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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. 51
    Steve Sadlov says:

    RE: #25 – You are correct. And you can count me among those who would constitute an intense opposition group. For the record, if there is any move to do anything more than carbon taxes or other subtle things such as reforestation, I will personally oppose it with every means I have available. There is way too much uncertainty to justify doing anything specific to try and overtly “cool” the earth directly. Let’s put it this way, imagine the worst case warming scenarios being stated within the legitimate scientific community. Let’s say we observed that we were well into such a scenario. Realistically, what would happen would be increases in consumption taxes and massive efforts globally like what was done to contain the dust bowl – tree plantings and the like. Assuming that everything really is as stated by the most vocal proponents of AGW, then we’d do like we’ve done with ozone, eventually tweaking PP CO2 down and if the AGW view is true, slowly cooling the climate. However, assume, on the other hand, that there are feedbacks we do not completely understand. Let’s say we take the aggressive engineering centric route and put reflective material on ice, pumped up abyssal waters, and put reflectors into orbit. Not understanding the feedbacks, we might induce a return to extended glaciation mode. Let me share something, it would be very, very difficult to undo that. Billions would die. Insurance? Heck, there would be no insurance companies left. We’d be thrown back into prehistoric existance. There is no way I would go with the program on such an aggressive approach. My own science and engineering ethics are far too strong to allow it.

  2. 52
    Richard LaRosa says:

    Re: 26 by Andrew Dodds asking for calculations on pumping up cold water from the ocean bottom. Idea was originally proposed for hurricane suppression. To reduce the surface temperature of the Loop Current in the Gulf of Mexico by 3.5 deg C, water from 1000 m depth must be pumped up at the rate of 1.2 million cubic meters/s. This is 4% of the Florida Current transport. Modeling is required to determine whether this upwelled water increases the Florida Current transport. I would guess that it replaces some of the Yucatan Passage surface flow with Windward Passage deep water. The Sun will reheat the water as it flows downstream, but the atmosphere will be cooled along the path. The forced upwelling will increase the thermohaline overturning.

  3. 53
    cwmagee says:

    What if you look at geoengineering from a retail, as opposed to a wholesail model?

    Example. Trans-pacific airliners. 4 times a day, a jumbo takes off from Sydney (35 south), and flies basically along the tropopause for 14 hours before landing at La (or SF) (35 north).

    From an economic perspective, high sulfur fuel is cheaper than low sulfur fuel. The plane is already in (or near) the stratosphere, since that is the most fuel efficient elevation at which to fly.

    There are very few viable renewable energy alternatives to avgas-powered jet flight.

    There are few big interest groups who would oppose this particular measure.

    So why not kit out trans-equitorial planes with engines that can use high S fuel, and relax sulfur emission restrictions on this sort of travel?

    If you don’t pick the low hanging fruit first, where will you get the sugar rush needed to climb the tree?

  4. 54
    Ken Johnson says:

    Re airline emissions and contrails:

    Night flights worsen climate-change peril Jun 14, 2006
    Restrictions on night flights could ease the aviation industry’s fast-growing contribution to global warming …
    … during daytime, these clouds [contrails] have a cooling effect because they are white and thus reflect some of the Sun’s energy back into space.
    Meteorologists at the University of Reading, southern England, estimated the radiation caused by contrails …
    Night flights account for only 22 percent of Britain’s annual air traffic but contribute between 60 to 80 percent of the greenhouse effect from contrails, the scientists found.
    The study appears in Nature …
    … passenger travel is growing at the rate of around five per cent a year …
    In addition to rescheduling night flights for the daytime, planes could diminish their contribution to global warming by changing their altitude.
    A study published last year in the journal Transportation Research suggests that the regions of “ice-supersaturated” air where contrails form is only about 500 metres (1,650 feet) thick.

  5. 55
    Stephen Leiper says:

    Perhaps you are right, Gavin. Did you look at the entire
    sequence I suggested, showing its evolution?

    Here’s a very different example from 08 June. What is
    the explanation for this? Ship trails? Starting and
    stopping like that? More likely, advertent aerosols to
    keep the eastern Pacific cool, whether ship-generated or
    by aircraft.

  6. 56
    Stephen Leiper says:

    Oops, the lengthy URL for the image referred to in comment 54 would not paste in your form. Once again, it is on the Naval Research Laboratory site ( on the Southwest VIS thumbnail, in the “Previous” archive for 20060608.1630

    [Response: Ship tracks would be most likely. Again, these do not always appear – it is only when the ship exhaust (with all it’s aerosols) finds itself in very humid (but not already cloudy) air. -gavin]

  7. 57
    brendon says:

    If you want to get rid of the carbon rather than cool the Earth, build a bunch of machines that run off solar/nuclear/heat pump that draw in air and remove the carbon, leaving little black blocks everywhere.
    Could be done by bioengineered plants too.

    To cool the Earth, we could float white stuff that was breathable on the oceans. Have to make it sink ten metres during storms or something…

    There are a lot of people thinking about this, I think deliberate climate control will be the next big thing for us, even after we solve the GHG issue…

    [Response: Little black blocks of carbon are no good. They’ll just oxidize. Bacteria are too good at respirating carbon. You’d have to bury the blocks of carbon someplace — sort of like growing trees then burying them someplace where they can’t get oxidized. Nature can do that over a few hundred million years, but to do it on a short time scale is a lot harder. Here’s a calculation you ought to do: How much energy does it take to extract CO2 from the atmosphere and pump it into a geological formation (or make it into limestone, which is more costly)? Would you be better off using that renewable energy to replace some coal burning instead? –raypierre]

  8. 58
    Matt says:

    My turn.

    If we look at the glacial cycle as a Hamiltonian energy cycle, then we are stuck at the top of the cycle at high potential heat storage and the natural phenomena causing us to go into kinetic energy phase at mid glacial is somehow stuck. In all probability, we will continue to heat up until something gives. Something will give in a thousand years or so without GHG or in 50 years with GHG. Putting out less fossil carbon is probably not enough.

    In other words, we are stuck with way too much carbon, with or without man’s foul up. Sometome soon, we will have to learn how to scrub carbon from the atmosphere and store it, for at least a few hundred years, minimum. That should be enough time for us to get a longer term handle on stabilizing carbon.

    The best carbon management is to simulate nature but do it much better. Ten thousand years at these temperatures means nature wants dead, deoxygenated seas and waterways, and we should get with nature’s program and help her out. We are fighting against nature if we think this garden of eden was meant to last.

    [Response: There is absolutely no scientific support for your claim that “with or without man’s foul up” we are stuck with too much carbon. Statements like this are just noise, and they don’t help the discussion. –raypierre]

  9. 59
    beezel says:

    Just to play devils advocate — it seems to me there must be a nuclear solution (a la the Russians).

    It wouldn’t pass all your stringent requirements, but it seems it could come into play at some point (say a few centuries from now when methane hydrates start floating up to the ocean surface at a good clip). Are there good papers available concerning geo-engineering aspects of nuclear bombs? How would you apply them most effectively? Melt the East Antarctic ice sheet to increase the pressure on hydrates, introduce stratospheric aerosols, induce upwelling of nutrient rich water, something else?

    Perhaps discussing possible geotechnical solutions is a good way of demonstrating to the public the magnitude of the problem.

  10. 60
    jr says:

    Great article. There’s a lot of cutting edge ideas floating around

  11. 61
    pete best says:

    Adopting energy efficiency measure such as 1/5th energy consumption light bulbs and hybrid cars makes more sense to me than attempting geo engineering projects that will take years to setup and execute.

  12. 62
    FredT34 says:

    I believe it’s scientifically (and technically) impossible, but well…politically…

    It’s quite easy to understand that complicated problems (such as global warming) can’t have simple solutions; but this GeoEngeneering thing alas would be a “good” campaign theme – and would brown-nose people on “America saves the world” theme…

    Reagan’s “Star Wars” or Strategic Defense Initiative couldn’t work, but this “splendid idea” [in which Edward Teller was already implicated (hmmm…)] cost at least 30$ billion. See articles in Wikipedia and MSN Encarta for project backgrounds and figures. (#25, #51)

  13. 63

    Re #44 — “#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?”

    The runaway greenhouse effect is something that happens to a planet early in its history when a feedback between hot surface temperatures and water vapor in the atmosphere becomes self-reinforcing. The oceans boil, sunlight photodissociates the water vapor, the hydrogen escapes, the oxygen combines with rocks. Carbon dioxide that would have gone into sea sediments as limestone instead remains in the atmosphere after the water vapor is gone, keeping the temperature in the hundreds of degrees C.

    It is not likely that this can be done to Earth, except possibly billions of years from now when the Sun goes off the main sequence. The main danger from global warming is not a runaway greenhouse, but disruption of agriculture and the economy and resulting property damage and famine.


  14. 64

    In his book, “Collapse”, Jared Diamond asks: “Will modern technology solve our problems, or is it creating new problems faster than it solves old ones?”
    If we try our hand on deliberately manipulating world climate, except by reversing the ways we have affected it already, I think I know the answer…

  15. 65
    Vince says:

    Regarding #53 (low hanging fruit) and some of the nuclear comments:

    The low-hanging fruit is currently conservation, through better system designs: homes, building, vehicles, etc., and maybe even better city/town layouts to minimize congestion and wasted time. Insulating my parent’s 1958-era split-level home has a three-year simple payback; my Prius pays off at around 85,000 miles at $2.20/gal; Clackamas High School (Clackamas, OR, ) was built to use 44% less energy than building to standard building codes, at no extra cost. That’s an example of making money right from the start. Good system design is key. The trick is to make your system need much less energy to begin with, then it becomes much easier and economical to fulfill that energy need with wind/solar/other. Las Vegas, NV is a perfect example of wasted energy (very few homes use solar power!) and where building codes should be improved….

    Growth in CO2 emissions can (probably) be stopped with current technology. Reversing it may be a problem, but we can attack that after implementing the easy and economical solutions first.

    As for nuclear power, it has pretty-much lost in the somewhat-free market. Even the insurance industry won’t take on the risk–at least for the first $10B or so. There are a lot of energy subsidies floating around, but still the growth rate in nuclear power is much less than for wind and solar. Nuclear power may be needed at some time in the future, but my choice would be energy efficiency first.

  16. 66
    Chuck Booth says:

    One geo-engineering solution to the problem of rising atmospheric levels of CO2 is to pump it into the deep ocean:
    P. G. Brewer, G. Friederich, E. T. Peltzer and F. M. Orr Jr.(1999) Direct Experiments on the Ocean Disposal of Fossil Fuel CO2. Science (16 July)
    Vol. 305. no. 5682, pp. 362 – 366

    See also: Cauldera and Roy (2000) Geophys. Res. Lett. 27, 225, and commentary on this article by Smith, H.J. (2000)Ocean Dumping of CO2. Science (4 February)
    Vol. 287. no. 5454, p. 769.

    This raises some obvious biological concerns:
    B. A. Seibel and P. J. Walsh (2001) Potential Impacts of CO2 Injection on Deep-Sea Biota. Science (12 October) Vol. 294. no. 5541, pp. 319 – 320
    [See also the Royal Society of the UK statement on ocean acidification due to rising atmospheric CO2 levels, June 2005; PDF available for free online at the Royal Society website)

    Here are some alternative ideas:

    K. S. Lackner (2003) A Guide to CO2 Sequestration. Science (3 June)Vol. 300. no. 5626, pp. 1677 – 1678

    Abstract: Carbon capture and storage (or sequestration) is receiving increasing attention as one tool for reducing carbon dioxide concentrations in the atmosphere. In his Perspective, Lackner discusses the advantages and disadvantages of different methods of carbon sequestration. He advises against sequestration in environmentally active carbon pools such as the oceans, because it may merely trade one environmental problem for another. Better sequestration options include underground injection and (possibly underground) neutralization. Taking into account carbon capture, transport, and storage, the author concludes that in the short and medium term, sequestration would almost certainly be cheaper than a full transition to nuclear, wind, or solar energy.

    Re: #47 All of the estimates I have seen for emissions of anthropogenic CO2 into the atmosphere (5-7 billion metric tons per year; IPCC 2001 report) include cement production, but this is only a small % of the total.

  17. 67
    Hal says:

    My understanding is that we’ve already passed the “tipping point”. Read Science at:
    “A central feature of this long baseline is this: At no time in at least the past 10 million years has the atmospheric concentration of CO2 exceeded the present value of 380 ppmv. At this time in the Miocene, there were no major ice sheets in Greenland, sea level was several meters higher than today’s (envision a very skinny Florida), and temperatures were several degrees higher.”

    This is just with 380 ppm, already higher than we’ve seen in 10 million years. We will pass 400 soon, and only with the most stringent controls could we hope to level off by 550 ppm, twice the pre-industrial level.

    The truth is that we are already committed to enough warming to melt the Greenland ice sheets and flood Florida and all coastal cities, exactly the scenario depicted in Gore’s documentary. The tipping point has been passed.

    The only solution at this point is technological remediation. It may be unpalatable, but we really don’t have any choice. CO2 levels are already too high and have “baked in” disastrous sea level rise. It’s only a matter of time at this point. In order to save our civilization we have to either remove CO2 from the atmosphere, or else take steps to reduce forcings in other ways.

    And the truth is, we’re already manipulating the climate; not just via CO2, but in the wide variety of ways that mankind changes and influences the globe. It’s time that we recognize this and begin dealing with things on a conscious and intentional level. It is a myth that we can live in a “natural” world that is somehow free of human influence. Humanity is rapidly becoming a dominant force in many aspects of the planetary ecosystem, and we can no longer afford to pretend otherwise.

    Here is Teller’s paper from Livermore Labs:

    He discusses both stratospheric particles (not necessarily sulfates) as well as space based shields. Those looking for more details on these proposals, like total mass requirements, will find some information here. Teller estimates costs of a few billion dollars a year starting around 2050. He points out that a ONE-TIME lump sum payment of a billion dollars invested for 50 years would generate enough interest to sustain the program indefinitely.

    UCI physicist Gregory Benford further discusses these ideas in this podcast:
    He suggests a pilot program at a cost of 1/10 of this, $100 million/year, targeted at protecting the arctic region and reducing the loss of polar ice. This way we could get experience with the technology and deal with any problems that arise before committing to a full scale effort.

    If these kinds of numbers hold up, remediation will be far cheaper economically than conservation could ever hope to be. If global warming can be substantially dealt with by a one time charge of fifteen cents per person, we need to rethink our strategies and our emphasis.

  18. 68
    Brian Gordon says:

    Re 67: Start geoengineering:

    “And the truth is, we’re already manipulating the climate; not just via CO2, but in the wide variety of ways that mankind changes and influences the globe. It’s time that we recognize this and begin dealing with things on a conscious and intentional level. It is a myth that we can live in a “natural” world that is somehow free of human influence. Humanity is rapidly becoming a dominant force in many aspects of the planetary ecosystem, and we can no longer afford to pretend otherwise.”
    A. I am opposed to geoengineering projects, until we have reduced CO2 to pre-industrial levels and then realise we still have a problem. I realise this is considered “impractical,” but only because of a commitment to doing things as they are currently done.
    B. Similarly, we have other things to do in an attempt to get the planet back in some sort of equilibrium that supports human life – and all the other lives, plant and animal, that we depend upon. Things like reduce overpopulation, pollution, loss of biodiversity, etc.
    C. Humanity is not “becoming a dominant force,” we are one. The only people “pretending” we are not are denialists, as far as I can tell.
    D. We have to live in a “natural world,” but of course it will not be free of human influence, any more than it is free of influence by deer and ants. The question is whether, at this ‘tipping point’ in human history, we make a conscious choice to return to living sustainably, or continue on our current path, where we believe we have the wisdom to control the planet’s ecosystem. History shows very clearly that we lack sufficient knowledge, wisdom, or humanity to be trusted with global systems.

    “If these kinds of numbers hold up, remediation will be far cheaper economically than conservation could ever hope to be.”
    Which pretty much proves that the numbers are wrong. The only way spending money costs less than not spending money is when crooked politicians do it. This is because they subsidize certain costs, distorting the true costs.

  19. 69
    Brian says:

    RealClimate Staff,
    On the general topic of geo-engineering, have any studies been done to determine the effects of massive worldwide irrigation techniques on local or global climate systems? My stepfather recently suggested this as a possibly significant factor in global change, but this was merely over dinner and wine so I’m not sure to the extent that he or others have substantiated such claims. His field of expertise is soil-plant-atmosphere processes in the Arctic, along with complex systems (well, as far as I know). Being a lay-person I can’t attest to the validity of his theory, but it does seem to intuitively make sense. Any thoughts?

  20. 70
    Doug Percival says:

    #67: “It’s time that we recognize this and begin dealing with things on a conscious and intentional level.”

    I imagine an alcoholic who has been told by his doctor that his alcohol consumption has already damaged his liver and he needs to stop drinking alcohol completely or he will die. Instead, he decides that he will take conscious and intentional control of the functioning of his liver through various technological interventions, and since he is so much smarter than his dumb old liver, he will be able to improve its functioning so it can handle the alcohol and he can go on drinking.

  21. 71
    Coby says:

    Just a thought about the ocean overturning idea: how much methane would escape from thawing clathrates if we raised deep ocean temperatures even a few degrees, let alone 15?! An awful lot I think…

  22. 72
    Richard LaRosa says:

    Re:71. My scheme for pumping up cold water requires much massive OTEC hardware to make a very small change in the surface temperature. There will be no increase in bottom temperature. Where did the 15 degree estimate come from?

  23. 73
    Richard LaRosa says:

    Re:71. My scheme for pumping up cold water requires much massive OTEC hardware to make a very small change in the surface temperature. There will be no increase in bottom temperature. Where did the 15 degree estimate come from?

  24. 74
    Hank Roberts says:

    Richard, the deep ocean temperature increase is already documented.
    Google will turn up examples; here’s one from a long time series; see the website from which this comes for more.

  25. 75
    Wacki says:

    “meteor, or even several thousand meteors, would not have enough cross section area to block the amount of sunlight you’d need to block.”

    Gavin, how big of meteors are we talking about?

  26. 76
    Wacki says:


    That podcast is awesome. Seems too good to be true.

  27. 77
    raypierre says:

    To me, the most hazardous aspect of the artificial stratospheric aerosol idea is the mismatch in time scales between aerosols and CO2. A good bit of the anthropogenic CO2 will stay in the atmosphere for a thousand years, whereas the aerosols will need to be renewed every few years. That means one is making the assumption that the world will remain rich enough and politically stable enough continuously over the next millennium to keep with the program. If there’s a world depression, or a global war that disrupts international cooperation for a few years, the planet would be hit with the full radiative forcing of all that CO2 in the space of just a few years. Talk about abrupt change!

    The sulfate scheme is a lot like putting nuclear waste above ground in Manhattan, in a plywood shelter that needs to be rebuilt every two or three years to keep it from rotting.

  28. 78
    Coby says:

    Richard, in #72:

    I got that 15o number from Andrew Dodds comment in #26, no opinion on the accuracy of the calculation. But regardless of the exact number the principals behind your idea require that warmer water replaces the cold water you are drawing up, no? You are taking heat out of the lower atmosphere and out of the upper oceans, it must go somewhere.

  29. 79
    Coby says:

    Sulphate aerosol cooling need not be maintained indefinately. The danger of the current climate change is its rapidity. Perhaps if we just slowed the warming, spread it out over a few centuries it would not be such a big problem, then the aerosols could be phased out. So now we only need political stability and cheap energy for maybe five hundred years, not a millemium, no problem, right?

    Oh yeah. There’s that darn ocean acidification again…so eat less sushi.

  30. 80
    John L. McCormick says:

    This ongoing discussion of sulphate aerosol cooling is getting too confusing because some replies are really ironic comments (meant) to dismiss the idea and that is a good thing. But,some of us may be trying to follow the logic of loading aerosols into the stratosphere.

    I’d like to focus on three aspects of artificial stratospheric aerosol geoengineering idea that could help move past this seemingly nonsensical idea.

    The residence time of sulphates is days to several weeks. When dissipated as sulfuric acid oceans, lakes and forests suffer unacceptable damage — intentionally increasing acidification of oceans sounds suicidal.

    The source of the sulphates will likely be coal or heavy oil. What? more atmospheric CO2 to remedy climate forcing.

    Finally, greenhouse warming warms the troposphere and thereby increases its depth and effectivly cools the stratopshere. Why then, would we think of further cooling the stratopshere and thereby decrease the ozone level in the statosphere over the arctic?

    Can anyone help me understand the last point more clearly?

  31. 81
    Jim Eberle says:

    Anytime an acid chemically reacts with a carbonate compound the products are a salt, water , and carbon dioxide. Therefore, if sulfate aerosols are added to the atmosphere and generate sulfuric acid rain, as this acid reacts with limestone (calcium carbonate), the products would be calcium sulfate, water and CO2. Ultimately, you would be accelerating the chemical weathering of limestone and further INCREASING the CO2 content of the atmosphere. The carbon cycle would be in a kind of overdrive. CO2 levels could only remain stable if biological processes accelerated the carbon sequestration process to match the accelerated chemical weathering of limestone. A little inorganic precipitation of carbonates might augment the biological process, but I can’t imagine that any of these processes could match the accelerated chemical weathering of limestone which would be caused by seeding the atmosphere with acid causing aerosols. Why am I not seeing any hypotheses like this in the popular literature. Can someone please comment?

  32. 82
    Coby says:

    Well, I am not very impressed by the idea of just blocking sunlight as a GW solution by any means, hence the ironic comments, but my point is still valid. We do not need to hold the temperature where it is now, we just have to keep it from moving too fast. Hence the notion that any such solution can eventually be phased out and need not remain in place forever.

    John, your last point: I think the cooling effect is at the earth’s surface, not in the stratosphere. Sulphates block visible light, which the stratosphere is transparent to. If anything, I’d expect some stratospheric warming from aerosols absorbing sunlight.

  33. 83
    Fernando Magyar says:

    Re 65

    “Las Vegas, NV is a perfect example of wasted energy (very few homes use solar power!) and where building codes should be improved….”

    Ditto For Florida. Incidentally I drive a 1993 Suzuki Swift with a manual transmission it gets over 45 mpg on the highway at 65 mph with the AC on. If I reduce my speed to 55 mph and put the AC on low and am careful with aceleration and braking I can get almost 50 mpg with this car. That is comparable to most new hybrids with the exception of the Prius and the Honda Insight which can get better gas mileage.

    So before we start with geo-engineering projects I would like to see a lot more done with already existing off the shelf technology and conservation.

    It may be that if there isn’t a voluntary step in this direction then it has to be mandated. I don’t recall that my quality of life was significantly diminished back in the days when we had a 55mph speed limit. I calculate my yearly CO2 output for the driving that I do to be around 4000 lbs. I know I can find ways to do even better than that.

    If everybody took mass transit when possible, walked a little more, rode their bicycles for short trips, turned down their thermostats, put their airconditioners on low and bought energy efficient appliances and lightbulbs, I really don’t think it would significantly alter our quality of life.

    It would however have an immediate quantitative impact on the reduction of CO2 being released into the atmosphere.

    So until I see the majority of the population adopting measures of conservation I too will be in vocal opposition to any geo-engineering projects.

    I know this idea won’t fly but how about attaching a fuel surcharge to the amount of CO2 a private vehicle produces, for example if you drive a small hybrid you pay $2.00 per gallon at the pump, if you drive a top of the line gas guzzling SUV you pay $10.00 a gallon for the same fuel. If you can afford the luxury than pay for it. Don’t expect the rest of society to subsidize your comfort our expense.

  34. 84
    Hecker says:

    The depth of the hostility towards the whole idea of geoengineering seems breathtaking to me. One may criticize a particular scheme as good or bad, but nowhere has it been proven that any and all geoengineering schemes are evil or worthless. There is a fear that such schemes may be regarded as a substitute for solving the underlying problems, and this is understandable; but this need not be so, and the underlying problems are not going to be solved overnight as some commenters too glibly suggest. I would say that 40-60 years is a reasonable minimum time to expect a transformation of society’s energy base to happen (terabucks’ worth of infrastructure will have to be replaced); but what about all the GHGs that will yet be dumped into the air in the meantime? Is it more virtuous just passively to accept the consequences of, say, 550-750 ppm carbon dioxide than to try to contain the thermal consequences until the levels can be brought back down? Where is the line between ideology and common sense?

  35. 85
    Chuck Booth says:

    Re #83
    How is a decision made globally about which fix to try? And if a geo-engineering fix turns out not to work and ends up making the situation worse, will it be possible to repair the damage? And what will it cost? And who will pay for it? Those are some of my concerns.

  36. 86
    Grant says:


    … nowhere has it been proven that any and all geoengineering schemes are evil or worthless

    I agree, but: geoengineering is a brand-new idea, and since earth is a large and complex system, there’s an immense amount we don’t know about the consequences. Noone would argue that surgery isn’t a life-saving option for many patients. But in the *early* days of surgery, a common outcome was: the operation was a success, and the patient died.

  37. 87
    maggie says:

    I’m debating climate change with my parents.
    Could you please give me the name of the scientist who reported on the fact that the glaciers were getting bigger on the inside, but were melting on the outside. I heard on a radio show that he was hoping to put a “stop use” on the people who were cherry picking his report to say that the glaciers were getting bigger.
    Any info on this would be helpful in getting my folks to listen up to the dangers their grandchildren may be facing.
    Best regards,

  38. 88
    Hank Roberts says:

    Maggie, here:

    Scientist to CEI: You Used My Research To “Confuse and Mislead …
    An editor of Science also said the ads misrepresent the findings of that study as well as a … The CEI ad “Glacier” quotes two studies in Science magazine, …

    Here’s how I found that:

    I searched google for: +glacier +scientist +ad +misrepresent

    That is the first item in the results

  39. 89
    Hank Roberts says:

    Ray, you were interested in the idea of setting up radiators tuned to the infrared frequencies in which the atmosphere is transparent (that IEEE paper discussed a while back).

    Perhaps there’s a practical way to do it — you’ve seen the so-called ‘day-glow’ paints that are pure molecules reflecting green and orange and yellow, that are optically very bright because (I’m told) they are reflecting only one wavelength or narrow band, rather than being a mixture of different colors as pigments usually are produced.

    We need a pigment that reflects efficiently in the useful infrared range, a pure paint color, for painting roofs and roads.

    But — we know about ‘red tide’ blooms.

    So, let’s ask someone to try to bioengineer by modifying some of our existing sea life an ‘infrared tide’ organism that will reflect from the sea surface in one of those useful frequency ranges, and
    — eat up CO2
    — thrive on the surface in an acidifying ocean
    — reflect infrared out into space through the transparent window
    — and die off and sink fairly fast so sequester material.
    === possibly producing some nice stable dense plastic ….

    Of course this leads awful close to the nanotech ‘gray goo’ disaster scenario. Maybe gray goo reflects infrared (sigh).

    [Response: I was much taken with the infrared transformer idea mainly because it turns into such a nice exam problem on radiative transfer. On a little reflection (no pun intended), I realized that it would be a lot simpler to just increase visible albedo and keep sunlight from turning to IR in the first place. Note that just reflecting thermal IR won’t do you much good. The original scheme relied on intercepting upwelling broadband IR and converting it to IR in the IR window channels where the atmosphere is fairly transparent. That’s a lot to ask of algae, bioengineered though they may be. Now, one could imagine bioengineering algae to increase ocean reflectivity, maybe even by emitting more DMSO to trigger low cloud production. However, talk about losing control — releasing genetically modified organisms into the environment would be a hard genie to put back in the bottle. The stratospheric aerosol idea looks benign by comparison.

    Some might fault Crutzen for even discussing this, since it opens the door to all sorts of abuse where people could be left with the impression that we don’t need to do anything to reduce CO2 emissions since we can always engineer our way out of the problem. I myself think that there are only a very few cases where the spirit of free scientific inquiry should be quashed, and that if scientists have to start thinking to defensively about their curiosity-driven research we’ll all lose. For that matter, if people start thinking about the reality of needing to sustain a livable climate by needing to maintain a worldwide campaign to renew stratospheric aerosols annually, that might be an eye-opener and start to make the whole thing more real. There are cases where I think scientists need to refrain from lines of research they’d otherwise be interested in pursuing, but I don’t think this is one of those cases. Teller’s drive to the H-bomb –based as much on his desire to prove his point by building his toy, as by his politics — is a cases where one could argue that restraint would have been desirable. Developing miniature nukes or neutron bombs in the US is another, since one could argue that if we don’t build such things nobody else has the research capability to do it. Similarly, I don’t think scientists should be messing around with genetically-engineered bioweapons. People should be free to think about all sorts of wild and not so wild geoengineering proposals, as long as they don’t get oversold as a solution. The reason I don’t like the high-CO2 plus high Sulfate Aerosol proposal is that it seems like balancing a load of bricks on a broomstick and keeping the thing from toppling by giving it a nudge in the right direction each year. Better to solve the problem by taking away the bricks instead — or not putting them up there in the first place. –raypierre]

  40. 90
    David donovan says:


    Maggie, follow the link below.

    Within that article follow the “Update link”.

  41. 91
    Fernando Magyar says:

    I for one am not hostile to the idea of geo-engineering per se, only concerned that it might be held up as another excuse for maintaining the status quo by those that have a vested interest in maintaining it.

    I think # 70 said it quite well by comparing the situation to that of an alcoholic looking for a technological fix to her problem.

    I have no hostility toward the idea of liver transplants either, there are times when they may be necessary and its good to know the technology is available. Though the common sense solution would be to stop denying that we have a problem and cut down on the margaritas. That doesn’t mean the liver transplant won’t still be necessary.

    When confronted with the truth of their problem the alcoholic usually denies it and tends to become hostile towards towards the person who tells them they should stop drinking.

    I think the fact that we are even begining to discuss geo-engineering as a solution to global warming at least makes it harder to deny that we have a problem.

  42. 92
    Eli Rabett says:

    Just to remind everyone about which boils your loooong URLs down to a small, easily pasted fragment.

  43. 93
    maggie says:

    Thanks for the help, you’re all dreamy!

  44. 94
    Coby says:

    [OT] About tinyurl etc, I don’t like not knowing what I am clicking on. I acknowledge the utility of a short, non-comma or other weird character filled URL for all the various ways blogs are written and read, but I rarely follow a tinyurl unless the person offering it has included an indication of where it will take me. (eg “check this article here:”)

  45. 95
    Eli Rabett says:

    This post brings out an important point, the inherently conservative nature of those who worry about climate change. Typically messing about with the environment has been a favorite of both the communists and the industrialists, groups who thought the road to progress was through industrial development. Environmentalism’s roots are among rural people, farmers and landowners.

    The rightward shift of evangelicals is important, because part of the price they pay to their new party is to abandon stewardship, a very important part of all religion. We are seeing this play out today with the beginning of pushback. Right now there are at least two competing petitions. The one on the nothing to worry about side has been signed by Roy Spencer and S. Fred Singer.

    The editors may want to cut the last paragraph

  46. 96
    Vincent Belovich says:

    83 & 84:

    I definitely agree that many conservation measures don’t require anyone to give up their lifestyle. And as better home, building, and vehicle designs become more prevalent, we will be getting even more services from the money we spend on energy. Regarding encouraging people to change behavior, I think consumers should be able to buy whatever vehicle they want, but I would suggest that they have to pay the external costs up front when they buy a vehicle: i.e., up front fees for health care costs (asthma, etc.), DOD costs (fighting for oil), global warming costs (this is a more difficult one to estimate), and pollution costs (CO, Unburned HC, NOx, SOx). This would be like taking responsibility for your actions. These fees could be ‘recycled’ into rebates for people to buy the top (say) five fuel-efficient vehicles. Similar measures could be enacted for homes and buildings.

    84: It may appear that some of us are hostile to geo-engineering proposals, but that is only because we (global “we”) need to be spending our money on the best buys first. Example: when the NE had the large blackout several years ago, many of our wonderful senators and congressman were tripping over themeselves to give $100 million to the energy industry to update the ‘grid.’ As a consumer, I would be willing to bet that if a complete economic/engineering analysis were done, that amount of money would be better spent on making all the homes and businesses involved, more energy efficient. That way, the amount of electricity flowing over the grid would be reduced. This not only gives the grid a longer life, but it reduces people’s electric bills, pollution, CO2, etc. More money is now available for the next step in energy efficiency, whatever that may be.

    Demand is key…consumers have the ultimate control, if we are just smart enough to use it.

  47. 97
    Gar Lipow says:

    >Response: There is absolutely no scientific support for your claim that “with or without man’s foul up” we are stuck with too much carbon. Statements like this are just noise, and they don’t help the discussion. –raypierre

    True and I gave links (in the comments of another post) to some places you (collective realclimate – though including you singular) have refuted it.. But I think it is the next major denier talking point. So a really concise really clear rebuttal would be welcome. I wonder if the ill considered blog could do one.

  48. 98
    Andrew Dodds says:

    Re: 72, 73:

    If you pump cold water up to cool the planet, then that cold water will become warm. Furthermore, since in order to offset AGW you must have a net absorbtion of heat (of an amount equal to the extra AGW forcing) into the oceans, you will end up warming the oceans. You can’t get around this without seriously violating the laws of physics.

    I chose 15K as a practical number for the temperature increase you could expect for a unit of water. Make that 1K and your scheme breaks down in just 70 years; the environmental side effects of overturning the entire ocean in 70 years would be fairly catastrophic, I expect.

    [Response: Here’s a nice little calculation for people to try their hands at. Consider one square meter of deep ocean. Compute the energy needed to lift M kilograms per second of cold water from the bottom to the surface in that square meter column (using just the potential energy, ignoring possible frictional dissipation in pipes, etc.). Then compute the effective cooling rate of the cold water flux, in Watts (which is M * Cp * dT, where dT is the temperature difference between the surface water that gets pushed aside and the cold water that replaces it). How does this flux compare with the energy flux needed to do the pumping? Is this a winner or loser? It’s like an engineered hurricane, so far as mixing is concerned. Of course, you can’t do this forever since ultimately the deep water will warm up, but you could do it for a long time before you run out of temperature gradient. (Bonus points for figuring out how long, based on choosing M so as to offset 4 W/m**2 from CO2). –raypierre]

  49. 99
    John L. McCormick says:

    RE: #82 Coby, thank you for the insight on aeorsols and cooling the stratosphere.

    If this thread has helped to shoot the legs off the idea of injecting sulphate aerosols into the atmosphere, could I take another shot at understanding the stratoshpere cooling concern — and this from the standpoint of launching reflective mirrors into orbit to cool the earth’s surface.

    As you said, in #82:

    John, your last point: I think the cooling effect is at the earth’s surface, not in the stratosphere. Sulphates block visible light, which the stratosphere is transparent to. If anything, I’d expect some stratospheric warming from aerosols absorbing sunlight.

    You helped me understand transparency of the stratosphere; but it can be heated by UV absorption, primarily in the ozone (O3) layer.

    Then from —

    I read the following:

    “Ozone’s impact on climate consists primarily of changes in temperature. The more ozone in a given parcel of air, the more heat it retains. Ozone generates heat in the stratosphere, both by absorbing the sun’s ultraviolet radiation and by absorbing upwelling infrared radiation from the lower atmosphere (troposphere). Consequently, decreased ozone in the stratosphere results in lower temperatures. Observations show that over recent decades, the mid to upper stratosphere (from 30 to 50 km above the Earth’s surface) has cooled by 1° to 6° C (2° to 11° F). This stratospheric cooling has taken place at the same time that greenhouse gas amounts in the lower atmosphere (troposphere) have risen. The two phenomena may be linked.”

    So, any attempt to reflect sun light back into space can have the effect of cooling the stratosphere and diminishing ozone concentration. That’s a bad thing. Am I getting it?

  50. 100
    Dan Hughes says:

    “Those who refuse to use arithmetic are doomed to failure.”