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Geo-engineering in vogue…

Filed under: — gavin @ 28 June 2006

There was an interesting article in the NY Times this week on possible geo-engineering solutions to the global warming problem. The story revolves around a paper that Paul Crutzen (Nobel Prize winner for chemistry related to the CFC/ozone depletion link) has written about deliberately adding sulphate aerosols in the stratosphere to increase the albedo and cool the planet – analogous to the natural effects of volcanoes. The paper is being published in Climatic Change, but unusually, with a suite of commentary articles by other scientists. This is because geo-engineering solutions do not have a good pedigree and, regardless of their merit or true potential, are often seized upon by people who for various reasons do not want to reduce greenhouse gas emissions. However, these ideas keep popping up naturally since significant emission cuts continue to be seen as difficult to achieve, and so should be considered fairly. After all, if there was a cheaper way to deal with the CO2 problem, or even a way to buy time, shouldn’t we take it?

First a little history [Update: See Spencer Weart’s essay on the history of climate modification ideas]. Geo-engineering ideas first reached the public in the 60s when there was still a lot of enthusiasm for technical fixes of the world’s problems. One example was suggested by the Soviets who wanted to melt the Arctic (either using soot or nuclear devices) in order to warm up their frozen North. More recently, there was a proposal to dam the Straits of Gibraltar in order to prevent more saline Mediterranean Sea water (because of the Aswan Dam) from affecting the North Atlantic conveyor circulation (no, it didn’t make sense to us either). With such a pedigree, geo-engineering is generally seen as fringe entertainment at best, although some of the new ideas concerning atmospheric carbon dioxide sequestration are being looked into seriously.

Edward Teller is the scientist most associated publicly with the idea of creating a stratospheric shield to prevent excessive global warming, though he built on an idea from Freeman Dyson (who has subsequently become a bit of global warming contrarian)*. However, as Teller’s collaborator Stanislaw Ulam once said after discussing some new ideas with him: “Edward is full of enthusiasm about these possibilities; this is perhaps an indication they will not work”. And given Teller’s estrangement from the scientific community in his later years, it was not likely that the concept would be taken very seriously, and indeed it hasn’t been.

*Which in turn built on a idea from Budyko…(see comment below).

But now Paul Crutzen has stepped into the fray. He has a much more solid reputation amongst climate scientists than Teller, and thus his ideas will be taken more seriously. I haven’t seen the new paper yet (it’s out in August) but there are a number of questions that need to be addressed before any geo-engineering proposal combatting global warming should be thought of as anything more than an interesting idea. First, the idea has to actually work, second, the side effects need to be minimal, and third, it has to be able to keep up with an increasing forcing from ever higher greenhouse gas levels, and fourth, it has to be cheaper than the simply reducing emissions at source. These are formidable hurdles.

Would it work? In most of the cases under discussion the target is the global mean temperature, and so something that balances the global radiative forcing of greenhouse gas increases is likely to ‘work’. However, having no global mean forcing is not the same as having no climate change. A world with higher GHGs and more stratospheric aerosols is not the same as a world with neither.

Thus there will be side effects. For the stratospheric sulphate idea, these fall into two classes – changes to the physical climate as a function of the changes in heating profiles in solar and longwave radiation, and chemical and ecological effects from the addition of so much sulphur to the system. Physically, one could expect a slight decrease in surface evaporation (a ‘dimming’ effect) and related changes to precipitation, a warming of the tropopause and lower stratosphere (and changes in static stability), increased Eurasian ‘winter warming’ effects (related to shifts in the wind patterns as are seen in the aftermath of volcanoes). Chemically, there will be an increase in ozone depletion (due to increases in heterogeneous surface chemistry in the stratosphere), increases in acid rain, possibly an increase in high cirrus cloud cover due to indirect effects of the sulphates on cloud lifetime. Light characteristics (the ratio of diffuse to direct sunlight) will change, and the biosphere may react to that. Dealing with the legal liability for these predictable consequences would promise to be a lively area of class action litigation…. On the positive side, sunsets will probably be more colorful.

Could it keep up? GHGs (particularly CO2) are accumulating in the atmosphere and so even with constant present-day emissions, the problem will continue to get worse. Any sulphates put in the stratosphere will only last a couple of years or so and need to be constantly updated to maintain concentrations. Therefore the need for the stratospheric sulphates will continue to increase much faster than any growth of CO2 emissions. This ever-increasing demand, coupled with the impossibility of stopping once this path is embarked upon is possibly the biggest concern.

How expensive would it be? I will leave the detailed costing to others, but stemming from the last point, the cost will continue to rise indefinitely into the future unless this proposal is coupled with an concomitant effort to reduce CO2 emissions (and concentrations) such that the need for the sulphates will diminish in time.

Crutzen’s paper may well address these issues comprehensively (and I look forward to seeing it) but, in my opinion, the proposals are unlikely to gain much traction. Maybe an analogy is useful to see why. Think of the climate as a small boat on a rather choppy ocean. Under normal circumstances the boat will rock to and fro, and there is a finite risk that the boat could be overturned by a rogue wave. But now one of the passengers has decided to stand up and is deliberately rocking the boat ever more violently. Someone suggests that this is likely to increase the chances of the boat capsizing. Another passenger then proposes that with his knowledge of chaotic dynamics he can counterbalance the first passenger and indeed, counter the natural rocking caused by the waves. But to do so he needs a huge array of sensors and enormous computational resources to be ready to react efficiently but still wouldn’t be able to guarantee absolute stability, and indeed, since the system is untested it might make things worse.

So is the answer to a known and increasing human influence on climate an ever more elaborate system to control the climate? Or should the person rocking the boat just sit down?

270 Responses to “Geo-engineering in vogue…”

  1. 1
    Johnno says:

    The first time a tomato crop gets a frost in an area it never happened before the ‘geo-engineers’ will get sued.

  2. 2
    Almuth Ernsting says:

    And even if it was possible to cool the planet, this type of geo-engineering won’t stop our seas from becoming acidic and much of marine life being wiped out. It would still leave us with a much diminished planet.

  3. 3
    David B. Benson says:

    This reminded me of a song. It begins

    “I know an old lady who swallowed a fly…”

  4. 4
    Patrick Kennedy says:

    I read the article. It was interesting. However, if we are going to consider radical solutions (which we should), we should also consider standing down the greenhouse gas economy, except for essential services, for some periods of time each year. We could survive not driving our cars or running our factories and businesses for a few weeks each year if we plan it carefully. Like other forms of conservation planned annual stand downs of our economy could be a significant contributor to a mix of approaches and technologies that reduce greenhouse gas emissions.

  5. 5
    Catherine Jansen says:

    Most credible scientists seem to suggest that reducing emissions is the only practical and prudent approach to mitigating climate change. However, geo-engineering may be worth exploring as a possible reaction to severe runaway climate impacts.

  6. 6
    Steve Latham says:

    I don’t know if most skeptics are “good faith” skeptics, but if one assumes so, one can be more understanding of the techno-fix appeal. For one, if one already adopts the skeptic position that climate isn’t changing much anyway, then the techno-fix wouldn’t be as difficult or costly in their estimation (e.g., less sulfur would need to be pumped into the atmosphere). Of course, to argue that way, one would have to eat the argument that we’re insignificant and can’t influence climate (e.g., one might have to admit that aerosols were highly responsible for cooling from 1940-1970).

    I have a different reason for liking the techno-fix, and Gavin alluded to it: “if there was a cheaper way to deal with the CO2 problem, or even a way to buy time, shouldn’t we take it?” Say we need 20 years to get our sh*t together and reduce emissions, but we only have 10 before the tipping point (where ice melting becomes irreversible, for example), maybe it’s worthwhile to pump out massive amounts of harmful junk, paint roofs white, whatever is possible, to avoid that tipping point. I’m thinking (hoping in vain?) that the techno-fix approach is also a bit of a practical response to geographic non-conformity in reducing emissions. That is, if some countries simply can’t/won’t alter their emissions trajectories on the needed timeline, perhaps by forcing them to emit sulfur is a way of putting the costs on them. Alternatively, for countries too small to absorb the costs (in terms of acid rain and other pollution in their own skies) strategic siting of sulfur emissions by other countries can make them bear the costs of their refusal to reduce CO2 emissions.

    I dunno much about legal and other ways that countries interact, but it seems like there must be a way to pressure them ( The link is for a story about German decisions weakening the attempts of other EU countries to reduce emissions. It would be nice if pressure points could be found that act in the opposite direction.

  7. 7
    Hank Roberts says:

    Seattle PI story among the first hits:

    “You don’t have to believe in climate change to believe that this is happening,” said Joanie Kleypas, an oceanographer with the University Corporation for Atmospheric Research, a non-profit organization based in Boulder, Colo. “It’s pretty much simple thermodynamics.”

    “Acidification is more frightening than a lot of the climate change issues … “

  8. 8
    Gar Lipow says:

    As someone said – if we are going to look at this we should at least look at the real cost of a combination of efficiency measures and renewable. I suspect the lower cost from efficiency combined with the higher cost of renewables would yield a net cost of zero to get off of fossil fuels.

  9. 9
    Wacki says:

    I have to admit, the fact that this is being discussed makes me sick. The stratospheric sulphate will cause acid rain. If this acid rain is in any significant quantity it will send insurance bills soaring. Just look at the EPA’s acid rain projections:

    “A 2005 study estimates that in 2010, the Acid Rain Program’s annual benefits will be approximately $122 billion (2000$),”

    “When fully implemented by the year 2010, the public health benefits of the Acid Rain Program are estimated to be valued at $50 billion annually, due to decreased mortality, hospital admissions, and emergency room visits.”

    Those are some big numbers.

    There are a lot of physicists that are calling for an energy Manhattan project yet their voices fall on death ears. And it’s not just republicans that don’t seem to hear them. I mean you never see articles in the newspapers pushing for an energy Manhattan project. Those that do hear the physicists seem so say “what can we do?” and yet there seems to be so many possibilities to me. I even made a website listing them:

    An energy Manhattan project would require $10 billion a year. $10 billion a year is nothing in relation to the $3 trillion energy industry or even the acid rain induced medical bills. I’m currently writing an article about this on my website to convince all the right wingers/neocons I know. Liberals are easy to convince when it comes to the environment. Republicans require a different approach. Ironically, after doing some research for this article, global warming went from primary concern to a mere “secondary” concern simply because there are so many other threats we have to deal with. Threats that seem to go ignored.

  10. 10
    Joel Shore says:

    Re #3: Great (or not so great!) minds think a like. Just last night in another forum commenting on this article, I called it the “swallow a spider to catch the fly” approach. Not that I think these things aren’t worth thinking about…especially as backup plasn if we get desperate. But, I do find it ironic when these approaches are often put forward by the same folks who say that the science is fraught with uncertainties. To me, this is the sort of approach that requires far more certainty in our understanding of the full climate system than to simply try to reduce our perturbation on the system (which I guess is basically the point of Gavin’s rocking-the-boat analogy).

  11. 11

    Nuclear energy needs and deserves climate scientists’ endorsement. Efficiency and renewables are fossil fuel tax beneficiaries’ code words. They mean whatever doesn’t work; whatever keeps the oil and gas tax money coming in.

    Public money has those strings attached. Taking it and not endorsing nuclear energy is not at all a morally neutral act; it’s going along to get along.

    I won’t be upset if this comment does not appear.

    — G. R. L. Cowan, former hydrogen fan

  12. 12
    Chuck Booth says:

    Re #1: If a geo-technical fix has widespread unanticipated negative consequences (ala John Miller’s famous quip about fertilizing the subtropical Pacific with iron, “Give me a freighter full of iron filings and I’ll give you another ice age” – or words to that effect – we’ll have a real Tragedy of the Commons.

  13. 13
    edward lanwermeyer says:

    There are these wild swings, in posting themes. Is this a system just a trifle chaotic, perhaps ??

    Just recently, we have a plea and post to look more carefully at paleoclimate, as perhaps as one of several possibilities–and reasonably measured ideas– for better understanding of the underlying present geophysics at work in global change melting , and now this really far out global engineering idea, from a Nobel prize winner, no less.

    Ok, maybe chaos is bit of a natural phemonenon. But…??

    from an interested, and duly amazed, non climate scientist type.

  14. 14
    Chuck Booth says:

    Oops – I meant geo-engineering fix.
    As I recall,it was Willard Bascom, an engineer-turned-oceanographer who coined the slogan, ” The solution to pollution is dilution” back in the early ’70s to justify using the ocean as a dumping ground. While that sometimes works on a small scale, it clearly has backfired on a global scale. That is one of the problems with engineers – they are trained to solve practical problems but often fail to see the big picture, or fail to appreciate the esthetic components of possible solutions.

  15. 15
    Eugene says:

    I remember hearing that the US temperature was raised noticeably after 9-11 when planes were grounded, giving credence to the theory that air plane jets act as a noticeable shadow reflecting UV away from earth. I am afraid of “our” ability to control gases in such a large proportion to make a difference, and by the time we do, if might be too late to belatedly find out another unintended consequence. I am thinking of so many 19th century colonial screwups such as goarse in NZ, brought in for farm fencing, which took over the country rapidly… So maybe there is another way to do something but more nimbly in case it backfires.

    Perhaps a quick fix would be to launch into space some large object to act as a partial light shield (modular construction could be enlarged in space, honey comb form allowing some light). It need not cover the earth, just the poles. — The closer we get it to the sun, the smaller the object need be. Thrusters would make sure it would attain an orbit around the sun mimicking the Earth’s. This object would be positioned to be a partial shadow of the North pole in its summer, and the south pole in its summer. Effects would be able to be tracked immediately and if they do other unintended consequences, it could be removed immediately.

    On a related note, I also remember seeing that one of the methods they are looking into for meteor deflection, is to attract it to a space craft and nudge it using thrusters. Perhaps we can use a meteor as a light shield — force it into a similar orbit shielding parts of the north pole, or south pole.

    Does any of this make sense?

    [Response: No, it doesn’t. A meteor, or even several thousand meteors, would not have enough cross section area to block the amount of sunlight you’d need to block. There were proposals to build a shield either with mylar mirrors or with an orbiting ring of copper needles. The mirror is hard to keep in place and maintain, and the problem with the needles is that if you’ve overdone it and don’t like the climate you like, it’s hard to gather up the junk and undo the damage. –raypierre]

  16. 16
    Eli Rabett says:

    The Romans had a phrase for such things that they borrowed from the Greeks: Deus ex machina or ἀπὸ μηχανῆς θεός ápo mēchanēs theós, (OK, I copied the last one) for those of you who slept through classics.

  17. 17
    Guy Schiavone says:

    What if we did inject sulphate aerosols into the stratosphere, and then a large volcanic eruption occurred? It would be too late to change our minds. Would we then experience a “year without a summer”, as has happened after other large eruptions? Any safe geo-engineering solution must provide the capability for almost immediate adjustments, so we can compensate for natural fluctuations that are out of our control. Civilization may be much less robust to sudden severe climate changes then it was in the 18th century.

  18. 18
    Jaime Frontero says:

    When I was a kid in 1950’s Los Angeles, watching folks drop like flies from smog inversions, a proposed solution to air pollution was to blow up a mountain at the periphery of the Valley – using an atomic device! – so the smog would be blown into the desert through the gap in the mountains.

    Hmmm. So the solution to Global Warming is… the world should generate its power using high-sulphur coal?

    Frankly, I like the A-bomb idea better.


  19. 19
    Richard LaRosa says:

    There is a lot of cold water at the bottom of the ocean. It can be pumped to the surface and discharged through perforated fabric hoses so that it will mix with the surface water and lower the surface temperature. The enormous pump power required to pump the enormous quantity of cold water can be supplied by using the OTEC (ocean thermal energy conversion) technology developed in the 70’s and later.

  20. 20
    Hank Roberts says:

    Eugene, look at the geometry and sizes to get an idea how big a sunshade is needed and what shape the shadows are since the Sun is so much bigger than Earth

    “… the sun is about 400 times farther from the earth than the moon, and its diameter is approximately 109 times greater than that of earth.”

  21. 21
    Stormy says:

    I can’t wait for the movie where the hero and heroine struggle to set off matching volcanoes on either side of the world with split second timing. Global warming has reach critical…a suicidal CEO is intent on thwarting their plans because his son did not get into Harvard.

  22. 22
    Mark J. Fiore says:

    There is only one number that fortells the fate for humans, and that number is how many parts per million co2 is in the atmosphere. Levels on Earth will soon force the North Atlantic current to shut down. Humans will lose the northern and southern icecaps, as well as the mountain glaciers.Superstorms will bankrupt the insurance industry as well as the reinsurance industry. Carbon taxes will bring co2 to above $170 per ton,US, and you will need a permit to exercise outside, never mind driving a vehicle. Oh, by the way, the sulpher dimming idea is just plain dumb.Also, by the way, many earthlike planets have suffered the same fate. Earth is in no way special, having thus shown so far the total paucity of vision and intelligence from the “dominant” species.Good luck, humans.PS,I thought that most people who read this website had already passed global warming 101.P.PS. if it seems that I am both arrogant and highly educated it is because I am.

  23. 23

    This is wat i believe………..A general prediction of global warming does not just suggest that there will be an average higher world temperature. It also proposes that there will be greater variations in temperature with more extremes of local heat and cold, higher or lower precipitation, more storms and more droughts.

  24. 24
    Jessica says:

    I do not think that cooling the planet artifically is even close to a good idea. How are we to know the consequences of our cooling actions? Who’s to say that the cloud bursting in China is not encouraging wild fires in the states? It is much better to fix the problem rather try to engineer a band aid solution.

  25. 25
    jamjam says:

    The only real benefit to this proposal I can see is the prospect it offers of separating researchers who really don’t believe Global Warming is taking place (if there are any) from those who are merely taking the money and running their mouths according to the wishes of their paymasters.

    The former will oppose this desperately, because they’ll see it as giving chemotherapy to a patient misdiagnosed with cancer; the latter will rush to embrace it because that’s what their bosses will want. Their bosses will want it, of course, because they think it may buy them a few more years to do with the world as they will, even though they will realize the scheme is ridiculous.

  26. 26
    Andrew Dodds says:

    Re: 13

    Certainly the idea of a solar shield at the Lagrange point between the Earth and Sun has been mooted. It’s certainly better than sulphate aerosols, with the minor problem that an accident or metorite strike could destroy the whole thing in a single go..

    As others have pointed out, it would still not prevent ocean acidification, and the overall heat distribution may well change.


    An interesting idea, but I’d like to see the underlying calculations. What proportion of the oceans would have to be overturned each year (the natural rate being circa 0.1%).

    If we are warming water by 15K, that means that every cubic kilometer of water overturned will absorb 4.2*15*10^15 J. (~6×10^16 J)

    If we take total forcing as 4W/m2 x 5.1×10^14 = 2×10^15W

    (for a year, this would be 3×10^7 x 2×10^15 = 6×10^22 J)

    This implies 10^6 cubic kilometers. The volume of the cold, deep oceans is around 10^9 cubic kilometers. So we could in theory do this for 1000 years before the entire ocean was warmed to 15C. This would, I believe, raise sea levels by up to 10 meters. More to the point, within a relatively short time of starting this pumping scheme, natural ocean circulation would be disrupted.

    Re: 9

    Yes, replacing coal burning with nuclear would appear to be one of the easiest, pain-free ways to reduce CO2 emissions. But that’s a bit off-topic.

  27. 27
    Jean-Luc P says:

    PLease don’t forget side effects :

    as it was previously said here, it won’t prevent acidification of oceans but such molecules like sulphates are known to provoke acidic rains, and even atmospheric pollution for some sensitive organisms like lichens.

    And the other question, like it was previously discussed for stabilisation of the ozone layer, is what quantities of enginered gazes would have been released to neutralise warming effects of carbone dioxide and methane ? Is the range compatible with the scale developped countries could be ready to give to such a strategy.

    Really sceptic I am considering all these considerations in balance…

  28. 28
    Jean-Luc P says:

    When will Humanity be able to live in harmony with its environnement ?

    Trying to correct a problem by addind another layer of engineering is noting less that adding complexity and unpredictability to the system, running to a global disaster when no solution will remain to balance a higly modified complex oceano-atmosperic system…

  29. 29
    I'm OK You're NOT OK says:

    There’s no reason to reduce CO2 in the first place.

    CO2……. is good.

    You guys not worked that out yet?

    Seems you are a bit slow.

  30. 30
    Tony Noerpel says:

    How about these radical geo-engineering concepts: conservation and birth control?

  31. 31
    Dan Hughes says:

    The opening sentence of this thread states,” … the global warming problem.” Can anyone here direct me to documents in which are described the processes and procedures that were used to arrive at an exact and accurate specification of ” … the global warming problem.” Exact and accurate specifications in the sense of the known/proven consequences if “the problem” is neglected and the rank of “the problem” in a list of pressing issues facing humankind world wide.

    This blog in my opinion continues to accelerate its movement away from its originally stated purpose. As support for this statement I point to the increasing number of threads based on issues that appear in the daily newspapers and “news releases”.

    [Response: The main reason for this blog was to provide context for the public discussion of climate change. And that’s what we do. For a detailed specification of the problem, read the IPCC TAR and references therein. – gavin]

  32. 32
    dotti says:

    I wonder why it is that these types of solutions seem more ‘possible’ than emissions reduction strategies? Is it the seductiveness of the grand project? Or perhaps, some other attribute of centralized solutions? Just what are the barriers that reductions face that these proposals avoid? Cheaper? For who, by what calculation?

    Even if we didn’t face climate change, even if it were for reasons of health or aesthetics, wouldn’t pollution reduction be worthwhile anyway? Unless we can redefine what is ‘possible’, I find little reason for optimism.

  33. 33

    The idea of spreading particles in the stratosphere to retard global warming did not originate with Dyson but, so far as I know, with the Russian climatologist Mikhail I. Budyko ca. 1974. This was in keeping with Soviet dreams of “conquering” nature, but even Soviet scientists were dubious about such schemes. See (comments welcome).

    [Response: Thanks! Serves me right for reading Teller’s papers a little too uncritically. – gavin]

  34. 34
    JMG says:

    Speaking of geoengineering, can anyone comment on this book: “Plows, Plagues, and Petroleum: How humans took control of climate” by William Ruddiman? I’m looking for a copy but the publisher’s blurb on the Powells Bookstore website gave me pause because it seemed to suggest that human-caused climate forcings were all that stood between us and another ice age (which sounds too much like the Western Fuels Assn. for my taste).

  35. 35
    JMG says:

    Re: #11 (arguing that we must go nuclear to reduce greenhouse gases):
    Here is a letter I just sent to an author proposing the same:
    Dear Mr. Sweet,

    I just finished your book, Kicking the Carbon Habit: Global Warming and the Case for Renewable and Nuclear Energy, and I wanted to write to commend you for it.

    However, I must add (as an undergraduate nuclear engineer who later taught nuclear plant operations in the Navy and who took a a master’s in engineering management while working at the Hanford nuclear reservation, before becoming an attorney) that the discussion of nuclear power needs significant expansion to address a key issue, one that you clearly recognize as critical when discussing other forms of energy. We can call this the EROEI (energy return on energy invested).

    There is a growing realization that nuclear plants require so much embedded energy that they are net energy sinks for a non-trivial period, and that nearly all of this energy causes the release of CO2.

    That is, the enormous amounts of energy that go into making the plants (particularly in concrete but also in various steels) and the fuel rods (mining, milling, enriching, fabricating) is not at all insubstantial.

    Thus, it is incorrect to ignore this or to say that nuclear plants are essentially zero carbon plants. Sure, they don’t emit carbon (or anything else) while burning fuel, but that’s like saying that hydrogen is a zero carbon fuel by ignoring all the carbon released in making hydrogen.

    Naval nuclear plants, for example, use such high-enrichment fuel (to avoid refueling requirements) that they _never_ produce net energy. And while civilian light water reactors do not require that kind of enrichment, new nuclear plants still start out with a huge carbon and energy debt to work off, which means it is years before they produce more energy than they consumed along the way (I have heard estimates exceeding 15 years when all the construction and fuel cycle energy use is accounted for).

    Given that a plant ordered tomorrow would probably not carry base load for ten years, and would probably not reach an energy profit for at least another decade, it’s very unclear whether the commitment of $100 billion for nuclear plants is a very wise investment for the United States. On a CO2 reduction per dollar basis, I suggest that the same money would be far more effectively spent on national and local rail projects (to elminate truck transport and to slash airline travel), combined heat and power plants (such as Tom Casten proposes, which you seemed to dismiss far too lightly), conservation, and small, distributed generation projects.

    Again, I want to commend you for the book, especially for the sections discussing the climate modelers, which was fascinating. And I do hope you will revise and expand the third section so that it offers lay readers a more rigorous look at the energy alternatives and the net energy return they offer.

  36. 36
    Vince says:

    Ahhh, the surgeon heals by cutting, the medical doctor by dispensing drugs, the chemist proposes more chemical reactions.

    Maybe I’m just a simple engineer, but I would agree with comment #8 whole heartedly (no offense #8). Many issues are much too complex to be looked at from one point of view. When it comes to energy use and global warming, I believe the bigger the system you look at–both thermodynamically and economically–the more efficiency and renewables become the best possible solution. When you include energy subsidies on the supply side, include health care costs due to pollution, DoD costs to maintain supplies, costs due to global warming, etc., energy efficiency is cheap and easy. We need much better designs of our systems–the technology is already there.

    A good intro to this way of thinking can be found in a Harvard Business Review paper by the folks at the Rocky Mountain Institute:

  37. 37
    Hank Roberts says:

    JMG, type “Ruddiman” into the Search box at top of home page; Dr. Ruddiman has participated here in discussion of his work.

  38. 38
    shargash says:

    Re: 15

    The study of temperatures after 9/11 showed that the difference between the daytime high and nighttime low temperature increased. Daily temperature variations are too great for the researchers to have determined if temperatures increased in an absolute sens, or not. If we were to block sunlight and leave the CO2 in the atmosphere, we would compress the day-night temperature variations, and the compression would increase over time. I have no idea of the long-term consequences of that. I don’t believe anyone else does either.

  39. 39
    Jim Torson says:

    The idea that nuclear power is the answer to global climate change keeps popping up. Here are a few different views:

    Nuclear Power: economics and climate-protection potential

    Insurmountable Risks: The Dangers of Using Nuclear Power to Combat Global Climate Change

    A soon-to-be-published book by Helen Caldicott:
    Nuclear Power is Not the Answer

    By the way, the numbering of comments seems to sometimes change. It would be useful if someone could find a “technical fix” for this problem.

  40. 40
    Michael Jankowski says:

    The [Update: See Spencer Weart’s essay on the history of climate modification ideas]. didn’t work for me. It just brought-up the same RealClimate article again.

    [Response: Fixed. sorry!- gavin]

    I seem to remember a number of suggested engineered solutions back in the early 90s or late 80s in “Newsweek” magazine (yes, quite a long time ago). I imagine they are mostly the same ones being discussed here.

    I would worry in general about the cost, efficacy, and potential side effects.

    Any potential particulates that could be introduced that would reflect sunlight but would not produce acid rain or other severe side effects?

    Re#6- “if one already adopts the skeptic position that climate isn’t changing much anyway, then the techno-fix wouldn’t be as difficult or costly in their estimation”
    I think a more appropriate skeptic position is that the climate isn’t changing much anyway due to anthropogenic GHG emissions.

    Most skeptics (and even some believers of significant AGW) oppose expensive measures like Kyoto, and they would likely similarly oppose these “technical fixes” as being too costly with too little benefit and too many potential side effects.

  41. 41
    Brian Gordon says:

    We have ‘geoengineered’ the planet into its current state. More of the same in a different direction will only make things much worse. We (humans in general, but industrialized humans in particular) lack the wisdom to realize this. If we do ‘buy some time’ with one of the methods mentioned, we will surely use it to pump more GHGs into the atmosphere and expand our populations and wealth, not find real solutions. Do you think the US government is suddenly going to acknowledge that climate change is real, dangerous, and human-caused, and then take drastic steps to reduce CO2 emissions?

    I would suggest that geoengineering projects may initially be proposed and started by well-meaning people…and it would rapidly go to heck from there. Who better to run global-scale geoengineering projects than big multinationals? Once these companies start running the projects, concern for poorer, militarily weaker nations will become secondary, as it is now. If Africans sue the US, is the US going to pay, or change behavior? In addition, once a major industry is underway, vested interests will automatically arise to sustain that industry, even if it is causing more harm than good. The American auto industry is a prime example.

    Nuclear power is also not a solution. In addition to the problems mentioned in JMG’s post #35, there is also the risk of contamination. The world is getting less stable, and climate change and increased oil prices (and reduced supply) are only going to make this worse. Do we really want to build nuclear plants in a world that is becoming less politically, economically, and socially stable? Why not spend the $100B on conservation, on car-less cities, and so on?

    There is a solution, but it is not popular, because it means significantly changing “the economy,” and this has been conflated with destroying the economy. Or, as one of your most senior leaders laughably said, “The American Way of Life is not negotiable.” (He must have been warning God or Mother Nature.) Living in harmony with our environment does NOT necessarily mean a decrease in our standard of living, and it could offer a better way of life. Ultimately, it will be the only solution.

  42. 42
    Brian Gordon says:

    BTW, the link to “Spencer Weart’s essay on the history of climate modification ideas” just brings me back to the RC home page. I tried it in Opera and Firefox.

    [Response: Fixed. sorry! – gavin]

  43. 43

    Five years ago, of 100 units of electricity generated using slightly enriched uranium, over 98 units were net of the enrichment process.

    The recent licensing of a gas-centrifuge plant in the USA is part of a continuing process in which that fraction moves into the high 990s per thousand. For heavy-water-cooled and some gas-cooled reactors it has, of course, always been 1.000.

    The hand-waving reference to “not at all insubstantial” energies invested in nuclear plant concrete is an appeal to innumeracy that I trust won’t get far here. Concrete requires high-temperature calcination of clinker, so that a tonne of it represents a 1.4-GJ energy investment, and this means a 1-gigawatt nuclear electric station that feeds 800 MW to a resistance-heated clinker kiln for a year would power the production of 18 million tonnes of concrete. So it can pay for its own concrete’s production in less than a month.

  44. 44
    Wacki says:

    A few quick questions.

    #1) For the solar shield to work, how big would it have to be? Roughly.

    #2) At what point do scientists project the “tipping point” point will occur? In other words, at which year/CO2 ppm will a runaway greenhouse effect comes into play?

  45. 45
    Josh says:

    Something that wasn’t taken into account in the article or in the responses is that the climate is not static – it readilly changes with or without our help. The next ice age will be just as destructive as the worst case global warming predictions, is it okay that billions of people die because it’s ‘natural’ or should we do something about it? Geo-engineering will be required at some point (we’re near the end of the current interglacial period compared to the length of the previous ones) – should we investigate it now and find comprehensive solutions to climate change no matter the cause, or devote all our resources to a one-off solution to the unique problem we currently face?

    The least expensive and most useful solution is probably to grab the low laying fruit in conservation and alternative energy, and make up for any shortcomings with geo-engineering. Then when mother nature throws us a curveball in the future, a field of hardened, experienced geo-engineers will be ready to save billions of lives.

  46. 46
    JMG says:

    re: #43– Thanks for suggesting that the energy cost of certain pieces of the nuclear process are low. I (and perhaps others here) would welcome pointers to any peer-reviewed reports you are aware of that assess the energy cost of the entire nuclear life-cycle (from mining through waste storage and monitoring) so that the overall EROEI for the entire nuclear energy life cycle can be known (the kind of thing being done for ethanol).

    I think we very much need that kind of information if we are to make good choices. Certainly we would have to be able to show that kind of data to be able to get enough people to support the kind of “Coal/Nuclear Covenant” proposed by R. T. Pierrehumbert that we need [6 Chi J Intl Law ___, Winter 2006].

  47. 47
    JMG says:

    P.S. Sorry–forgot to add that the CO2 driven off in concrete production is a concern all on its own, isn’t it?

  48. 48

    It’s worth noting that the IPCC WGIII 2001 report addresses geoengineering briefly in Section 4.7:

    On a separate thread here, and on , I recently argued as follows

    And there is geoengineering to deflect solar radiation. My impression
    is that it’s almost certainly a bad idea. If someone could get that
    to work, it could prevent the mean surface temperature of the earth
    from rising, but it could not balance out the local forcings.

    While I don’t find the following decisive, it is fair to point out that there is some evidence to the contrary. An anonymous correspondent on the globalchange list pointed out that the referenced section of the WGIII report addresses this point in an optimistic way.

    “One of the perennial concerns about possibilities for modifying the
    earth’s radiation balance has been that even if these methods could
    compensate for increased GHGs in the global and annual mean, they might
    have very different spatial and temporal effects and impact the
    regional and seasonal climates in a very different way than GHGs.
    Recent analyses using the CCM3 climate model (Govindasamy and Caldeira,
    2000) suggest, however, that a 1.7% decrease in solar luminosity would
    closely counterbalance a doubling of CO2 at the regional and seasonal
    scale (in addition to that at the global and annual scale) despite
    differences in radiative forcing patterns.”

    My intuition is that models with more degrees of freedom may not yield such pleasant results. Has this been further investigated?

    I’d also suggest that any geoengineering system which does not “fail safe”, i.e., quickly decay to natural conditions without explicit human maintenance, is far too dangerous to contemplate. We can’t risk iatrogenic disease in Gaia.


  49. 49
    Stephen Leiper says:

    Many of us have been saying for years that there is already in place some form of geoengineering, for whatever purpose, but the assertion is scoffed at.

    Take a look at a particularly blatant current example of atmospheric manipulation on the NRL Monterey Weather Satellite site:

    Here’s how to navigate the site:

    Click on West Coast & EPAC (top left box)

    Scroll down to Los Angeles-San Diego VIS thumbnail (right-hand side)

    Click on that, then go up to bar on top to Previous, click on that to access Index of archives.

    Scroll down to 20060624 sequence of June 24, 2006 (left column currently)

    Click on 20060624.1900 for most blatant image (click to enlarge)

    Look at 1600, 1630, 1700, 1730, 1800 to see the evolution of a completely unnatural pattern in the atmosphere.

    This is only one recent example of many weather satellite anomalies that cannot be explained as contrails left by airliners. Something is going on here that needs to be taken into account.

    [Response: The image in question shows a gravity wave that is close enough to the cloud layer to affect the relative humidity as it passes through (becasue of the vertical motions associated with the wave). Gravity waves are caused by winds intersecting with mountain ranges (lee waves etc.), moist convective activity, shear in the atmosphere etc. They resemble surface waves on the ocean, but exist in the atmosphere between layers of slightly different density. You only see them when they get accentuated by clouds in air that is close to 100% saturation. No mystery there…. but it is a good image. – gavin]

  50. 50
    Jim Roland says:

    I will bet one thing about the idea of spreading white films on rocky deserts: the carbon offsetting industry will soon be trying to buy up the most convenient sites as ‘low-hanging fruit’.

    I wonder if there is a particular need for local geo-engineering, in particular to protect peat bogs from carbon dioxide attack, see here, by introducing certain plants, or otherwise altering their ph or salinity. Or, if it turns out that warming is a threat to them, by deploying local passive wind- or solar- mist-making devices.

    Less seriously, what about combining geo-engineering with carbon sequestration and burial? That is, take the oxygen-depleted air left over, lighter than normal air, and trap it in huge white polythene balloons short of full inflation. These would float around for ages, surely, reflecting sunlight?

    Sulphates? What if someone drilled deep into the Yellowstone lake and breached the magma chamber? Would this be like loosening the valve on a bicycle tyre compared with piercing it, create a sulphate-dispensing geyser system, and save humanity from a future super-volcanic blast?