Climate Feedback


I wrote a longish feature for Nature this week on geoengineering. It goes into various details perhaps a little deeper than some accounts have, and of course also leaves out stuff that in an ideal world it would have got in. The bottom line is that lowering the earth’s average temperature by putting long-lived particles of some sort into the stratosphere is, as has long been known, technologically feasible, and would alter the course of, but not completely stop, climate change. Crucially, as yet we cannot predict with any confidence what the net changes under a warming+cooling regime would be, and though there are signs they might be a little smaller than was once thought they could easily be large enough to be complete showstoppers. The article gives, I think, full voice to the uncertainties and risks involved (though I suspect some will differ, especially since the article has served as a springboard for the AEI, which makes this comment peculiarly ironic).

There are some things it doesn’t do: it doesn’t go into the fact that we have no way of deciding, as a world, whether to do this, nor of setting up reliable systems for managing a century long geoengineering strategy. (I say century long because the people I was talking to all seemed to be thinking about geoengineering as either a time-limited stop-gap to buy time for mitigation to get into full swing or as a way to take the edge off the worst of the warming that would accompany an “overshoot” in greenhouse gas levels before they settled down to a stabilisation plateau. No one, as I understood it, was talking about an open ended commitment that would allow emissions to go unchecked forever.) Nor does the article explore the fact that it would be conceivable for a country to embark on such a scheme unilaterally. It certainly doesn’t advocate doing anything along these lines, unilaterally or multilaterally. (It also doesn’t know its history, and lamentably gave Ralph Cicerone a Nobel prize that he doesn’t have. I am a fool.)

What I did try and do, at least a little, was explore the reasons why many researchers don’t even want to look at this issue. There’s a fairly widespread feeling that even studying it lends it a certain legitimacy, and that that legitimacy could be used as a rhetorical tool — or even as a basis for real-world programs — by people who have no interest in reducing CO2 emissions. I can understand this as a position; people obviously have a right to avoid doing research that they believe will be misappropriated. But that said I think that this view is at least somewhat on the wane. One reason is Paul Crutzen‘s intervention last year (see further discussion in the journal Climate Change). Another, I think, is increasing consciousness of ocean acidification, though this is speculation on my part, and didn’t as I recall make it into the finished article. Ocean acidification provides a really strong argument for cutting carbon dioxide emissions that geoengineering can do nothing about. Its acknowledgement may thus, in a strange way, provide people with a license to speculate about such ideas, since it allows all such speculation to carry the firm proviso that even if you did try geoengineering, you’d have to cut emissions anyway — that there’s no either/or.

Predating this, though, I suspect there’s been a feeling that even if there were no practical drawbacks to such schemes — and again, let me stress, there are — they would be inherently inferior solutions to the problem than limiting emissions. The idea is that changing human economies and societies (and for some more fundamentalist greens, human nature) is inherently preferable to changing the natural world. I followed David Keith in mapping these ideas onto the distinction Simon makes between natural science and the sciences of the artificial. Here’s where I ended up:

Although in the past two decades climate scientists have been confronted with the social, technological and economic implications of their work, they are not scientists of the artificial. Hans Feichter, a climate modeller at the Max Planck Institute for Meteorology in Hamburg, speaks for the vast majority of his colleagues when he says “the role of a geoscientist is to understand nature, not to change it.” Climate scientists have proved themselves happy to advocate massive changes aimed at shifting the climate. But they are massive changes in technology, in geopolitics, in social norms — changes that require the sciences of the artificial. Not changes in the workings of the stratosphere. Not changes in the natural.

In the past year, climate scientists have shown new willingness to study the pathways by which the Earth might be deliberately changed, although many will do so in large part simply to show, with authority, that all such paths are dead-end streets. But they are not willing to abandon the realm of natural science, and commit themselves to an artificial Earth.

It may be that that is overstated. For one thing, it’s clear that geoengineering, like mitigation, would also involve a large political intervention. Anyway, I’d be interested to hear your views.


  1. Report this comment

    Mark Bahner said:

    Oliver Morton writes, ""The article gives, I think, full voice to the uncertainties and risks involved (though I suspect some will differ, especially since the article has served as a springboard for the AEI, which makes this comment peculiarly ironic)…"

    And then he links to his response to my comment that quoted Joel Schwartz (a visiting fellow at AEI) as predicting that, even assuming gasoline usage increases by 2 percent per year from 2004 to 2024, NOx emissions from automobiles and light trucks in the U.S. are expected to decrease by 85% from 2004 to 2024.

    Just why do you think that comment was “peculiarly ironic”?

    I (approvingly) quoted Joel Schwartz as estimating that NOx emissions from automobiles and light trucks would decline by approximately 85% from 2004 to 2024. I quoted Joel Schwartz approvingly because I know (to an engineering approximation) he’s right. Not because of where he works. I don’t give a damn where ANYONE works on matters of science/engineering. All that matters to me is whether they are right or wrong.

    And how do I know he’s right (to an engineering approximation)? I know because I have a Bachelors Degree in Mechanical Engineering and a Masters Degree in Environmental Engineering, and have about 20 years experience in environmental analysis, mostly related to air pollution. In short, I know he’s right because it’s my business to know such things.

    Pray tell Mr. Morton, just what do YOU think will happen to NOx emissions from automobiles and light duty trucks in the U.S. from 2004 to 2024? And what are YOUR sources?

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    Tim Lundeen said:

    If we go the geoengineering route, it sounds like we will have to look at ocean acidification, which could potentially be solved through the large-scale plankton farming proposals; these proposals would also reduce CO2 levels.

    My own view is that techology is changing so quickly that we will likely have non-CO2 emitting solutions soon that are so much cheaper than oil/coal that they will have rapid uptake.

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    Eli Rabett said:

    Geoengineering is primarily a way to buy time, with the exception of carbon sequestration. IMHO of course.

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    Russell Seitz said:

    I’m glad to see Nature proper host a more nuanced introduction to this aspect of antropogenic change than that afforded by Quirin Schiermeier’s dismissive Nature News piece on CO2 sequestration via iron fertilization of phytoplankton .

    It is indeed ironic that AEI should weigh in , but at least it indicates that someone there is bucking the system by acknowledging the existence of the primary scientific literature , if only as a point of polemic reference.

    It will be interesting to see what happens on the other side of the political aisle – as can be seen:

    technical illiteracy remains a bipartisan problem as well as a source of bemusement.

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    Oliver said:

    Mark Bahner: If you think Schwartz’s figures are good for the US then I am happy to go along with you until I have cause to delve further; but I don’t think I said anywhere in the previous post that I was talking about the US. I quite agree that the fact that the AEI has an agenda doesn’t disqualify all scholarship associated with it, but I don’t think I said that it did.

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    Dan Wentworth said:

    Oliver, I found your article to be very informative. I thought it approached a delicate topic most tactfully. It was very clear that these were proposed as an emergency measures only and not panaceas, and they were filled with significant unknowns and hazards. The issues you mention now concerning world decisions and unilateral implementation are important ones, and would have fit in well, but frankly they came to my mind as I read the article.

    “Ocean acidification” did make it into the article as a downside to continued carbon emissions in the form of a quote from Wigley.

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    Hal said:

    My question is whether there is a consistent philosophical position behind the sentiment, “that changing human economies and societies (and for some more fundamentalist greens, human nature) is inherently preferable to changing the natural world.” People have been changing the natural world at least since the first caveman started burning logs. Taken literally, this philosophy would require renouncing technology and returning to an animalistic state. Perhaps “deep Greens” can endorse this view but the rest of us would be looking for some sort of a compromise.

    It is not the place of scientists to be making these decisions. They have their own motives and values which have driven them to an unusual and sometimes difficult career path, and we all salute their efforts. But their values do not necessarily match those of the larger society in a world where there is still much poverty and human suffering.

    One relevant factor not mentioned in the article is the relative costs of achieving a certain degree of cooling reduction by geoengineering versus GHG reduction. Several studies have found the economic cost of greenhouse reductions to be high, potentially dragging down future economic growth. Such costs are acceptable only because the alternatives are worse. But if geoengineering alters that equation by providing a lower cost pathway to mitigating warming, that is something the world would like to know about.

    I am frankly appalled to see scientists in effect boycotting the study of these technologies because they don’t like what people might do with them. Most scientists are publicly funded and work as part of an implicit social contract which supports their efforts in exchange for the valuable information they provide, the growth in human knowledge. Scientific objectivity should demand the courage to improve our understanding of nature irrespective of political correctness. Leave to the larger society the decisions about how best to utilize the knowledge science provides. Scientists should of course participate in that decision, but on an equal footing with all others who have a vested interest in the nature of future human society.

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    M. Simon said:

    I wonder how ocean flora and fuana survived when atmospheric CO2 was at levels about 7X current levels for tens of millions of years?

    Is there something special about the CO2 we make today?

  9. Report this comment

    Oliver said:

    M. Simon: nothing special about the carbon dioxide, but something very special about the rate of its increase, which outstrips the oceans’ capacity to buffer their changing pH. The Royal Society report I linked to in the post goes into some of the details.

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    Gregory Benford said:

    Here’s a larger look at a letter I wrote Nature already:

    While appreciating your treating of other solutions to global climate change in your May 10 issue, I wonder why your sidebars solely highlighted moral objections, not scientific issues. (As with, “The role of a geoscientist is to understand nature, not to change it.” — Hans Feichter)

    These plainly regard active roles as corrupt. Yet we are already engineering our planet inadvertently. Surely we do not want to privilege ignorance?

    We can regard these ideas, and the scientific knowledge we gain from such experiments, as tools in a possible future technology of putting benign aerosols in the high atmosphere, to rain out before reaching the lower troposphere.There could be many useful variables in such a climate technology, including particle size, particle nature, altitude deployed (and therefore duration in the atmosphere), and much else.

    This idea is only the first step in making climate science, which has always been passive, into an active science. Astronomy was passive until the space program began to give us the power to explore the planets a half century ago. We now do experiments on the soil of Mars, the atmosphere of Jupiter and Venus. With direct measurement comes a new era in any science.

    The thrust here is to use carefully our ability to attack warming at its roots — reflecting incoming sunlight now, as a bridge to lessening carbon dioxide emissions later. Given the magnitude of the warming threat to all societies, such preparations are merely prudent, not radical. Having only one slow tactic—emission reduction—is a huge gamble. We can study study several approaches now. For our proposed Arctic experiment, costs seem low—a few hundreds of millions of dollars a year.

    The idea is to learn by small perturbations how the natural system responds. Both science and engineering progress this way when dealing with complex, interactive systems—superconductivity, to take an historical example.

    It’s not as though we don’t know what high altitude aerosols do. Volcanoes have cooled our world repeatedly, notably in the Pinatubo eruption. That ejected enough aerosol into the stratosphere to decrease temperatures in the Northern Hemisphere for years by several tenths of a degree Celsius. When (not if) we get into trouble with an ever-warming climate, we will need to act.

    The time to do this research is now. As economist Robert Samuelson (who also doesn’t believe that emission restriction will work) recently said, “The trouble with the global warming debate is that it has become a moral crusade when it’s really an engineering problem. The inconvenient truth is that if we don’t solve the engineering problem, we’re helpless.”

    Gregory Benford Univ Calif, Irvine

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    piglet said:

    I’m sorry but the claim that “Global Warming is an engineering problem” is utterly foolish and betrays a very dangerous hubris. We have ignorantly managed to mess with the planet’s climate, and now you think we are qualified to solve that mess by “engineering” the planet a bit more? And what will you tell your children if your magic “enginnering solution” doesn’t work as intended? Or if it has some nasty side effects that the clever engineers didn’t think of before, as has happened often enough in the history of technology? Yopu should really know better.

    As to Robert Samuelson, what needed to be said about him can be found on the Scientific American blog:

    Btw Samuelson isn’t even an engineer, in fact he has no scientific qualification whatsoever so why trust him?

    [Moderator note: Piglet, a real email address (which as mentioned elsewhere we do not divulge) would be gratefully received. ]

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    Mark Bahner said:

    The debate on geoengineering is conspicuous not only in that moral issues seem to predominate over engineering issues, but also in that the geoengineering measures proposed so far have been so limited.

    To my knowledge, there has been no significant attempt at “brainstorming” regarding geoengineering solutions to climate change problems.

    For example, just today Kevin Trenberth has posted a comment about how global warmings should result in more and more intense hurricanes. However, has anyone seriously looked at geoengineering that could address both this potential problem and global warming itself?

    Tropical waters absorb tremendous amounts of heat primarily because they have such a low albedo (reflectivity). Geoengineering measures might be able to significantly increase the reflectivity of tropical waters. This would result in both regional and global cooling, and would significantly reduce sea surface temperatures (SSTs).

    But how could that be achieved? The possibilities are virtually limitless. A biogedradable white foam could be spread on large patches of ocean. This would make the waters at the earth’s equator much more reflective, and would also reduce SSTs. Alternatively, floating reflective balls or plates (again biodegradeable, or perhaps even edible by fish) could be spread on large parts of the ocean waters.

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    Hal said:

    There was an article in the September, 2004 Scientific American about controlling hurricanes to steer them away from populated areas or reduce their intensity:

    To the extent that storm damage becomes a major component of the additional costs of global warming, this may be an attractive mitigation strategy. The good thing is that localized weather patterns are thought to be chaotic, hence in principle small changes in inputs can cause large changes in effects. Exploiting chaos requires lots of information and simulation capacity, both of which are areas where future technological improvements should show real benefits.

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    Franz D. Oeste said:

    The geoengineering proposals made by Paul Crutzen, James Lovelock and others to burn sulfur or sulfur-rich fuel are disadvantegous because this measures will acidify land and water.

    Measures to cool the climate should work as close as possible to nature’s measures. Sulfur-rich volcanic eruptions emit lots of fine divided iron containing silicate aerosols along with lower parts of sulfur. Sulfuric acid generated from the emitted volcanic sulfur dioxide reacts within the atmosphere in contact with the iron oxide containing ash aerosol, oxygen and water vapour catalytically to sulfuric acid which than reacts by neutralization with the silicates to sulfuric acid salts and silicon acid. From this we may learn, that Crutzen’s and Lovelock’s geoengineering proposals are harmful and inadequate.

    In the early nineties K.I. Zamaraev described the loess dust clouds, eraising into the atmosphere, as “kidneys of the earth” because of their iron content which should produce hydroxyl radicals by photolytic reactions. Long known is the ability of iron salts as they are produced especially when coming into contact with air-borne ingredients like sea-spray, nitrogen oxides sulfur oxides, dimethyl sulfide, hydrogen peroxide or organic acids to decompose within the sunlight producing chlorine- and hydroxyl radicals, by Fenton- and photo-reactions raising the radical level within the dust cloud and by this oxidizing the greenhouse methane. Over that, the catalytic active iron compounds within the loess dust are readily oxidizing the natural occuring organics without the need of consuming the photo-produced hydroxyl radicals; thus all atmospheric radical power might concentrate on the oxidation of methane.

    We have lots of signs the climate may be cooled the more the loess dust concentration within the atmosphere rises. The analysis of the ice cores from antarctica and greenland have shown, that lowest temperatures, lowest methane- and CO2-levels correspond to highest dust levels correspondent and vice versa.

    Well known is the effect of loess dust falling into the ocean producing the phyto plankton bloom, sequestering CO2-Carbon by transfer of the dead plankton mass into the sediment as methane hydrate- and kerogen-carbon.

    On the base of the three main nature climate cooling priciples, the shading of earth by sulfates, the destruction of atmospheric methane as well as transformation of CO2 carbon by biological reduction within the sediments into methane hydrate carbon,I propose a cheap and sustainable geoengineering process:

    Mixing iron organics like ferrocene as additive into ship- and jet-fuel will produce finest devided pure fractal iron oxide aerosol particles with the exhaust gases. Reacting with the exhaust gas sulfur immediately after emission the iron oxide particles coate themselfes by sulate layer producing effective cloud condensation nuclei. As soon as the humidity rises, dense albedo-intensive clouds arise, cooling the earth physically. Ferrocene or iron naphthenate are used to minimize the soot emissions of heating oil combustion. Reducing the carbon soot production around ship- and jet-traffic lines will reduce additional the heat absorption within the troposphere. Comparing the catalytic and photolyic activity the combustion derived iron oxide aerosol with loess dust aerosol the further has several orders higher activity and as long it stays within the atmosphere it will clean off the methane.

    Falling at last into the ocean, the biological part of the combustion-derived iron oxide will start its work in the same way like loess dust.

    Comparing to all other geoengineering processes the here proposed will cool better and this will do no harm to men and environment at all and this will need nearly no expenses!

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