When a report on climate change hit the U.S. president's desk, the suggestion was not to cut greenhouse gas emissions. Rather, scientific advisors counseled intervention via technology in the climate system itself—a practice now known as geoengineering. And the president was not Barack Obama, George W. Bush or even Bill Clinton—it was Lyndon Johnson in 1965.

"This generation has altered the composition of the atmosphere on a global scale through…a steady increase in carbon dioxide from the burning of fossil fuels," President Johnson told Congress in February of that year. To address the problem, his science advisors suggested spreading reflective particles over 13 million square kilometers of ocean in order to reflect an extra 1 percent of sunlight away from Earth.

Today, with climate change accelerating and little being done to curb the greenhouse gas emissions, some scientists have resurrected the idea of "deliberate large-scale manipulation of the planetary environment," as the U.K.'s Royal Society puts it. After all, it's an idea nearly as old as the understanding of the physical principles behind global warming itself. Swedish chemist Svante Arrhenius thought that global warming would be a boon to humanity and therefore fossil fuel burning should be encouraged, after calculating by hand the likely temperature impact of continued coal-burning and rising carbon dioxide (CO2) concentrations in the late 19th century—roughly matching the United Nations Intergovernmental Panel on Climate Change and their computer models more than a century later.

That's why 175 scientists and other interested folks (including companies looking to profit from geoengineering) gathered in the Asilomar conference center near the end of March to try to repeat the success of molecular biologists who gathered there in 1975 to reassure a skeptical public about genetic engineering. Ultimately, the gathered would-be geoengineers released a statement calling for, among other things, "further research in all relevant disciplines to better understand and communicate whether additional strategies to moderate future climate change are, or are not, viable, appropriate and ethical."

The list of unintended consequences of human manipulation of natural systems is long: concrete jungles creating urban heat islands, vast oceanic dead zones resulting from fertilizer use on inland agricultural fields, and intentionally introduced species, such as the cane toad in Australia, that then wreak havoc on ecosystems, among others. Whether the idea is to mimic a volcano's cooling impact on climate by continuously pumping sulfates into the stratosphere or to brighten clouds via crewless ships spewing water vapor, possible problems range from shutting down rainfall in certain regions to unilateral declarations of war.

As the Royal Society noted in its 2009 report on geoengineering: "The safest and most predictable method of moderating climate change is to take early and effective action to reduce emissions of greenhouse gases. No geoengineering method can provide an easy or readily acceptable alternative solution to the problem of climate change."

Nevertheless, humans are already managing the climate, even with actions intended to improve the environment. A recent decision to cut sulfate pollution from cargo ships will, in effect, further warm the globe as more cooling particles are removed from the sky.

ScientificAmerican.com spoke to climate modeler and geoengineering expert Ken Caldeira of the Carnegie Institution's Department of Global Ecology at Stanford University, who coined the term "solar radiation management" for efforts to dim the sun (though he now prefers "climate intervention"), about why humans might want to get smart about planetary management.

[An edited transcript of the interview follows.]

First off, what is geoengineering?
Geoengineering is a word that means many different things to many different people. Typically what people call geoengineering is divided into two major classes. There are approaches which attempt to reduce the amount of climate change produced by an increase in greenhouse gas concentrations and there are approaches that try to remove greenhouse gases that have already been released to the atmosphere.

The Earth is warmed by sunlight and the heat that is absorbed by the Earth is later re-radiated back to space. Greenhouse gases make it more difficult for the Earth to radiate energy to space. So the two main ways you can cause Earth to cool are either to create conditions such that Earth absorbs less sunlight or make it easier for the Earth to radiate heat energy back to space.

The first category of approaches typically includes things like: putting giant satellites in space to deflect sunlight away from Earth, putting tiny particles in the stratosphere, whitening clouds over the ocean, or perhaps whitening roofs or planting lighter [colored] crops. They are all attempts to deflect sunlight away from Earth.

The second allows more heat energy to escape.

There is one more category that some people propose: that we might take heat that exists near the surface of the Earth and stuff it down deep into the ocean. This hasn't been looked at very much. But it's another way of altering Earth's surface temperatures.

Why do we even need to think about this?
If we froze greenhouse gas concentrations at current levels the Earth would continue to warm for many decades if not centuries. We did a study showing that if we want to stabilize temperatures through emission reductions, they would need to be cut to zero. Emissions would need to be eliminated entirely. Under every emission scenario considered by the [United Nations Intergovernmental Panel on Climate Change], temperatures continue to increase throughout this century.

Given all of the inertia in the physical climate system, in our energy infrastructure, and our political system, there's really no practical way that emission reductions can reduce the pace of climate change or greatly reduce the amount of climate risk. Emission reductions cannot start cooling the Earth this century, especially if we also control sulfur emissions from power plants, which exert a cooling influence today.

Near the end of this century, if current trends continue, almost every summer in the tropics will be hotter than the hottest yet experienced. That presents the possibility that there could be widespread crop failures and famines. If these kinds of terrible conditions start becoming commonplace we would be facing a situation where many people are starving with the prospect of continued warming for decades and possibly centuries into the future.

Given the enormous stakes and the essential irreversibility of warming through greenhouse gas emission reductions this century, it's only responsible to think about what we would do in the face of a climate emergency. Part of this involves thinking about geoengineering. But we also need to be thinking about developing crop varieties that can grow in hot and dry conditions. We need to be thinking about how to help [developing nations] that can't grow food [in the future] to industrialize so they can get foreign exchange to buy food.

How did you first start studying geoengineering?
I first heard about these ideas in 1998 from [physicist] Lowell Wood, who was a protégé of [physicist and hydrogen bomb–maker] Edward Teller. Teller was pessimistic about human nature and optimistic about technology…. In the mid-1980s, Teller started thinking about climate change. He didn't trust human institutions to develop the capability to reduce greenhouse gas emissions. So he wondered are there technical means to address the climate change problem which wouldn't require changes in human institutions or human nature? He came across the idea of geoengineering.

Geoengineering has deep historical roots. A 1965 report to President Johnson said warming from greenhouse gases could pose a risk to the U.S. It suggested that we might spread reflective particles across the surface of the ocean and this would offset the warming. The concept of reflecting sunlight to space to address climate change has deeper historical roots than reducing greenhouse gas emissions. Nobody suggested that to Johnson.

In 1998, [physicist and geoengineer] David Keith and I were at a meeting with Lowell Wood talking about ways to address climate change. Lowell suggested that we put a bunch of particles high in the stratosphere. I remember thinking, 'Oh, this will never work,' because greenhouse gases work day and night. They work at the North Pole and the equator and in winter or summer. But sunlight is strongest in the day, at the equator and in summer.

So I made an effort to show Lowell Wood was wrong. Back at the office, I worked with colleagues to do simulations that reflected sunlight away. Much to our surprise, reflecting sunlight offset most of the climate effect of increased CO2 both regionally and seasonally.

We set out to show it wouldn't work and our simulation ended up indicating that it basically would…. The resulting climate is pretty similar to the preindustrial climate. It's not exactly the same. You offset 90 percent of the temperature change and maybe 70 percent of the hydrological change.

… [But] CO2 is chemically active and in the oceans forms carbon acid, which attacks the shells and skeletons of marine organisms. These approaches won't do anything to help ocean acidification.

What are the other risks?
There are two main types of risk associated with these climate intervention approaches. One has to do with environmental science and intended or unintended consequences. The other is social, political or even military risks.

In the case of environmental risks, the offsetting of greenhouse gases by increasing the reflection of sunlight is not going to be perfect. Some people, potentially a small minority, will get less rainfall. There is concern about what particles might do to the ozone layer.

In 1991, a volcano in the Philippines known as Mount Pinatubo erupted and sent a huge amount of material into the stratosphere. It reflected two percent of sunlight back to space and Earth cooled by half a degree Celsius. That material fell out of the atmosphere after a year or so but had that material been maintained it would have been more than enough to offset all the global warming expected this century.

After Mt. Pinatubo there was a three percent reduction in the amount of ozone in the atmosphere. This loss of ozone looks like it might be more in springtime and more in northern latitudes. People living in northern Europe could be adversely affected.

… The offsetting of sunlight and CO2 is not perfect. We would expect there to be some impact on ocean circulation. Ocean currents could change dramatically.

We're basically entering into uncharted territory here. There's a host of potential bad things that could happen…. Any time you try to intervene in a complex system, you have unexpected results. But, with greenhouse gases, we are already intervening in a big way in a very complex system.

Environmental consequences are among the least of our worries…. Imagine a scenario where the world has gotten much hotter and China goes into a period of deep drought. The Chinese leaderships says, 'Our people are suffering. We're having a famine. Let's put aerosols in the stratosphere to restore our climate.' It's hard to imagine they would resist deploying that system.

Imagine they do this and then the U.S. goes into a decade or two of similar deep drought. Whether the Chinese intervention was the cause of the American drought or not is almost irrelevant. The U.S. population is highly likely to blame the Chinese for the descent into arid conditions. The potential for great political tension and possibly even military action is high.

I think it's highly likely that as a result of any climate intervention there will be winners and losers. In a nuclear-armed world, a world with terrorism and where losers have the ability to strike back at winners, the potential for the kind of political or military risk to overwhelm any environmental benefits is very real.

The clearest path to environmental risk reduction is greenhouse gas emission reductions. But emissions and global temperatures keep going up and up and up. We need to think about what we'll do if bad things happen…. If we were already on a trajectory of reducing greenhouse gas emissions and helping the most vulnerable develop their economies, I would feel very comfortable about developing these options. If we're still building coal-fired power plants and gas-guzzling SUVs at the same time we're developing these options? You wonder to what extent are these options facilitating bad behavior.

Can these risks be overcome?
The best way from the environmental perspective would be to kind of tiptoe into climate intervention: ramping it up gradually so if bad things started happening you could ramp it back down again. Unfortunately, that's probably the most politically difficult thing to do. We're never going to get consensus to deploy anything until a real climate crisis in which case the motivation will be to turn on the spigot at once to avert catastrophe. From an environmental perspective, that's the riskiest thing you can do.

Do we need to test these ideas? Or just model them?
It's premature to be doing field-testing of deployment systems. [But] a lot of the science you need to do around climate intervention is the same science you need to understand climate change, like understanding how do particles in the stratosphere affect stratospheric chemistry? How do particles in the lower atmosphere affect cloud formation?… It's really research that climate scientists should be doing anyway.

Where things get more controversial is when you start doing tests that are so big that they start affecting people across international borders or you want to conduct these tests in the oceans. These tests are controversial enough that it would be good to wait until there's a little more consensus that they need to be done.

Who can be trusted with this? There are companies looking to invest in this research, can they be trusted?
It's a slippery slope. Take the cloud whitening approach. It might be if you had a bunch of ships lightening clouds off the coast of Los Angeles and San Diego, it would blow cooler, moister air over the Desert Southwest of the U.S. There could be a big economic value to producing lighter clouds and there might be a role for private companies in that endeavor. But it's important to develop consensus about how these different issues will be handled before companies go out there doing their own field tests.

… I would like to see government investment. My druthers would be for the [U.S. National Science Foundation] to take leadership in this scientific investigation because I think a lot of the best science is really driven by university-based researchers motivated by the pursuit of truth and not any single outcome.

But can we trust the government?
I don't think we can trust the government. It's willing to kidnap and torture people and engage in secret wars…. [But] peer-reviewed open inquiry promoted by the normal scientific method is an institution that is really wonderful. It's not perfect in that bad papers get published and sometimes results are kept secret that should be more open.  Keeping this research in publicly funded, non-classified, open journals is very good.

What is the significance of the recent Asilomar conference on geoengineering?
… The Council on Foreign Relations held a meeting two years ago in [Washington], D.C., on governance of these technologies. Another group held a meeting in Lisbon last year on similar issues. The Royal Society is holding a meeting this fall. There is an ongoing conversation about how to govern these technologies. I see this meeting as a continuation and broadening of that discussion. I have no issue with what happened at the meeting at all. [Caldeira did not attend, because of concerns about the financial interests of the organizers.] These issues are complex and are not going to be resolved in a few days.

Ultimately, do you think we'll ever use these ideas?
Nobody can foresee the future. I have friends who think it's almost certain that these kinds of systems will someday be deployed. My hunch is that we will never deploy these systems.

But I think the stakes are high enough that we need to understand whether these systems can help in the event of a climate crisis…. Experts are very bad at predicting the future. All we can do is develop options that we think can reduce risk under a wide range of scenarios. There's a non-zero chance that terrible outcomes might happen [as a result of climate change]. We should prepare for them. Because the cost of catastrophe is so large and the cost of developing [geoengineering] is so relatively small.

Whether it's ever deployed? I hope not.

55 Comments

1. 1. jtdwyer 11:27 AM 4/6/10

   You know, I'd feel much more confident in the vast knowledge of geoengineers if they could demonstrate that geothermal activity can meet all of our energy needs before they start full scale uncontrolled experiments on the Earth. Maybe we could let them play around with the moon for a while first, you know, to get a little experience?
   
   Of course I can take great comfort in knowing that political and economic interests will provide direction and guidance to these amazing planetary engineers.

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2. 2. agenthucky 12:35 PM 4/6/10

   No, no, no, no , NO!
   
   Geoengineering is certainly not the way to go. We must certainly tailor our actions to our environment, and not our environment to our actions!
   
   The author makes a comparison to genetic engineering, which produces about 90% failed experiments at best, while we benefit from the 10% that doesn't. This is fine when dealing with seeds or mice. Surely geoengineers cannot be 100% effective without any unknown effects. Landing on the Moon took a few tries.
   
   Thinking this is an option is the wrong mentality.

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3. 3. candide in reply to agenthucky 01:26 PM 4/6/10

   We ARE currently Geo-engineering.
   
   All those millions of cars, millions of factories, BILLIONOS of home heating devices are belching out millions of tons of various gasses and ARE re-engineering the atmosphere.
   
   I agree, we should STOP all of that.
   
   Imagine if cars (and other devices) were so clean (cleaner than the ambient air) that they became scrubbers instead of polluters?

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4. 4. agenthucky in reply to candide 01:35 PM 4/6/10

   My point, two wrongs don't make a right.
   
   

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5. 5. candide 01:39 PM 4/6/10

   So we should keep doing an admitted "wrong" ?
   Interesting theory...

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6. 6. agenthucky in reply to candide 01:47 PM 4/6/10

   One wrong doesn't make a right as well...

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7. 7. doug l 02:31 PM 4/6/10

   Planting a billion trees to sequester CO2 sounds good as a geoengineering project. It's easy and relatively benign. Why it's not being done, while our energy industry continues to move towards nuclear fission and eventually fusion, or while solar (ideally space based if we can just look beyond our insistence on launching systems designed for cold war era missiles), is a mystery.
   In the mean time, geoengineering should concern itself with creating barriers against the ocean's effects on coastlines...no matter if sea levels rise of even if they go down, the threat of tsunami and impact waves in the case of asteroids is still something our cities on the coast where our greatest populations are tending to live, need to address in a technically engineered manner soon.

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8. 8. elsa 03:17 PM 4/6/10

   Even though reduced emissions would be ideal, Columbia University economist Scott Barrett says countries are more likely to geoengineer than to cut back on carbon. In fact, he says geoengineering is more likely to happen than not. (See http://www.sais-jhu.edu/bin/w/p/Geoengineering.pdf) But then, how to prevent a geoengineering arms race? Barrett is actually online for discussion through April 19-- he's taking questions and comments at http://ow.ly/1vfzR

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9. 9. jtdwyer in reply to doug l 03:22 PM 4/6/10

   doug l - Very good, positive, low risk suggestions to benefit the environment and counteract potential climate impacts. I almost regret my earlier facetious commentary, but then I remember that this article seemed more like a trade show for prospective inventors. A new city technology center, just like Silicone Valley. Experiments in profitable... you get the idea. The reason your suggestions haven't already been implemented is most likely that there's no profit in it for anyone with investment capital. How sad, because your suggestions are very good ones. These do sound like just the type of investments a national government should be making, but you'd have to stand in a long line to receive any consideration.

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10. 10. jtdwyer in reply to elsa 03:32 PM 4/6/10

    elsa - Great info! Scary as hell, though - literally. Nothing like independent, large scale, uncontrolled experimentation to collapse a complex, critical system. Imagine running a network this way.
    
    The end is near - no, even nearer. Sorry, but this is bad news.

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11. 11. jtdwyer 05:47 PM 4/6/10

    mememine69 - So, butthead, you have no concern for massive efforts to inflict change on a system that you insist is not broken? Don't bother to respond.

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12. 12. GRLCowan 09:19 PM 4/6/10

    Contact between air and powder made from very abundant silicate rocks such as peridotite and dunite removes CO2 from air. A coal-fired electricity plant built on top of land that is made of peridotite or dunite, and dedicated to powdering it and dispersing it, would make itself and about seven other coal plants carbon-neutral.
    
    Of course the power plant need not be coal-fired; it could be nuclear, and compensate for eight coal plants.
    
    A demonstrated instance of large-scale artificial sequestration by such a method: http://adsabs.harvard.edu/abs/2005AGUFM.B33A1014W
    

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13. 13. jtdwyer 10:08 PM 4/6/10

    GRLCowan - According to the abstract you linked to, this study considered the hydration of magnesium carbonate mine tailings for existing global mining operations to be capable of sequestering around 100M tons of CO2 annually. I don't understand your relating this process to powerplant construction. Presuming there were acceptable environmental impact (very large scale hydration of magnesium powders might poison a lot of land), this appears encouraging, if optimistic and premature. I expect it will be pursued as it employs a waste product of mining operations presumedly producing a revenue stream from somewhere for mining companies.

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14. 14. jtdwyer in reply to jtdwyer 10:57 PM 4/6/10

    I'm just guessing here, but doesn't binding of hydrated granulated minerals with CO2 produce a relatively unstable carbonaceous compound that requires continuous hydration to retain its bound CO2?
    
    Couldn't other factors, perhaps increasing temperatures, also cause the CO2 to be released?
    
    Sequestering a few hundred million tons of CO2 only to suddenly lose it all due to some system failure might produce other problems.

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15. 15. Natedog 09:35 AM 4/7/10

    I always get a laugh from posters like mememine69. They will talk about anything under the sun in an attempt to demonize the subject of climate change except the actual science.
    
    The love to post their politically charged rants, which frankly has nothing at all to do with the subject at hand, and then convince themselves that those of us who disagree only so so out of an equally motivated sense of liberalism.
    
    Sadly for mememine69 many of us require pesky little things like empirical evidence to help shape our opinions. Something mememine69 and his ilk consistently fail to provide.
    

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16. 16. Bill Crofut 10:41 AM 4/7/10

    Here's an interesting twist on global warming:
    
    ...[o]ne of the reasons paleontologists today believe one of the reasons dinosaurs grew so large, was that they werent cold-blooded like todays lizards; they were lukewarm-blooded....But another reason for their size may have been the sweltering oxygen-rich environment that came to dominate the dinosaur era; an environment triggered by volcanism....It was global warming gone wild; CO2 levels increased over 500 percent and temperatures soared. In the greenhouse conditions this created, huge tropical forests spread over many of the continents....Many scientists believe that evolving for millions of years, in this warm, oxygen-rich world, allowed the lukewarm-blooded dinosaurs to reach their enormous sizes. Huge dinosaurs may have been a biological response to a volcanically over-active planet....65 million years ago. The planet was lush. Vegetation was thick on the surface. Living things were prospering like never before."
    
    [2007. How the Earth was Made, DVD. London: Pioneer Productions for the History Channel, 55 min., ff., 1 hr., 3 min.]
    

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17. 17. rotay 12:09 PM 4/7/10

    So the assumption is that global warming is true and that we should intervene more than we have already?
    
    My experience of summer camping in the mountains of southern France is that the climate became progressively warmer and drier from mid1970s to mid1990s. Since the mid1990s the climate has become progressively cooler and wetter. August 2008 was so cold up there I had to leave for the warmer lowlands.
    
    These new 'geoengineering' plans could amplify a cooling trend and tip our climate into back into an Ice Age.

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18. 18. jtdwyer in reply to Bill Crofut 01:03 PM 4/7/10

    Bill Crofut - This is not my area of expertise, but I think I recall that it was the earlier periods of dinosaurs' occupation that was oxygen rich. Even more telling, the size of insects increases dramatically during periods of high oxygen levels.
    
    The dinosaurs grew much larger later, I think, because they apparently all had the highly efficient air-sac respiratory system, which now allows birds to fly at oxygen poor high altitudes without stopping to rest. The progenitors of birds, at least, likely were also fairly warm blooded.
    
    None of this reputes the quoted inferences regarding past CO2, O2 and temperature, although it does not confirm it, either. It does seem to me that the conditions described did occur in the past. The high O2 levels may have taken a great deal of time to be produced by photosynthesizing plant life prior to the emergence of O2 respiring creatures.
    
    If we (accidentally) create high CO2, high temperature conditions, it may take hundreds of millions of years for thriving photosynthetics to accumulate sufficient O2 to stimulate a revival of large insects, dinosaurs, lizards, or something else. Maybe even mammals would make a comeback!

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19. 19. GRLCowan in reply to jtdwyer 05:17 PM 4/7/10

    Also see ftp://ftp.geog.uu.nl/pub/posters/2008/Let_the_earth_help_us_to_save_the_earth-Schuiling_June2008.pdf and http://www.miller-mccune.com/science-environment/a-rock-that-helps-out-in-a-hard-place-10909/
    
    The carbonate that is produced, magnesite, is a commercial product one could look up. Heat can refree the CO2, but the heat of a kitchen oven would not be sufficient. If magnesite dissolves in the sea it does so as magnesium bicarbonate, and thus binds more CO2.

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20. 20. Anyones Guess? 05:43 PM 4/7/10

    I personally don't see the issue with using some scientific innovation to quickly reduce the co2 in the atmosphere, as well as seriously adapting our lifestyles to reduce emmissions. as a student studying this topic i think the scariest thought is that of atmospheric lagtime... the fact that it takes "x" amount of time for Co2 and other atmospheric pollutions to to be reabsorbed out of the atmosphere therefore even if we reduce emmissions now! the earth will still warm. the sea will still rise and there will still be alot of devestation to many areas.
    
    we do need to change our lifestyles dramatically. but scientific innovation may buy us the time to do this.
    
    however climate change isnt the only major issue which is going to effect us if our lifestyles dont change... population rise in my opinion is a much more serious problem...as ways to create space for more people (as well as power,food, belongings for the increase) secondarily worsen climate change due to deforestation, more emmissions etc.

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21. 21. jtdwyer in reply to GRLCowan 07:02 PM 4/7/10

    GRLCowan - Thanks. That is interesting, as its effective usefulness increases with its stability. While I do not completely accept the assertion that humanity's increasing contribution of atmospheric CO2 is the factor primarily responsible for global warming, having a mechanism that could reliably affect its significant change is crucial to both making that determination and correcting the condition in the global environment.
    
    Given the possibility that the increase in atmospheric CO2 is the product of increasing temperature (which is also inferred by experimental results), careful and precise monitoring and control of any large scale correction process is crucial to the survival of our species.

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22. 22. outsidethebox 08:31 PM 4/7/10

    There is an essential dichotomy of thought here. If we don't do anything then the world will come to an end (so we hear). But if we do something other than what the high priests of AGW demand then something unfortunate might happen. My question is: you mean compared the world coming to an end? It rather reveals the underlying thought is more about human control rather than climate control.

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23. 23. jtdwyer in reply to outsidethebox 09:09 PM 4/7/10

    outsidethebox - Yeah, the really scary thing would be for many groups to take dramatic actions to significantly affect the environment based on their own interpretation of the problem, its causation and its solution. While we've been playing Russian roulette with the environment for decades, that'd be like playing with a fully loaded gun, extra bullets and everybody takes a turn.

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24. 24. mag2.7j 02:15 AM 4/8/10

    Seems to me what we should be trying to do here
    is lessen the carbon content in the fuel that we
    burn and also find another type of catalylist that
    would reduce or remove co2 out of the exhaust
    stream this would at least lessen the output

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25. 25. scots engineer in reply to jtdwyer 07:52 AM 4/8/10

    Hi jtdwyer - following the logic of your metaphor I foresee a sudden and intense outbreak of politeness. " After you old chap, please allow me to let you go first etc "

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26. 26. NeoDim 05:12 PM 4/8/10

    The Earth was released from such pollution, as volcanic products. Mechanisms usual and natural - evaporations, a rain, snow. Chemically active connections cannot be long free. Natural processes are, of course, slow, but it is possible to take them for a basis at system engineering of clearing of atmosphere.

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27. 27. bertwindon 02:58 AM 4/9/10

    (Non verbatim) quote "To what extent might these options merely facilitate bad behaviour"
    Exactly that. "Oh it doesn't matter about leaving the light ON, because it's a H.E. lamp" - etc.
    Population expansion, like wreckless stupidity and ignorance (because allthough " - of the law is no excuse" when it comes to environmental issues we get-away with it) just keeps-on expanding until the conditions become intolerable - or totally un-survivable. It seems to me to be a "law of nature". Like the "If it CAN happen, then sooner or later it WILL happen", "law". This latter one would explain how the first self-replicating molecule appeared by chance. And, I guess, The Earth itself - but probably only once in the entirety of space and time. (Oh - we'll fix it ! Like Oh, wind-energy - easy peasy !)
    To increase happiness and living-standard requires not only energy - which has allways been, and will allways be, supplied by the Sun and the wind - but also a system that uses that energy what could be called "intelligently". The extreme antithesis of this is a bomb. What we have at present is a strange slow kind of slow "combustion process", so slow that many are still in disbelief that anything is ammiss. Nuclear energy will only accelerate the process without the "intelligent"
    ( rather than "who can pay for it gets it, it's very "cheap"" ) system to use the energy to HELP the natural world rather than hammer it some more - wring some more out of it.
    What "Intelligent" is would need to be debated, but I would suggest that, apart from all else, it would be investment of this energy in systems which collected more energy during their lives (from Wind and Sun) than it takes to replace them
    - and re-forestation. The above definition rules-out "modern windfarms" btw.

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28. 28. bertwindon in reply to jtdwyer 03:28 AM 4/9/10

    @jtdwyer
    I haven't read it yet but I can believe it. Don't encourage them. e.g. The CO2 emission from creating anti-tsunami coastal barriers doesn't bear thinking about. Any ideas you give them they will create another Bigger mess with. Most of them forgot anything they may have learned at kindergarten, because they now "have degrees" and The Earth can just have a shot of novocaine and wait for it. They are morons. They haven't managed to make so much as a wind-energy system that returns more than is required to make another, but they don't let this cramp their style. Windfarms fool "the Greens" and most of the public, and they get their cheques to spend on oil-based produce. What more is their for their plastic fantastic lives ?

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29. 29. Macrocompassion 10:56 AM 4/9/10

    The movement to plant trees ("The Men of the Trees") came into being when it was realized that many trees were not being replaced after their timber was harvested, and that this was affecting the amount of rain and producing desert regions out of rain-forrests. So the policy of more trees should be enforced on a world scale, particularly in places where it will do the most good, that is on the edges of deserts. But how do you get more rain there to help the trees to grow? Here is a possible solution:
    
    Many countries in the regions so described have winds that prevail from one direction for a good part of the year. In cases where these winds blow over the sea they can pick up moisture and can later precipitate it as rain. This natural process is associated with cyclonic air movements which move with the general wind direction, so the idea is to encourage the cyclones to develop at the desired places and times. How to do this?
    
    Use a large fleet of Jumbo jet aircraft to scoop up sea water and then fly to maximum altitude where the conditions are freezing. The aircraft should fly in a big circle in the same direction as the cyclone rotates. The water when dispersed at altitude will immediately freeze into ice droplets. As they fall they will cool the surrounding air causing it to contract in volume. This will cause outside air to flow into the circular (cylindrical) region and when this occurs naturally it causes a cyclone due to the well-known Corriolis effect (associated with the naturally occuring storms anyway).
    
    Hopefully these effects can be engineered to occur over a large region and one that is unstable and waiting for such a start to be made and to "encourage" its growth into a larger cyclone of useful rain-carrying proportions.
    
    Please add this suggestion to the list of possible ways to improve the amount of forests on the surface of our planet.

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30. 30. Daniel35 03:47 PM 4/9/10

    I say, "geoengineering" is ANYTHING we do intentionally, or choose not to do, on a global scale. This might include CO2 emissions, but most definitely cutting back on them. Every action will have both good and bad effects, immediately or eventually. In each case, we have to balance and choose to act, or not. At this point I doubt we'll choose to cut back on a large enough scale, unless we get 'lucky' and a large Antarctic glacier suddenly slides into the ocean, raising sea levels and disrupting corporate shipping.
    
    In lieu of this, I still think iron fertilization of the oceans is the best idea. Yes, limited first tests show it creates toxic algae, but maybe it could be 'fine-tuned'. How long do the toxins last? Aren't there mid-ocean areas with no fish, where the toxins could dissipate? If some fish die, isn't that better than some global warming possibilities? It seems in many ways we blame innovations for the bad but ignore the good.

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31. 31. outsidethebox in reply to jtdwyer 08:10 PM 4/9/10

    You lost me somewhere there. How is your position an argument against geo-engineering?

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32. 32. jtdwyer in reply to outsidethebox 03:15 PM 4/10/10

    outsidethebox - Assuming that you're referring to my off-the-cuff comment relating en masse attempts to implement uncoordinated global scale engineering projects to modify the Earth's environment based on unproven theories of causality to Russian roulette, what is there to not understand?
    
    For illustration, let's pretend that your car broke down an some good Samaritans stopped by to help:
    
    - One had a hammer - he thinks the problem is a nail
    - One had a screwdriver - he thinks the problem is a screw
    - One had a saw - he didn't care what the problem is: he can fix it
    
    Would you accept all their generous offers to help?

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33. 33. Macrocompassion in reply to pokerplyer 11:23 AM 4/11/10

    It is possible. Slower propeller-driven aircraft do it when fighting fires, so for jet powered aircraft its simply a matter of sensible engineering, albeit in a more intensive form than in the past.

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34. 34. jtdwyer in reply to Macrocompassion 12:24 PM 4/11/10

    Macrocompassion - I'm no aeronautical engineer, but I have flown in a few jumbo jets. They require continuous high velocity airflow over the wings to generate lift, so any kind of water scooping action would likely turn a jumbo jet into a submarine. What seems quite feasible is often practically impossible when it comes time to actually doing it, especially for those who intend to survive the ordeal.
    
    What is that proverb, something about bad judgment produces experience, and experiences produce wisdom?

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35. 35. jtdwyer in reply to jtdwyer 12:50 PM 4/11/10

    Oh yeah - it follows then that bad judgment produces wisdom!

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36. 36. JamesDavis 02:50 PM 4/11/10

    Excellent article! It would be nice if all of SciAm's articles was as informative as this one.
    
    I am 100% behind geothermal engineering and we should build a geothermal power plant in each state so each state can produce their own electricity for the upcoming electric cars. Geothermal Power Plants, outside wind, solar, and hydro, is the safest, cleanest, and cheapest form of producing electricity available.

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37. 37. jtdwyer in reply to JamesDavis 04:57 PM 4/11/10

    JamesDavis - I really, really hate to bring this up, since you enjoyed this article so much, but it had absolutely nothing to do with geothermal anything. The text 'thermal' is nowhere to be found, because this article is about reengineering Earth's environment, especially its atmosphere, primarily to counteract global warming.

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38. 38. eco-steve 12:14 PM 4/12/10

    There is an tried economical method of inversing climate change. Biomass captures CO2 in the air. Biomass pyrolysis converts biomass into biochar and hydrogen. Biochar is buried as a soil ammendment. See www.eprida.com. Current research is experimenting on removing carbon from crude oil and methane before burning it, again using pyrolysis. So the technology is there and will beome worldwide when small investors buy farm-scale plant.

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39. 39. UrbanEmissions 12:43 AM 4/13/10

    Among the few scientists, the leading voice for reengineering comes from Dr. Paul J. Crutzen, who won the Nobel Prize in Chemistry for formation and decomposition of Ozone. The theory revolves around blocking and reflecting the sun light by spreading sulphur-aerosols into the atmosphere. The immediate impacts of such an exercise not tested in a laboratory, but are already observed nature. The Mount Pinatubo eruption in the Philippines in 1991 cooled global temperatures by about half a degree Celsius for the next few years.
    
    The aerosol plan is also cheap - so cheap that it completely overturns conventional analysis of how to mitigate climate change. In the past, Thomas C. Schelling, who won the 2005 Nobel Prize in economics, has pointed out how difficult it is to get vast international agreements - such as the Kyoto Protocol - to stick. But a geo-engineering strategy like sulphur aerosol changes everything.
    
    Dr. Schelling argues that while the big emitters are bickering about the emission caps and whether or not to mitigate the greenhouse gases fast; who will stop a small nation like Maldives or Bangladesh from attempting to cool down the temperatures fast and cheap by pumping aerosols. At the end, this is the step they may have to take in their national interest, to save the millions of the poor and thousands of hectares of drowning land resources?
    
    I hope it will not come to this.
    
    In 1999 Movie, “The Matrix”, Neo “the one” learns that it is the humans who scorched the sky, in order to block the sun and stop the life support to the machines. The unintended consequences led to the end of humanity on earth, but they managed to block the sun.
    
    While the short term measures like sulphur-aerosols are intended to provide immediate relief, this is only postponing the long term damage. The unintended impacts of higher sulphur in the atmosphere mean more incidences of acid rain and further ecosystem damage.
    
    A recent study published by the Pacific Northwest National Laboratories, that bad air quality (due to aerosols) in the Eastern China is affecting the rainfall patterns, thus the country's ability to raise crops as well as contributing to health and environmental problems.
    
    The interaction of policies and knowledge base to better understand the air pollution (aerosols) and climate change have not been sufficiently investigated and there is a tremendous potential for co-benefits.
    
    Policy research aimed at clarifying the synergies and trade-offs in this field could help to develop instruments that work both ways. And in the mean time, hope that no radical measures are implemented for short term benefits and people will listen to the likes of Dr. James Hansen for stringent mitigation measures on the ground.

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40. 40. jtdwyer 03:29 AM 4/13/10

    UrbanEmissions - Thanks - excellent summary report.
    
    The effects of long term retention of aerosols in the atmosphere are unknown. IMO climate models cannot produce reliable assessments.
    
    With the basic science undetermined, I can't comprehend how policy research can help. I expect that results in one region will not apply to other regions as a result of their diverse atmospheric dynamics.

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41. 41. jtdwyer in reply to UrbanEmissions 06:13 AM 4/13/10

    UrbanEmissions - Surely there's no possibility that repeated use of sulfur aerosols could produce persistent clouds of sulfuric acid in the upper atmosphere, is there?

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42. 42. dobermanmacleod 01:38 AM 4/15/10

    I think this whole debate about geoengineering is hilarious. It just goes to show the number of people who aren't in touch with reality. Mankind is going to INCREASE emissions over 50% over the next two decades. Furthermore, in a warming world natural emission are going to overwhelm any cuts we make. In other words, a severe carbon diet is unfeasible, and those who prescribe it ought to wake up and smell the coffee.
    
    Soon severe heat waves will routinely destroy non-irrigated crops. Hunger (and consequentially war) will be a tremendous motivation to use geoengineering. Or, do you think mankind will just starve rather than try to dim the sun a little (more)?

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43. 43. Sisko 09:15 AM 4/15/10

    @dobermanmacleod- Your view of a warmer planet is dramatic, but unsupported by any facts/data. A warmer planet may be worse for humanity, or it may be better. There is NO reliable data that supports either conclusion.

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44. 44. jtdwyer in reply to Sisko 12:48 PM 4/15/10

    Sisko - If I understand what dobermanmacleod is referring to, I think there is substantial data that can be used to support his views.
    
    If the global population continues to increase and populations now producing less GHGs produce more, and efforts to reduce CO2 production fail, humanity's rate of GHG production could significantly increase (the 50% increase in the next 2 decades is conjecture).
    
    Presuming the increase in GHGs produces global warming, which produces drought in agricultural regions, failing crops along with increasing population will likely produce famine. Large scale famine would certainly increase political tensions and could produce war. Starving combatants would be very likely to take drastic actions to change the unfavorable climatic conditions.
    
    Other scenarios can also be argued, but whether the planet is warmer or not and dryer or not, if the population continues to increase the most likely outcome is sever resource shortages, especially for food and fuel and/or energy.
    
    Unfortunately any effort to isolate or insulate from these conditions can only be successful for a brief time, or for very few. The data supporting and increasing global population seems to be highly reliable.

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45. 45. Veracity 11:11 AM 4/17/10

    "In 1991, a volcano in the Philippines known as Mount Pinatubo erupted and sent a huge amount of material into the stratosphere. It reflected two percent of sunlight back to space and Earth cooled by half a degree Celsius. That material fell out of the atmosphere after a year or so but had that material been maintained it would have been more than enough to offset all the global warming expected this century."
    Iceland Volcano Erruption-- another opportunity.

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46. 46. jtdwyer in reply to Veracity 02:50 PM 4/17/10

    Veracity - I wonder if we could get it right, especially on the first attempt? See Wikipedia re. the Little Ice Age:
    
    http://en.wikipedia.org/wiki/Little_Ice_Age#Volcanic_activity
    
    "The 1815 eruption of Tambora in Indonesia blanketed the atmosphere with ash; the following year, 1816, came to be known as the Year Without a Summer."
    
    Climatic systems are so complex that IMO the effects of any major action are indeterminable. Moreover, I think any affects would be subject to delay due to the masses involved, encouraging the determined experimenter to try some more...
    
    I think that the fundamental problem is that the human population increasingly exceeds the capacity of the Earth's environment. As a result, the more humans produced, the greater the eventual human suffering. When humanity's population is adjusted by natural conditions, the human suffering that will result will be the greatest of all time. We must achieve the managed reduction of our population to minimize eventual human suffering.

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47. 47. chaosnet3 03:28 AM 4/20/10

    efforts concerted globally .. but in need to put aside .. to the point to be put away, permanently .. the money factor .. money to be made .. for individuals to get rich .. for the handful of individuals of this earth, that for their sake .. whatever it is globally produced .. goes for
    
    the resources available .. human and material .. to be put directly into projects which will alleviate earth .. from the burden caused .. instead of expected out of the current system to provide the means to do so ..
    
    under the current system .. free markets and all .. what is beneficial for every human individual upon earth .. will always be neglected .. will always come second .. will never materialise
    
    each party involved .. pursuing their own selfish interests .. be that .. certain human individuals, corporations, states, countries, nations ..
    
    when costs referred to .. are only seen from the perspective .. that the current system entails .. expected to be afforded by .. countries, for the system to gain out of it .. just another scheme .. for the rich to get richer

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48. 48. my cat is psychic in reply to jtdwyer 01:51 AM 4/25/10

    dwyer james davis was helping you get your head out of your arrogant ass.
    See dwyer ,if you listened to james you may not have topretend that your smart.

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49. 49. my cat is psychic in reply to jtdwyer 02:04 AM 4/25/10

    dweyer davis was giving concrete suggestions, and for that you jumped him. shame on you

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50. 50. my cat is psychic 02:19 AM 4/25/10

    dweyer how do you propose to manage reduction of human population in a humane way

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51. 51. awm 11:49 AM 5/17/10

    With all due respect, Ken Caldeira is not a " geoengineering expert" and SciAm is mistaken to think so. "Geoengineering" is merely a clever misnomer intended to give credibility that rightly belongs solely with the proven traditional engineering disciplines to what is otherwise just blatant experimentation with the atmosphere. An "expert" is an authority possessing special knowledge, demonstrated for instance, by a lifetime career, published papers, peer recognition, and distinguished awards. Mr. Caldeira states he began studying the subject in 1998, which only allows 12 years in which to become the "expert" in this new, unproven, and undeveloped "engineering" discipline. "We're basically entering into uncharted territory here. There's a host of potential bad things that could happen" - this is not an expert talking, this is what an imaginative experimenter would say.
    
    Mr. Calderia states "It's premature to be doing field-testing of deployment systems" and, later "My hunch is that we will never deploy these systems." This is pure gibberish and a complete denial of the facts. Deployment of atmospheric particle spraying has been ongoing for ten years or more. An internet search of the so-called chemtrails phenomenon yields extensive information that documents this activity around the world. He's hardly the expert if he does not know this is happening!
    
    Mr. Caldeira talks out of both sides of his mouth at once. Consider: "I don't think we can trust the government" and then, "I have no issue with what happened at the [Council of Foreign Relations] meeting at all." Anyone with the least bit of investigative curiosity can find overwhelming evidence that the CFR historically has been and still is actively engaged in influencing, some say making, government policy on a wide range of issues. Is Mr. Caldeira so naive as to think there's no connection between the two? Is this an "expert" talking?
    
    Finally, Mr. Caldeira proves his ignorance and total lack of compassion for the planet's well-being. He states "Experts are very bad at predicting the future", and "Because the cost of catastrophe (i.e. from climate change) is so large and the cost of developing [geoengineering] is so relatively small." Here he acknowledges that predictions about a catastrophe from climate change or from geoengineering are equally unknown, but opts for geoengineering because it is cheap. This kind of brilliance we can all do without, thank you very much, and likewise with the vaporous dreams of what "geoengineering" can do for the planet.

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52. 52. neogeo9 08:10 AM 5/31/10

    <span onmouseover="_tipon(this)" onmouseout="_tipoff()"><span class="google-src-text" style="direction: ltr; text-align: left">Enter Your Comment Here.</span> Adja meg Hozz�sz�l�sa itt.</span>

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53. 53. fred.evergreen.farms@gmail.com 05:34 PM 7/22/10

    About 50 million years ago something drastic happened here on Earth that wiped out the Dinosaur and most biological life form. That's well before man started burning fossil fuel, which that epoch in time eventually produced, to cook, light, and power the human race. Indirectly their CO2 is now killing us? Maybe what we are experiencing is Earth's normal Geologic forces and there's little if anything man can do to change natural evolution. Maybe if we study and analyze changes our Earth has gone through in past Geologic time to develop a better understanding of what might lie ahead then look at ways to cope with said change rather than try to alter something we have little or no control over, we will be better prepared for what is to come. The dinosaurs disappeared but man, with our innate ability to improvise and develop fixes can surly find ways to cope if we know what's coming. The last North American ice cap reached as far South as St. Louis. If that were to happen again maybe Yankees would learn to live like Eskimos or move South.
    
    Just a thought but my associates and I, using existing technology with a few innovations, can take Sea Water which is loaded with the 52 nutrients we need to grow vegetables and fruit hydroponically, after we remove the NaCl (Salt), to feed large numbers of people in major population centers anywhere in the world, year round. We can also generate clean electricity through bio-mass conversion using binary GenSets to provide clean renewable energy. Throw in some R60 housing that will with stand tornados and you have a pretty sustainable Micro Community scalable to meet most needs we humans have become accustom to. There are and will be many more ways to adapt to changing environments once we realize we are not in control.
    
    

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54. 54. Plain-2009 10:33 PM 8/16/12

    Of course careful calculations are required. But at first sight it seems that the only intelligent thing to do is not to throw dangerous pollutants into the atmosphere. All other ideas, even when they should be studied, seem stupid or entirely crazy to carry out.

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55. 55. hishamt 05:07 PM 5/14/13

    I recently patented 2 inventions that would de-industerraise industries i.e start new zero carbon emission industry based on highly condensed solar energy and storage,the problem I donot know where to start ! I need help from green energy supporters.

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