Science Sunday: “The economics (or lack thereof) of aerosol geoengineering”

Is the aerosol strategy intergenerationally unethical?


The Gist: Putting reflective aerosols high into the atmosphere to slow climate change is too risky and not cost effective.

That’s Climate Central describing the core conclusions of the Climatic Change paper “The economics (or lack thereof) of aerosol geoengineering,” (full paper online here).

This study would seem to support the view that if you don’t do aggressive greenhouse mitigation starting now, you pretty much take aerosol geo-engineering off the table as a very limited (but still dubious) add-on strategy “” as even geo-engineering experts like climatologist Ken Caldeira have made clear.

What’s nice about this study is that it doesn’t just do an economic analysis, but also discusses intergenerational ethics.  I’ll excerpt the study itself at length — after the full Climate Central summary:

Summary: Some have argued that if human society cannot sufficiently reduce its greenhouse gas emissions, than we could still avoid the worst consequences of global warming by putting highly reflective particles, known as aerosols, high into the atmosphere. These aerosols would reflect light back to space, thus counteracting warming from greenhouse gases.

The authors of this paper use an integrated assessment model to determine how costly such a method would be. The authors discuss the potential side effects of this so-called “geoengineering” strategy, since adding aerosols to the atmosphere could have unintended consequences, such as significantly altering weather patterns and damaging stratospheric ozone. Also, aerosols are short-lived, and would have to be continuously added to the atmosphere in order for this scheme to work. If society stopped injecting them, the result would be a rapid shift in the climate, something this paper argues would be highly damaging.

The authors calculate that if there is greater than a 15 percent chance that such a method will be shut down, or if the unintended consequences of aerosols are greater than half a percent of the world’s economy, then this method of geoengineering is not worth the effort.

And let’s not forget that the aerosol ‘solution’ does nothing to stop the consequences of ocean acidification, which recent studies suggest will be devastating all by itself (see Geological Society: Acidifying oceans spell marine biological meltdown “by end of century”).

Here is the conclusion to the study itself:

First, aerosol geoengineering hinges on counterbalancing the forcing effects of greenhouse gas emissions (which decay over centuries) with the forcing effects of aerosol emissions (which decay within years). Aerosol geoengineering can hence lead to abrupt climate change if the aerosol forcing is not sustained. The possibility of an intermittent aerosol geoengineering forcing as well as negative impacts of the aerosol forcing itself may cause economic damages that far exceed the benefits. Aerosol geoengineering may hence pose more than just “minimal climate risks,” contrary to the claim of Wigley (2006). Second, substituting aerosol geoengineering for CO2 abatement fails an economic cost-benefit test in our model for arguably reasonable assumptions. In contrast, (and as shown in numerous previous studies) fast and sizeable cuts in CO2 emissions (far in excess of the currently implemented measures) pass a costbenefit test. Third, aerosol geoengineering constitutes a conscious temporal risk transfer that arguably violates the ethical objectives of intergenerational justice.

Our analysis has barely scratched the surface and is silent on many important aspects. More than a decade ago, a Unites States National Academies of Science committee assessing geoengineering strategies concluded that “Engineering countermeasures need to be evaluated but should not be implemented without broad understanding of the direct effects and the potential side effects, the ethical issues, and the risks” (COSEPUP, 1992). Today, we are still lacking this broad understanding.

Caldeira made some similar points to me in a 2009 e-mail interview:

Nobody has written about this that I know of, but “¦.

If we keep emitting greenhouse gases with the intent of offsetting the global warming with ever increasing loadings of particles in the stratosphere, we will be heading to a planet with extremely high greenhouse gases and a thick stratospheric haze that we would need to main[tain] more-or-less indefinitely. This seems to be a dystopic world out of a science fiction story. First, we can assume the oceans have been heavily acidified with shellfish and corals largely a thing of the past. We can assume that ecosystems will be greatly affected by the high CO2 / low sunlight conditions “” similar to what Earth experienced hundreds of millions years ago. The sunlight would likely be very diffuse “” maybe good for portrait photography, but with unknown consequences for ecosystems.

We know also that CO2 and sunlight affect Earth’s climate system in different ways. For the same amount of change in rainfall, CO2 affects temperature more than sunlight, so if we are to try to correct for changes in precipitation patterns, we will be left with some residual warming that would grow with time.

And what will this increasing loading of particles in the stratosphere do to the ozone layer and the other parts of Earth’s climate system that we depend on?

On top of all of these environmental considerations, there are socio-political considerations: We we have a cooperative world government deciding exactly how much geoengineering to deploy where? What if China were to go into decades of drought? Would they sit idly by as the Climate Intervention Bureau apparently ignores their plight? And what if political instability where to mean that for a few years, the intervention system were not maintained “¦ all of that accumulated pent-up climate change would be unleashed upon the Earth “¦ and perhaps make “The Day After” movie look less silly than it does.

Long-term risk reduction depends on greenhouse gas emissions reduction. Nevertheless, there is a chance that some of these options might be able to diminish short-term risk in the event of a climate crisis.

I would add the grave risk that that after injecting massive amounts of sulfate aerosols into the atmosphere for a decade or more, we might experience some unexpectedly bad side effect that just gets worse and worse.  After all, the top climate scientists underestimated the speed and scale of greenhouse gas impacts (and the magnitude of synergistic ones, like bark beetle infestations and forest fires).

We would be in incompletely unexplored territory “” what I call an experimental chemotherapy and radiation therapy combined.  There is no possible way of predicting the long-term effect of the thick stratospheric haze (which, unlike GHGs, has no recent or paleoclimate analog).  If it turned out to have unexpected catastrophic impacts of its own (other than drought), we’d be totally screwed (see “the definitive killer objection to geoengineering as even a temporary fix”).

Or, rather, our children and grand-children would be totally screwed, not that our actions today suggest we care about them very much (see Is the global economy a Ponzi scheme?).  The study has this to say about the intergenerational ethics issue:

While there have been careful analyses of the significance of intergenerational justice in the wider context of climate change (Gardiner, 2009; Page, 2006; Wolf, 2009), our study is the first to quantitatively examine issues of intergenerational justice raised by aerosol geoengineering for the case that aerosol geoengineering can be intermittent and the aerosol forcing can cause harm. Our analysis shows, for example, that substituting aerosol geoengineering for CO2 emissions abatement is a risk transfer from current to future generations (Figures 4 to 7). In addition, the impacts of the abrupt warming due to a discontinuation of the aerosol forcing would place a heavy burden on human communities and ecosystem integrity (Alley et al., 2002) and thus threaten the conditions required to satisfy basic welfare rights of future generations. Substituting aerosol geoengineering for CO2 emissions abatement decreases the required abatement costs in the near term but imposes sizeable risks for more distant generations (Figure 4 a, b). Since Rawlsian intergenerational distributive justice requires that current generations avoid policies that create benefits for themselves but impose costs on future generations, substituting aerosol geoengineering for CO2 abatement fails on the grounds of this particular approach to ethics.

It would appear that what science advisor John Holdren reasserted in 2009 remains true today, “The ‘geo-engineering’ approaches considered so far appear to be afflicted with some combination of high costs, low leverage, and a high likelihood of serious side effects.

Mitigate, mitigate, mitigate — or punish countless future generations.

Related Post:

29 Responses to Science Sunday: “The economics (or lack thereof) of aerosol geoengineering”

  1. Tom Bennion says:

    I wonder why we dont automatically consider existing or proposed coal fired power stations to be geoengineering projects. It may help to see them that way, particularly proposed stations. They get a sort of “free pass” by being seen as part of the “business as usual” equation, while the suggestion that someone might inject aerosols into the atmosphere is immediately (and justifiably) met with calls for international treaties before such drastic action is taken.

  2. Merrelyn Emery says:

    Thank goodness for that. After our nasty little experiment with nuclear, we should be developing a slight awareness of our technological hubris, ME

  3. Leif says:

    ” Since Rawlsian intergenerational distributive justice requires that current generations avoid policies that create benefits for themselves but impose costs on future generations, substituting aerosol geoengineering for CO2 abatement fails on the grounds of this particular approach to ethics.”

    Failure to aggressively address green house gas build up itself fails the very same policy. Except that study after study, (Not GOBP studies), show a currently addressed progressive mitigation policy would be great for our economy. The rich just have to see that and need to enthusiastically participate or have a dead planet in short order with no manpower to clean up the carnage.

  4. scas says:

    Regardless of what any paper says, if we don’t prevent heating from preventing global catastrophe, then it will eventually be tried out of desperation.

    Aren’t we already blocking 1.4 w/m-2 and artificially keeping ourselves cool? Based on the statement below we’re almost certainly going to need it.

    Methane levels in 2011 are 1.8 ppm, an atmospheric total of ~3.5 Gt C. As of 2009 methane fluxes in the ESAS are 3.5 Gt C [1]. Fortunately the mixing times and oxidation times mean we are avoiding the worst. Releases of up to 50 Gt of hydrate is possible at any time [2]. Mixing time for methane is about a year; major releases in the Arctic would take 15-40 years to spread to the South Pole [3].

    “Thermal shocks, which occur when surface temperatures change, take time to penetrate into sediment (Nisbet 1989). Thus, if the surface temperature changes,say by 10 ◦C (as is expected in the high Arctic in this century), it may take 100 yr for significant heating to penetrate 100 m, and 1000 yr to penetrate 500 m into permafrost
    sediment. If the hydrate is 200 m down, then the warming effect may take 100–500 yr to have impact. But, though slow, the warming is inevitable. Once the warming pulse is put into the sediment, it moves down inexorably. If the surface cools again, a cooling pulse will follow the warming pulse, but the warming cannot be halted. If the warming effect is large enough, the hydrate will break down into
    water and free methane.”


  5. Matt says:

    I wonder if this has been done… Take some photographs of a sunny day and dim them to represent the amount of haze under various aerosol geo-engineering assumptions… basically a quantitatively accurate version of the title image of this post. I’ve seen this done to represent various particulate concentration levels for a city skyline (although these are real photos).

  6. Mulga Mumblebrain says:

    The notion of ‘intergenerational equity’ is, clearly, one which the Right rejects. Just as it rejects ‘equity’ or ‘equality’ or ‘social justice’ or collaboration, or co-operation or socialism or social democracy in the here and now. For the Right two concepts comprise the entirety of the known universe. One is greed, the piling up of stuff, particularly money, by which means they seek to inflate their pathetic presence on the planet. The second is dominance, the power to force others to do what the Right wishes, even at great personal expense to the victim. Authoritarianism is absolutely essential to the Rightist character, and it is swiftly morphing into totalitarianism everywhere they feel the need to do so in order to protect their power.
    We are living through a truly nightmarish process where every life-supporting ecological system is under unprecedented strain or collapsing with increasing rapidity. Hideous facts like the disappearance of the planet’s fishes, or the transformation of rain-forests into savannah or the acidification of the oceans, now are treated with absolute indifference by a deracinated and literally demoralised population which cares more for its plasma TVs than life itself. I’ve always had a pretty low estimation of society in this country, but I’m frankly amazed and horrified at the combination of ignorance, imbecility and total indifference to the fate of humanity that is running rampant these days. Absolute passivity in the face of catastrophe is the norm, or, worse, a belligerent idiocy that denies every single tragedy, without rational argument, by but simple egotistical assertion.
    The puny, putrid and puerile quarter-measure of a ‘carbon price’ in this country has turned into yet another moral and intellectual debacle. Not only is the measure useless, being all set about with exemptions and compensation for avaricious business thugs who have done nothing in twenty years to prepare for this inevitability, but the Dullard regime has acted with characteristic gutlessness and incompetence in trying to introduce it. The whole thing was announced without any detail, giving the Right, led, as ever, by the moral delinquency of the Murdoch apparat, to run one of its trademark fear and loathing campaigns of extreme propaganda. And, as you could have bet your last dollar on, the effect has been typical of this country. The voices against, the deranged geriatrics leaping and bellowing because they don’t wish to pay another dollar, and, in any case, they’ll very soon be dead and to hell with the grandkids, have had all the MSM attention and adulation, and the other side, mostly young and informed, have been ignored. All of business is now organising against the carbon price, evidence of ideological unity in protecting business prerogatives and profits before all else, and the MSM is growing in hysteria. Rigged letters pages, uniformly anti-carbon price opinion pieces, preposterous editorials-the usual tactics of Rightwing manipulation and social engineering. We just have to face facts. The Right and business only care for money, and the population is too dull, too greedy, too indifferent to the fate of its own children to even act at this late hour. Humanity, barring some miracle that I cannot foresee penetrating the denialist carapace, has failed the supreme test of evolution, the fitness to survive. Ours has been a moral, intellectual and spiritual failure, engineered by the worst human beings who have ever existed, and that covers a lot of territory.

  7. Wit's End says:

    First of all, we already have reduced the impact of global warming because there already exists “global dimming” from aerosols…see the fascinating movie, Insidious Soup, featuring Peter Cox of the UK Met Office, here:

    Second, any further addition to the existing phenomenon of global dimming with purposeful geoengineering (and it’s unknown consequences to the health of humans and ecosystems) would, as stated, do nothing to prevent catastrophic ocean acidification – and it would also do nothing to reduce the carnage created by the other emissions of burning fuel, volatile organic compounds and such that form toxic ozone, the background level of which is inexorably rising and relentless corroding our lungs, and the lungs of the earth (trees).

    Advocating geoengineering is as moral as advertising “light” cigarettes – which studies have proven are nothing but a scam, because they are no better than regular cigarettes, since smokers just inhale more deeply and frequently. Implementing geothermal strategies as even a partial solution to climate change will have the same result. Terminal Cancer for the planet.

    Dr. Michio Kaku just advocated (you can see the interview if you scroll down a couple of posts on my blog) that the government in Japan should take over Fukushima because TEPCO is inept and corrupt. The same is true for climate change in the US. The government should nationalize all fuel companies as an emergency, except solar and wind and geothermal – ration fossil and biofuel use to make it fair on a strict per-person basis which will force people to drastically conserve, meanwhile, subsidize the transition to clean energy.

  8. Joan Savage says:

    You mentioned, “I would add the grave risk that that after injecting massive amounts of sulfate aerosols into the atmosphere for a decade or more, we might experience some unexpectedly bad side effect that just gets worse and worse.”

    Atmospheric sulfur compounds were part of the acid rain which killed off fish in lakes in the Adirondacks. The Adirondacks are metamorphic rock with little limestone available to buffer the acidity.

    Deliberately adding sulfur to atmosphere to increase cloud cover would come with an almost immediate price to any ecosystem that didn’t already have buffering capacity from surface limestone or other carbonates. It would push acidification in the oceans, which have already hit buffering capacity for CO2 in some areas.

  9. Lou Grinzo says:

    Geoengineering, particularly via aerosols, is the climate change equivalent of using nearly all the available fossil fuels: Claiming that we’ll resist doing it becomes harder to defend every day.

    I strongly suspect that we’ll resort to aerosols and whole host of geohacking techniques, some very localized (e.g. wrapping glaciers in white plastic insulation, as has already been done in a few places), some regional, some possibly even global.

    The next 50 to 100 years sure won’t be dull…

  10. Neal J. King says:

    Another point that I don’t recall having been mentioned before: The basic problem we’re having is that we use GHG-producing fossil fuels to power our civilization. The ultimate cure will presumably rely to some degree on renewable energy, which is ultimately solar power. If we try to do a “quick fix” by increasing planetary albedo, we will reduce our access to solar power, and thus put our ultimate cure further out of reach.

  11. just another doomer2 says:

    Again, from the National Academy of Sciences report last year

    “Finally, aerosol emissions represent an important dilemma facing policy makers trying to limit the magnitude of future climate change. If aerosol emissions are reduced for health reasons, or as a result of actions taken to reduce GHG emissions, the net negative climate forcing associated with aerosols would decline much more rapidly than the positive forcing associated with GHGs due to the much shorter atmospheric lifetime of aerosols, and this could potentially lead to a rapid acceleration of global warming (see, e.g., Arneth et al., 2009). Understanding the many and diverse effects of aerosols is also important for helping policymakers evaluate proposals to artificially increase the amount of aerosols in the stratosphere in an attempt to offset global warming (see Chapter 15).”

    Hansen just calls it “Humaity’s Own Trap”.

    Point is, it’s not either-or, it’s that BOTH emissions reductions AND geo-engineering (whichever bad idea you like) are needed to stabilize overall climate forcing.

  12. Mike Roddy says:

    Mad scientists will be coming out of the woodwork soon, the same ones who show up once in a while with putative ultra low cost energy schemes, more accurate bombs, better surveillance, and miracle crops. When things take a turn for the worse, there will be money to be made with atmospheric reflectors, though, as with most of the contents of your medicine cabinet, you’re better off leaving well enough alone.

    Scientists who just measure and communicate important data- such as climate scientists- lack a market.

    This is the world we live in. It is going to change drastically anyway in the next couple of decades. Whoever prevails will be the most heroic people in history. The Right senses the upcoming struggle though, like the Confederate Army, they’re choosing the wrong side.

    I don’t see defeating people like Mitch McConnell and David Koch unless they are fought all the way and not, as Democrats are wont to do, by finding a middle ground. If the other people win (and they’re currently favored), it will be hard to make a case for homo sapiens as deserving even a piece of this wondrous world.

    Interesting times indeed. I hope that young people fight nonviolently but relentlessly, and don’t rest until they have won.

  13. Aaron Lewis says:

    Blocking enough visible radiation to have an effect on AGW, would have an prompt effect on agricultural production. Corn, soybeans, wheat, rice, sorghum, alfalfa, and the pasture grasses all want as much light as possible.

    We do not have large food surpluses to carry us over as we experiment with climate geoengineering, and we do not have a lot of available, but unused agricultural land to move into production as per acre yields decline. Thus, if per acre yield of agricultural crops decline, then we have food shortages.

    Sizable aerosol injections would result in food shortages, resulting in social chaos, that would put a prompt end to an expensive experiment. There is no intergenerational cost transfer, because the experiment will not last that long. The people that implement the experiment are the ones that will suffer. The experiment would not run until large numbers of people starved to death. It would only run until we had a couple of crop failures, high food prices, and people tearing down their governments.

    This would not be entirely fair as given prospects for extreme weather, crop failures, and high food prices; people tearing down their governments can be expected without invoking geoengineering.

  14. Wit's End says:

    Ah, Mike Roddy, you have made me weep. There’s no way for our children to survive this unscathed. They can’t win a war we have already lost for them. We have gobbled up everything, and there is precious little left.

  15. Sasparilla says:

    I agree with Lou Grinzo’s analysis…we’re already on the worst case scenario express train with no sign of slowing down – we’ve essentially blown it when it comes to plausible emissions reductions allowing us to avoid runaway warming. I’m always open to miracles (we need a serious one), but short of that, its over.

    I’m guessing in a decade or so it will finally become clear in the U.S. that climate change can’t be denied anymore and something has to be done. This will be in a panic of course, by that time, and it will also be too late (we needed serious emissions reductions, 80%, by 2020) to prevent runaway warming. Over the next decades (2030’s and beyond), with human civilization looking into the maw of oblivion (via runaway warming) – and with some countries in much worse shape than others (initial effects will be far worse on some than others) some crazy stuff will get tried, just to give us time to try to fix things enough to prevent or shut down runaway warming (cause we’re going there).

    As a great book (climate wars) posits, say you go for the aerosols, the world has been warming, but stopping them doesn’t result in an immediate stopping of their effects (it takes years for them to fall out of the atmosphere, just like Mt. Pinatubo) – then you have another Mt. Pinatubo or worse…all those crops adjusted for warm temps won’t like it and cause serious political fallout.

    It will be playing with fire and it looks like the Republican party of the United States of America (and its corporate sponsors) are going to drive the world right into that briar patch – interesting that one political party from one country will be able to be buttonholed for this but history has examples of just such instances. This is the slow motion train wreck from heck to the nth degree, so sad and so unnecessary.

  16. adelady says:

    I’m in favour of CO2 neutralising dusts from olivine and similar rocks. Mainly because that’s just speeding up a geological process which normally absorbs CO2. It just happens too slowly to soak up our 3 million years per year rate of releasing fossil carbon.

    I doubt they’d have much albedo effect because we wouldn’t want to expend too much power putting them too high. And we really want them to get into the waterways and oceans fairly quickly rather than circulating in the atmosphere for too long.

    We just need to find out what negative effects there might be. I’ve not heard of any, though I presume there’d be some nasty coloured skies in various places for varying periods of time. We already know enough about sulphates to know they’re a really bad idea. (Why would we create acid rain to ruin our efforts at reforestation if we’re serious about doing everything we can to fix our problems?)

  17. ryan says:

    “…This seems to be a dystopic world out of a science fiction story.”

    understatement. things at present are already way weirder than anything you could imagine even if you stayed awake for 2 weeks eating LSD and watching mad max,

  18. Dan Miller says:

    Regarding plants responding to aerosols, they grow better after a major volcanic eruption because diffuse light is better for them (the light reaches more leaves). I’m not saying there won’t be horrible side effects from aerosols, but from what I understand, plants can grow just fine in more diffuse light.

    There is a class of geo-engineering that will likely have mostly good side effects, and that is “Carbon Reduction Strategies”, i.e., sucking CO2 out of the air. I spoke with a scientist working on this and he thought it would only cost about a trillion dollars per year to eliminate a years worth of current emissions. This would be a tremendous bargain. Other related schemes such as planting trees and biochar also have positive side effects. Unfortunately, these schemes do cost money and don’t have much of a business case except for saving the world and people don’t seem to be very interested in that.

  19. Richard Brenne says:

    ryan (#17) – Who leaked my next two weeks To Do List?

  20. Stephen watson says:

    Given fossil fuel pollution, aquifer depletion, rainforest destruction, spent nuclear fuel disposal and the deployment of some very dodgy military weaponry, it’s already too clear that we care very little for those who will come after us so appealing to intergenerational ethics as a reason not to try geo-engineering is not really going to cut much ice with the current economic juggernaut’s drivers.

    Our current approach to just about everything (waste, food growing, oil dependency, motoring, flying, fishing, etc, etc) shows that we will do whatever is deemed necessary to maintain business profitability and our current lifestyles, whatever the consequences now or in the future.

  21. Joan Savage says:

    The prospect of geoengineering synthetic clouds that would decrease photosynthesis on land and sea prompts thinking of another area for modeling, that of global atmospheric oxygen, which heretofore has been declining relatively slowly.

    To ryan (#17) and Richard Brenne (#18), having lived through a Mad Max marathon with almost-teens, I have to admit I had some perverse fun and gained no little respect from picking at the weaknesses in the films.

    The idea that a petroleum refinery would calmly be producing gas while anarchy swirled over a denuded non-food-producing countryside was one of my targets. Since then, we have plenty of examples in Iraq and Libya in which the refinery shuts down, at least for a bit. And, food and water becomes at least as interesting as a full gas tank.
    I skipped the drug and sleeplessness side of your agenda, and I hope to see you continuing your writing without that. I’m sounding like the mom that I am, with complete disregard for our relative ages!

    Courage, my friends!

  22. Lewis C says:

    Given the present rate of the interactive feedbacks’ forcings, such as Cryosphere-decline reportedly causing a forcing equivalent to 30% of total annual anthro-CO2 outputs, the case for sufficient geo-engineering to complement rapid global contraction of GHG outputs seems indisputable.

    It seems vital that current estimates of the annual outputs of feedbacks are published in accessible form (and if not here on CP then where ?) if their significance, and their rates of acceleration, are to be more widely understood. With that wider understanding, the necessity of rapid GHG contraction is suddenly obvious to a swathe of middle ground opinion, who are becoming increasingly aware of the ongoing destabilization of climate.

    In response to that shift, the Right will I think predictably re-flip its climate stance to demand the cheapest, dirtiest and best-proven albido-restoration technique – namely sulphate aerosols – as a means to offset ‘mostly natural’ warming. That is the point at which we either have promising alternatives undergoing well-funded R&D which we can propose, or we are again sidelined as having ‘nothing relevant to offer’ the debate.

    Personally, even though Cryosphere-decline alone already represents ‘a new China’ in its warming impact, I’d oppose the deployment of a viable locally-targetted Albido Restoration technique as sole back-up to rapid GHG contraction. Without the inclusion in negotiations of effective Carbon Recovery techniques we should be phasing out additions to the problem of excess airborne GHGs and merely treating its symptoms – but we’d not be ending the problem by cleansing the atmosphere over the coming decades.

    The argument of inter-generational equity certainly offers potent support to the case for GHG contraction plus Carbon Recovery plus interim Albido Restoration. Anything less than all three being applied globally, effectively and rapidly now means that the feedbacks will likely become self-fuelling, and thus generate warming that is massively destructive of future generations’ prospects – particularly those of feeding themselves.

    The Right’s flip to outright denial of the science has never seemed to me to be more than cabaret to strengthen the US position against developing nations’ demands that it acknowledges its climate liabilities (with the profitable advantages of continued fossil income streams in the interim).

    That flip was very distinct and very well recorded; its reverse is thus predictable when conditions demand it. I suggest that publishing data on the annual best estimates of the interactive feedbacks’ CO2e forcings and their rates of change will advance the date of the re-flip substantially by recruiting critical middle-ground opinion. In addition, the provision of cogent critiques of the Right’s favoured option of sulphate aerosols – such as Joe’s above, will leave it wrong-footed in attempting to push an already discredited technology.

    So kudos to Joe for this timely article, alongside a request for an overview of the interactive feedbacks’ current and projected activity.



  23. Mike Roddy says:

    Thanks for the many brilliant comments today, and thanks, especially, to you, Joe Romm, for providing such a great forum.

  24. jaydayrock says:

    It’s a little hard to believe all these people are unaware of the
    ongoing global spraying of aerosols which has been going on for at
    least 20 years.

    The results of this spraying is global solar dimming, epidemic Vitamin D
    deficiency, rickets in children in the developed world, extremely high rates of respiratory disease, heart disease, high blood pressure, and massive tree die off. The soil and water have extremely high percentages of barium and aluminum, to the point that Monsanto has developed an aluminum resistant strain of seeds.

    See Clifford Carnicom, also What in the World are They Spraying, (video).


  25. Ed Hummel says:

    I still think that human civilization has attained a status similar to the asteroid that struck the Yucatan 65 million years ago. That one only took a few minutes to do its work whereas our civilization is taking a few hundred years. But the results will probably end up being similar.

  26. Mike # 22 says:

    A story which CP has not covered much is the severe impact a few degrees warming will have on grain production especially maize, soybean and rice–indeed, studies are showing that even the modest warming we have had so far has a measurable negative impact despite overall increases. If aerosols can be made to perform similar to volcanic eruptions, then it becomes highly likely that aerosol cooling would be considered for crop protection. The political pressure to cool things down will be overwhelming.

  27. Sailesh Rao says:

    In a world beset by human caterpillars, with even the largest ones refusing to undergo metamorphosis, it is difficult to imagine a future filled with butterflies…

  28. llewelly says:

    adelady | April 18, 2011 at 12:35 am:

    I’m in favour of CO2 neutralising dusts from olivine and similar rocks.

    I too hope people begin using CO2 neutralising rock of some sort soon. (And other carbon-reduction strategies, such as biochar.) However – keep in mind that relying on them alone would require grinding up gigatons of rock every year just to keep up with annual CO2 emissions. (Biochar faces a similar problem; the plant material necessary to absorb a year’s worth of global emissions is roughly equivalent to 1600 100 meter tall Coast Redwoods each year.)

    We just need to find out what negative effects there might be.

    Fine dust is never good for the lungs. Flour, cotton, coal dust, clay dust, dust from grinding and carving rocks of many sorts – from granite, marble, and monzanite is all known to cause lung damage, and long term diseases like pneumoconiosis. The sand and dust storms of North Africa and the Middle East are known to cause pneumoconiosis as well. We can be essentially certain that exposure to olivine dust will result in pneumoconiosis, although I don’t think there is precise understanding of the danger.
    Grinding up of olivine and similar rocks will need to be subject to some sort of compromise. The finer the grind, the greater the surface area, and the more CO2 it will absorb. But finer grind also means more aerosolization, and thus, more exposure of people’s lungs to the danger. Perhaps we’ll have to build plants that suck in air, add water vapor and olivine dust, mix until the CO2 is absorbed, filter the air, and pump it back out. But that would seem to be too energy-intensive. Perhaps we’ll have to be content with beds of fine (or even coarse) olivine gravel (soaked in water, naturally) rather than dust.
    The sorts of questions illustrate another huge advantage of emissions reductions – much more is known about how to proceed. With every other sort of proposal made to deal with global warming, there are numerous risk trade-offs technical issues to be worked out, and missing technologies to be invented, before people are even ready to make complete proposals.
    But in the realm of emissions reductions, the necessary technologies are already extent (there are some nice-to-haves that are some way off, especially for those who favor a relatively nuclear-intense approach). A great deal of work has been done on most of the technical issues, and most of the risk trade-offs. There are many sophisticated and workable proposals on how to proceed. The only unsolved problem that remains is the ferocious, humanity-destroying greed of the Simonist future-eating idiots.
    That’s a problem every approach to coping with global warming will face, in one degree or another. I think there is reason to hope that other approaches will face fewer political difficulties than emissions reduction, but at this point they all remain to vague for this to be knowable.

  29. Joan Savage says:

    For future reference:

    Geo-engineers using sulfur would not get to pick and choose which parts of the world to cool off, based on the conclusions of a recent dissertation by Alyson Lanciki.

    “… stratospheric oxidative chemistry involving photolysis of sulfur compounds is globally homogeneous.”
    Alyson Lanciki (2010) Discovery of Sulfur Mass-Independent Fraction (MIF) Anomaly of Stratospheric Volcanic Eruptions in Greenland Ice Cores (Dissertation)

    Lanciki noted in her 2009 paper on the Cold Decade that tropospheric releases of sulfuric acid do not appreciably decrease global temperature, while higher altitude volcanic ejecta into the stratosphere are more consequential to temperature.

    “Cold Decade (AD 1810-1819) Caused by Tambora (1815) and Another (1809) Stratospheric Volcanic Eruption” by Alyson Lanciki Geophys. Res. Lett., 2009, doi:10.1029/2009GL040882

    This is readable on the web, but requires subscription for download.