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A Saturated Gassy Argument

Filed under: — group @ 26 June 2007 - (Português)

A guest post by Spencer Weart, in collaboration with Raymond T. Pierrehumbert

The simple physics explanations for the greenhouse effect that you find on the internet are often quite wrong. These well-meaning errors can promote confusion about whether humanity is truly causing global warming by adding carbon dioxide to the atmosphere. Some people have been arguing that simple physics shows there is already so much CO2 in the air that its effect on infrared radiation is "saturated"— meaning that adding more gas can make scarcely any difference in how much radiation gets through the atmosphere, since all the radiation is already blocked. And besides, isn’t water vapor already blocking all the infrared rays that CO2 ever would?

The arguments do sound good, so good that in fact they helped to suppress research on the greenhouse effect for half a century. In 1900, shortly after Svante Arrhenius published his pathbreaking argument that our use of fossil fuels will eventually warm the planet, another scientist, Knut Ångström, asked an assistant, Herr J. Koch, to do a simple experiment. He sent infrared radiation through a tube filled with carbon dioxide, containing somewhat less gas in total then would be found in a column of air reaching to the top of the atmosphere. That’s not much, since the concentration in air is only a few hundred parts per million. Herr Koch did his experiments in a 30cm long tube, though 250cm would have been closer to the right length to use to represent the amount of CO2 in the atmosphere. Herr Koch reported that when he cut the amount of gas in the tube by one-third, the amount of radiation that got through scarcely changed. The American meteorological community was alerted to Ångström’s result in a commentary appearing in the June, 1901 issue of Monthly Weather Review, which used the result to caution "geologists" against adhering to Arrhenius’ wild ideas.

Still more persuasive to scientists of the day was the fact that water vapor, which is far more abundant in the air than carbon dioxide, also intercepts infrared radiation. In the infrared spectrum, the main bands where each gas blocked radiation overlapped one another. How could adding CO2 affect radiation in bands of the spectrum that H2O (not to mention CO2 itself) already made opaque? As these ideas spread, even scientists who had been enthusiastic about Arrhenius’s work decided it was in error. Work on the question stagnated. If there was ever an “establishment” view about the greenhouse effect, it was confidence that the CO2 emitted by humans could not affect anything so grand as the Earth’s climate.

Nobody was interested in thinking about the matter deeply enough to notice the flaw in the argument. The scientists were looking at warming from ground level, so to speak, asking about the radiation that reaches and leaves the surface of the Earth. Like Ångström, they tended to treat the atmosphere overhead as a unit, as if it were a single sheet of glass. (Thus the “greenhouse” analogy.) But this is not how global warming actually works.

What happens to infrared radiation emitted by the Earth’s surface? As it moves up layer by layer through the atmosphere, some is stopped in each layer. To be specific: a molecule of carbon dioxide, water vapor or some other greenhouse gas absorbs a bit of energy from the radiation. The molecule may radiate the energy back out again in a random direction. Or it may transfer the energy into velocity in collisions with other air molecules, so that the layer of air where it sits gets warmer. The layer of air radiates some of the energy it has absorbed back toward the ground, and some upwards to higher layers. As you go higher, the atmosphere gets thinner and colder. Eventually the energy reaches a layer so thin that radiation can escape into space.

What happens if we add more carbon dioxide? In the layers so high and thin that much of the heat radiation from lower down slips through, adding more greenhouse gas molecules means the layer will absorb more of the rays. So the place from which most of the heat energy finally leaves the Earth will shift to higher layers. Those are colder layers, so they do not radiate heat as well. The planet as a whole is now taking in more energy than it radiates (which is in fact our current situation). As the higher levels radiate some of the excess downwards, all the lower levels down to the surface warm up. The imbalance must continue until the high levels get hot enough to radiate as much energy back out as the planet is receiving.

Any saturation at lower levels would not change this, since it is the layers from which radiation does escape that determine the planet’s heat balance. The basic logic was neatly explained by John Tyndall back in 1862: "As a dam built across a river causes a local deepening of the stream, so our atmosphere, thrown as a barrier across the terrestrial [infrared] rays, produces a local heightening of the temperature at the Earth’s surface."

Even a simple explanation can be hard to grasp in all its implications, and scientists only worked those out piecewise. First they had to understand that it was worth the trouble to think about carbon dioxide at all. Didn’t the fact that water vapor thoroughly blocks infrared radiation mean that any changes in CO2 are meaningless? Again, the scientists of the day got caught in the trap of thinking of the atmosphere as a single slab. Although they knew that the higher you went, the drier the air got, they only considered the total water vapor in the column.

The breakthroughs that finally set the field back on the right track came from research during the 1940s. Military officers lavishly funded research on the high layers of the air where their bombers operated, layers traversed by the infrared radiation they might use to detect enemies. Theoretical analysis of absorption leaped forward, with results confirmed by laboratory studies using techniques orders of magnitude better than Ångström could deploy. The resulting developments stimulated new and clearer thinking about atmospheric radiation.

Among other things, the new studies showed that in the frigid and rarified upper atmosphere where the crucial infrared absorption takes place, the nature of the absorption is different from what scientists had assumed from the old sea-level measurements. Take a single molecule of CO2 or H2O. It will absorb light only in a set of specific wavelengths, which show up as thin dark lines in a spectrum. In a gas at sea-level temperature and pressure, the countless molecules colliding with one another at different velocities each absorb at slightly different wavelengths, so the lines are broadened and overlap to a considerable extent. Even at sea level pressure, the absorption is concentrated into discrete spikes, but the gaps between the spikes are fairly narrow and the "valleys" between the spikes are not terribly deep. (see Part II) None of this was known a century ago. With the primitive infrared instruments available in the early 20th century, scientists saw the absorption smeared out into wide bands. And they had no theory to suggest anything different.

Measurements done for the US Air Force drew scientists’ attention to the details of the absorption, and especially at high altitudes. At low pressure the spikes become much more sharply defined, like a picket fence. There are gaps between the H2O lines where radiation can get through unless blocked by CO2 lines. Moreover, researchers had become acutely aware of how very dry the air gets at upper altitudes — indeed the stratosphere has scarcely any water vapor at all. By contrast, CO2 is well mixed all through the atmosphere, so as you look higher it becomes relatively more significant. The main points could have been understood already in the 1930s if scientists had looked at the greenhouse effect closely (in fact one physicist, E.O. Hulbert, did make a pretty good calculation, but the matter was of so little interest that nobody noticed.)

As we have seen, in the higher layers where radiation starts to slip through easily, adding some greenhouse gas must warm the Earth regardless of how the absorption works. The changes in the H2O and CO2 absorption lines with pressure and temperature only shift the layers where the main action takes place. You do need to take it all into account to make an exact calculation of the warming. In the 1950s, after good infrared data and digital computers became available, the physicist Gilbert Plass took time off from what seemed like more important research to work through lengthy calculations of the radiation balance, layer by layer in the atmosphere and point by point in the spectrum. He announced that adding CO2 really could cause a degree or so of global warming. Plass’s calculations were too primitive to account for many important effects. (Heat energy moves up not only by radiation but by convection, some radiation is blocked not by gas but by clouds, etc.) But for the few scientists who paid attention, it was now clear that the question was worth studying. Decades more would pass before scientists began to give the public a clear explanation of what was really going on in these calculations, drawing attention to the high, cold layers of the atmosphere. Even today, many popularizers try to explain the greenhouse effect as if the atmosphere were a single sheet of glass.

In sum, the way radiation is absorbed only matters if you want to calculate the exact degree of warming — adding carbon dioxide will make the greenhouse effect stronger regardless of saturation in the lower atmosphere. But in fact, the Earth’s atmosphere is not even close to being in a state of saturation. With the primitive techniques of his day, Ångström got a bad result, as explained in the Part II . Actually, it’s not clear that he would have appreciated the significance of his result even if he had gotten the correct answer for the way absorption varies with CO2 amount. From his writing, it’s a pretty good guess that he’d think a change of absorption of a percent or so upon doubling CO2 would be insignificant. In reality, that mere percent increase, when combined properly with the "thinning and cooling" argument, adds 4 Watts per square meter to the planets radiation balance for doubled CO2. That’s only about a percent of the solar energy absorbed by the Earth, but it’s a highly important percent to us! After all, a mere one percent change in the 280 Kelvin surface temperature of the Earth is 2.8 Kelvin (which is also 2.8 Celsius). And that’s without even taking into account the radiative forcing from all those amplifying feedbacks, like those due to water vapor and ice-albedo.

In any event, modern measurements show that there is not nearly enough CO2 in the atmosphere to block most of the infrared radiation in the bands of the spectrum where the gas absorbs. That’s even the case for water vapor in places where the air is very dry. (When night falls in a desert, the temperature can quickly drop from warm to freezing. Radiation from the surface escapes directly into space unless there are clouds to block it.)

So, if a skeptical friend hits you with the "saturation argument" against global warming, here’s all you need to say: (a) You’d still get an increase in greenhouse warming even if the atmosphere were saturated, because it’s the absorption in the thin upper atmosphere (which is unsaturated) that counts (b) It’s not even true that the atmosphere is actually saturated with respect to absorption by CO2, (c) Water vapor doesn’t overwhelm the effects of CO2 because there’s little water vapor in the high, cold regions from which infrared escapes, and at the low pressures there water vapor absorption is like a leaky sieve, which would let a lot more radiation through were it not for CO2, and (d) These issues were satisfactorily addressed by physicists 50 years ago, and the necessary physics is included in all climate models.

Then you can heave a sigh, and wonder how much different the world would be today if these arguments were understood in the 1920’s, as they could well have been if anybody had thought it important enough to think through.

For Further Reading

References and a more detailed history can be found here and here.

Some aspects of the "thinning and cooling" argument, and the importance of the radiating level are found in the post A Busy Week for Water Vapor, which also contains a discussion of water vapor radiative effects on the top-of-atmosphere vs. surface radiation budget. A general discussion of the relative roles of water vapor and CO2 is given in Gavin’s post on ths subject.

You can get a good feel for the way CO2 and water vapor affect the spectrum of radiation escaping the Earth by playing around with Dave Archer’s online radiation model here. It would help, of course, to read through the explanation of radiating levels in Archer’s book, Understanding the Forecast. A discussion of radiating levels for real and idealized cases, at a more advance level, can be found in the draft of Pierrehumbert’s ClimateBook; see Chapters 3 and 4.

The Monthly Weather Review article commenting on Ångström’s work is here, and Ångström’s original article is here.

281 Responses to “A Saturated Gassy Argument”

  1. 101

    [[In particular sunshine amounts and temperature show a matching upward trend from 1987 (fig 3 and fig 15)and both have reached record unprecedented levels at the end of the series in 2003/4. And my subjective observations are that the Matching Trend continues upwards for 2005/6.
    The exact correlation between sunshine amounts and temperature, region by region, is so perfect that I have had to read it several times to make sure I wasn’t making a mistake.

    I think you may be conflating sunshine received at the ground with solar output, which isn’t necessarily a one to one relationship. We’ve been measuring solar output from satellites since the 1960s, and continuously since 1979, and it just hasn’t increased enough to explain the current global warming.

  2. 102

    re: #96

    thank you PHE for posting such a reasonable comment. I have still to understand why people cannot tolerate nuances about GW, and if somebody dare suggest he/she is yet to be convinced, there come the cries of “denialist” and “contrarian”.

    re: #98

    John: I think it’s still too difficult to understand climate variations at regional and country level. For example I would be surprised to hear that clouds in the UK are only made out of local moisture. If there are fewer clouds, somehow the Atlantic weather fronts have changed, in intensity, duration or direction. I don’t think the Met office document mentions that? As a matter of fact, the NAO changed in 1989. Perhaps that’s just a coincidence.


    The difficulty with climate science as it stands now is that there’s only so much you can squeeze out of models, and especially global models. And so despite all the “consensus”, the discipline looks dead in the water.

    If the G8 countries will tackle CO2 the way they have tackled drug trafficking and world poverty, there is no danger of any success whatsoever…

    We need climate science to make local models making local predictions in the timescales of months, to compare to actual observations of the now instead of vague terrors of the 2050’s. Otherwise the whole GW business will remain a shot in the dark: a reasoned shot, but still pretty much in-the-dark.

    On the other hand if we finally could see some BIG change such as hurricane seasons in the south Atlantic, sustained rain in the Sahara or the Atacama desert, or anything else of truly historical magnitude, there would be a much stronger convincing argument. Time will tell.

  3. 103
    ray ladbury says:

    If you seek to avoid the “denialist” label, there are some important things you can do to not look like a denialist (maybe we need Jeff Foxworthy here, “If you can simultaneously argue that the small amount of CO2 in the atmosphere makes it impossible as the cause AND that CO2 is saturated… you may be a denialist….”)
    First and most important, NEVER think that calling something a THEORY trivializes it. Gravity is a theory, but she is also a harsh mistress. Relativity is a theory, but there are >100000 Japanese who would attest to its truth had they survived the attack of the Enola Gay and so on. Dismissing something as a “theory” will damage your credibility in scientific circles faster than saying “Waddup, Ni—-…” at a hip-hop concert.
    Second, if you are going to make a claim like “…the view that CO2 emissions are the ONLY explanation is unconvincing,” it would be helpful for you to list some proposed candidate explanations. That way it appears as if you have actually done your homework and looked into the subject and not just said “There must be something…”
    Third, similar considerations apply to your claims that the warming we are experiencing is neither rapid nor dangerous.
    Finally, the climate change issue must be a good thing, right? I mean look how many people have discovered a new-found interest in the plight of poor African and Indian peasants. Now PHE, you may be sincere in your interest in the poor, but your contention that we must address EITHER climate change OR these other issues is false. We will not resolve climate issues unless we provide a path for developing nations to address these other issues without increasing greenhouse gases. And, climate change is likely to exacerbate most of these issues, so they cannot really be addressed separately from climate. So, rejoice PHE, you can have your humanitarian causes AND accept the scientific evidence, too.
    A true skeptic has reasons for his skepticism that could be resolved with the right evidence. What evidence do you require?

  4. 104
    ray ladbury says:

    First, John, reduced clouds do not necessarily mean less water vapor. Clouds form when the humidity rises above 100%–either due to increasing water vapor or decreasing temperature. Second, of course more sunshine means higher temperatures: Sunlight dominates the energy budget of Earth. To see the effect of greenhouse it helps to go where the influence of the Sun is diminished–the poles, night time, Winter. All these are warming even faster that other places/times. Don’t confuse local sunny weather with global trends. Overall, solar output isn’t changing enough to account for the observed changes.

  5. 105
    Hank Roberts says:

    Is this current info? It’s a very small amount per decade.

    “… Sun’s radiation has increased by .05 percent per decade since the late 1970s.
    “The increase would only be significant to Earth’s climate if it has been going on for a century or more, said study leader Richard Willson, a Columbia University researcher also affiliated with NASA’s Goddard Institute for Space Studies…”

    NOTE the numbers on the X-axis, rather than proclaiming this proves the sun’s responsible for anything comparable to current rate of change, fellow readers.

  6. 106

    In comment 78 Rod B. asks,

    doesn’t the H2 need to be manufactured on board as needed from hydrocarbons, and isn’t that process currently too slow, energy intensive, and cumbersome for that? If pure H2 is stored (in liquid form??) on the vehicle it seems the fire/explosive hazard would be prohibitive, but, more significantly, wouldn’t the “gas tank”, to handle the high pressure, need 2-4 tons of thick high-grade steel? Wouldn’t all of this make H2 a non-starter? Or am I way behind the times and science?

    In reverse order … No; H2 has been a non-starter for about 35 years now. (Put the mouse cursor on the “Cars” button, then select the “1807-1999” menu item.)

    If hydrogen is stored on board as liquid, then the only pressure involved is its vapour pressure, which is just 1 atm at 20.28 K. A typical tank for liquid has a relief valve that lets gaseous hydrogen out at 4 bar. It goes to a fuel cell that promptly oxidizes it, preventing an explosive buildup. The time it takes for the pressure to rise from 1 atm to 4 atm is several days, much longer than a motorist is likely to wait, so usually there would be no venting. Rather, quick withdrawal of the vapour would drop the temperature below 20.28 K, and vapour pressure would no longer help the fuel come out; so there’s actually an electric heater to prevent that.

    Because the pressure is not high, such tanks, while they are heavy, aren’t any two tonnes. One such tank has an empty mass of 145 kg, full 154.5 kg. Much heavier than an equivalent full gasoline tank.

    Hydrocarbon on board, reformed to hydrogen? No; that would be ridiculously inefficient compared to just burning the hydrocarbon. Not that it hasn’t been tried, though, and that such a stupid thing would be tried strongly suggests recent hydrogen-car efforts were a deliberate waste of researchers’ time. (Fuel cells in FCEVs are not efficient compared to internal combustion motors burning the same fuel. The efficiency advantage, being negative or, ideally, zero, does not make up for energy lost in chemical processing of hydrocarbons, on-board or elsewhere.)

  7. 107
    john says:

    Re 101, 102 and 104,

    Thanks for replying, the increase in sunshine amounts in UK is staggering some 20-40% in Winter, 5-10% in summer, etc. over the last 40 years. The maps at end of report really are an eyeopener.

    This tendency to clear skies is observable even at the subjective man in the street level, which is where I started, after the sunniest and warmest April on record, there was hardly a cloud in the sky all month. For a resident of UK this is unprecedented we are used to cloudy overcast skies.

    It isn’t being talked about by the Climate Scientists/ Meteorologists in UK, even though it is an unprecedented fact.

    More direct sunshine reaching the surface must mean higher observed surface temperatures because that is what we are measuring. I know its boring and not very exciting but that is what is happening in UK. I could also envisage that all this extra direct sunshine might impart extra energy into the surface climate, particularly the oceans, and “liven” things up a bit, so you might get some unprecedented extremes.

  8. 108
    Lurker says:

    #103 – That’s a tired old misnomer. Gravity is not a theory, it’s an observable phenomenon. The string theorists are still arguing over the theory of gravity, and there’s no “consensus”. Just because there’s no consensus on the theory of gravity doesn’t mean that things don’t fall down. Go over to Motls if you want to learn something about current state-of-the-art gravity theories, but don’t expect any consensus, because there isn’t one. Even if there were a consensus, that doesn’t guarantee that it’s right. How many centuries did we have a consensus that the sun orbited the earth?

    There’s an analogy here wrt global warming, with the added problem that the observable phenomenon itself is a lot more ambiguous than watching the sun come up in the morning.

  9. 109
    ray ladbury says:

    Lurker, note that I didn’t mention any specific theory of gravity. I said gravity–as in the force between two objects with mass. And yes, it is a theory. Evolution is a theory. Conservation of energy is a theory (and yes, physicists considered giving it up only 80 years ago when confronted with beta decay–instead they postulated the neutrino).
    There is nothing ambiguous about climate change if you live in the arctic of on the pacific islands. There’s nothing ambiguous about it if you look at data from Icesat. There’s also nothing ambiguous about the basic physics. Climate change is a reality, and if you think we aren’t causing it, maybe you can suggest where all that energy is coming from.

  10. 110
    Lurker says:

    Burn pure – The liquid H2 scheme that you propose would be practical for commercial vehicles, but for private transportation, when you use it for 1-2 hours out of the day or less, the losses due to venting will make it forever impractical. Your name seems to imply an alternative energy medium scheme, and whether it’s B-O2 or some alternative, I think where we will be in 50 years is with something other than H2. There are, as your name suggests, alternatives.

    I also expect to see fuel cells in commercial vehicles first, and we may never see them in personal vehicles, for similar reasons. Not without a breakthrough in cold fuel cell chemistry, anyway. But microturbine hybrids will be slightly less efficient, and we almost know how to build them now. But I do think that over the 30-50 year horizon, the only hydrocarbon fuels may end up being biofuels for niche applications.

  11. 111
    James says:

    Re #106: [If hydrogen is stored on board as liquid, then the only pressure involved is its vapour pressure…]

    Am I missing something here? Or forgetting those long-ago chemistry lessons in which I seem to remember learning that the critical point of H2 is somewhere around -400F, therefore it can’t be a stable liquid near ambient temps at any pressure? That the only way to keep for any length of time at all is in a good dewar flask? So you leave your liquid H2-fueled car e.g.parked at the airport while you go on a long trip, and come back to find that all your fuel has evaporated :-(

    Then there’s the other side of the equation: the amount of energy needed to cool H2 to a liquid, none of which (AFAIK) is recovered when it vaporizes.

  12. 112

    As mentioned, the Magna-Steyr tank I had in mind weighs 145 kg empty. Much of that mass is because it is, in fact, a good Dewar flask — a tough one that, I seem to recall, has passed crash tests.

    As mentioned, “any length of time at all” is in this case a few days before venting begins, and I suppose a few weeks before it’s all vented. It is catalytically oxidized as it comes out. One could indeed find one’s car inert in the airport carpark on return from a long trip. There would presumably be a big parking bill also.

    Another poster seemed not to understand that normal use would, by reducing the pressure in the vapour space in the top of the tank, knock the temperature back down, so an ordinary driver would use up all the hydrogen he bought and never let the relief valve take any.

    [Response: Look, guys what the heck does the hydrogen economy have to do with radiative transfer? Unless you want to relate this specifically to radiative effects of H2, please stop. That goes for the off-topic and rather confused thread going on about UK cloudiness as well. If this discussion doesn’t move back on-topic soon, I’m going to have to close down the thread. Probably about time to do that anyway. –raypierre]

  13. 113
    David B. Benson says:

    As long as we are so far off-topic to consider alternate transportation energies, I’ll suggest using bio-oils in a gas turbine. The bio-oils are obtained by pyrolysis of essentially any form of bio-mass, so the production of the bio-mass need not compete with growing food and animal feed.

    I’ve previously attempted to provide, again, a link to a useful site, which is working again now, but somehow the filters catch it. Instead, I’ll suggest web trawling on the search term “Shimbir Demon biochar”…

  14. 114
    Alex Nichols says:

    I don’t agree that the points made in #98 are supported by the document

    If you read it carefully, the increase in annual sunshine hours is mainly in the autumn/winter months and is attributed to the Clean Air Acts.

    Domestic coal fires used to be one of the main causes of fogs in urban areas, which happen during still anti-cyclonic conditions in cold air.
    Since the 70’s smokeless fuel and gas have replaced coal fires, so the amount of winter fogs has decreased and days that might have remained foggy end up with bright sunshine.

    There’s no real evidence this is anything more than a localised phenomenon, or that it’s correlated with rising temperatures.

  15. 115
    Robert Jacobs says:

    Its my impression that nobody wants to take an objective look at all data and make assumptions on what the trends appear to show. Any mathematical model developed in this world was based on Calculus and acceptable errors: STATISTICS in the end. Newton’s law of gravity was based on a best fir line with acceptable error. But several have reported that Newton did through away outliers, which can be scientifically taboo. Nevertheless, it’s a mathematical model, just some work better than others.

  16. 116
    Timothy Chase says:

    Charles Lyell (#115) wrote:

    Why don’t we deal with the root problem nobody wants to address: OVER POPULATION.

    The population is going to level out around 11 billion, last I heard. Population growth has been decelerating since the 1980s. The big question at this point is how do we get enough energy to support that many people without wrecking the climate.

    The way things are going right now, the glaciers of the Himalayas will be gone by 2100 causing massive water shortages directly affecting over a billion people and drastically reducing agricultural output in Asia, agriculture will have virtually been wiped out in the United States around the same time, and water levels may very well rise several meters in the interim – with about half of humanity living within fifty miles of coastline. The damage to the world economy will in all likelihood be unprecedented – and well before the end of the century – unless we start doing something about climate change soon. And it has to be soon, because we are beginning to set in motion processes which will take on a life of their own.

  17. 117
    pete best says:

    Re #113 no significant dent in Oil consumption will be made until second generation biofuels are successfully conquered, then maybe we can make a dent in oils CO2 emissions. Th USA has just this week allocated $275 million to this very task but although it seems easy it reckon it will take a decade or two before this technology is viable.

  18. 118
    pete best says:

    Re #109, I do not know what you mean by the term theory but in scientific terms in means a law or model of reality. There is confusion here as laid out by lay people as theory means talking nonsense but in scientific parlance it has a totally different meaning.

    Evolution is a model of how organisms evolve and through genetics we now appear to have the mechanisms of how they do it to.
    Gravity, Einsteins special and general relativities are models of how gravity works.
    Conservation laws, again a model of how matter and energy interact.

    Simple really.

  19. 119

    [[Gravity is not a theory, it’s an observable phenomenon. The string theorists are still arguing over the theory of gravity, and there’s no “consensus”. Just because there’s no consensus on the theory of gravity doesn’t mean that things don’t fall down. Go over to Motls if you want to learn something about current state-of-the-art gravity theories, but don’t expect any consensus, because there isn’t one.]]

    Yes there is. Gravity is a result of the warping of space as described by general relativity, the best-tested theory of all time. A theory is as good as it gets in science; thus gravitational theory, quantum theory, theory of relativity. Saying a scientific consensus is “only a theory” is a sure sign of pseudoscientific belief. I think it originated with the creationists.

  20. 120
    john says:


    So what you are saying is that it is not getting warmer because of the extra sunshine, for whatever reason we have extra unprecedented amounts of sunshine, but you want me to believe this is not affecting the measured surface temperature. Which is where I started I don’t understand this view.

    I have no theory on why this is happening, it just is.

    We maybe need a climate scientist or theoretical physicist to say why we have extra sunshine, I think I can work out that extra sunshine amounts will substantially explain why the recorded average surface temperature in UK has gone up, I only have to walk out the front door.

  21. 121
    Hank Roberts says:

    John, try an analogy,

    —- imagine you’re standing in an empty swimming pool and someone’s running a hose pointed into the swimming pool.
    Meanwhile, outside, someone’s slowly closing the drain valve.

    Sometimes your head gets soaked —- if you happen to be standing under the hose. You may believe more water is coming in.
    It seems obvious, from your position.

    Other times your head gets dry — if you happen not to be standing under the hose. You may believe less water is coming in.
    It seems obvious, from where you’re standing, looking up.

    But all the time, the water’s slowly rising around your ankles.

    Same with sunshine —- the amount coming in from the sun hasn’t changed greatly. 2 or 3 out of 1300, reading the charts.

    What’s changed is how much is going _out_, overall, total, from the pool. That’s why the water’s rising.

  22. 122
    Sam says:

    Tim #100
    “Moreover, the honesty of the process itself is highlighted by their openness and transparency in making available the criticisms which guided the final editing of the report.”

    It is my understanding, and please correct me if I am wrong, that past IPCC policy was to provide the review comments only to authors/commentators, and that the comments were not to be distributed or published. What happened here is that government agencies that participated in the report and had the comments were hit with freedom of information requests to release the comments. Faced with certain release through that mechanism, IPCC relented and published the comments. Open and transparent has not been part of the process up to this point. I will leave judgment of the character of the comments and responses to those that have read the full review comment and response document.

  23. 123
    COLORADO BOB says:

    An FYI :
    Found: The Clearest Ocean Waters On Earth

    Raimbault made another surprising discovery: the patch of the ocean that is poorest in life appears to be extremely rich in dissolved organic carbon.

    He is currently teasing apart data in an attempt to explain the apparent contradiction, but believes it may be that the limited availability of nutrients such as nitrogen and phosphorus means the bacteria that would normally degrade the dissolved organic matter are not able to complete the task.

    Story Here

  24. 124
    Pod B says:

    re 106 (BBIPO2…..) Thanks for the info.

    How do you get liquid H2 without high pressure and/or really low temperatures?

    Haven’t seen your posts for awhile…

  25. 125
    Chuck Booth says:

    Rre 125 clear ocean
    I don’t know what this story has to do with the topic of this thread, but it is really not very suprising for the reason mentioned – open ocean food chains are not usually limited by dissolved organic carbon.

  26. 126
    john says:

    re 123

    Hank I give up, you seem to be able to see things I can’t.

    The Temperature Graphs Start At 1914 the sunshine at 1929, the maps normalise it all from 1961 to 2004.

    The warmest year occurred in 2003 which was also the sunniest

  27. 127
    Pod B says:

    re 115: [… Humans are the only species that continue to reproduce while resources disappear….]

    That’s simply fallacious prima facie. How on earth does the hound cognitively decide he’s running low on Alpo and had better not impregnate that cute little in heat hound today??

  28. 128
    Alex Nichols says:

    #re 123 and previous comments

    I think he’s trying to reintroduce the cosmic-ray argument by the back-door, but there’s absolutely no evidence that this is anything other than a local U.K. phenomenon

    Even the data he’s quoted doesn’t support the argument.
    For instance, Northern Scotland is reported as having a slight fall in average annual temperature, but an increase in recorded sunshine.

    (By the way, the paper is unpublished and has dropped off the server)

    As an example of why this idea just won’t work, here’s some data from Cambridge NIAB for June and July.

    yyyy tmax tmin Sun hours
    1959 21.6 10.1 252.4
    1962 19.6 8.0 289.6 *
    1969 19.4 8.6 268.7
    1976 24.5 11.4 277.8 ~
    2006 22.5 11.2 220.2

    1959 23.9 12.2 270.7 *
    1962 19.4 11.0 126.4 +
    1995 25.8 13.4 234.9
    2006 28.3 14.1 253.5 ~

    * heighest sunshine total
    + lowest sunshine total
    ~ warmest


    June ’62 was sunnier, but much cooler than June ’76
    July ’62 also had less than half the sunshine of the preceding June, but was warmer, due to higher night time temps)
    July ’06 is by far the warmest month, but has less hours of sun than July ’59.

  29. 129
    James says:

    Re #112: [One could indeed find one’s car inert in the airport carpark on return from a long trip. There would presumably be a big parking bill also.]

    Whereas I’ve left my Insight hybrid parked (though not at the airport :-)) for months at a time while away on trips, and it starts right up with no fuel lost, and no obvious battery decay.

    If you look at everything that goes into a hydrogen economy, you find that it’s a real non-starter. I think the only reason the idea ever became popular was as high-tech “pie in the sky” that let certain powers-that-be give the impression of doing something while in fact continuing with business as usual.

  30. 130
    Timothy Chase says:

    Why the IPCC Released the Internal Comments

    Sam (#124) wrote:

    Tim #100
    “Moreover, the honesty of the process itself is highlighted by their openness and transparency in making available the criticisms which guided the final editing of the report.”

    It is my understanding, and please correct me if I am wrong, that past IPCC policy was to provide the review comments only to authors/commentators, and that the comments were not to be distributed or published. What happened here is that government agencies that participated in the report and had the comments were hit with freedom of information requests to release the comments. Faced with certain release through that mechanism, IPCC relented and published the comments. Open and transparent has not been part of the process up to this point. I will leave judgment of the character of the comments and responses to those that have read the full review comment and response document.

    A fair hypothesis.

    However you yourself have just given good reason to discount it.

    Surely contrarians have insisted that they had the right to such information in the past – as they could have mined it for mud to sling at the report itself, much like creationists will dig-up material from the 1930s regarding earlier controversies in evolutionary biology which have long been settled and only tell what parts suit them. But the IPCC did not release the information on those earlier occasions now, did it? You said so yourself. And surely Exxon would have requested such information if it thought that it had any chance of obtaining it for the purpose of selective quotes and the slinging of mud – but they realized it would have made them look foolish.

    Therefore one can only conclude that the IPCC is under no obligation to release the internal comments, and that the Freedom of Information which exists in some countries is non-binding on the IPCC.

    However, rather than relying upon such logic, I went ahead and performed a search on both Google News and the Google News Archives using the two phrases “freedom of information” and “international panel on climate change.” Nothing on the first, two identical hits on the second, niether of which were relevant.


    No doubt the contrarians will find more “dirt,” but at this point all that the contrarian Heartland Institute has found that they thought they could use as “dirt” is RealClimate contributor Eric Steig’s criticism – which they conveniently edited in a highly selective manner.

    And as I stated above with respect to Eric Steig’s comments:

    It is obvious that Eric agrees that climate change is a serious issue and a serious threat. At the same time, he wanted the report to be bulletproof so that it could be taken seriously by fellow scientists as an undistorted product of the best science available at the time. I am not sure that he was entirely happy with it, but that was the final draft and they presumably incorporated many of his suggestions.

    He illustrates the honesty and integrity of the participating scientists that went into the process.

    Some of the authors had gotten overly enthusiastic in their claims and he called them on it, specifically with respect to the suddenness of catastrophic climate change. It may very well be the case that things can occur that quickly – but we do not as of yet have the evidence required to claim the degree of justification they wished to claim. So as a matter of honesty and as a matter of upholding the integrity of the science he was blunt. Yet at the same time he pointed out what he thought was right in the sections which he commented on.

    The IPCC released the comments in large part due to its recognition of the urgency of our present situation and their recognition that the science is strong enough to justify acting in recognition of this urgency, not due to legal issues. They realize that the best way of communicating this urgency is by being transparent and releasing the comments – despite the fact that they would be providing contrarians with potential material to sling at the report.

    In any case, I wish to thank for giving me the opportunity to clarify the nature of their decision and underscoring the need for such clarification.

  31. 131
    Edward H. Moran says:

    First of All,

    I sent in plenty of comments using my name and email account way before this started and I still don’t see anything posted. You blocked my access to the site. Right before you Shut down my internet access and attacked my computer. But you didn’t know the other names, amazing how they got through.

    Now you don’t post this and my point taken.

    Would you guys like to see my Firewall log or let’s go even deeper and I’ll get my internet provider involved. I wonder how the scientists represented on this website would feel about this.

    You still don’t talk about the science, WHY?

    You present yourselves as a science discussion forum, but for the past 2 days all you were concerned about is defacing and smearing two scientists that want to make a difference in this world. Well good luck with that; hope all that works out for you!.

    [Response: Frankly, I have no idea what you are talking about. You have posted under at least three different names from the same Colorado IP address and posted almost identical content from other nearby locations, and on one occasion from alaska (good one!). I searched the logs and can’t find any comments under your name prior to this thread. You are welcome to continue to post, but this kind of whinge is not particularly constructive. Your paper has been criticised because it correlates two time series that are dominated by strong linear trends without any mechanism or any appreciation for the actual state of the science. If you want to defend that, go right ahead. If you want to stoke your persecution complex, please go elsewhere. – gavin]

  32. 132
    Edward H. Moran says:

    Good Point Gavin,

    But CO2 and temperature also show linear trends, Isn’t that what we’re concerned about?

  33. 133
    Sam says:

    Tim – You are welcome. I was glad to give you the opportunity to clarify and underscore the need for the clarification.

  34. 134
    raypierre says:

    Please, everybody, stick to the topic or I’ll close down the thread. Why do people feel the right to start the silly season on every article when we get past comment #100 or so? If we’re out of things to say about the topic, it’s time to just move on anyway.

  35. 135
    ray ladbury says:

    Edward H. Moran, I am sorry if you were offended by the appellation “nutjob”. As a physicist, many times in the past, I have been handed a dog-eared manuscript (and yes many were written in longhand) whose author claimed that it “disproved” relativity or some equally well established area of physics. Almost invariably, I have found that the writing of the piece was motivated by the same thing that caused its failure: the author did not understand the science behind it. I have tended to refer to such monomaniacs–many of whom were sane in every other way–as nutjobs. I do not offer any excuses and I do apologize.
    I have provided fairly detailed criticism of your paper elsewhere. I reiterate here:
    1)The reference section is extremely weak. None of the climate references (other than the databases) dates after 1979! The references for geomagnetism are even worse–a single reference to a freshman physics text–and that reference is irrelevant for the geodynamo.
    2)The interpretation of the statistics is completely incorrect. To state that a R^2 of 0.792 “explains” 79.2% of an effect is just flat wrong. All it says is that two variables are weakly correlated, and that correlation in no way implies causation or if there is causation which way it acts.
    3)You propose no physical mechanism for your purported cause–and indeed it is difficult to imagine such a mechainism.
    4)To achieve even the weak level of correlation you demonstrate, you introduce a completely ad hoc, adjustable parameter–unmotivated by any scientific argument.

    These weaknesses would have been sufficient to cause me to recommend that the paper be rejected.
    Now, add to that fact that you short-circuit the normal peer review process and have the paper published in an on-line journal, where your co-author is on the editorial board. The journal in question is NOT a climate journal, or even, as near as I can tell, a science journal. There is no evidence I have found that any of the editorial board possesses any expertise in climate science or any related field. Yet the journal claims to be a peer-reviewed journal, and the paper is published as a regular paper and not an editorial. Then we start seeing the article being promoted on various climate-related websites under various aliases–many of which it appears turn out to be…you. You come on here alleging character assassination and censorship–not behavior that usually generates a good first impression.

    Again, I apologize for the nutjob reference (actually, what I did was lump you in with the nutjobs). However, I hope you can see that your behavior in this matter might be characterized as less than exemplary for a scientist.

  36. 136
    ray ladbury says:

    Raypierre–I agree, but I saw this after I posted. Please feel free to move my comment to the curve manipulation post where it would be appropriate, or just forward it to Ed Moran. And needless to say, I won’t jump down your throat if you don’t publish this or the other. Ray

  37. 137
    Timothy Chase says:

    Edward H. Moran (#134) wrote:

    Good Point Gavin,

    But CO2 and temperature also show linear trends, Isn’t that what we’re concerned about?

    How odd.

    This doesn’t look at all linear to me:

    Highly correlated – as one would expect from two variables between which there exists strong positive feedback, but not at all linear.

    Wait a second – that was plotting temperature and CO2 against time for the past 400,000 years. If we plot temperature against CO2, then we get the following:

    You are quite right – that does appear to be quite linear – and it doesn’t require any unidentified ad hoc polynomial function (#242) to make it work, either.

  38. 138
    Timothy Chase says:

    raypierre (#134) wrote:

    Please, everybody, stick to the topic or I’ll close down the thread. Why do people feel the right to start the silly season on every article when we get past comment #100 or so? If we’re out of things to say about the topic, it’s time to just move on anyway.

    I am hoping that we can get back to the topic. Besides what is currently being discussed with Mr. Moran would seem more appropriate to other recent threads, and while it is less demanding, it also seems less rewarding.

  39. 139
    Alex Nichols says:

    #128 Sorry if this is regarded as an off topic sub-plot but:

    erratum: “Northern Scotland is reported as having a slight fall in average annual temperature, but an increase in recorded sunshine.”

    Sorry, the document was unavailable when I wrote that. Of course it’s the other way round N.Scotland annual sunshine total -5.6% since 1929. Annual temp increase since 1914 is 0.37C.

    All UK regions show warming trend!

  40. 140
    Timothy Chase says:

    Some questions for the authors…

    1. I understand that the absorption of energy is roughly linear for peaks far from saturation, roughly proportional to the square root as one begins to approach saturation, and logarithmic when the peak itself is nearly saturated. However, I would assume that this can be all described by a single function for which the linear, root and logarithmic behavior are only good approximations over certain ranges. Does this function differ from gas to gas? Peak to peak?

    2. When the bands are narrow at low temperatures and low pressures, essentially what one has are well-defined spikes. When bands are broad, there is a range over which a given band is able to absorb. With those who are less acquainted with the greenhouse effect (including myself) I have noticed a certain difficulty in understanding how a narrow peak is able to be so effective in amplifying infrared. For example, near the ground, water vapor has a fairly broad main band. In the stratosphere, carbon dioxide has a fairly narrow main band, yet the effectiveness of the main band of carbon dioxide is within the same order of magnitude as that of water vapor.

    How can this be the case?

    What I noticed with the later paper is that the broad bands actually still consist of spikes, but a great many narrow spikes. Is this part of the key? Is it that each of the smaller spikes are less effective than the centerline of the broad band when it is not saturated, but there are more of them?

    3. The diagrams (which are logarithmic along the absorption factor axis) show the smaller spikes as always being there. Are they, or are they themselves a function of the saturation/temperature/pressure?

    4. Eli Rabett mentioned that the broadening of the bands is due primarily to how the wavefunctions change in shape as the result of interaction between a molecule and its environment – which largely consists of other molecules. Given the fact that those molecules which are disturbing the wavefunction for the molecule which is absorbing and re-emitting radiation are themselves interacting with other molecules and should therefore have their wavefunctions disturbed by those molecules, I would assume that there is always a finer level of detail where one would pick up additional spikes – except possibly once one hits the lifetime spreading due to the uncertainty principle as it applies to energy and time. Is this the case?

    Anyway, I will appreciate whatever response you might give me.

  41. 141
    john says:

    Dear Real Climate. “unprecendeted sunshine amounts in UK climate observations”

    This is my last blog on your site. I sent you observations, not a Theory or a Prediction, from the UK met office showing a upward and record trend in sunshine amounts for all regions of UK. The data and statistical analysis is of the highest quality and presented in a clear and concise fashion.

    I subjectively linked these to the rising temperature Trend in UK, which was probably an error, as although a common sense subjective view says they are linked I did not go on to prove it.

    However, this site is entitled “Real Climate” and I sent you real climate observations of an unprecedented nature, but you all seem so tied up in defending your CO2 position, that I really believe you are at risk of missing something important. It seems unlikely that such a definite Trend is a “localised effect”.

    Subjectively, April in UK was the most unusual April I have ever known in my 55years, with day after day of cloudless skies it got to be quite alarming being under the unforgiving sun day after day. When I checked through the Met office observational record I found this was part of a definite and sharp upward Trend.

    I thought I would share this with you, but will now leave you all to carry on.

  42. 142
    Steve Bloom says:

    Re #134: Ray, may I suggest again that the way to keep this sort of thing from becoming a problem is to have something like a weekly open thread a la John Quiggin (actually he does two, including a weekend one, but I’m not sure why he thinks both are needed). That way anything off-topic in a thread like this could be deleted out of hand and the value of the entire thread preserved for future readers. As it stands, I think the value goes away the moment the off-topic stuff starts in, and that’s unfortunate as there are often useful points made in the midst of the dross.

  43. 143
    Steve Bloom says:

    Re #142: Just to add, looking upthread about half of the coments in #s 9 through 20 were partly or wholly off-topic, which IMHO was already coming close to making the thread useless for someone trying to read through and extract useful information later. If there were a weekly open thread and a clear direction at the top of each thread for OT comments to be posted there instead, most of the problem would solve itself (perhaps to an extent that it would constitute a net decrease in work for the moderators).

  44. 144
    Rod B says:

    re 130, Timothy, it sounds like you believe records from the IPCC should not be released because maybe some mean ole nasty skeptics might find something to debate with. Well, so much for open science!

    I do agree that what I would call working discussions/papers ought to be kept private. Otherwise the participants become inhibited and less effective. But semi-formal discourses or opinions ought to certainly be put out in public for scrutinity.

  45. 145
    James says:

    Re #132: [But CO2 and temperature also show linear trends, Isn’t that what we’re concerned about?]

    It’s not just picking two variables, noticing that they are somewhat correlated, and postulating that a cause-effect relation exists. (And I’m still not sure how you decided which was cause, and which effect.) Instead, there’s an observation – CO2 is increasing due to human activity – and a prediction, backed up by a lot of theoretical & experimental work, that temperature will change as a consequence. So if we do see temperature increases that accord with predictions, that’s supporting data. See the difference?

  46. 146
    Eli Rabett says:

    Motl has run a simple scam. He compares the observed increase in global temperature to that predicted by Lindzen EXCLUDING feedbacks. He says we are 40% towards doubling CO2, but uses Lindzen’s sensitivity to doubling CO2 without feedbacks of 0.6 K with an increase in global temperature of 0.4 K, This puts the world 2/3 of the way and reaching doubled CO2 would only increase the global temperature by 0.2 K. OTOH, if we use the best estimate climate sensitivity of 3.0K and the observed 0.7 K increase in the last century we would be ~25% of the way. If we include the ~0.5 K of warming built into the system due to radiative imbalance we would be 40% of the way.

  47. 147
    Edward H. Moran says:

    However, all you need is one major volcano to go off and all bets are off for some time on temperature increase.

  48. 148
    Edward H. Moran says:

    With environmental data, what constitutes a significant weak, medium, or strong coefficient of determination?

  49. 149
    Edward H. Moran says:

    Additionally, what method was used to determine:

    “CO2 is increasing due to human activity – and a prediction, backed up by a lot of theoretical & experimental work, that temperature will change as a consequence. So if we do see temperature increases that accord with predictions, that’s supporting data. See the difference?”

  50. 150
    Edward H. Moran says:

    [MODERATOR Gavin],

    I think I know where Rob B. came from, I hope your not assuming again that it came from me.