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Geo-engineering in vogue…

Filed under: — gavin @ 28 June 2006

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

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

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

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

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

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

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

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

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

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

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

270 Responses to “Geo-engineering in vogue…”

  1. 251
    John L. McCormick says:

    RE: 250

    I appreciate your question:

    If sulfates (or metal particles, as often proposed) are already being injected into the atmosphere on a massive scale, should this be legalized or forbidden?

    Help this thread by opening the discussion of your essential question by reading —

    Geoengineering the Climate: History and Prospect by David Keith at:

    Or use the Tiny url at:

    Then read the international treaty drawn up by the UN in 1977:

    Convention on the Prohibition of Military or Any Other Hostile
    Use of Environmental Modification Techniques

    It was opened for signature at Geneva: 18 May 1977, Entered into force: 5 October 1978 Depositary: Secretary-General of the United Nations

    and can be accessed at:

    or at Tiny URL:

    Finaly, offer your views. I have read the documents and they are a good place to start if one is looking to start from a point of reality.

    I believe this thread is desparately in need of some up front thought about legalities, rights, liabilities, etc. Maybe this thread can actually produce a very useful product.

  2. 252
    Joseph O'Sullivan says:

    Geo-engineering might have some potential, but as far as I know there are many uncertainties about its effectiveness and potential side effects.

    As far as researching geo-engineering projects where will the research funds come from? Research funds are always limited, and there are other things that needed to be researched but are not being done at the level that is needed.

    For example climate scientist Michael Oppenheimer wrote that the resources needed to study the Antarctic and Greenland ice sheets are lacking. “Currently the resources to do any of these at the appropriate level are lacking”, to provide a direct quote from the Ice Sheets and Sea Level Rise: Model Failure is the Key Issue post. Thanks Dr. Oppenheimer for taking the time to submit a post to RealClimate. Its always good to hear from the other members of the climate science community on RealClimate.

    Considering the effects that ice sheet behavior could have on sea level, shouldn’t that be a funding priority? There are lots of question about the climate that need to be answered. Wouldn’t it be better to understand more about the climate before we try to alter it?

    #250 (W. Hall) & 251 (John McCormick) proposals to add aerosols could run afoul of the Clean Air Act in the U.S., especially sulphates and metal particulates. A good summary of the Clean Air Act is here:

  3. 253
    George A. Gonzalez says:

    It is difficult to believe that the law, national or international, would stand in the way of an effort to save the planet. (It should be noted that environmental laws are regularly disregarded.) I would think that good sense would prompt us to ignore any statutes that stand in the way of geoengineering efforts to regulate the climate and/or CO2 atmospheric levels. If not, it would be tantamount to not putting out a fire because of laws prohibiting water damage.

  4. 254
    John L. McCormick says:

    George, you are not making any sense here. Read your comments before hitting the post button.

    by John L. McCormick

  5. 255
    W. Hall says:

    Geoengineering and Legality
    Contribution from Daniel Bodansky

    ‘For the purposes of this talk, Bodansky defines geoengineering as large-scale, intentional efforts to change the climate system. Climate engineering proposals include those aimed at removing GHGs from the atmosphere, for example, through afforestation or iron fertilization of plankton in the oceans and those aimed at screening out sunlight by injecting aerosols into the atmosphere to create cloud condensation nuclei and hence more clouds, by injecting dust into the stratosphere to screen out sunlight, by launching reflective balloons into the stratosphere, or by space mirrors or screens to act as a constant shield from the sun.

    Proponents of geoengineering claim that its benefits include technical feasibility (injecting dust in the stratosphere with airplanes or cannons), relatively low costs ($30 billion to inject dust), and administrative feasibility (wouldn’t require complex regulatory regime; could be done unilaterally without collective action problems).

    Problematic features include the fact that it is intentional (and thus attracts greater scrutiny), has global effects, involves high uncertainties (with an indeterminate risk of some thing going wrong), and non-uniform effects (winners and losers result). These features of geoengineering raise several governance issues. The fact that geoengineering is an intentional activity with global effects raises the issue of who should decide whether to proceed. Should all countries be able to participate in decision making since all will be affected and there will be both positive and negative impacts? Also, how should liability and compensation for damages be addressed?

    The fact that geoengineering is an intentional activity with global effects raises the issue of who should decide whether to proceed.

    There are not many precedents for how to address geoengineering in international law. Weather modification activities that took place in the 1970s are one precedent. In 1980, the United Nations Environment Programme (UNEP) produced a set of Weather Modification Guidelines. Weather modification was defined as “Any action performed with the intention of producing artificial changes in the properties of the atmosphere for purposes such as increasing, decreasing or redistributing precipitation or cloud coverage, moderating severe storms and tropical cyclones, decreasing or suppressing hail or lightning or dissipating fog.” Recommendations of the guidelines included:

    â?¢ States should undertake prior environmental assessments of prospective activities likely to affect other states or the global commons.
    â?¢ States should exchange technical and scientific information on weather modification activities through the World Meteorological Organization.
    â?¢ States should provide timely notice to and consult with potentially affected states.
    â?¢ Weather modification activities should be conducted in a manner designed to ensure that they do not cause damage to the environment of other states or of areas beyond the limits of national jurisdiction.

    The second precedent was prompted by the use of weather modification by the U. S. in Vietnam for military purposes. The Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques (ENMOD) was adopted in 1977. It prohibits any hostile use of environmental modification techniques, but was neutral regarding the use of such techniques for peaceful purposes. Relevant provisions
    â?¢ recognize the potential of environmental modification techniques to preserve and improve the environment for the benefit of present and future generations.
    â?¢ state that ENMOD does not hinder the use of environmental modification techniques for peaceful purposes, and is without prejudice to the generally recognized principles and applicable rules of international law concerning the use of environmental modification for peaceful purposes.
    A number of general norms in international law provide background and set the terms of the debate on whether climate geoengineering or similar activities should be allowed to proceed. These include:
    â?¢ Duty to prevent transboundary harm
    â?¢ Precautionary principle, which states that if there is a potential for irreversible or catastrophic harm, the burden of proof should be on those proposing the action.
    â?¢ Principle of intergenerational equity
    â?¢ Duty to undertake prior assessments
    â?¢ Duty to provide notice to and consult with potentially affected states

    The United Nation (UN) Framework Convention on Climate Change (FCCC) is silent on the subject of geoengineering. In general, it promotes scientific cooperation and mentions a duty to minimize adverse effects from projects to mitigate climate change. Most importantly, it creates a governance structure to address climate issues, including a Conference of the Parties (CoP) and a Subsidiary Body for Scientific and Technological Advice (SBSTA).

    In addition to general international norms and the FCCC, there are a number of specific norms that relate to climate engineering proposals. With respect to afforestation, if a country is planting trees in its own territory, then as a matter of international law this is a permissible exercise of national sovereignty because it takes place entirely within the country’s borders. But when one country wants to offset emissions by planting trees in another country, sovereignty and internal political issues may arise. For example, a national government may approve a tree planting scheme as part of an international agreement, but the local people may not want the trees planted in their area since it may have the effect of hindering development.

    On the subject of ocean fertilization schemes, the 1982 UN Convention on the Law of the Sea generally provides for freedom of the high seas for research and other peaceful uses. There is also the Antarctic Treaty System which contains no specific prohibition on ocean fertilization but establishes an effective governance system through the Antarctic Treaty Consultative Meetings.

    Regarding the space mirrors proposal, the Outer Space Treaty of 1967 applies. It says that outer space is the “province of all mankind” and any state is free to engage in peaceful uses. There is a duty to avoid adverse environmental changes and to consult with other potentially affected states if there is any question about adverse effects.

    Schemes to inject dust or release balloons into the atmosphere are the most problematic of the geoengineering proposals in terms of existing international law because the atmosphere above a country, including the stratosphere, is part of its air space. Nations have claimed this area and acted on their claims (e.g., by shooting down aircraft).

    Geoengineering proposals involving the atmosphere thus could be viewed as an infringement and incursion on national territory.

    The precautionary principle says, in essence, “when in doubt, don’t,” and this would probably be the general response to geoengineering.

    Although existing international legal norms are generally permissive, they are unlikely to be a reliable guide to how the international community will react if geoengineering schemes are seriously proposed. Instead, there is likely to be a great deal of resistance. Absent some crisis, there will probably be a drive for the regulation of these activities, and perhaps for their prohibition, because it is very difficult to discern what the inadvertent consequences of such proposals might be. The precautionary principle says, in essence, “when in doubt, don’t,” and this would probably be the general response to geoengineering. Some international precedents that might be relevant to geoengineering include:
    â?¢ Ban on Antarctic mineral activities
    â?¢ Ban on commercial whaling and driftnet fishing
    â?¢ Ban on ocean incineration and ocean dumping of low-level radioactive waste

    Thus, the ultimate obstacles to geoengineering may not be technical or economic, but may instead be political.

  6. 256
    W. Hall says:

    Re 251. Even before having read all of the links (for which, thank you) I will offer the following views, so as not merely to be in the role of inquisitor:

    Most geoengineering proposals seem to be extremely bad. In fact, if one is to describe them as a “cure”, then the cure seems worse than the disease. But this does not mean that “we” can or should be content with the disease as the lesser evil.

    One of the roots of the disease is recognition as a partner in democratic public debate of sources that should be excluded from such debate on account of their dishonesty. Toleration of disingenuous input exploiting public ignorance is an unaffordable luxury:

    Take for example this comment by Anne Ridenour on James Hansen’s decision not to participate in a recent congressional hearing on global warming:

    Exposure of all the realities concerning geoengineering (including the difficulties of legalizing it and resultant vulnerabilities to litigation, including litigation from people such as Anne Ridenour) would de facto silence input such as this bad-faith criticism of James Hansen by the National Center for Public Policy research.

    “Geoengineering” has climate scientists in a bind. If the mainstream political system through fears of being condemned for “censorship” is unable to cut the Gordian knot, alternative institutions must come into existence that are free from structurally inbuilt knots.

    The Social Forum system that has developed within the framework of the international movement against neo-liberal globalization is one such possible institution. At the moment the social forums are other-directed, the political control taking the form of a quasi-Leftist “political correctness”. But the influx into them of more clearly thinking and better informed citizens could emancipate the forums from this limitation.

    In the European Union, also, which has not yet fully crystallized politically and institutionally, there is perhaps greater leeway – and official demand – for the development of new policy-making institutions.

    Already the National Center for Public Policy Research and other NGOs of this kind would not have access to the deliberations of the Social Forums of the international movement against neo-liberal globalization. This already existing “censorship” mechanism should be taken advantage of and made more conscious.

    The declaration that the climate change debate “is over” must cease to be merely an assertion of one side in the debate. Today’s climate change “debate” with those described by James Hansen as “contrarians” must be evicted and replaced by a geoengineering debate whose starting point is recognition of reality.

  7. 257
    George A. Gonzalez says:

    re: #255

    I am normally a proponent of the precautionary principle — hence my objection to nuclear power. The difficulty is that CO2 atmospheric levels have probably already made the planet hostile to human life. It is only seemingly a matter of time before the catastrophic effects of CO2 emissions are fully felt. In light of this, geoengineering seems like a rational response. It is worth stressing that humanity abandoned the precautionary principle when it began pumping massive amounts of CO2 into the atmosphere, and deforesting much of the planet.

    Respectfully yours,

  8. 258
    Hank Roberts says:

    Here’s how volcanic sulfate plumes are tracked; the little one here wouldn’t have made much if any detectable difference in temperature and lasted only a few days, but it’s an example of what can be seen:

  9. 259
    W. Hall says:

    From the latest ‘Guardian’: ‘If a new breed of budget long-haul airlines have their way, Brits could soon be jetting off to Asia and America on fares costing next to nothing (save the irreversible damage to the environment). It has just been announced that from mid-October tourists will be able to hop from London to Hong Kong and back for just $130.

    Oasis Hong Kong Airlines is joining a small but expanding group of companies seeking to make budget flights truly global. First up was Canadian outfit Zoom, which in 2002 started to sell flights between transatlantic hotspots such as Calgary and Glasgow for $115. It was soon followed by India-based Air Sahara, taking Britons to India for less than the price of a weekly supermarket shop.

    So how can airlines whisk us around the planet so cheaply? It seems that low-wage Chinese workers and weak unions in Asia, coupled with ‘pay-per-frill’ services that force passengers to cough up extra for peanuts and blankets allow airlines to keep their costs to a minimum. But not everyone is reaching for their passport. ‘These kinds of ridiculously cheap fares are completely artifical,’ says Jim Footner, a campaigner at Greenpeace. ‘The whole plan is economically and environmentally unsustainable.’

    Who of the experts and insiders on this thread can provide us with an explanation for the ‘next to nothing’ fare prices phenomenon that insults our intelligence a little less than the above peanuts and blankets theories. Are these cut-price airlines (and perhaps other airlines also) receiving subsidies for geoengineering services rendered?

    I ask this question to everyone, but perhaps particularly George Gonzalez
    and John L. McCormick. If you don’t know, would you like to speculate?

    Perhaps I (or we) should try to ask Jim Footner in what way these cheap airline ticket prices are “artificial”.

  10. 260
    John L. McCormick says:

    W. Hall, with regard to your including me as a possible source of speculation on the economic sustainability of cheap transcon flights, I will not ascribe to any sort of collusion between airline operators, their insurance underwriters and geoengineering scientists.

    Plausable explanations might include venture capitalists free to invest speculators dollars into the business or the airlines willingness to fill their wide body cargo hold with high grade goods and deliverables for which the airline will be paid handsomely.

  11. 261
    George A. Gonzalez says:

    re: #259

    I imagine that airplanes would have to be specially fitted to deliver aerosols, and such a configuration would be evident to would-be passengers and/or other on-lookers (e.g., baggage handlers). I would also think that the most cost effective geoengineering operations would involve planes full of aerosols, as opposed to filling them with passengers and luggage. A covert geoengineering operation (if that is what you are suggesting) would most likely involve military flights — where airplanes are under less public scrutiny and much tighter security.

  12. 262
    W. Hall says:

    re 260 and 261. Of course this discussion on the economics of cheap flights is not taking us forward in the debate on whether geoengineering techniques should be legalized or banned. John L. McCormick has expressed interest in our pursuing that debate, and I am similarly interested.

    I have no view on whether the possible explanation suggested by John L. McCormick for the cheap flight phenomenon is likely to be part of the story, or the whole story. Wouldn’t it be worthwhile to try to get organizations such as Greenpeace that are campaigning against cheap flights to be more forthcoming in their responses to the question of how such flights are possible?

    As for airplanes needing to be specially fitted to deliver aerosols, in Gregory Benford’s 1996 article in Reason magazine the author says that: ‘Changing the fuel mixture in a jet engine to burn rich can leave a ribbon of fog behind for up to three months, though as it spreads it becomes invisible to the eye. These motes would also come down mostly in rain, not troubling the brow of the EPA. Fuel costs about 15 percent of airlines’ cash operating expenses, and running rich increases costs by only a few percent. For about $10 million, this method would offset the 1990 U.S. greenhouse emissions. Adding this to the cost of an airline ticket would boost prices perhaps 1 percent. An added asset is that quietly running rich on airline fuel will attract little notice, doesn’t even change sunsets, and is hard to muster a media-saturated demonstration against.’

    It would seem to me that changes in the engine fuel are not something that would necessarily have to be noticed by passengers.

    Also, if you look at this photograph from Airliners net

    the aircraft that is making this remarkable ‘contrail’ is identified as a Pakistan airlines passenger airliner, not a military aircraft.

    The anonymous insider to a geoengineering programme identified as ‘Deep Shield’
    also said in one of his interviews with the activist David Stewart (a person who is contactable and probably available for on-line interrogation) that both military and civilian aircraft were involved in the programme’s operations.

    David Stewart has said that he is not absolutely sure that the late
    ‘Deep Shield’ really was who he was claiming to be. Stewart’s interviews of the anonymous ‘insider’, cannot be treated as being of more than anecdotal significance, as he himself acknowledges. Nevertheless, the view is there, for what it is worth, that not only military aircraft are involved in geoengineering operations.

  13. 263
    George A. Gonzalez says:

    This was sent to me today. It is a synopsis of an article in the _Independent_:

    “Maybe I’m Amazoned at the Way I Really Need You:
    Drought could turn Amazon into desert, researchers warn”

    The Amazon rainforest — soon to be called The Artist Formerly Known as the Amazon Rainforest, and then just some weird little symbol — appears to be undergoing a second year of drought, and that has researchers seriously alarmed. Starting in 2002, scientists at the Woods Hole Research Center simulated drought on a small section of the Amazon and found that after two years, the trees began to die, fall, and release more than two-thirds of their lifetime storage of carbon dioxide. Widespread desertification of the rainforest would likely spread drought into the northern hemisphere; the Amazon contains 90 billion tons of CO2, enough to accelerate global warming by 50 percent, spinning it out of control and eventually making the world uninhabitable. Computer models predict that harm to 50 percent of the Amazon would represent a tipping point — after that, the whole thing starts going down the tubes. Today, about 20 percent has been totally razed and 22 percent has been harmed by logging. Oy. It’s only Tuesday and we’re already doomed.

  14. 264
    W. Hall says:

    I was not my objective to silence discussion when I started posting at this thread.

    Is the choice before us really one of conducting a censored or self-censoring debate or no debate at all?

  15. 265
    John L. McCormick says:

    W. Hall, I am still here.

    The August issue of Climatic Change printed the editorial essay of Dr. Paul Crutzen — Albedo Enhancement by Stratospheric Sulfur Injection: A contribution to Resolve a Policy Dilemma.

    He makes a convincing case and his strong reputation lends more rationale to his proposition.

    I agree with his basic premise:

    [Given the grossly disappointing international political response to the required greenhouse gas emissions, and further considering some drastic results of recent studies, research on the feasibility and environmental consequences of climate engineering of the kind presented in this paper, which might need to be deployed in the future, should not be tabooed.]

    As one who has voiced concern that geoengineering the atmosphere does not address the possibly larger concern of increasing acidity of the oceans, (reducing CO2 input is likely the only remedy) I must say his approach has merit.

    He advoactes cautious research steps and an initial trial that could be [stopped on short notice if undesirable and unforeseen side effects become apparent, which would allow the atmosphere to return to its prior state within a few years].

    Dr. Crutzen suggests a stratospheric loading of 1-2 Tg S and that compares to the 1991 Mt. Pinatubo volcanic eruption which injected an estimated 10 Tg S into the tropical stratosphere for which [Hansen calculated a radiative cooling of 4.5 W/m2 caused by 6 Tg S, the amount of S that remained in the stratosphere as sulfate six months after the eruption from initially 10Tg s]. Since we have recently witnessed and measured his idea on a much greater scale, we should have confidence the planet could tolerate his experiment.

    But, this is not my urging that we proceed! Make no mistake about this: any discussion of, or approach to, geoengineering cannot replace or diminish every conceivable effort to reduce global use of carbon-emiting fuels and deforestation.

    One has to be a pessimist to arrive upon such far-reaching and risky measures as geoengineering the atmosphere in a manner suggested by Dr. Crutzen. I confess my optimism is waning fast despite the projections of expanding renewable energy deployment and using topsoil to substitute for gasoline.

    This thread deserves more serious attention and discussion on last-hope measures (pulling the rip cord on the reserve parachute)and particularly pertaining to legal and societal implications.

    Our children must have available to them all the options we can provide (and that includes bioengineering and 4th generation nuclear power technology) because this generation is failing miserably where it counts most; a global recognition and acceptance that a 60 to 80 percent reduction of CO2 emissions is mandatory.

  16. 266
    W. Hall says:

    There must be many people who would like to challenge your views on nuclear energy but perhaps they don’t think this thread is the place to do it.

    My basic point is that the whole climate change debate would gain greater urgency if it were acknowledged that the “geoengineering” discussion is not theoretical.

    Whatever problems such an acknowledgement might cause, they are less than the problems that are caused by non-acknowledgement, which is a
    factor lending credibility to the cynical and humiliating contrarian jibe that climate change is a hoax. I marvel that scientists are able to stomach continual political humiliation of this kind without revolting against it.

  17. 267
    John L. McCormick says:

    W. Hall, your last paragraph made no sense whatsoever. On a more topical level, do you have any comments on Crutzen’s paper?

  18. 268
    W. Hall says:

    John L. McCormick did you read the paper on-line or do you have a subscription to the magazine “Climatic Change”?

  19. 269

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