Climate change methadone?

Geoengineering is increasingly being discussed (not so sotto voce any more) in many forums. The current wave of interest has been piqued by Paul Crutzen’s 2005 editorial and a number of workshops (commentary) and high profile advocacy. But most of the discussion has occurred in almost total ignorance of the consequences of embarking on such a course.

A wider range of people have now started to publish relevant studies – showing clearly the value of continued research on the topic – and a key one came out this week in JGR-Atmospheres. Robock et al used a coupled GCM with interactive aerosols to see what would happen if they injected huge amounts of SO2 (the precursor of sulphate aerosols) into the tropical or Arctic stratosphere. This is the most talked about (and most feasible) geoengineering idea, based on the cooling impacts of large tropical volcanic eruptions (like Mt. Pinatubo in 1991). Bottom line? This is no panacea.

Figure 1: Results from Robock et al showing the imapct on temperature of their scenarios.

So what are the problems? Robock’s study looks at a subset of the potential ones – in particular, the impacts on precipitation. These arise because evaporation is more sensitive to changes in solar radiation than it is to long-wave radiation – so increasing LW and decreasing SW (as you would have in a geo-engineered future) gives a net reduction in evaporation even if the temperatures stay pretty constant. In the experiments they report on, there is a substantial reduction in rainfall in the northern tropics (especially the Sahel and the monsoonal belts). This is actually quite a robust result: reductions in tropical precipitation were reported in simpler tests of this idea in papers by Matthews and Caldiera and Bala et al.

Figure 2: The impact on precipitation in the geoengineered case compared to the control (no GHGs or geoengineering).

Other problems relate to the speed of any recovery if geo-engineering efforts should falter (let’s really talk about rapid climate change!), and impacts on stratospheric ozone, increases in acid rain in polar regions, possible indirect aerosol effects on high cirrus clouds (hopefully other studies in future will better quantify these). But the results so far give a flavour of the kind of issues any geoengineering implementation will involve. Notably, how does anyone balance temperature changes that effect ice sheets versus the failure of the Indian Monsoon? The Amazon drying up versus the North Atlantic overturning circulation? It would make the current international climate negotiators seem rather like medieval theologians.

Recently I heard geo-engineering likened to climate change methadone – an emergency treatment to substitute one addiction (carbon emissions) with another. This seems rather apt, and like the analogous situation with heroin, methadone isn’t going to be a cure.

145 comments on this post.
  1. David Lankshear:

    Yes, some of those geo-engineering recommendations scare me as well. However, the one topic that does not seem to have been covered as dramatically as it appears it should is the subject of Biochar and its ability to ‘sequester’ carbon into the soil in HUGE volumes, as well as the other benefits of preparing the soil for post-oil agriculture and providing some carbon-negative liquid fuel energy from agriwaste. (Biochar is not food Vs fuel).

    Some have claimed that an large enough agricultural area, possibly the size of France, could store all human Co2 emissions. (See my blog page here for a variety of links).

    Tim Flannery is at this year’s International Biochar Initiative conference, so I’m hoping to hear a report from him as to volumes, but written clearly for non-techies like myself.

    Cheers, and keep up the great work!

  2. plover:

    Prof Barry Brook has a couple of good posts on this topic at his new blog It is worth a look. Another quality site backed by science like Real Climate.

  3. Ron Crouch:

    The geo-engineering experiment that we entered into upon the advent of the Industrial Revolution has yielded poor results, and it has been determined that the outcome will not be conducive to most life on Earth as we know it today. So why should we be insane enough to even consider entering into a whole new experiment to act as a band-aid for the failed initial attempt. There is no rhyme where there is no reason.

  4. Fabien Bulabois:

    Geo-engineering is akin to Central Banks trying to keep the economy on track; it is to the scientific community what interest rates are to Central Banks; tools whose effects are mostly uncertain. And once you start interfering with a system that was previously self-regulated, it is virtually impossible to look back.

    Most Central Bank decisions are arguably not preventative but reactive e.g. in response to the current credit crunch, while the Fed – and its peers outside the US – are being granted increasingly more powers to regulate the financial markets.

    Detractors of Central Bank intervention even argue that they only make matters worse by focusing on short-term considerations and thereby create bubbles that would have never existed otherwise, for example by keeping the cost of credit artificially low.

    Furthermore, Central Banks can only intervene within the boundaries of their hosting nations: the US for the Fed, the Eurozone for the ECB… and unless they act in tandem with each other, or at least take a global view of the economy, they are bound to fail to have a positive impact. Similarly, how do we intend to settle the disagreements between countries that benefit from global warming and those who don’t? Whose decision will prevail?

    For those of us working in financial markets, the limitations and drawbacks of intervention should be obvious. I worry that geo-engineering is adding another layer of complexity to our societies, thereby making it more vulnerable to “system failures” (leading to runaway climatic change) and to human inability to foresee the consequences of their acts.

    But do we still have a choice not to intervene? Let’s remember that the Fed was born of panic, crises and crashes…

  5. J:

    We need to distinguish between geo-engineering methods that only “mask” the rising CO2, by increasing the planetary albedo (sulfates, etc.) versus those that actually remove CO2.

    Even disregarding the concerns about effectiveness raised in this thread, sulfates and other albedo-based geoengineering approaches won’t prevent changes to ocean chemistry (“ocean acidification”) or other non-radiative impacts of a higher-CO2 atmosphere.

  6. Arch Stanton:

    LOL Gavin.

    In case any of the rest of you missed the timeliness of the reference you should Google “methadone death” in news.

    (recatcha fortunecookie: comfort ping)

    [Response: Actually that’s just a coincidence. But possibly salutary. – gavin]

  7. Andrew:

    W. Edwards Deming, the great statistician and management theorist, showed that a lack of understanding of a system led invariably to its tweaking. Geo-engineering is the tweaking of the system rit-large. The system is our planet’s biosphere, and tweaking it may very well lead, as Deming warned, to sub-optimization, decay, and the eventual destruction of the system. The fact that such ideas as geo-engineering are being given such serious discussion is troubling.

  8. J:

    Yet another problem with geoengineering is that nobody will agree on what the “optimum” climate conditions are. Let’s say that India would (on the whole) benefit from Climate X while China would benefit more from Climate Y. We could see different groups each adopting their own geoengineering strategies (or working to sabotage their opponents’) in a struggle for control of the climate system.

    Likewise, once you start tampering with the climate, people will hold you responsible for every warm/cold/wet/dry anomaly. We already see this with arguments over whether hurricanes/fires/etc are affected by our “accidental” geoengineering experiment of pumping CO2 into the atmosphere. When you tell the rest of the world that you’re going to use sulfates to “set” the climate of the earth as if it were some kind of thermostat, expect to get the blame for every piece of bad weather anywhere (and no credit for good weather….)

  9. Ray Ladbury:

    J–wrt the optimum climate. In the absense of geopolitical concerns, we could define optimum climate as that which maximizes sustainable production of food from agriculture, aquaculture, etc., could we not? If that is the case, given that the infrastructure of agriculture all developed at a time when climate and CO2 were pretty stable (the past 10000 years), the preindustrial climate would likely be considered “optimum”.

  10. Nick Gotts:

    I don’t think your definition will work. First, what the maximum sustainable food production is, depends on what you want to produce (e.g., how much meat), and what technologies you have available. Second, there are other issues to consider – like disease, and rates of species extinction.

  11. SecularAnimist:

    We not only need to stop all anthropogenic emissions of CO2 and methane as quickly as possible — which means ending all use of fossil fuels, ending deforestation, and ending “industrial” agriculture, especially animal agriculture — but we also need to reduce the existing anthropogenic excess of atmospheric CO2, bringing it back down to pre-industrial levels. The best way to accomplish this is through large-scale reforestation and organic agriculture techniques that sequester carbon in the soil. These approaches are not “geo-engineering”, which suggests imposing some kind of human control on the Earth system to maintain it in whatever state we think will suit us. Rather, these approaches are all about changing the way that we humans “make a living”, so as to bring ourselves back into sustainable balance with the rest of the biosphere and live within the carrying capacity of the Earth.

  12. llewelly:

    Notably, how does anyone balance temperature changes that effect ice sheets versus the failure of the Indian Monsoon?

    effect => affect

  13. J:


    Nice idea, but that sounds very speculative to me. I’m not sure there is a single distinct climate pattern that “maximizes sustainable production of food from agriculture, aquaculture, etc.” without making assumptions about things like the amount of meat in the diet, etc.

    More importantly there’s no sense in talking about this “[i]n the absense of geopolitical concerns”. It seems obvious to me that different countries would benefit more from different potential climate modifications. If we go down that road, no country is going to accept the idea that its own agriculture should suffer for the cause of maximizing productivity somewhere else.

    I agree that the best solution is to aim for as little anthropogenic tampering with the climate as possible. In my case, though, that conclusion comes from emphasizing the political and physical problems with geoengineering, not from an argument that a preindustrial climate would maximize productivity.

  14. Jim Galasyn:

    Andrew writes: The system is our planet’s biosphere, and tweaking it may very well lead, as Deming warned, to sub-optimization, decay, and the eventual destruction of the system.

    I hate to break it to you, but we’re already way beyond “tweaking.” We’re well down the curves of sub-optimization and decay, and the wholesale destruction of the biosphere is clearly visible on the near horizon.

    Add warming and ocean acidification into the mix, and it’s hard to see how even the smallest parts of the biosphere will survive to the end of this century.

    [Response: Let’s not get carried away. Some parts of the biosphere survived Snowball Earth and the KT impact event – they will survive us. – gavin]

  15. Russell Seitz:

    Geoengineering is no bowl of cherries, but if Robock wants to avoid Pat Michaels’ fate, Figure 1 will need extension into the post-fossil fuel era.

    Picking a modeling interval where switching off the aerosol shade coincides with peak oil and coal CO2 forcing is a choice guaranteed to produce an apocalyptic temperature snap-back.

    This amounts to sharp analytical practice, because Crutzen’s stated aim is getting us past the CO2 production peak, not throwing us off the top of it.

  16. Ray Ladbury:

    Nick, I would say that disease and species extinction would be considered as part of the adjective sustainable, and with 9 billion folks on the way, meat will be one helluva luxury under the best case scenario. My point is that agricultural production–on which all of civilization depends–is most likely to be optimal and sustainable for the conditions under which it evolved, that is if we don’t muck with the climate too much.

    Of course, the other thing about “geoengineering solutions” is that in addition to the undesirable side effects, the timescales on which they act are very much shorter than that of CO2. As such, it’s hard to view them as anything other than an act of desperation to buy more time.

  17. Timo Hämeranta:

    Instead of prevailing policies, with interest I follow when capturing CO2 from the air will be the lowest-cost system.

    Please see

    Stolaroff, Joshuah K., 2006. Capturing CO2 from air: a feasibility assessment. Thesis, Carnegie Mellon University, August 17, 2006, online

    “…We find that the cost of capturing CO2 with the complete system would fall between 80 and 250 $/t-CO2, and improvements are suggested which reduce the upper-bound cost to 130 $/t-CO2. Even at the high calculated cost, air capture has implications for climate policy, however dedicated engineering and technological innovation have potential to produce much lower-cost systems.“

    [Response: Marvellous. Does this mean you support a carbon tax of up to $250 ton-CO2 to pay for it? – gavin]

  18. Jeffrey Davis:

    I wonder how far the analogy can be pushed. Methadone, for example, is far more addictive than heroin.

  19. Rando:

    Re: #11 SecularAnimist

    ….wouldn’t the increase of certain types of vegatative biota also result in additional increases in CH4? If this is the case (which apparently it is), going ‘green’ may not be the answer.

  20. cat black:

    Geoengineering of the atmosphere is suicidal. What if we got started and had some cooling. I claim with virtual certainty that the same political slimemolds that promoted BAU even in the face of rising temps will leap in glee at the prospect that we Solved The Problem.

    More mining, more pumping, more carbon releases. No alternative energy, no conservation, no carbon emission reductions. Losers before we even got started.

    We will have bought our fossil fuel consumption “right” at the cost of eternally geoengineering an entire PLANET. What will be the cost of this in real dollars? What political cost? And what treaty will bind all nations to this program for all eternity? What wars will erupt if someone decides not to play along? Which large nation will be the first to hold the rest of the world at ransom because they could destroy the planet by not supporting the geoengineering objectives?

    Then 30 years later when the budget for geoengineering runs out (it will) or the treaties break down (as they must) and the aerosols or shiny metal flecks or whatever leach out of the atmosphere… there is all that carbon, ready to murder us in our sleep.

    But people will want it, oh yes. They will hang on high any politician that doesn’t give them their energy binky. Just give them a pill they can take for this little “problem”, even if it is forever. But don’t ask them to change anything or look at how they live. They have a right to be the way they want to be, granted by God.

    I have faith that geoengineering will never take off. We don’t have the budget for it, we can’t craft the treaties in time, and the scale of the effort dwarfs individual nations. So, DOA and just as well. What will likely happen however is that the fossil energy industry will trot out geoengineering sooth-sayers to calm the masses and give politicians an excuse to hold off actually doing anything useful. We will have a pill for you! Just wait. Just a little longer… oops.

    — act fast decide fast —

  21. Tom Woods:

    I posted this over at Tamino’s site a couple days ago but his backache seems to have captured all the other bloggers attention. Then today I come here and see this entry and thought “how relevant”.

    Recent studies have shown a doubling of stratospheric water vapour, likely from increasing atmospheric heights due to global warming, overshooting thunderstorm tops from stronger tropical cyclones and mesoscale convective systems etc…

    Since sulfur dioxide reacts with water vapour in the stratosphere to form sulfuric acid droplets, would SO2 flux from volcanic activity cause even greater swings in global temperatures?

    I would assume that the increase in stratospheric water vapour would make for a thicker vail of sulfuric acid given a large volcanic eruption. Even a smaller eruption that manages to have an eruptive plume that reaches the stratosphere could very well have greater implications on global temperatures if there’s more water vapour for SO2 to react with.

    Perhaps in the future a large volcanic eruption (VEI 5-6 or greater) may cause 1-2°C swings in global temperatures as they rise further as we go from enhanced greenhouse effect to enhanced reductions in insolation from thicker sulfuric acid vails.

    I bring this up due to the eruption of the Kasatochi volcano, which had an estimated 1.5Tg flux of SO2. This is only around 10% of the SO2 flux from Pinatubo but it got me thinking…

    Anyone with any input on this I’d like to hear from.

  22. Richard Pauli:

    Methadone is a pretty good metaphor — kind of like saccharine, sugarless sodas, and decaf coffee. Not really facing the problem.

    Geoengineering works to enable and prolong high-carbon usage.
    Politicians will seize the panacea to demonstrate problem solving attention.
    Public mollified.
    Essential problem remains.

    Substitutes will do little to change the underlying habit and have unforeseen complications.

  23. Aaron Lewis:

    The public (including politicians and nontechnical managers) seem to have a taste for technical quick fixes to AGW, without regard for their feasibility or effectiveness. (e.g., “use radio reflective material on the polar ice caps”) Consider for example the discovery Channel program where they intend to “test” a group of such fixes and the interest in such fixes in some of the “fantasy futures” polls such as the one run by abc7news.

    This makes me wonder how firm a grasp on reality our society has given the recent poll that “Many think God’s intervention can revive the dying” (

    I am not sure that our society differentiates between, “God will save us” and “new technology that I do not understand will save us.” I think we should reread the story of Noah in the Bible. The real lessons are: 1) God does not save people. 2) The people that survive are the ones that understand technology (i.e., ark building), have self discipline, and work very hard. God did not give Noah an easy solution. Nothing about the AGW problem is going to be easy. This is not a lesson that people want to hear.

    Any solution to AGW will be technically/ logistcally complex and will require sacrifice. That will be a hard sell. Finding solutions to AGW is easy. Selling those solutions to the public is hard. Thus, we keep looking for solutions that are easier to sell to the public, rather than aggressively implementing solutions that we already know would work.

  24. Lynn Vincentnathan:

    Creating more acid rain, which comes from SO2 (also from NOx from cars), is no solution at all — acid rain destroys forests, lakes, soil, buildings, and lungs. It has tremendous costs and tolls.

    We need to drastically reduce both the CO2 and SO2 from going into the atmosphere, and the only way to do that is stop burning fossil fuels.

    Become energy/resource efficient/conservative. Reduce, reuse, recycle, & use alt energy. These are the best, easiest solutions, and can be done cost effectively for at least a three-fourths reduction in the U.S. We just need the will to do it.

    If people don’t have much upfront money & our govt is dragging its heals in helping, they can start with the most cost-effective measures, such as a $6 low-flow showerhead with an off-on switch, which can reduce hot water use by half & save over $100 per year on water and energy bills. Then with those savings invest in compact fluorescent bulbs, insulate, caulk windows. Move closer to work on next house move. And there are hundreds of other low-cost and free measures that save $$$ without lowering living standards. Eventually one might even save enough to buy a Sunfrost refrigerator (uses only 10% the energy, costs $2600, but saves enough to pay for itself in about 12 years, counting also less veggie spoilage — and goes on to save hundreds every year. Then, who knows, maybe one could save enough for an energy efficient hybrid, EV, or plug-in EV, or at least a good down-payment for one.

    This all takes time, and we should have started down this path 20 years ago. What a shame and waste. Light trucks were only 10% of the car market in 1980, but in recent years (with SUVs, which are classified as light trucks) about 50% of the new car market. They emit 47% more pollution and 43% more greenhouse gases than regular cars. Even though auto efficiency has vastly improved, we’ve been going backwards full-speed behind. Considering SUVs/trucks are more dangerous to their drivers & passengers, and to others on the road, this is utter craziness.

    And don’t get me started on peak oil, which John Q public has known about since the 1970s, but apparently had a concussion and forgot about it — probably in an SUV roll-over accident.

  25. Alvia Gaskill:

    We spent some time discussing this paper before its publication as can be seen from the back and forth between Alan Robock, Tom Wigley and myself in the link above.

    Of note is my comment:

    “As noted, the models do not consider the possibility of an equilibration of the climate with a steady increase in aerosol as would actually occur. Thus, the modeling is deficient in addressing this important reality.”

    And Alan’s response:

    “I am not sure what you mean by “important reality.” As we point out in the paper, such scenarios could be investigated, but first you have to decide on how you want to control the climate. Do you want to keep it constant? Cool it back to pre-industrial times? Tom Wigley already used a gradually ramped up aerosol loading in his 2006 Science paper, and other presented such scenarios at AGU. What we present is the climate equilibration to a constant SO2 emission and gradually changing anthropogenic forcing. The results are as interesting as any other hypothetical forcing scenario.”

    So it is important to consider the assumptions made in these modeling studies in assessing their value in predicting changes in precipitation.

    I also point out that the predicted decreases in precipitation from the modeling are within the normal range, although a prolonged decrease of the magnitude predicted might have a more significant impact on agriculture. The models don’t take into account lessened evaporation and adjustments to crop irrigation over decades that could compensate for the reduced rainfall.

    Those of us studying geoengineering, almost universally, do not advocate it as a substitute for emissions reductions, only to give time for the development and deployment of the replacement technologies.

    Thus, the methadone analogy used is inappropriate. The treatment of Type II diabetes is a better one.

    There is no hard evidence that aerosol geoengineering would (a) result in dangerous reductions in stratospheric ozone or (b) lead to harmful acid precipitation.

    While it is true that implementation of aerosol geoengineering alone or in combination with some other geoengineering technology or technologies will likely involve some trade offs, these have yet to be discerned and to cavalierly dismiss geoengineering as is still the conventional wisdom among the scientific community and the chattering class is itself a risk we cannot afford to take.

  26. Rod B:

    Richard (22), interesting scenario that gives one pause — the politicians will love it. Plus don’t forget their glee with the massive resources they’ll control and dole out with a major geoengineering solution.

  27. Timo Hämeranta:

    Re 17 Gacin

    when I write “with interest I follow when capturing CO2 from the air will be the lowest-cost system”, you ask: “Does this mean you support a carbon tax of up to $250 ton-CO2 to pay for it?” ???

    I see I’m dealing with a topic you aren’t familiar with.

    Well, it’s really advisable climatologists don’t mess with economy and technical innovations to solve the problems they try to foresee.

    [Response: I might say the same thing about lawyers and climate science, but that would be unproductive. Since air capture is always going to have a finite cost (and will always be more expensive than CCS at power stations and other point sources) (see our previous discussion), it places a cap on how expensive any other solution can be. But regardless, it still needs to be paid for. Why did you bring it up now in the first place? – gavin]

  28. BillS:

    Proponents of geoengineering should probably read R.K. Merton’s “The unanticipated consequences of purposive social action”. Published in 1936, it is widely available on the web and still germane for all who practice science and engineering.

  29. Hank Roberts:

    coming up 404 not found at the moment.

    Do they address whether this much sulfate will cause a transient spike in surface ocean pH as it rains out? I’d guess the total is trivial once completely dispersed in the ocean but the transient might be a worry.
    (Not to mention whatever excess fossil fuel is burned during a geoengineering interval)

  30. DBrown:

    The person with their comment #8 has started a good point – the Geoengineering modelers did not consider the effects of war as nations decide to stop the experiment that might cause massive destruction in their countries … trying to get countries to agree and then not go to war for trivial reasons (such as non-existent WMD’s) is hard enough – the major threat of changing rain patterns for the ill and/or agriculture collapse is the stuff of nightmares for world stability. Then, simply trying to create the international law required, and prevent any resulting war if some major country suffers one or more of these possible problems, would appear to rule out any possibility of such an experiment ever really being attempted.

  31. James Staples:

    I can only hope that those who wish to use Stratospheric Sufur Dioxide Injections to ‘Geoengineer’ us out of having to deal with ‘The Global Warming Crisis’ most pressing Consequences in a sensible ‘Al Gore-ish’ manner, can also figure out a way to ‘Geoengineer’ us a New Source of Oxygen! :-(
    Though no one seems to have considered this fact; put-ting all of that additional SO2 into the Atmosphere will only contrubute (along with the CO2) to the Acid Rain that will then itself contribute to the Major Issue of ‘Oceanic Acidulation’, which is itself predicted to reach ‘The Crisis Point’ by as early as 2030.
    This ‘other problem’ – which is also exacerbated by the increasing Atmospheric CO2 Levels, our Industrialized Farming Practices (the source of ‘Dead Zones’), and various other Industrial Processes – is threatening to kill off the Oceans Tiny (but very Important!) Phytoplankton; as it will soon begin to prevent them from forming their Carbonate Shells!!!
    Because Phytoplankton produce up to 60% of The Oxygen that we ALL Breathe, and we’ve already cut down TOO MANY oof The Rainforests’ Trees that are the source of the other 40%; just how are we going to replace BOTH of these Sources, once they’re BOTH gone! :-(
    Oxidizing Coal to make the Power to electrolicise(spelling?) H2O?!? :-(
    Got Maxwells Demon in a Bottle, do ya’ Dr. Wood?!?
    You must be NUTS – or out of synch with Oceanographic Sciences, Bubba!!! :-(
    Please apply that ‘Great Mind’ of yours to the problem of getting all of us off of our Carbon Junkie habits!!!
    Think: Old School ‘Yankee Ingenuity’ to the Rescue! ;-)
    If we Free our Minds – and do this thing Right, then the World will be bound to FOLLOW! ;-)

  32. Chris Colose:

    Geoengineering can only be a feasible short-term “solution” in sync with a longer term one. We cannot commit to throwing out SO2 for centuries to millennia (the long CO2 lifetime), it does not solve ocean acidification, there are regional effects even if the global average remains unchanged, and other things. Actually removing the CO2 from the atmosphere is an interesting idea, but I don’t really know much about it.

  33. CL:

    Alvia Gaskill,25, wrote :

    “There is no hard evidence that aerosol geoengineering would (a) result in dangerous reductions in stratospheric ozone or (b) lead to harmful acid precipitation.”

    Hang on. You seem to have this the wrong way around. I want hard evidence that it *would not* lead to a) or b) or any other similar catastrophic unpredicted results.

    I consider the proposal to be utterly irresponsible.

    I remember similar proposals, to fly ozone in balloons up to the stratosphere when the cfc disaster became apparent. And putting giant mirrors into space orbit, and so forth. The media and politicians just love a sci-fi techno-fix. But, IMO, all this proposed tinkering is like mediaeval medicine, ‘apply leeches and mercury and sheep-droppings’. The unfortunate patient is hastened to their demise.

    If it goes wrong, we don’t have a second planet from which to observe our mistake, and say ‘Hey, that’s not right, let’s try Plan B’. The dumb experiment we’re already conducting now, by failing to reduce CO2 emissions, is reckless enough, without adding more follies that multiply the problems we already have.

  34. captdallas2:

    Hey why don’t we just mandate a 25% increase in airline seat width and leg room then required contrail only flight altitudes until we figure the rest out?

  35. David B. Benson:

    (1) Produce carbonaceous materials such as biochar or torrified wood from biomass.
    (2) Sequester in abandoned mines or carbon landfills.

    The cost is less than about $135 per tonne of carbon in developed countries and I opine about half that in the Global South.

    Just this, spending about 1–2% of WGP for the rest of the century reduces atmospheric CO2 to around 290—300 ppm (and solves the ocean acidification as well). Of course, it makes more economic sense to burn the torrified wood instead of coal, so reducing the proportion of the GP required for sequestering the excess carbon already added to the active carbon cycle.

  36. Sam Vilain:

    Presumably this doesn’t apply to geoengineering, where the direct effect of the engineering is to remove CO2 from the system (as in dumping slaked lime in the ocean)?

  37. Nigel Williams:

    ..and surely the simple act of ‘putting’ 100Mt of anything up to 100km altitude will require the emission of a bit of carbon – like about 5e6 tonnes as a minimum if we get it there with 100% efficiency. As with most of these efforts we simply start chasing our tell to hell – basically!

  38. Lawrence Brown:

    A modest (apologies to Jonathan Swift) geo-engineering proposal:

    The 1400 watts per square meter we receive from the Sun at the top of our atmosphere translates to about 240 watts per square meter at the surface of the Earth when albedo and the Earth’s rotatation are taken into account.. This assumes a mean distance from the Sun of about 150 million kilometers. If the Earth were 152 million kilometers from the Sun we could reduce the Solar constant from 240 to about 235 watts per square meter!* Since a doubling of anthropogenic carbon dioxide in the atmosphere increases the energy forcing by about 4.5 watts per square meter, the 5 watts/meter^2 would offset the effects of a doubling of CO2!

    In other words to erase the projected forcing of global warming by doubling the atmospheric CO2 we would merely have to move the Earth about 2 million kilometers further from the Sun, perhaps by “launching” our satellite Earth using the thrust needed by means of nuclear explosions on the floor of the Pacific (Don’t try this at home).
    I say ‘merely’ but there are downsides to this solution. For one thing we could overshoot and a possible outcome could be that we’d become a satellite of Jupiter! There would also be effects from the force caused by the initial acceleration in accord with Newton’s second law. Who knows what these effects would be. Momentous earthquakes? Seismic sea waves tens (hundreds?)of meters high? In that case we could resort to other geo- engineering solutions, e.g. building massive sea walls around contintental perimeters, beforehand.

    Or maybe we’d just be better off by switching to alternative fuels.

    * Total Solar radiation at a Solar surface temperature of 5800K and a radius of 7.0 x10^11m, Ss= 4piR^2xsigma(T^4)=
    The solar constant, on a unit normal area per unit time, falling to Earth is given by Ss=4pi(D^2)Se or Se=Ss/4pi(D^2)
    (from “Exercises in Environmental Physics” by Valerio Faraoni, Springer, 2006)
    , Se = Ss/4pi(D^2)= 3.95×10^26W/ 4xpi(1.50×10^11)^2=1398~1400W/m^2
    Adjusting for albedo and geometry 1400(1-.31)/4=241or about 240W/m^2
    If the Earth Sun Distance were 1.52 x10^11m then 3.95×10^26/ 4pi)(1.52×10^11)^2=1360W

  39. Edward Greisch:

    1. Reference Book: “The Paranoia Switch” by Martha Stout. Coal companies push your buttons and pull your chain, just like George W. Bush, [edit] Senator McCarthy and others. MRI used to be called NMR. The name was changed to get patients into the scanner. Most Americans are paranoid of terrorists and all things nuclear. If the “human” brain had been designed by a competent god, the coal industry would not have a $100 Billion per year cash flow and George W. Bush would never have had a chance of being elected once. We all know that we have to convert all coal fired power plants to nuclear worldwide by 2015, but it won’t happen because the average American has an irrational fear of all things nuclear. To solve the global warming problem, the whole USA needs to be sent to a mental health professional. We have enough time and technology. It is only mental health and intelligence that is lacking.

    2. I infer that putting light deflectors at the first earth-sun lagrangian point L1 would be more expensive that putting SO2 in the stratosphere. Would the L1 solution meet with approval climate wise? The L1 solution would at least avoid the SO2.

    [Response: Worse. Much more expensive. How do you easily turn it off if it doesn’t work out? It doesn’t deal with acidification either etc… -gavin]

    3. I have heard a rumor that the US government is already putting something bad high in the atmosphere already. See Any comments on chemtrails in the sky?

    [Response: Paranoid delusions. – gavin]

    4. No, it isn’t a carbon tax that we want. We want the burning of coal to make electricity to be illegal, worldwide, and soon. A carbon tax that ramps up steeply with time would be inadequate. Cap and trade is not a guarantee either.

    5. Sequestering CO2 should be reserved for industrial processes because industrial processes are the second largest source of CO2. Burning coal to make electricity is both the biggest single source of CO2 and the biggest source of non-natural radiation and metallic poison. Coal contains: URANIUM, ARSENIC, LEAD, MERCURY, Antimony, Cobalt, Nickel, Copper, Selenium, Barium, Fluorine, Silver, Beryllium, Iron, Sulfur, Boron, Titanium, Cadmium, Magnesium, Thorium, Calcium, Manganese, Vanadium, Chlorine, Aluminum, Chromium, Molybdenum and Zinc. There is so much of these elements in coal that cinders and coal smoke are actually valuable ores. We should be able to get all the uranium and thorium we need to fuel nuclear power plants for centuries by using cinders and smoke as ore. The impurities in coal vary wildly from place to place. Chinese industrial grade coal is sometimes stolen by peasants for cooking. The result is that the whole family dies of arsenic poisoning because Chinese industrial grade coal contains large amounts of arsenic.

    6. Moving earth to a higher orbit: See “New Earths” by Jim Oberg. You do it by making large asteroids pass in front of the earth, exchanging momentum by means of gravity. This is not recommended without first figuring out the consequences for orbital stability. Also, we would have to inhabit the entire solar system first, and terraform Mars, rendering the project moot.

    I have zero financial interest in nuclear power, and I never have had a financial interest in nuclear power. My sole motivation in writing this is to avoid extinction by H2S gas due to global warming.

  40. John Mashey:

    Since this is all depressing, perhaps a bit of levity regarding changing Earth’s orbit outward: World Jump Day.

  41. Brad Arnold:

    OK, so geoengineering by putting a small amount of engineered sun dimming aerosol into the upper atmosphere isn’t a magic bullet (i.e. change in precipitation levels). What is the alternative?

    The reason I bring this up is: “There is no linear predictability in terms of how ecosystems respond. The phenomena of collapse is one that we have under-appreciated, partly because of the feed-back mechanisms that we are still trying to understand.” –Achim Steiner, head of the UN Environment Programme, Oct. ’07

    “Leemans and Eickhout (2004) found that adaptive capacity decreases rapidly with an increasing rate of climate change. Their study finds that five percent of all ecosystems cannot adapt more quickly than 0.1 C per decade over time. Forests will be among the ecosystems to experience problems first because their ability to migrate to stay within the climate zone they are adapted to is limited. If the rate is 0.3 C per decade, 15 percent of ecosystems will not be able to adapt. If the rate should exceed 0.4 C per decade, all ecosystems will be quickly destroyed, opportunistic species will dominate, and the breakdown of biological material will lead to even greater emissions of CO2. This will in turn increase the rate of warming” –Leemans and Eickhout (2004), “Another reason for concern: regional and global impacts on ecosystems for different levels of climate change,” Global Environmental Change 14, 219–228

    In other words, any other viable alternative scheme to geoengineering must stop Earth’s surface temperatures from rise above the rate of 0.4 C/decade. By the way, in my opinion, the elevated greenhouse gas levels already in the air, combined with the future emissions from machines already built, plus increased natural emissions from carbon sinks becoming carbon emitters (i.e. permafrost melting) will cause the rate of warming to top 0.4 C/decade by mid-century.

    “Few seem to realise that the present IPCC models predict almost unanimously that by 2040 the average summer in Europe will be as hot as the summer of 2003 when over 30,000 died from heat. By then we may cool ourselves with air conditioning and learn to live in a climate no worse than that of Baghdad now. But without extensive irrigation the plants will die and both farming and natural ecosystems will be replaced by scrub and desert. What will there be to eat? The same dire changes will affect the rest of the world and I can envisage Americans migrating into Canada and the Chinese into Siberia but there may be little food for any of them.” –Dr James Lovelock’s lecture to the Royal Society, 29 Oct. ’07

    “Peak temperatures may rise twice as fast as average temperatures as climate change hots up.” –“Summer scorchers outpace global warming,” The New Scientist, 20 August 2008

  42. Timo Hämeranta:

    Re 27 Gavin,

    Frank Zeman speaks about sodium or potassium, but I had in mind ‘artificial trees’. I had discussed of this alternative e.g. with my dear friend Alan Robock. He is reluctant, but I see it very interesting and promising way of geoengineering.

    About the IPCC recommendations and prevailing policies I copy one of my emails last year:

    (Instead of emission reductions) “again I refer to the total abstention from other future possibilities, although all the concerns deal with possible futures.

    Please see again:

    Goettmann, Frédéric, Arne Thomas, and Markus Antonietti, 2007. Metal-Free Activation of CO2 by Mesoporous Graphitic Carbon Nitride. Angewandte Chemie Vol. 46, No 15, pp. 2717-2720, April 2, 2007

    If needed, the future solution is e.g. this Artificial Photosynthesis.

    Besides, Nature and Man gets the extra biomass urgently needed.

    The main message is that Human Ingenuity will resolve this CO2 problem (if it exists at all).”

  43. Brad Arnold:

    Sorry to double post, but putting sulfate particles into the air to dim the sun is a strawman argument against geoengineering since using engineered particles instead would be much less expensive and could be designed to avoid damaging the ozone layer:

    “A much-discussed idea to offset global warming by injecting sulfate particles into the stratosphere would have a drastic impact on Earth’s protective ozone layer, new research concludes. The study, led by Simone Tilmes of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., warns that such an approach would delay the recovery of the Antarctic ozone hole by decades and cause significant ozone loss over the Arctic.” –“Injecting Sulfate Particles into Stratosphere Could Have Drastic Impact on Earth’s Ozone Layer,” National Science Foundation, 24 April 2008

    But: “The economics of geoengineering are—there is no better word for it—incredible. According to Teller et al. (2003: 5), engineered particles would be even cheaper (mainly because of the reduced volume of material that would need to be put into the stratosphere); they estimate that the sunlight scattering needed to offset the warming effect of rising greenhouse gas concentrations by the year 2100 would cost just $1 billion per year.” –“The Incredible Economics of Geoengineering,” Scott Barrett, 6 December 2007

    The scheme of dimming the sun with engineered particles injected into the upper atmosphere is a short run strategy of buying time to impliment the long run scheme of changing the carbon budget of the Earth.

    “The Greens’ resistance to geo-engineering sits very uncomfortably with its message that the planet is screwed and we’re all going to die…It suggests that they don’t actually believe their own press releases, and that they know the situation is not as dire as they would like the rest of us to think it is…It suggests that Environmentalists regard science and engineering as the cause of problems, and not the solution.” –Climate Resistance, 24 March 2008

  44. DBrown:

    If people are interested in possible solutions to the energy issue without need of increasing CO2, then thermo-nuclear fusion is a good option.
    Direct drive thermo-nuclear fusion is a possible solution. A Navy group proposed a KrF direct drive laser implosion system that was peer reviewed by an international team of experts in the field and deemed not just viable but likely to succeed. The cost, under half a billion dollars for a proto-type power plant. Development time, under ten years. Such a plant could replace all coal plants without the massive and extremely radioactive waste from a regular fission plant nor the danger of a runaway melt down or extreme danger of a nuclear explosion from a breeder fission reactor.
    Of course, the DOE does not have the money for such a test plant so the proposal was turned down.

  45. Bart Verheggen:

    At the EGU last year there was a very interesting panel discussion on geo-engineering (with Ken Caldeira a.o.). An important point of discussion was whether the possibility of geo-engineering could decrease attempts to reduce emissions. Measures that alleviate negative consequences induce risky behavior, eg seatbelts cause drivers to drive less safely. But that shouldn’t translate in not using seatbelts, was the response. There is a real risk of a trade-off between geo-engineering and emission reduction, but I don’t want to summarily dismiss it either.

    “I hope I never need a parachute, but if my plane is going down in flames, I sure hope I have a parachute handy,” Caldeira said. “I hope we’ll never need geoengineering schemes, but if a climate catastrophe occurs, I sure hope we will have thought through our options carefully.” ( and elsewhere.) Initial model simulations suggest that a high-CO2 world with geoengineering is likely to be closer to the pre-industrial world than a high-CO2 world without geoengineering. (

    The challenge is to investigate the consequences and viability of different schemes, while being careful that it is not being (ab)used as an alibi not to work on emission reduction, which should be the first and foremost strategy to prevent dangerous climate change. Thus, geoengineering schemes should only be put into practice when catastrophe is imminent, as a last resort. Who will decide on that is a tricky question of course, to which I don’t have an answer. Hopefully any such decision will be informed by science however, and not overpowered by lobby groups. The influence of lobby groups on the current public and political discussion does not bode well that we can prevent or substantially decrease their influence in the near future, when they may call to focus on geoengineering instead of emission reduction strategies (rather than focus on both, but in reverse order).

    On a more “practical” note: Isn’t the scheme originally proposed by Latham (1990, 2002) to seed maritime clouds with sea salt aerosol (to enhance their reflectivity) probably more benign than injection SO2 into the stratosphere? It doesn’t seem impossible or prohibitively expensive either (which a space-based sunscreen would be for example).

  46. MichaelT:

    Many thanks for the highly interesting post, Gavin! Realclimate is *the* site for me to get the ammo to fight the sceptics’ pseudo-arguments.

    I just tried to download Robock’s paper but got a “Not found” message. This seems to be the correct link now:

  47. Jim Galasyn:

    Of course, Gavin is correct — What I mean to say is that it’s hard to imagine the current biosphere, i.e., the the one humans evolved in, surviving this century.

    Jeremy Jackson sees three scenarios for the oceans over the next 20-30 years, from best to worst:

    Scenario 1: Carbon emissions capped, nutrient runoff stopped, overfishing stopped

    Dead zones decrease; too late for megafauna; small fish survive.

    Scenario 2: Carbon emissions not capped, but nutrient runoff and overfishing are stopped

    Acidic, stratified oceans; demise of calcified organisms; anoxia below thermocline.

    Scenario 3: Carbon emissions not capped, nutrient runoff not stopped, overfishing is/isn’t stopped

    Global dead zones dominated by jellyfish and microbes; coastal waters too toxic for aquaculture and human habitation.

    Watch his presentation from December, Brave New Oceans. Then take a X-a-n-a-x.

  48. Nick Gotts:

    Brad Arnold,
    The most general reason for doubt about proposed geoengineering solutions is the likelihood of unintended and unpredictable side-effects – a point that has been made repeatedly. Denialists are often very keen to point out that the climate system is complex, much remains to be understood, etc., etc. – so you would think denialist sites such as “Climate Resistance” would find this point easy to grasp. The fact that they pretend not to in the quote you give casts serious doubt on their honesty.

  49. Richard Ordway:

    re 22 Richard “Methadone is a pretty good metaphor — kind of like saccharine, sugarless sodas, and decaf coffee. Not really facing the problem.”

    Errr, you forgot “clean coal”?

  50. Hank Roberts:

    Jim, it’s not the whole biosphere at risk here, except for very human-centric definitions of biosphere. It’s mostly the charismatic megafauna that are in trouble (if you include people as charismatic; debatable, yes).

    I’m sure the beetles will be fine — creation has always had “an inordinate fondness for beetles.”

    That experiment has already been run in many ways — wildlife finds H. sapiens more troublesome than any other environmental factor, vide the Korean DMZ, the Chernobyl hot zone, and so forth.

    Once the people are out of the way, Earth abides.

    Oh, wait …