is this the basic complaint?

  2. 2
    Steve Bloom says:

    Re #1 (Matt): It is well-accepted that Milankovitch cycles (the combination of three kinds of orbital perturbations – roundness of orbit, degree of axial tilt and precession of the axis, if I recall correctly) essentially control the timing of the glaciations. Noting that carbon also comes out of the crust via volcanism, I haven’t seen any scientific claim that somehow the amount of available carbon is declining in a manner that would control glaciations. In any case the interglacials are not in any kind of consistent decline in length, and the Milankovitch cycles do seem to sufficiently explain the observed changes. That said, it’s also clear that glaciations (which have not been present throughout much of history, with ice-free conditions existing as recently as 30M years ago and the current severe glaciations – the Pleistocene – having kicked in just a couple of million years ago) have not been able to exist in the past whenever CO2 has been above a certain level in the atmosphere. The complaint about the current pace of putting CO2 into the atmosphere is that we will rapidly reach such a level and that (among numerous other effects, the bulk of them unpleasant) part of the ice caps will melt, raising sea level by substantial amounts. Complete melting of the ice seems beyond our present reach, but maybe if we keep trying hard enough… :(

    BTW, all of the carbon that is not active in the climate cycle (i.e., present in the ocean or atmosphere) is sequestered, even if not in the form of fossil fuel, so the fact of prior sequestration is part of what defines the problem. Oil is just one source — coal, gas, wood and peat are others.

  3. 3
    Mark A. York says:

    The alarmist claim is a political one and nothing more. It’s a fogging of the issue and unfortunately always has a possibility of working. Keep after it Gavin. This fight is real. We want truth to prevail. I’m pretty sure the whole world does.

  4. 4
    Tom Fiddaman says:

    In some ways Lindzen’s thinking on the climate change issue has not changed much since 1999

    Actually it’s been quite a bit longer than that; see for example his 1991 testimony. In it he discusses low climate sensitivity and the possibility of negative water vapor feedback. In fact he was writing about 2xCO2 climate sensitivity well before AGW got much attention. The origins of some of his ’91 comments are in an ’82 paper, although interestingly that paper seems to accept positive water vapor feedback and reports a climate sensitivity of just under 2K.

    I hesitate to dismiss Lindzen because he seems to be a sort of modern Diogenes’ last honest climate skeptic. I’d love to see him get 10 grad students for 5 years to see what came out – though I suspect that like the Adaptive Iris (which he seems to have set aside for other pursuits) it wouldn’t work out.

    I find it ironic that Lindzen is skeptical of climate science, but when he ventures into the policy arena, he uncritically accepts the far less scientific notion that emissions reductions are extremely costly.

  5. 5
    Matt says:

    Carbon, my favorite subject.

    Why, in the absence of man, are not the old growth forests part of the carbon forcing? During a 10,000 year hot, dry spell like we have, wouldn’t they have burned off? Isn’t the glacial period, right now, trying its best to oxidize whatever carbon it can peel back from the earth? The glacial cycle should be oxidizing enough carbon to get that ice melted.

    I am still confused as to why the glacial drop in temperature is delayed, for it seem clear that we start the drop in temperature when reach the magic 6 degrees off nominal (mid glacial cycle). We should be seeing that by now, man or no man. Why hasn’t the ice caps melted yet? And better yet, what has held the CO2 levels so low for the past 10,000 years?

    I am also confused that we do not recognize the lengthening of the glacial period as in:

    where clearly the cycle seems to be taking longer and longer.

    Why do we think the oxidation of land carbon is not the driver, perhaps not the pacemaker, but at least the amplifier? We are awfully hot and dry, and there is about twice the available carbon in plants and soil as in the ocean.

    I guess, what I am driving at is this. The earth, at this part of the cycle seems awfully sensitive to carbon sources, the rise in CO2 levels have been delayed for so long. Are we really completely to blame, or have we just shifted short term carbon around, delaying and controlling oxidation (until 1950, that is).

  6. 6
    Ike Solem says:

    Re #1 and #2,

    I had thought that the actual difference in Milankovich forcing (between extremes) was much smaller then current CO2 et al forcing. Are Milankovich cycles seen as a trigger for postive feedbacks going into or out of glacial periods? But then, ice records show associated CO2 changes, but is this the chicken or the egg? In any case, how much can we learn about our current interglacial but getting warmer situation from looking only at the past millions of years of glacial/interglacial cycles? Glacial cycles are apparently associated with a drying and cooling of the atmosphere. It seems that a warmer world would be a wetter world, unlike Lindzens argument r.e. water vapor feedbacks.

    From listening to Lindzen, it seems he believes strongly in stable equilibrium – the notion that a stable system will respond to stress in such a manner as to restore stability. This is still a valid scientific viewpoint, which could account for Lindzen’s credibility. Some systems (buffers, for example) display this behavior, but it doesn’t seem to apply to the climate system, which has many positive feedbacks (pebbles starting avalanches). The large swings of glacial cycles and sea levels in the absence of any human perturbation should suggest a relatively sensitive climate, especially if the glacial/interglacial switches occurred very rapidly (100-1000 years?).

    Lindzen should consider that an honest approach to the problem involves openminded consideration of all possible forcings and feedbacks, not just those that happen to fit with one’s notions. Calling people ‘alarmists’ and suggesting they are trying to terrify the public into funding science is reducing a scientific debate to a political squabble. In any scientific area one can find a dissenting scientific opinion, whether you are talking about the K-T boundary and the extinction of the dinosaurs, quantum mechanical theories, or whatever. Generally, unless they have some startling new evidence, outliers to general scientific consensus are not handed bullhorns and invited to speak to Parliament.

  7. 7
    Brian Forbes says:

    I agree with Lindzen.When you consider the Ice Ages we know that the CO2 started climbing after the the temperature rose and fell after the temperature fell. Furthermore if the temperature was influenced by the CO2 as much as you claim then we would expect the temperature ( strickly speaking the 4th power of the temp in degrees absolute) to have risen faster as the CO2 increased: it didn’t.Moreover the CO2 increase accelerated as the temperature increased.
    When the temperature fell the CO2 fell only slowly (perhaps because the biosphere used less). The scource of the CO2 was the sea and it was reabsorbed as the global temperature fell.

    [Response: Errrm, you have a lot of this rather badly wrong. If you are getting your fourth power from R prop T^4, then its the other way round: T increases as the fourth root of radiative forcing. Just as well, really (though I suspect that for the relatively small perturbations we’re in, the linearised version will do). But anyway, the radiative forcing isn’t proportional to CO2 concentration, its proportional to its log – William]

  8. 8
    Matt says:

    Regarding the lag in CO2 vs temp.

    If I eyeball the latest vostok ice core, I find the CO2 data correlates well on the rising slope of the cycle, but lags on the falling slope. Peaks in temp seem to correlate with simultaneous peaks in CO2, indicating, to my untrained eye, that CO2 dominates heating but ice melt dominates cooling.

    I have a hard time understanding that slight orbital changes in sun angle could cause such a rapid rise in temperature.

    Where would all that CO2 come from, the oceans being so cold? From the rotting of dead biomass near the tropics, I presume.

    On the way down the slope, the rains are falling on land, temps are not so hot, things are growing. The Northern hemisphere is going from ice to temperate forests, absorbing how much carbon? Well, my envelope calculation says that forest development in North America could take up 400 million tons. How much co2 do we have in the atmosphere now? 600 million tons?

    Please feel free to correct my numbers.

  9. 9
    Joel Shore says:

    In regards to Lindzen’s discussion of the water vapor feedback: I agree that his statements are misleading, although to be fair if you read the full context of his quote, you can see that he could argue that the “that is shared universally” could refer to the idea he then discusses in answering the question of the warming being fairly modest in the absence of any positive water vapor feedback. What he did though to mislead is to answer the question only in this very limited way. I.e., he took a general question about whether his view on water vapor is shared by other scientists and then answered it in a way that said “Yes” and then going on to discuss only the part of his view that is shared by others without mentioning that all the other stuff he had said about a negative feedback is not. It is the old political trick of not answering the question that you were asked but rather the question that you wish were asked and pretending like it is really answering the question you were asked.

    At any rate, I found the last few sentences in his answer to Question 143 to be even more bizarre. How does his claim that the climate system must have negative rather than positive feedbacks jive with the known strong instability of the climate system? In fact, his argument flies in the face of many of the other deniers who use the fact that the climate system is so unstable to somehow imply that the current warming is likely just a natural oscillation. Or is the climate system somehow designed to be highly unstable in response to natural forcings but stable to the forcings that we put on it? [And as an aside, what does Lindzen mean by “but it is politically incorrect these days to speak of the world, or the earth, as in some sense being engineered”? Is he going to come out in favor of intelligent design just as Roy Spencer did?]

  10. 10
    Stefan says:

    The first Lindzen lecture I attended was in the early nineties. Back then he argued that the Ice Ages did not challenge but rather confirm his hypothesis. He emphasised that the planet did not get cold globally during Ice Ages: the tropics remained warm, only higher latitudes cooled. From that he concluded that a negative feedback keeps the tropics at constant temperature. At the time, that was a defensible position: it was early days with proxy data, and these (the famous CLIMAP reconstruction) seemed to show that tropical sea surface temperatures were hardly cooler than today at the height of the last Ice Age. A nagging contradiction (not mentioned by him) was, however, that proxies for tropical land temperatures (e.g. snowlines) did show major cooling.
    In the meantime, proxy methodology has advanced and new proxies have emerged (e.g., alkenones and the magnesium/calcium ratio). It is now generally acknowledged that the CLIMAP reconstruction was not correct in the tropics, and that tropical sea temperatures during the last glacial maximum were in fact much colder than today (e.g., SCHAEFER-NETH and PAUL 2003 find 2-4K cooling in the tropical Atlantic). As Gavin wrote, this much glacial cooling is what is expected with mid-range climate sensitivity (SCHNEIDER VON DEIMLING ET AL. in press), and in my view it clearly shows that there is no such negative feedback as postulated by Lindzen, that would stop the tropics from changing. (Besides, the ongoing melting of most tropical mountain glaciers shows that tropical warming is happening as we speak.)
    As our knowledge advances through better data, one would expect Lindzen to change his assessment; instead he just does not mention the Ice Age any more in his more recent talks, as the data don’t fit his message any more.

  11. 11
    Stefan says:

    The fact that “climate sceptics” like Lindzen often resort to the accusation that climatologists are “alarmist” to get more funding shows that they’ve run out of factual arguments. But this conspiracy theory also shows very poor logic: climatologists are telling their governments that we know enough to act, not that we are still uncertain and need more research money. If I were cynical, I would welcome the “climate sceptics” – if everything were still as uncertain as they claim, this would be a great reason for me to ask for more funding for basic climate research. Unfortunately, I tend to care a lot more about the future of our children than about my research funding.

  12. 12

    It appears to me that Linzden is acting less like a scientist, and more like an advocate promoting a preconceived agenda. Rather than following the evidence where it leads, he is starting with a conclusion, and misrepresenting the facts to fit his preconceived opinions.

    The fact that he has many important papers to his credit amplifies the power of his rhetoric, and gives a veneer of credibility to those who insist that the human cause of global warming is far from settled science.

    And yet Linzden’s message is founded on an attack against science itself. The danger from Lindzen’s rhetoric lies in the implicit attack on the scientific method. If scientists can’t be believed because they are alarming the public into funding ever more research, than the scientific method is no better than think tank ideology at uncovering the mysteries of the natural world. The greatest damage done to the public mind is that so many people have come to believe this. As a result, many ordinary people have come to think that qualified scientists are nothing but doom and gloom scare mongers, and think tank ideologues are brave defenders of the truth.

    This irresponsible idea can only harm to the public good.

  13. 13
    Brian Forbes says:

    Is the latest vostok ice coe the only vostok ice core?
    “have a hard time understanding that slight orbital changes in sun angle could cause such a rapid rise in temperature.”
    It is not just the angle of the sun,it is it’s distance from the earth and it’s activity (which is infuenced by the planetry positions) which affect the Global temperature.
    “Where would all that CO2 come from, the oceans being so cold?”
    The oceans over most of the Globe weren’t cold and as they warmed up they released CO2.
    “On the way down”(surely this should be up) “the slope, the rains are falling on land, temps are not so hot, things are growing. The Northern hemisphere is going from ice to temperate forests, absorbing how much carbon? Well, my envelope calculation says that forest development in North America could take up 400 million tons. How much co2 do we have in the atmosphere now? 600 million tons?”
    Non sequitur
    The rising concentration of CO2 does not accelerate the rise in temperature and it should, if it as effective as a GHG as you insist”

  14. 14

    Re #8 and “On the way down the slope, the rains are falling on land, temps are not so hot, things are growing. The Northern hemisphere is going from ice to temperate forests, absorbing how much carbon? Well, my envelope calculation says that forest development in North America could take up 400 million tons. How much co2 do we have in the atmosphere now? 600 million tons?”

    The mass fraction of a gas in the atmosphere is related to the volume fraction by the ratio of molecular weights. The total mass of Earth’s atmosphere is about 5.136×10^18 kg according to recent estimates. CO2 is about 0.00038 of that, times 44.01 AMUs for CO2, divided by 28.92 for normally wet air, from which I get the atmospheric mass of CO2 to be 3.0 x 10^15 kilograms — three quadrillion kilograms or three trillion tonnes.

  15. 15
    Igor J. says:

    I have just reviewed the testimony and it mentions:
    “According to any textbook on dynamic meteorology, one may reasonably conclude that in a warmer world, extratropical storminess and weather variability will actually decrease…”

    I have seen a post on RC about evidence (=measurement not model) for increased storm/hurricane intensity (=as result of warming).

    Can you comment on this issue??

  16. 16
    Matt says:

    Fascinating stuff, really. I get more questions not less.

    I stand corrected on the carbon budget absolute values, but not on the relative values. I use this carbon cycle diagram from Dr. Haughton:

    Now my questions.

    Why didn’t the co2 levels peak 10,000 years ago, like they have done before?

    Are we trying to say that something changed the glacial cycle so that we are supposed to be stuck at this relatively hot, dry part of the cycle?

    Do we really believe that green house carbon did not melt the ice in recent cycles?

    Why am I wrong in assuming that as the glacial ice retreats, the first order of business is the direct oxidation of uncovered soils, accelerating carbon release?

    Surface carbon on land, plants and soils, is twice the amount in ocean and twice the amount in atmosphere. Given the large scale change on land with advancing and retreating ice, and changes in precipition/temp over the cycle, I would assume land carbon plays a much bigger role than we assume.

  17. 17
    Joel Shore says:

    Re #15: Note the word “extratropical,” which excludes hurricanes. I think the basic argument is that since the polar regions will warm more under global warming than the tropics, the difference in temperature between the two will decrease and since extratropical storms are driven in part by this temperature difference, they will tend to decrease in intensity.

    The pros here are RC can comment more on this…but I believe that this reasoning is believed to be too simplistic. I.e., there are other effects to consider (such as a warming atmosphere holding more water vapor).

    For tropical systems, i.e. hurricanes, the situation is different…as the driving force for them is apparently in large part convection which depends on the difference between the temperature at the surface and the temperatures higher up in the atmosphere. There are some basic physical reasons why global warming ought to make the hurricanes that do form more intense although there is no strong evidence either way for an increase or decrease in the number of them that form.

  18. 18
    Timothy says:

    Re: #15 – extratropical storminess.

    There are two separate effects here. Firstly the storms in the extratropics [50-60N or so] are the mechanism that the atmosphere uses to mix heat towards the poles and away from the tropics [since the Hadley direct circulation can’t work away from the equator because the Earth is spinning]. Consequently, in a warmer world, with amplified polar warming, less heat will need to be transported north and so ‘extratropical storminess’ will be less. This is normally an actual decrease in the absolute number of cyclnoes/storms.

    However, number two, there is some evidence, from models and observations, that the intensity and strength of cyclones [whether extratropical or tropical ie hurricanes] is correlated with SST. Consequently, in a warmer world, where the sea temperatures are warmer where the cyclones form, there would be more energy available to the cyclone and therefore more ‘storminess’.

    So I guess it depends on how exactly you ask the question.

  19. 19
    Timothy says:

    Re my own #18. I should say that this combination of fewer, but more intense storms, is predicted by at least some of the latest climate models, in response to the lower temperature gradient and higher SSTs.

  20. 20
    Leonard Evens says:

    Could anyone comment on why Lindzen was testifying before the House of Lords? Have other been also called to testify on question related to climate change?

  21. 21
    Brian Forbes says:

    re 16 Matt
    “Why am I wrong in assuming that as the glacial ice retreats, the first order of business is the direct oxidation of uncovered soils, accelerating carbon releas”
    What mechanism do you propose for this oxidation?
    You would get fewer questions if you answered them reasonably

  22. 22
    Hank Roberts says:

    Matt, have you visited a glacier? They push, not cover, soil. When they retreat they leave gravel and rock.
    Where did you get the information you’re assuming is true, where did you get the assumptions underlying your questions? Point us to the source of those and we can talk about them.

  23. 23
    Mike Salem says:

    Although I trust that the writers and moderators for this site are not trying to deceive me, for other viewers this article presents an interesting opportunity: can the moderators encourage Lindzen to give a reply? I imagine that naysayers might dismiss this commentary as reflecting the power of having the ‘last word’ in an argument, however this charge is easily dismissed if Lindzen is properly alerted to this venue.

    BTW, this is the first time I’ve contributed to this blog, but I read it regularly and as an outsider to the climate science community I am very grateful for what you do here. I understand this must be a significant distraction from your professions but for open minded individuals who do not always trust what they read in the popular media, this site is an excellent resource.

  24. 24
    Matt says:

    “Point us to the source of those and we can talk about them.”

    Well, I am asking for sources, sorry, I am the student here.

    “Till is material that is deposited as glaciers retreat, leaving behind mounds of gravel, small rocks, sand and mud. It is made from the rock and soil ground up beneath the glacier as it moves. Glacial till can form excellent soil for farmland.”

    Like clear cut soil, the first thing that happens is carbon release until new plant life takes off.

    Tundra is a better example. When it melts it become a co2 source via microbial oxidation. How much tundra did we have 20,0000 years ago?
    The tundra belt would have advance south in front of the polar ice sheet during the last down swing, leaving carbon encapsulated. As the system warmed, all the carbon would successively been released with the retreating ice.

    So, the speculation is the ice retreated too fast for plant growth to keep up, and the uncovered carbon never had a chance to fixate, forcing even faster greenhouse build up. Positive feed back.

    If the ice retreated fast enough, I would think it worthwhile to consider whether direct burning at the peat soil may even have occured, (natural surface coal does burn) but rapid desertification after the retreating ice surely would have reinfoced carbon release.

    Some stuff about Tundra

    Stuff about ice sheet expansion and the tundra belt over the last cycle.

  25. 25
    mr. green says:

    Does this website do polls? I think it would be great
    to see a poll for the readers and contributers on the
    next few years. How much north pole ice cap shrinks.
    How much the Artic mean temp goes up. How much
    the global mean temp goes up. How much the research budget for
    global warming goes up (or down).

    Does anybody have any good references how much money is spent
    on researching the climate problems? Budget of IPCC? Budget
    of think tanks involved? Is there is list anywhere of big
    questions or problems that we know are slowing our understanding.

    Or maybe a poll on the which 100 million dollar experiment or
    sensory system would give the research community the best data.

    Thank you for all the smart talk on this site. This site rules.

  26. 26
    Hank Roberts says:

    Most of us are students here!

    We try to attract the experts — by making our conversation friendly and interesting enough to attract them to participate, I hope.

    On what’s left behind as glaciers recede:

    Try this info:

    “Just over 70 years ago, the Mendenhall Glacier rested where you stand. As you look at the glacier, notice the vegetation on the hillside to each side of the lake. As the glacier advanced, it stripped the valley walls of all vegetation much as a giant bulldozer might prepare a yard for landscaping. This trimline, where light and dark green vegetation meet, indicates the highest point reached by glacial ice. The new growth, indicated by the lighter green vegetation, colonized the exposed rock surface as the glacier receded.”


    “As the glacier advanced over this area, it rounded and polished any jagged edges of bedrock over which it flowed. After the ice melted away, windborne spores of mosses and lichens â�� the pioneering plants of succession â�� spread rapidly into the area. They first took hold in cracks and issures, modifying their environment until colonizing plants, such as fireweed, willow, alder, and lupine, were able to get a foothold.”

    On what’s left behind as an ice cap melts, I’ll go look. I know there’s some info on the Kilimanjaro and South American icecaps at the Ohio State Polar Research page.

    I know there’s info somewhere about tundra, but tundra isn’t what’s _under_ ice caps as far as I’m aware. I think most of what’s at the bottom of the ice caps is rock and traces of material, not a large layer of buried soil. At the bottom some melting happens due to pressure and heat that would slowly wash out organic material, I think. That’s just my speculation though.

  27. 27
    Hank Roberts says:

    More for Matt (re #23)
    What’s left behind as an ice cap melts — two presentations from field observations here include a close look at quite a few melting ice caps recently:
    one a movie:
    one a PowerPoint presentation:

  28. 28
    Pat Neuman says:

    Global warming and ‘religious beliefs’

    On one hand,

    December 02, 2004
    Washington ( – An MIT meteorologist Wednesday dismissed alarmist fears about human induced global warming as nothing more than ‘religious beliefs.’

    “Essentially if whatever you are told is alleged to be supported by ‘all scientists,’ you don’t have to understand [the issue] anymore. You simply go back to treating it as a matter of religious belief,” Lindzen said. His speech was titled, “Climate Alarmism: The Misuse of ‘Science'” and was sponsored by the free market George C. Marshall Institute. Lindzen is a professor at MIT’s Department of Earth, Atmospheric, and Planetary Sciences.

    Once a person becomes a believer of global warming, “you never have to defend this belief except to claim that you are supported by all scientists — except for a handful of corrupted heretics,” Lindzen added.

    “Meteorologist Likens Fear of Global Warming to ‘Religious Belief’ ”
    By Marc Morano Senior Staff Writer

    On the other hand,

    February 09, 2006
    … “A prominent pastor from the Twin Cities was among 86 national evangelical leaders Wednesday who said that global warming is a real and serious problem that needs immediate attention in Congress.
    Rev. Leith Anderson, senior pastor of Wooddale Church in Eden Prairie, said the effort is important both to God, who has entrusted the Earth to humans, and to the “poorest of the poor and the marginalized of society,” who are disproportionately affected by climate change.”

    “A prominent Twin Cities pastor said global warming needs immediate attention in Congress”
    Minneapolis Star Tribune
    Tom Meersman and Aaron Blake
    Also see:

  29. 29
    Mark Chandler says:

    For a more complete view of the Evangelical support for immediate action on global warming (strange bedfellows, and all that) check out the Evangelical Climate Initiative. This traditionally conservative christian “denomination”, provides some frank discussion of basic global warming issues in its FAQ

    Apparently the movement is supported by many of the Evangelical church’s most high-profile leaders, though no consensus is apparently possible within the church do to polarizing viewpoints on the subject.

  30. 30
    Hank Roberts says:

    Lindzen’s bio here:
    emphasizes theory and modeling, and MIT’s site says they’re building a new generation model.

    Wonder what it’ll suggest is happening. Any one know?

    NASA’s supposed to be about finishing up their tropical convection study combining high altitude flights and satellite passes, to get some actual real data on what the atmosphere’s doing around Costa Rica — in the area where the clouds actually drive up to the stratosphere, instead of topping out below it. That would, I suppose, give information relevant to his work.

    I don’t know anything more about either the models or the flight research on tropical convection. I hope there were some testable hypotheses on record that the data will inform.

  31. 31
    Chris Schoneveld says:

    In Lindzen’s defence, I must say that it is often tempting (i.e. human) to overstate the importance of an observation or a point if you are representing a minority view, as his is. The risk is that you get attacked on those points and your other (possibly valid?) points get snowed under. He is not just appearing at conferences/institutes that support the sceptical view (like the Marshall Institute). Lindzen did present a paper at the international conference “Global Warming: Looking Beyond Kyoto” which was held on 21/22 October 2005 and hosted by the “Yale Center for the Study of Globalization”. This was not a conference just for the “believers” or just the “sceptics”. Check their website. I have a natural aversion for accepting a (claimed?) majority opinion and more keen in reading the minority position and I am also allergic to claims that a scientist has an agenda or is sponsored by interest groups, as a way of discrediting him/her. (This applies to “believers” and sceptics” alike)
    Many brilliant scientists have resisted a common scientific opinion and dared to come up with a dissenting view. Case in point, the two Australian Nobel prize winners who – against the opinion all other scientists in their field – claimed that ulcers were not caused by stress but by a bacteria. Let that be a lesson to those students that read or contribute to this forum. Let us not forget the prediction of scientists in the 70’s that we were at the point of entering another Ice Age.

    [Response: Since this is wrong, you rather destroy your line of arguement… however, its a common myth – William]

    And what about the erroneous predictions of the Club of Rome soon thereafter. Unfortunately we cannot easily google for articles written in the early seventies. Most of today’s students had not been born or were just toddlers and have not had the luxury to be sceptical. I am 58 (a geologist) and have seen alarmist’s science before, although the past is not necessarily a reliable guide to the future. On global warming, yes it could indeed be anthropogenic, but I am inclined to support Lomborg and rather spend the billions of dollars on helping fight poverty and disease than trying (in vain) to contain it.

  32. 32
    Olivier Morand says:

    Could Lindzen have been the basis for (one of) the main character in Crichton’s book “State of Confusion?”
    Many thanks to Gavin and all for such an informative web site: your audience is growing everyday.

  33. 33
    Jeffrey Davis says:

    Rec #31 and ulcers.

    It’s useful to remember, if you approach science with a view to rooting for the underdog, that AGW is the new kid on the block and it’s history is about as recent as the discovery of H. pylori.

  34. 34
    Joel Shore says:

    Re #31 (specifically the stuff about ulcers): Yes, all knowledge is provisional and it is possible for new knowledge to overturn previous knowledge. As #33 points out, this is how things have in fact worked for AGW which encountered plenty of resistance in its ~100 year history before gaining acceptance (see for a history).

    However, what you have to remember is that for every “Galileo” shouting in the wilderness, there are probably a thousand Pat’s, Richard’s, and Sallie’s who oppose the current scientific wisdom and turn out to be wrong. If your recipe for having science guide policy is to wait until there is complete unanimity on a subject before doing anything (because those who are disagreeing with the general scientific consensus may be right and the consensus wrong), then you really just might as well propose we simply don’t use science to guide policy decisions because it will amount to the same thing.

  35. 35
    Joel Shore says:

    As another comment on #31, why does the subject of fighting poverty and disease seem to come up so much when talking about spending money to protect our environment? It is not like these are the only two choices in the world. How about all the money we have wasted on the Iraq War, for example…What if all of that money had been redirected toward weaning us fossil fuels?

  36. 36
    Matt says:

    Another naive question, if you please.

    Can anyone help me discover how much ice was lost during previous glacial minimums compared to the amount of ice we have today?

    [Response: About 120,000 yrs ago, sea levels were higher by about 5m, compared to about 80m sea-level-equivalent ice existing today. -gavin]

  37. 37
    Pat Neuman says:

    re 34.


    Now that I think I’m in the books as retired (from NOAA NWS river forecasting after 30 years), I’d like to bring up an analogy between not predicting climate change and not predicting a flood.

    In flood prediction, if your recipe is to have science and scientific observations guide your policy to take action to save a town by waiting until there is complete unanimity before doing anything, then you’ll have a Grand Forks like disaster in the making for your town.

    In climate prediction, if your recipe is to have science and scientific observations guide your policy to take action to save the world by waiting until there is complete unanimity before doing anything, then you’ll have a Katrina like disaster in the making for your world.

  38. 38
    Leonard Evens says:

    Fighting poverty?

    How about imposing a high gas tax in the US, the proceeds of which would go towards fighting international poverty. That would lower our dependence on oil, a worthwhile goal in any case. As Thomas Friedman and others have pointed out, oil rich nations tend towards corruption and tyranny because rulers have this large source of income they can exploit, which they can use to pacify their populations without giving them much freedom.

    I’m pretty sure Senator Inhofe would not support such a proposal. But perhaps he can find some other way to divert funds that might otherwise be spent to avert global warming to alleviating poverty? I won’t hold my breath waiting.

  39. 39
    FishEpid says:

    Another skeptic:

    Khabibullo Abdusamatov – chief of the Space Exploration Department of the Central Astronomical Observatory of the Russian Academy of Sciences, the supervisor of the Astrometria project of the Russian part of the International Space Station, Doctor of Physical Sciences.

    The scientist particularly said that a global reduction of temperatures would hit planet Earth in the middle of the 21st century because of receding solar radiation. Mr. Abdusamatov told Pravda.Ru that the new Ice Age will start very slowly. According to the scientist, the process will gather pace in 2050-55.

  40. 40
    Tom Fiddaman says:

    Re 31

    And what about the erroneous predictions of the Club of Rome soon thereafter.

    I’ll hazard a guess that this refers to an incorrect but oft-repeated strawdog criticism of the Limits to Growth (LTG) report.

    The basic critique runs, “LTG predicted the end of the world in year XXXX, and it didn’t happen.” Usually the year XXXX is chosen, not from one of the World3 runs, but from a table of resource lifetime indices in the chapter on nonrenewable resources, which were not forecasts at all. If you flip through a copy of LTG, you won’t find any runs where industrial output peaks before about 2010, and you will find a number of comments to the effect of “this is a choice, not a forecast” or “more study is needed.” The plots in the book deliberately used a minimally-labeled time axis to highlight the fact that output was meant to illustrate generic behavior modes of a system with rapid growth, long delays, and limits, rather than point predictions of future conditions.

    As an example, Bjorn Lomborg writes in The Skeptical Environmentalist (pg. 121 of my edition), “Along with numerous other resources, Limits to Growth showed us that we would have run out of oil before 1992.” What he refers to is a table on pg. 58 of LTG showing static reserve life indices (SRLI) and their dynamic equivalents for a variety of resources. If you read the accompanying text, it’s clear that the table has little to do with forecasting exhaustion. Instead it simply makes the point that the static index (=reserves/current use) is a poor measure of the true lifetime of a resource with exponentially growing use. LTG also recognizes the distinction between reserves and resources, and includes a second column of dynamic indices at arbitrary 5x reserves, to make the point that even large increases in reserves can be overwhelmed quickly by growth. For oil, this yields a dynamic lifetime of 50 years (again, not a forecast and not model-based, but implying exhaustion in 2022, not 1992). Lomborg happily ignores these subtleties and publishes a table of updated SRLIs a few pages later.

    I recently skimmed the text for the word “forecast,” unsuccessfully. The closest I could come is (pg. 126): “We can thus say with some confidence that, under the assumption of no major change in the present system, population and industrial growth will certainly stop within the next century, at the latest.” So the jury’s out for seven more decades.

    While there are valid things to criticize about LTG (e.g. the Thiessen critique of the nonrenewable resource structure), I get the sense that many critics haven’t actually read the book; they’re just repeating something they heard about it years ago, from someone who didn’t read it either.

    Ironically, given that Meadows et al. were regarded as heretics at the time, by the “daring brilliant minority dissent” criteria one could conclude that they were Galileos.

  41. 41
    Dano says:

    RE #36 [Matt]:

    Can anyone help me discover [fill in topic here]…

    Google Scholar filters out the noise.



  42. 42
    Hank Roberts says:

    Matt, are you near a public library? Basic school-paper questions are a specialty of the Reference Desk at almost every library — a person worth knowing, wherever you live.

    They say research on the Internet is like walking into a huge library and shouting your question into the dark, never knowing who if anyone might answer and how much truth they’re telling you. The Reference Desk is a human face on knowledge and the sources are reliable and checkable.

  43. 43
    Lynn Vincentnathan says:

    Lindzen, Lovelock. What is the conscientious layperson to do? How about this: HOPE Lindzen is right, but EXPECT & BE PREPARED for Lovelock’s scenario — or at least for the upper end projections of working climate scientists.

    It seems Lindzen is focused very strongly on all that could go right, the lowest end projections, or even below those. Maybe he has a lot of kids and can’t stomach the idea that he (& the other 6 billion of us) have ruined the world for them. Better just to keep one’s head in the sand.

    Now, I’ve always fretted that the scientists might even be underestimating the future GW disaster, since they’re just working with what they know, and new knowledge (findings & theories) keep cropping up. The latest one I read is at:

    It says we’ve underestimated the amount of CO2 being pumped out of plant via bacteria under warming conditions, greatly overriding the CO2 intake of plants, and that warming oceans will take in less CO2 than expected. It says the warming by 2100 will be .1 to 1.5 degrees C higher than the accepted range of 1.4 – 5.8.

    So best case, that means 1.5 increase. But please let’s not fail to do some planning for the worst case, 7.3. Or, better yet, why don’t we just reduce our GHGs & save money & help the economy. If it takes “alarmists” to get a fire going under people’s backsides to do this, then bring on the alarmists.

  44. 44
    Steve Bloom says:

    Re #39: Call me cynical, but I notice that he picked a date for the cooling that’s sufficiently far off in the future so that even with continued warming he can plan to retire safe in the knowledge that he hasn’t yet been proven wrong by actual temperature measurements.

  45. 45

    Re #42; I think that is inappropriate. The reason Matt isn’t getting quick answers is because he is asking pretty difficult questions. I doubt that the average reference librarian could help.

    Regarding the interglacial carbon cycle, a good place to start is here:

    For what it is worth, my intuition agrees in some ways with Matt’s, if I understand correctly what he is trying to say. My conversations with some of the field’s experts (I won’t embarrass them by naming names) hasn’t entirely dissuaded me from suspecting that that carbon exposed by retreating glaciers and sequestered by advancing glaciers plays a key role in the striking asymmetry of the Quaternary glacial oscillations.

  46. 46
    Hank Roberts says:

    >42, 45
    Matt, I found with Google mention of quite a few books — all teacher’s study guide links, no full text online.

    ” * Another sidebar (pg. 11) shows how scientists calculate the total amount of ice on Earth…. “Dr. Lonnie Thompson: Glaciologist & Adventurer”

    So the info is there. I also found the question several times in exam sample question sets, but again, no answer. I only spent about five minutes looking, though.

  47. 47
    Doug Clover says:

    Re #40

    Thank you Tom. I am very familiar with the LTG rebuttal used by those wishing to undermine environmental science. You have summarised the work by Meadows et al and its miss use very succinctly. I work in environmental policy (mainly energy issues and climate change) and have heard this claim so often that I had to go and get (from Amazon) a copy of the original book so that when someone next made this statement I could point out what was actually said in the original book and what has been said in the revisions. Quietly stated facts have had the effect of stopping the conversation in its tracks.

    I classify the LTG misquote as one of the Lomborgians key throwaway talking points which they pepper through out their speeches. Some of the others include M&M on the Hockey stick, Lindzen et al on water vapour, Spenser and Christy on Temperature records. A big thanks to Real Climate for helping me with my responses when faced by these claims. Also a big thanks to William for my response to the Ice Age claim of the 1970s.

    While I am on this topic of Lomborgian throwaways a big thanks to Tim Lambert, over at ScienceBlogs, for his work on the real policy on the use and non-use of DDT to fight Malaria.

    As Pterry says
    ‘A Lie can run around the world before the truth has got its boots on’ Terry Pratchett (after Mark Twain apparently)

  48. 48
    Dano says:

    RE current #s 36, 41, 42, 45 (Matt looking for information on a little-studied phenomenon):

    If I may, I think Matt’s questions are good, and his search for sources getting three different responses is indicative of the larger difficulty/enterprise at work here.

    I think it is instructive that Matt has chosen to ask questions rather than look for quick answers. For those looking for quick, digestable answers then we can thank the authors and this post for pointing out a source and the issues with finding quick answers.

    For those looking for the right questions (and the answers that come from those questions, and then questions that come from the answers…usw.), there is no one good source and this is where wisdom and learning come in.

    Five minutes of Googling likely isn’t going to give you a good answer, unless you are one that is satisfied with five minutes of effort.

    The different responses to Matt’s questions reflect different ways of going about the problem, none of which are right or wrong in themselves, but are context-dependent.

    All this preamble to say it is better to get your information from journals in a library than a quick Google…



  49. 49
    colorado bob says:

    OT…Drudge has up a tease of Sundays 60 mins. Scott Pelley is going to Greenland with: Bob Correll

    One more tid bit: Laurie David posted this morning on the maple syrup run in Ohio this year, it didn’t happen. They’re #3 in production, the farmers there are on 100 + year-old farms, it’s never happened in their records. Their trees have already budded.

  50. 50
    raypierre says:

    With regard to minority opinions in science, the example of Galileo tends to come up often. However, what is generally ignored is that Galileo did not face repression from a community of fellow scientists. It was from an orthodoxy of an entirely different type that he met resistance.

    In fact, throughout history it has been remarkable how the scientific community has welcomed cataclysmic change with open arms, when it proved to bring a better explanation of the natural world. Centuries of Newtonian time and space, then Einstein comes along and says neither is absolute. No problem! Centuries of a deterministic and continuous world, then Planck, Pauli Dirac and Heisenberg come along and say it must be otherwise. No problem! It is ironic that, in this instance, Einstein was a voice in the wilderness among scientists, arguing for some kind of preservation of the old deterministic orthodoxy.