This is not a document cast in stone, but a non-technical draft proposal. Anyone with doubts, queries, suggestions, objections, or corrections should please feel welcome to contact me.

If you do so, please let me know whether your correspondence is in confidence, or you would like to be credited with any changes or additions that you might inspire.

Of course there also would be no hard feelings if you preferred to write an independent document of your own without consulting me.

Why Read This At All?

I suppose he's entitled to his opinion, but I don't suppose it very hard.
Isaac Asimov

This essay discusses certain options for climate engineering that seem to have been neglected or denigrated in many publications up to the time of writing.

By adapting our strategies for controlling our climate, to concentrate on certain of the major paths by which heat enters or leaves Earth’s atmosphere, we could adequately correct or override any foreseeable warming or cooling trends, whether anthropogenic or adventitious. An important illustrative example is that intelligent use of cationic materials dispersed into the high troposphere and low stratosphere offers particularly attractive options. Simultaneously it could hasten the recovery of the ozone layer from damage allegedly caused by anthropogenic halogen compounds.

Such concerns and associated options are of course closely associated with global energy supplies, distribution, application, and consumption.

Global Warming, Scepticism, Agnosticism, and Denial

Gall's Vector Theory of systems:
Systems run best when designed to run downhill.
John Gall Systemantics

Though such a precaution should not be necessary in a document of this nature, I begin with a few of my background opinions and disclaimers. Please note however, that those are not what this essay is about. The main reason I mention them at all is that otherwise it is certain that many readers will ascribe prejudices and intentions, and more often personal interests, that have nothing to do with either me or the thesis of the article. I am vividly aware that some readers will ignore this protestation, but I know better than to take such persons seriously.

Firstly then, I disclaim any connection, professional or otherwise, with any company, government, industry, political party, formal or informal group or institution whatever, whether directly implicated in the climate change debacle or not, either at present or in recent years. Also, I write this at nobody's enticement, pressure, or instigation but my own. (That at least I do not expect anyone to doubt, especially anyone who knows me!)

I have my own views (though not verdicts) on global warming, anthropogenic global warming in particular, its reality, context, desirability and undesirability. However, those views are of little relevance here and to discuss them gives rise to more hysterically dogmatic digressions than I have the patience to deal with. Accordingly I do not choose this platform to defend my views on the subject. Anyone wishing to attack or endorse them is welcome to being ignored, but my natural kindness moves me in advance to assure everyone in such a category that the chances that they have correctly attributed to me any views on the subject at all, are negligible. So such persons should not let their feelings be hurt at being ignored.

I cannot think of any other issue in recent decades that has given rise to such a scale, variety, and intensity of ad hominem and often outright unethical polemics, invective, dishonesty, and flat incompetence, in scientific matters that should be dealt with as matters of fact rather than matters of opinion.

Mind you, I wrote this years before the CoViD19 drama, and I admit that the likes of the associated anti-vax virulence leaves me unwilling to judge between them and anthropogenic global warming hysteria.

The principle of GIGO, "garbage in, garbage out" has widely been ignored in disciplines where people should be keeping it permanently and prominently in mind. Similarly, computer modelling has been misapplied and the results widely cited as conclusive arguments in contexts where, logically, only empirical evidence could be persuasive, let alone cogent.

Along the same lines, statistical techniques have been misapplied in contempt of the fundamental principle that statistical analysis can give meaningful answers only to meaningful questions in meaningful contexts, and in particular only to the extent that it is based upon sound data. Statistics is another prime example of a discipline subject to the principle of GIGO.

A disturbing observation is that on occasion, in defiance of the stated standards of certain journals, data on which formal publications were allegedly based, were not tendered, leaving one wondering about their soundness or the very point of their standards of refereeing. In at least some cases the data remained unpublished in the face of legitimate requests for their release. Sometimes even the validity of the data was left in doubt, leaving readers wondering why published articles referring to those data were not withdrawn.

Another annoyance is that both the authors of such publications, and public figures prominent in the arena of anthropogenic climate change, have repeatedly latched on to and generalised conclusions based on investigations conducted in limited contexts. They have applied such material as universal truths in the face of common sense observations; in brief, the assertions commonly fail embarrassingly to apply in various systems that are geographically separated; they also fail to match climatic realities within recent history (the last few centuries, say), much less during palaeontological periods.

Perhaps not worst, but most obviously offensive, has been the substitution of invective for substance in a field where such things have no place and should be unthinkable. I never thought I would live to see the day where in the context of scientific contention, words like "denialist" or "sceptic" would be applied as invective in default of factual or logical argument. No more did I expect that dissent or even doubt should be likened explicitly unto holocaust revisionism, genocide, and similar abuse more appropriate to the correspondence columns of sensational tabloids, or repartee in trailer park trash television actuality shows.

It all leaves me with a growing conviction that anyone practising or publishing as a scientist should be subject to professional discipline of a strictness comparable to that in the medical field.

These are nauseating reflections, but very relevant, if only as background to the point of this essay. I have little to say either for or against the banner arguments of the currently popular schools of contention in the field of anthropogenic climate change. I simply present recommendations and lines of thought that are of urgent importance almost irrespective of who might be right or wrong.

Let us consider some such.

By now unoriginally, but along with many other things in this essay, I have been saying this for a long time, I start by pointing out that: climatic change is perennial, and though change is inconsistent from place to place, in particular differing substantially between the Northern and Southern hemispheres, it certainly is ubiquitous.

It does not follow that such change, "natural" or otherwise, is benign, much less desirable to humanity. Changes have included the beginnings and endings of ice ages, the creation of deserts, disastrously hot, dry, wet, or cold places, incidents and periods, and both local and global disasters of many kinds, often repeatedly and sometimes rapidly.

In this shouting match I can hardly think offhand of a non-trivial point that any parties have denied without other parties affirming it, and given that this must be obvious to anyone who has followed the action even at a trivial level, it is startling to see how partisans will snatch at any opportunity to quote isolated results as a basis for general arguments, and behaviour of a model as the behaviour of its intended object. It has got to the point that I ignore reports of new record temperatures or rainfall (high or low or displaced) out of sheer boredom, let alone scepticism and irritation.

Particularly nonplussing is the way that journalists will ride the anthropogenic global warming bandwagon with reports along the lines that such and such a place has experienced the (check one of: hottest, coldest, wettest, driest) (check one of: day, month, season, year, decade) for (check one of: a year, a decade, several decades, a century, several centuries). (And no, I do not exaggerate!) What on earth could they possibly have in mind? If those conditions were not a global disaster the previous times they happened, then what is so special about our situation, either now or in the next few (check one of: seasons, years, decades, etc)? Now if they had said "since the Permian", or "since the Cretaceous", it would be interesting if believable, but since the 1990s...???

The technically illiterate will always be with us, I am sorry to reflect.

As a biologist, and one to whom every species is precious, I strongly disapprove of pollution of every pernicious sort, including gross ocean acidification, ultraviolet radiation, cooling, and warming. All the same, the routine hand-wringing over the gross extinctions to be expected are annoying, when other causes are equally probable. Again and again we get routine panicking over the highest or lowest temperature, rainfall, or hurricane frequency since… say a decade ago. Meanwhile, granting that there may be genuine damage, the fossil record shows that say, corals, and foraminifera or other plankton have survived far more drastic circumstances time and again, sometimes without obvious damage, sometimes with reasonably quick recovery, and sometimes with selective loss, adaptation, or redistribution of species.

As long as the oceans are full of plankton or other small organisms with short life cycles, one can be reasonably confident that natural selection will drive rapid adaptation to changed circumstances. The adaptation might certainly involve much pain or dismay (read Steinbeck's "The Grapes of Wrath") and I do not ignore either the associated losses, nor neglect to rail at the parties that caused or failed to provide for such events, but hand-wringing and tirades are no substitute for sense or constructiveness.

The UV intensity has risen, has it? Perhaps, perhaps not. Plankton has died as a result, has it? Perhaps, perhaps not. Its daily cycle of surfacing and sinking has been disrupted, has it? Still perhaps, perhaps not. Each and every one of those would be a disaster, yes?

Wait for it... Perhaps, perhaps not.

Please don't quote me as affirming or denying any of those here.

All I would pin my faith on, is that a change of such a nature, if real and intense and novel, would drive adaptive selection at high rates. This emphatically does not imply that such matters are trivial, but it does challenge predictions of large scale exterminations, let alone extinctions.

Even more, and far more importantly, it does challenge the idea that all that can be done, or should be done, is to reshuffle or re-deal carbon credits.

A question frequently begged is whether the optimal climate for the world as we know it is the climate of this century. Oops! Bad example… Well, say mid nineteenth er, eighteenth, er, seventeenth. . .

Well, would you settle for tenth century?

Everyone has been complaining about the weather for as long as we have records, formal or informal. If we are indeed moving into new record figures for the last 15,000 years or so, that is to say for about as long as we have had anything resembling agriculture, then are the new records good or bad in the long run?

And, if bad, whose fault is it? Even when I was at school there was idle science-fiction speculation about how marvellous it would be if we could melt the poles. I now regard the problem of melting the poles as fairly trivial, and the concomitant benefits or disasters as less obviously attractive, but the point is that it is by no means a simple matter to define any optimum to suit all points of view. In particular it certainly does not follow that we can simply point at a given year and say: "That is the correct climate for this planet and anything else is the fault of human folly and accordingly evil."

As for the greenhouse effect, without going into details on its true technical nature, it is plain that we need a greenhouse effect, or we all would freeze.

How intense we need that greenhouse effect to be is a totally different question. Which greenhouse materials we need in our atmosphere, in which concentrations, in which areas and at which altitudes and wavelengths, all are vexed questions.

But you would not think so if you went by the media.

The commonest assumption is that carbon dioxide concentrations are causing global warming, and are doing so anthropogenically and harmfully, and doing it in response to the combustion of fossil fuel. Occasionally some technological sophisticate mentions methane.Hardly any mention water.

I certainly disapprove of wanton combustion of fuels, especially fossil fuels, but that disapproval is for largely different reasons. My favourite cliché for decades has been that burning fossil fuels makes as much sense as burning banknotes: it is a filthy, unconstructive waste of precious materials. Frankly, I suspect that by the time we have consumed all our fossil resources, we should be looking at problems of our oxygen supply, never mind energy! So far burning fossil fuels has hardly been avoidable, but we should long ago have been looking seriously at the alternatives. And burning biomass is at best slightly (and not necessarily) better.

Irrespective of such considerations, in my opinion, for what that is worth, climatic change is inevitable and perennial. It simultaneously may be variably beneficial, harmful, or disastrous, all of those largely simultaneously.

I am firmly of the opinion that vast amounts of total rubbish have been spoken on such subjects recently, largely to make political capital, and that some of it has been ill intentioned as well as ill conceived.

However even that is not what this essay is about.

The main theme is that whether climate change is real or not, anthropogenic or not, desirable or not; it can be controlled, practically, economically, flexibly,
and on a larger scale than any foreseeable climatic excursions might demand.

So: to neglect the development of such technologies
is criminal.

And such development has been neglected for decades too long

As I see it our technological and infrastructural options for necessary control measures are at once adequate and practicable. Some could be mainly global or at least hemispherical in their effect; some could be applied regionally.

There are limits of course: if Earth suddenly were hit by a salvo of super solar emissions, each on a scale to dwarf the Carrington Event, or a shower of comets, each one of dino-killer size, or an explosive version of the Deccan traps eruption, or any of a number of events, similarly trivial for the planet, but globally lethal for humanity, we could not do much about it. For just that reason however, we may as well ignore any such prospect until we are ableto re-establish human civilisation (if you will excuse the term) somewhere off this planet.

How bad control can be

Positive, adj.: Mistaken at the top of one's voice.
Ambrose Bierce — The Devil's Dictionary

I have been of the opinion, long and loudly, that various forms of effective geoengineering aimed at control of the climate not only could be practical, cheap, and relatively quick, but should be compulsory. Mind you, in context I dislike the term "geoengineering", which seems far too broad to deal with what in the current controversy amounts to no more than tinkering with the climate. Be that as it may, Luddites claim that even to investigate anything of the kind would be prohibitively expensive and extremely dangerous. It would be impossible to predict, control or reverse.

And of course, irremediably immoral. Any progress simply would encourage the major culprits to continue their abuses.

Frankly, in my opinion, the Luddites simply dread the loss or vitiation of their pet doomsday prognostications.

Now, if I were to claim that climate engineering is a simple matter, or that it should be easy to control the weather, that would be different; it is not and cannot be: the systems under consideration are at once complex, chaotic, and on a huge scale. However, I do argue that, whereas full control is not a realistic prospect, a modest degree of climate control should be adequate to stave off disaster, and, possibly paradoxically, is an altogether less formidable challenge than weather control. It probably would be cheaper as well.

Also, in my not very well informed opinion, we already have been changing the climate to a considerable extent and not till recently most dramatically by contribution from carbon dioxide, which I suspect still to be a side issue of greater practical importance to politicians and profiteers than climatologists.

Whether in consequence of pollution or other influences, whether by human agency or natural processes, some regions have warmed noticeably during various recent periods, and others cooled. For the most dramatic and facile example of anthropogenic change that I can think of, readers may recall the flight ban over the United States immediately after the 9/11 disasters. Reduction in condensation trails led to significant local warming, not just within years, nor yet weeks, but within days.

Notice that the cooling effect of the condensation trails plainly did not result from the large volumes of carbon dioxide that the aircraft emit; it was in fact the exact opposite of the effect that one would have predicted if the greenhouse effect of the carbon dioxide were the dominant influence of the trails.

Notice too that it is common ground among the technically literate, that water molecules are far more powerful infrared absorbers than carbon dioxide. Remember also that a wide assortment of techno-sceptics have long argued that cloud cover should in general lead to increased climatic warming rather than increased cooling.

Well, such observations are of great interest in various contexts and in both directions, but the important thing from our point of view at this point in this essay, is that rapid, drastic, economical, and controllable effects on weather and climatic variables are at our disposal, and that our practical expectations should be based on empirical observation and experiment rather than handwaving.

Since I wrote the original version of this essay, I have read the following article in the Journal Nature: https://doi.org/10.1038/s41467-023-42891-2 (peer reviewed and all that Good Stuff! Stuff that I have girded at for years, in case anyone accuses me of bias!) And what is its burden? The following quote is from the abstract:

...results suggest that the future aerosol reductions significantly contribute to
climate warming and increase the frequency and intensity of extreme weathers
toward carbon neutrality and aerosol impacts far outweigh those of GHGs and
tropospheric O3. It reverses the knowledge that the changing GHGs dominate
the future climate changes as predicted in the middle of the road pathway.

My insistence on the cooling effects of particulate sunshades has left even myself weary of the sound of my nagging, so forgive me while I smug.

Green zealots swear that all intervention based on principles derived from such observations necessarily must be uncontrollable, irreversible, and ecologically harmful. They dismiss the most reasoned objections out of hand with sweeping assertions on "unintended consequences".

All such arguments I reject categorically.

Before anyone hastens to point out that the best-laid schemes gang oft agley and that unintended consequences are practically universal, let me forestall them.

Yes certainly! Any option whatever can go wrong, and emergent consequences are universal.

And doing nothing in particular is also an option, commonly one of the most important. And it is an option that can go wrong as easily and drastically as any other. We have been doing a lot of nothing in particular lately and that option clearly is going wrong as we talk.

That is the precise problem. Had we intervened with a bit of foresight (fat hope!) the current debate would at least have taken a very different form. Talk about unintended consequences! It is high time to try other options. There is no more reason to fear ecological harm from responsible climate control programs than from any other reasoned measures, definitely including reasoned inaction.

As for unreasoned measures. . .

The very zealots who condemn any thought of climate engineering are only too eager to promote the idea of drastic, expensive, useless options, most prominently reduction and removal of carbon dioxide. It seems that such "green" interventions need not pass any tests of reasoned evaluation of their risk, timing, effectuality, and unintended consequences.

In short, blanket condemnation of intervention just won't do.

Historically whole classes of action and reaction have turned out to be incidentally beneficial, particularly in ecological terms. For example many marine constructions such as drilling platforms and breakwaters that had attracted adverse and alarmist criticism at the stage of planning, rapidly developed into protective and productive reefs and fish nurseries. Discharges of coolant water from nuclear power plants attracted warmth-loving organisms and promoted their propagation. The best spiny lobster fisheries in many regions are at sewage outfalls.

Such effects might even be the rule rather than the exception. In fact the only exceptions I can think of arose when the new system was associated with gross pollution or gross damage to ecological components such as mangrove forests and reefs, or the cutting off, deviation, or speeding up of river inflows or ocean currents. Granted, there have been plenty such harmful examples, but on what principle must we accept that harmful intervention is the only possible kind of intervention? Some projects proved beneficial simply by incidentally excluding exploitative fishing, thereby constituting de facto nature reservations.

There are many similar examples. Certainly it is much easier to produce harmful effects than desirable ones, for instance by abuse of rain forests, or by causing disastrous erosion, silting, or pollution; I could weep to contemplate Madagascar or New Zealand, among dozens of similar examples. But commonly the reflex hysterical subjunctive is as counter-productive in applied ecology as in other fields.

Consider in particular the claim that so-called geoengineering by injecting material into the stratosphere is likely to be both irreversible and unpredictable in the direction of the effects. This is a priori ridiculous and in practice it repeatedly has been shown to be ridiculous. For example practically every major explosive volcanic eruption injects far more dust, gas and liquid into the stratosphere than any human initiative could do, and yet the stratosphere clears itself within months or in the worst cases within a few years.

And those cases really are exceptional. We don't have a Tambora every year. And without exception such cases led to cooling; not warming.

Secondly, emissions from commercial aircraft have caused dramatic local climatic changes in widely scattered areas around the world; and always where the traffic was considerable.

Conversely, some other areas have hardly been affected. In my own experience a contrail in the comparatively dry air of South Africa is fairly unusual. A contrail that lasts an hour in this country is exceptional, only to be expected in limited regions and particular seasons. Though I have no hard data to go on, I should be surprised if local flying activity has had any noticeable climatic effect, even though the major local airports support significant activity.

In contrast, in Europe I have seen many contrails that not only persisted, but visibly built up into banks of clouds. Again without hard evidence to date, I should not be in the least surprised to hear evidence that even at comparatively minor airports in such regions, they had indeed had material climatic effects.

In regions where air travel has been halted temporarily we repeatedly have seen those cooling clouds go the way of all clouds in their own good time, leaving warmer weather behind them. The 9/11 observation was dramatic, but hardly novel.

Some changes resulting from such influences have been regrettable, others desirable. It all depends on local circumstances. It would be irrational to expect every change to be purely good or purely harmful. Intelligently planned interventions in particular might be expected to be ecologically beneficial, and where expectations prove to be invalid, the reversibility of such interventions enables us to adjust our errors comparatively harmlessly. More often than achieving either gross disaster or pure success, we find that we must modify our strategies and adapt our measures. Radical cancellation of a program at the first signs of untoward effects rarely is the most rational response.

Thirdly, it makes no sense to expect such interventions to be uncontrollable. One probably could think of examples of intervention that theoretically might turn out to be insufficiently controllable to be useful, but the simple facts are that most interventions under consideration here are on a very large scale and affect systems with considerable internal negative feedback and time lag. We cannot simply snap our fingers to produce a Tambora-type volcanic injection of dust into the stratosphere. The implication is that any realistic process will take effect relatively gradually. This in turn suggests that we usually could correct such a process simply by stopping doing whatever threatens to do more harm than good.

Certainly the planetary climatic system in which we are working is both chaotic and extremely complex. Some argue that it follows that any intervention could as easily lead to outright disaster as to transient benefit. That inference however, is simplistic and unpractical. It would militate just as strongly against any attempt to reduce carbon dioxide levels, as against any other measure such as ocean fertilisation. Mature real life systems tend to include high degrees of negative feedback.

If things were otherwise no living systems would have been left on the planet after the first few million years, whereas in fact we repeatedly have had both beneficial and disastrous modification, collapse, or growth of major ecosystems during billions of years. Some were local. A few were planet-wide. Some lasted weeks or years, some decades or centuries, some tens of thousands or tens of millions of years.

Some have not reversed in hundreds of millions of years, of which the most extreme and arguably the most disastrous may have been the original increase of oxygen in the atmosphere.

We certainly do not want to cause anything that would show in the geological record as a disaster in our time, though, let's face the fact: the rise of “civilisation” has done so already. All the same we need not spend every day worrying about total global collapse just because a butterfly chaotically flapped its wings in Texas.

For what it is worth, I reserve judgement on many of the loudest assertions about current global warming, but irrespective of their merits, I still think that we should be studying options for climate control such as those I discuss in this essay. However dramatic the current effect of anthropogenic climate change may be, climate always is changing, not always for the better, sometimes perniciously, and it is high time that we learned what to do about it.

Now let us consider some examples of interventions that might be relevant to concerns about climate change.

Needs and options

Anybody can-a make-a car stop, but it takes a geeenius to make it go!
Peter Ustinov's Gibraltar Grand Prix

Warner's Curse

Everybody talks about the weather but nobody does anything about it.

Attributed to Charles Dudley Warner

Climate comprises far more than just warming or cooling. There also are such things as rainfall, wind, illumination, electricity, chemical effects, and all the events that go to make up the weather. However, the flow of energy, particularly in the form of heat, arguably is the most fundamental variable of all. In many respects the available heat and its distribution, control humidity, wind, and all their various consequences. Accordingly our interest in global and local warming or cooling are well justified.

What is more, if we are to think of controlling the climate, we need to think not merely in terms of cooling the system, but also in terms of warming. It is not rational to build or buy a car that can only accelerate or only brake; competent driving requires both. Just a few decades ago the fashionable concern was about global cooling and at that time it was no more irrational than the current concern about global warming.

These observations suggest that controlling the energy flow within our climate should be the most promising prospect for achieving our major objectives. Such control certainly will strain our resources of good sense, but without good sense we need not bother with the problem at all.

Note that the sheer scale of the heat supply, drainage and flow is so vast that we cannot realistically control the climate directly by supplying or depriving the system of heat; instead control must be indirect. Examples include feedback controls to deflect the flow of heat, for instance by judiciously applied reflection or absorption, not by direct transport. Analogously we would prefer to move a river by parsimonious deflection, not by carrying all its water into the new channel.

Our main source of heat on the surface of our planet is sunlight. It follows that if we can do enough to control the flow of sunlight, either directly by affecting the input, or indirectly by controlling the flow of infrared light from heated objects, we probably can reduce the whole problem to acceptable proportions.

This observation is sufficiently obvious to have prompted proposals for sunshades in space, typically at the Earth/Sun L1 point. Fortunately the sheer impracticability of such a scheme for a species that cannot even make a decent space station, rules it out for the present. If by some disastrous fluke we did manage to station such a ruinous white elephant, it would be for all practical purposes impossible to apply its effects selectively. Why on earth do so many people seem to think that too much sun over all means that you can solve your problems with one sunshade? This is typical of the grade of thinking that leads to so much nonsense in the geoengineering proposals in the popular press.

Down here, controlling our heat flux from the sun is not as simple as it sounds. We cannot assume that because we have let more heat into the system, we necessarily have caused everything to warm up. There is a great deal of feedback, and some of that feedback is negative. The most prominent example is that warming up the system causes more water to evaporate and form clouds. That cloud might cause some regions to cool down more than the heat had warmed up other regions.

First let us consider some examples of where we wish to conserve, redirect, or harness heat.

Holding onto Surface Heat, or Rejecting it.

Science and religion definitely are compatible. For example:
you need scientists to make bombs, but religious people to drop them.
Worryingly, we seem to have a lot more religious people than scientists. Anon.

It may seem odd to begin a discussion on global warming with subjects such as the conservation of heat, but it all is part of the same control system. For instance if we successfully cool down the planet in general we might find that some local areas require more warmth, not less. In some places we might wish for increased evaporation or the melting of snow or ice. Large reductions in evaporation cause major droughts. Recent ice ages were periods of such global drought that sea levels dropped by tens of metres or more, and deserts were created.

In those days Britain was part of Europe and the English Channel and shallow banks of the North Sea would have been better farming and hunting territory than most of the surrounding countryside is today. Similarly, within sight of where I live there is a large bay that less than 20,000 years ago used to be a valley.

Whatever caused the big melt some tens of thousands of years ago, we can be sure of one thing: if the likes of us had been present they would have regarded it as a disaster beside which our current fears of anthropogenic global warming would seem minor. I don't know how large an area of what used to be valuable land, either seaside or island, is now under water, but it certainly would have been huge, larger than many countries today. And yet, would it have been rational to prevent the melt and continue living with the threats of the glaciers of those days, the danger of their melting, and the deserts parched for lack of the water locked up within them?

There is no definitive answer to that.

Nor did climatic excursions stop there. Localised, comparatively minor, century-long droughts in historic or near-historic times, have shaken or actually destroyed civilisations. Long before the increasing output of CO₂ of our times even suggested any climatic significance; this happened repeatedly. We must not let ourselves be blinded to other important considerations by anyone's obsession with warming and hockey sticks, whether revisionist, jolly, or otherwise.

For one example of why we might wish to cause warming, remember that a popular horror among the doom mongers is that if we apply any forms of climatic adjustment, we might not be able to stop their effects if our cooling turned out to be more effective than we expected or desired. Like so many sorcerers' apprentices, but without the master magician to save us, we would be destroyed by our own meddling. Apparently pessimists feel that the merest tinkering to stop us roasting would doom us to freezing, if not to unexpectedly accelerated roasting.

In practice, should we find that we had overdone our planetary cooling, we should be able to reverse the process, simply by stopping the offending measures, and by melting snow, darkening surfaces, and thereby generally increasing solar absorption in strategically chosen regions. Seasonally spraying suitable pigments over snowfields, boreal vegetation, and deserts, at about 1 mg/m² should be adequate. A few heavy cargo aircraft should be able to cover millions of square kilometres per year, decreasing reflection and lengthening growing seasons.

All these are examples of short-term measures. We could discontinue them overnight, and reverse any of them within a year or so. Such actions would be safe, effective, non-disruptive, and cost millions rather than billions of dollars annually. They would be applicable on either a global scale or certain regional scales. It should be interesting to see what we could achieve by regionally cooling ocean surface temperatures seasonally to reduce tropical storm intensities, or tame the major oceanic oscillations, or banish el Niño, or ensure regular monsoons…

Any takers for modelling the requirements and effects?

However gloomy the idea may seem to gloom merchants, we could relegate global warming or cooling problems to history, but we would need serious projects and real-world measurement to control feedback. It seems likely that we could achieve more with less investment, than current international conferences with their corruption and slanging matches over rival computer models and carbon trading.

Failure to move at all, for fear of adverse effects, would show that for the international brotherhood of career politicians, their travel perks count for more than our future. A pandemic on them all, say I.

Surface albedo adjustment

Pushing on the system doesn't help.
John Gall: Systemantics

Apart from controlling droughts and melts, there can be many reasons why we might wish to cause an updraught in a given area, and the most obvious way to increase warming, updrafts, and evaporation is to darken the surface on which the sunlight falls.

Lightening the surface gives converse effects.

Those are the most obvious examples of surface albedo adjustment.

Surface albedo reduction is a class of options for melting surface ice and snow by spraying various pigments or microbes.

Conversely, instead of adjusting surface albedo to conserve or capture heat on cold surfaces, we could cool hot deserts by brightening them, or we could increase updrafts by darkening suitable areas of already hot ground. It might be worth investigating the degree to which we get similar darkening effects from fields dedicated to solar electricity generation. Updrafts can cause cloud formation, precipitation of rain, or deflection of winds. They also can cool ground areas by convection. All such effects might be important in various contexts. For instance clouds from a warm area can cause cooling in adjacent areas.

And wherever we generate large volumes of local updrafts, we might find it practical to extract precipitation from the cooling of the rising air. As an incidental effect of such updrafts, some deserts might be converted into arable regions.

Some people have proposed that we whiten road surfaces. Such a whitened surface strikes me as probably difficult to maintain, hard to drive on, and inadequate in effect, but at least it suggests a positive attitude. The idea might prove more effective when electric vehicles have come into general use, dirtying concrete road surfaces less than internal combustion, I suppose. I read that investigations have shown that in some regions pale concrete paving instead of asphalt, has given gratifying results. However, as always, simplistic assumptions are treacherous; in some situations, such as city streets among skyscrapers, pale paving has proven troublesome in reflecting heat onto surrounding buildings.

Still, even that is encouraging rather than alarming; it does show that the amount of heat reflected can be significant.

Conversely, some "acres of glass" skyscrapers have proven intolerably bright, reflecting heat downward, baking parking lots or buildings below; this too, implies opportunities. The availability of so much energy suggests either that it is worth deploying photovoltaic panels to intercept the light, or at least to assist in cooling the planet by placing grilles over the glass to reflect the heat back up, without interfering with incoming horizontal light or light from below.

It also suggests the possibility of profitably intercepting much of the city insolation with photovoltaic panels.

Proposals to whiten roofs might make sense too, especially in torrid countries, though roof area is only a small percentage of land surface area in most regions, and roof space is coming into more general use for photovoltaic electricity generation anyway.

Options for controlling solar radiation by strategically warming or cooling oceanic surfaces, offer important opportunities, whether for affecting ambient temperatures or raising the water content of the air and thereby increasing precipitation downwind. Less obvious objectives could be desirable as well. For example, if desert updrafts or offshore evaporation could counter El Nino effects, droughts, or monsoon failures, we should learn about such needs and opportunities as soon as possible, rather than wait until millions of people have already been exposed to avoidable famine.

There is nothing obscure or speculative about decreasing the albedo of land. We all have experienced the difference between the temperature of a tarred road in the sun and ordinary bare earth. And only the toughest bare feet can endure the temperature of dark paving, where white-painted surfaces are quite comfortable. Every glider pilot is intimately aware of the effects of dark surfaces and light surfaces below. Since I first wrote on the subject decades ago, the inadvertent deposition of carbon black and other dark pollution on snow and ice actually has been blamed for rapid melting of winter snow. It is possible to darken huge land and forest areas comparatively quickly and harmlessly by say, spraying just a few tonnes of carbon black from large aircraft, as I already have suggested.

Note that this does not imply blackening the landscape. Apart from expense and danger to health, a visible layer of carbon black would be harmful and in practically all places unnecessary. In a practical programme the probable applications of carbon might be of the order of milligrams per square metre, amounts that no one would notice as a rule; less than in fact many a slum is exposed to daily.

Carbon black absorbs light very effectively, but in spite of its cheapness and convenience it may not always be the pigment of choice. Some organic dyes should be about equally safe and effective, not especially expensive, and would have the incidental advantage of a more limited lifetime in the open. The likes of crystal violet and malachite green should do nicely. Sunlight and other influences should break down most such dyes within weeks. In some circumstances transience might be a disadvantage but for many strategies it is a useful option.

Engineering is largely a matter of intelligent choice of options.

Depending on available resources, there are other ways to darken the earth. Sometimes just harrowing a field will darken it enough for most purposes. No option is so simple that we should apply it without good sense, but simpler is better as a rule.

Prominent reasons for favouring the heating of forest or earth include such objectives as increasing the length of growing seasons and growth rates, either just to warm the area or the plant life in seasonally cold weather, or to melt off snow. They also include encouraging convection currents for control of air circulation and cooling of adjacent regions.

Darkening water surfaces is a more specialised and difficult requirement. Water tends to absorb sunlight fairly efficiently, so that the problem usually is not so much to capture heat as such, as to warm the water surface rather than the top few dozen metres. Typically this need arises when we want to evaporate as much water as possible, usually seawater. What best to do depends on the circumstances. Typically nothing of the kind is practical in rough water such as surf. To avoid ecological harm requires that the techniques be carefully chosen and carefully designed to suit the circumstances.

In general the principle is to place a light absorber within at most a few centimetres of the water surface. If this is done in open water, one must plan it so as to avoid ecological complications. Measures should entail no toxicity, no large, densely covered surfaces interfering with oxygenation of the water, and no risks of trapping aquatic creatures. Expedients might take the form of froth, turbidity, a film, floating balls, or constraining films of water under glass.

Reasons for darkening water surfaces probably are more varied and less direct than reasons for darkening the surface layer of land.

As a rule it would be more difficult to whiten land or water for cooling or evaporation, than to darken it to capture heat. Usually it would be more practical to intercept the heat in the atmosphere before it ever reaches the surface. Still, there are local applications where whitening the ground itself looks tempting.

Holding onto Atmospheric Heat, or Rejecting it.

PRAYER
to the sun above the clouds.

Sun that givest all things birth,
shine on everything on earth!

If that's too much to demand,
shine at least on this our land.

If even that's too much for thee,
shine at any rate on me.
Piet Hein Grook

It is quite shocking to see how simplistic and ill-informed the views of some of the most self-assured and outspoken adversaries to climate engineering may be. By way of an extreme example, one, a university lecturer no less, though, granted, in an arts faculty, who somehow had gained the impression that the ozone layer was a sort of membrane somewhere up there, and wondered why the atmosphere wasn't leaking out into space through the ozone hole. Few of his rivals could match that delusion for sheer style, but the scientifically illiterate can be breathtakingly creative.

Such people rarely understand the mechanism or significance of scattering or absorption of light in the high atmosphere, or the nature of the greenhouse effect and the absorption of various wavelengths in the lower atmosphere. Very few seem to understand the relevance of the altitude at which a mechanism takes effect.

In the field of climate control there currently is very little interest in augmenting the retention of heat in the lower atmosphere. That seldom is of much importance except in frost control. Heat retention usually results when atmospheric pollution absorbs infrared radiation from warm ground. At greater altitudes clouds become important in heat retention because they reflect heat back to the ground. There is of course their competing effect of blocking incoming solar energy.

At all events such absorption and reflection of infrared are vitally important. Without them we certainly would be in an ice age — a permanent ice age.

But if we get too much of a good thing, like retained heat, we bake.

Low altitude heat retention largely happens in highly populated areas. It is not clear that heat retention at high altitudes, say above 10000 metres, is anything like as important. It certainly is not clear to what extent carbon dioxide is a dominant factor in such retention, compared to say, water or organic compounds. Water and most organic compounds absorb infrared far more strongly than CO₂, but the higher the altitude, the less water and organic compounds one expects to find.

Except for pure water and possibly nitrogen, it is difficult to think of any gas produced by human activity that is in every sense harmless at low altitude. At high altitudes things can be very different. For example at ground level ozone is unacceptable at concentrations of 100 parts per billion, but in the stratosphere it is highly desirable as an ultraviolet screen at concentrations of parts per million. Similarly sulfur oxides, nitrogen oxides, and dust particles are undesirable at ground level, whereas in the stratosphere much of the radiation that they block is unwanted below.

Therefore, much of our pollution at low altitudes would largely have been be desirable if its components had occurred in the stratosphere instead. In general the most effective strategy for planetary cooling, where planetary cooling really is what we want, would be to intercept incoming sunlight at high altitudes and scatter or reflect it back into space. The next most important thing is to refrain from intercepting heat radiated or convected from Earth.

Scattering radiation may not sound like a very constructive or practical thing to do. Why not simply reflect it? However, simple reflection seldom is practical and often undesirable. Scattering on the other hand is simple and fairly effective; imagine a visible or long-wave photon striking the upper atmosphere: if the air is clear enough it generally will strike the earth, delivering its energy in the form of heat. Conversely if it strikes a sufficiently large particle on the way down it will be absorbed or scattered, either back where it came from, or to one side instead of towards the ground. If absorbed it will be converted largely to warmth that cannot do much harm in the stratosphere, which is in any case defined largely as an inversion, a layer of warm air overlying cold air.

That particular layer of warm air is important for our survival.

If the photon is scattered sufficiently frequently at a sufficiently high altitude it very likely never will reach the surface at all. By way of illustration, clouds cause cool, dark areas, even though they are not opaque. Now consider what proportion of photons we want to have scattered so that they vanish into outer space or heat the high atmosphere, compared to the proportion we want to have striking the surface of our planet. The desirable proportion may be surprisingly small. If we can scatter back just a few percent controllably, that will be quite enough to cool the planet down by a far larger margin than is necessary for countering our worst fears of global warming.

The smallness of that proportion has two implications at least:
Firstly we have the power to counter either natural or anthropogenic global warming with a comfortable margin of error.
Secondly, that margin gives us flexibility in our choice of the regions and the timing where we wish to adjust the heat budgets. We could for example, cool the equatorial zones, warm the temperate zones, and cool the polar zones. We could institute one program in the Northern Hemisphere and a different one in the Southern Hemisphere.

For a long time one passionate objection to such schemes has been that anything we put in the way of incoming radiation will also reflect outgoing radiation back downwards. This would seem to promise an inevitable greenhouse effect. In practice that is not a major concern, because although the idea is true in principle, reflected heat is fairly benign, largely preventing problems of frost at night.

Anyway, only a modest proportion of the radiated heat is reflected back down. Most of it would be scattered, and most of the scattering would be outwards or sideways, not back down. More importantly, the incoming heat is far greater than the re-radiated heat, so far more is scattered outwards on the way in than scattered inwards on the way out. Anyway, I shall show that there is a more powerful principle for preventing that particular aspect of the so-called greenhouse effect.

An example of the importance of regionality is the greenhouse effect of haze. Haze at any altitude can block radiation or reflect it or store heat, and do so in any combination. Which effects dominate, depends on the haze colour (generally pale or dark, depending on whether it is watery/solute-laden, or oily/sooty) and on the colour of the radiation: whether it is infrared, visible, or ultraviolet — details, details, but important details all the same.)

Now, at night, or at any time or place that incoming heat flux is low, such haze commonly acts as a blanket and for the most part it either absorbs or reflects heat radiated from below. In polar regions except at high summer, that blanketing effect tends to be dominant; it is altogether plausible that current density of haze is contributing dramatically to Arctic sea ice retreat. And high temperatures and human-generated pollution and humidity from lower latitudes might well be contributing to possibly disastrous effects nearer the poles. It is hard to be specific as yet, but it is hard to believe that such effects might be negligible.

And such blanketing has its effects at lower latitudes as well, which is important in several respects, both favourable and harmful. For instance, haze can prevent frosts that otherwise harm agriculture on a large scale in some regions, especially those with a continental climate.

But at the same time haze up in the atmosphere tends to cool regions below by blocking or reflecting incoming radiation, as we see when air traffic is abruptly decreased or increased. Not surprisingly, hazes created by shipping have similar effects over trading routes.

But this is an example of blow hot/blow cold magic; there are two major implications. Firstly, where there is more incoming radiation from the sun than outgoing from the Earth, the effect of blocking the radiation is cooling, not heating. This is what we see in warm or torrid regions by day. But where there is little incoming radiation, or lots of heat output, such as perhaps over some industrial regions at night, the effect is warming.

There is nothing surprising about this; we use the same principle when we cast off our blankets on a hot night, or put on the duvet in winter.

The other implication is that the effects, desirable or otherwise, are to some effect both reversible and regional.

And all such things indicate that control, though not necessarily fine control, is practicable, and in my opinion should be practical and probably adequate for managing our climatic planetary health.

And haze is not the only tool to hand in climate control.

Easy, isn't it?

Well, not actually easy, but certainly easier than control of the human and political factor.

Working Miracles with Anions and Cations

The fact that this effect had been discovered two years before,
and that North American’s own chemists had been
working with HF for at least a year, suggest that
there was a lack of communication somewhere,
or, perhaps, that engineers don’t read!

John D. Clark: Ignition

In my opinion practically anywhere between the Arctic and Antarctic circles that we can get a mist of fine particles high into the atmosphere would have a powerfully cooling effect on our planetary heat budget. Nearer the polar caps such particles might cause warming, thereby reducing the winter ozone holes, but how desirable that might be, I cannot guess. Nearer the equator far more incoming energy would be scattered away from the planet than outgoing heat would be scattered back. Most informed people on both sides of the debate agree on this point, although a noisy alarmist minority insists that there is serious doubt. I shall have more to say about that minority in due course, but for the moment I simply side with the vocal majority. After all, their argument does not depend only on computer models.

Practically everyone also agrees that the scale of any intervention of such a type must be immense. On that point I have reservations. But that too can wait for the moment. Still, I agree with those who say that the obvious screen against incoming light should be in the form of tiny particles or droplets, cheap, non-toxic, and strongly light-scattering.

Consider, we want characteristics such as:

· Cheap material and cheap to distribute

· Harmless or beneficial to the high environment

· Harmless or beneficial when it returns to earth

· Effective at blocking or scattering relevant wavelengths coming in from the sky

· Ineffective at blocking or scattering relevant wavelengths coming up from below

· Sufficiently persistently effective where applied in the target region

· Without long-term threat in the target region, or elsewhere

Cheapness is not independent of cost effectiveness. Suppose substance A costs ten times as much as B, but scatters relevant light ten times as well and costs half as much to apply; then it is a bargain in terms of cost effectiveness. All the substances I mention are industrially available, fairly cheap, and could be applied cheaply as oxides in commercial aircraft exhaust, having been injected into the combustion region as gaseous or liquid compounds: say, phosphorus in CS₂ solution, sulfur compounds in the fuel, carbonyl compounds, metal soaps in alcoholic solutions, or certain elements burnt or volatilised directly.

Incidentally, in this essay, to forestall irritation of readers with relevant chemical expertise, rest assured that I do know what anions and cations are, and when I speak of "anions" and "cations" it is slovenly shorthand for substances in which the operative components are anionic or prone to participate as anions, as in sulphates and silicates, as opposed to metal or alkaline-organic compounds. Be kind!

And if you happen to be a reader without such training, forget it; it is nice to know such things, but in this connection the distinction is hardly worth extra effort on your part unless you are young enough to make good the shortfall. Don't get me started on the value of chemistry as a component of a civilised education!

Well then. . .

In particular we do not want particles that are likely to cause chemical problems in the stratosphere. We have had a sufficiently bad experience with the ozone layer already. That happened when we innocently released chlorofluorocarbons (and in particular, chlorocarbons) into the atmosphere.

Volcanoes explosively release large quantities of dust and sulfur compounds into the stratosphere, and in doing so they offer us a demonstration of one thing that works. We cannot however match the amount of dust that volcanoes raise, and that remains aloft for long periods. The quantities are too huge to match, and the material is very hard to reduce to a degree of fineness that will keep it in the air for long, and it would require huge expenditure of energy to do so.

And volcanic dust that is not microscopic settles back to earth very soon; in days rather than years. And it generally has harmful short-term effects where large quantities do settle.

Anyway, we cannot order volcanoes to meet our desires on schedule.

Volcanic sulfur emissions however, give us a useful hint. Most of the sulfur goes up in the form of sulfur dioxide, which is a gas. As a dilute gas, even though sulfur dioxide is about twice as dense as air at the same pressure and temperature, it does not sink, but remains diffused into the surrounding air. Unfortunately it also does little to scatter incoming light, though it does absorb infrared better than CO₂. All the same, especially in the presence of humidity and sunlight, sooner or later it gets oxidised to sulfur trioxide. The trioxide forms tiny needles that scatter short-wave light such as visible or UV rather well. Sulfur trioxide also is intensely hygroscopic and reacts with any available water to produce sulfuric acid. The sulfuric acid forms microscopic droplets or frozen particles that replace the needles. Those droplets also scatter light more effectively than water would.

Unlike SO₂, sulfuric acid is not volatile, so it begins to settle out at once. However the droplets are so minute that they settle extremely slowly and this year's SO_xs may still be circling the globe as sulfuric acid or sulfates in the lower stratosphere two or three years from now.

The particle masses we contemplate here are in the range of picograms: something like the size of common bacteria. Or less.

Those acid particles certainly do not last for ever though. On the one hand that is good because, as we have already noted, we do not want whatever we deploy in stratosphere to stay up permanently. Understandably however, people worry loudly about what the acid might do when it comes down to earth again. Everyone knows that sulfuric acid is a dangerous and violently corrosive acid, and that it plays an important role in the weathering of buildings, statues, and so on. It has caused disastrous acid rain and has been accused of releasing harmful metal ions in sensitive soils.

All this is worth consideration as far as it goes but it is not half as bad as it sounds. For one thing, if measurements were to show that even such low levels of SO_x were really undesirable, (which I doubt, but then I have not measured it) then all we need do is stop the sulfur distribution. It all should rain out within a few years, because if it did not rain out, it would not be causing a problem in the first place!

Anyway, sulfate is a nutrient and on many heavily cropped soils it has become badly depleted in recent decades. Unfortunately, vast though the amounts that we need to inject into the stratosphere may be, they probably are too tiny to be of much use when they settle out evenly over the land below. The other side of the coin is that whatever we can inject into the stratosphere is likely to be an insignificant contribution to acid rain.

One way or the other, sulfur is probably the cheapest, safest effective material that we could send up. Just how to send it up is another matter. There have been some suggestions to shoot up such material using cannon, rockets, and the like, or to float up pipes through which to pump desirable gases into the stratosphere. In my offhand opinion we need better means of launching such material; I discuss some later in this essay.

Some people, perfectly rationally, have proposed sending up specialised dedicated aircraft to distribute the material in some suitable form. This may well become necessary or profitable, but I cannot see it as being the most desirable option except in particular regions.

One might object that incompletely burnt sulfur compounds for example, would react with ozone and destroy it. However, sulfates or their particles cannot compare with halogen atoms as a threat to ozone, and they even might assist in removing the halogens from the stratosphere.

Sulfur is not the only material that could be used in this way. Phosphorus compounds, or even elemental phosphorus, would behave very similarly, except that that phosphoric acid is far less harmful than sulfuric acid when it reaches the ground, and also more valuable as a plant food. It is more expensive but perhaps it would not be prohibitively so.

Another option would be to release small quantities of silicon compounds such as silane into the fuel of jet aircraft. Suitable silicon compounds would instantly burn into minute particles of silicon dioxide. They should be in all ways harmless high in the atmosphere, and should scatter light reasonably effectively. No doubt the Chicken Little brigade would squawk about silicosis, but they squawk about everything else too.

Yet another option would be to burn compounds that release very small particles of carbon black, or volatilise organic compounds such as glycerol. I am by no means sure how useful or acceptable they would be, but if the experiment showed them to be satisfactory, it would be a cheap way of producing large numbers of particles that scatter light effectively.

And now for the cations

Two years research can often save you ten minutes in a library. Anon.

Except for the metal soaps, the compounds I have discussed so far all produce non-ionic compounds, or at best elementary carbon or sulfur. Their operative components are their anions, in the terminology I explained in the foregoing section. They should do well enough in their way, but I think we may do better with cations.

To produce cationic particles we might inject suitable metallic elements or organometallic compounds into the aircraft fuel stream, vaporising or atomising and burning say, sodium, magnesium, zinc, potassium, calcium, or their combustible compounds.

Another interesting option would be to burn or volatilise iron pentacarbonyl.

Some of these substances would be more or less toxic in themselves, but none would burn to yield anything harmful in context. In the quantities under discussion every single combustion product would be a nutrient or at least harmless. Most of those of the greatest interest would be cheap to use and available in large quantities. The choice of which to use would be a matter for research into the nature of the particles and of costs and benefits.

Emissions of such cationic types offer certain bonuses. They all burn to produce solid particles. This should be particularly valuable when the particles are plate or needle shaped, as I discuss below.

In the presence of the slightest traces of moisture, particles of metal oxides, particularly Na, K, Mg, Ca, and Zn, should have a beneficial effect on O₃ because their oxides should scavenge chlorine and other ozone-destroying stratospheric halogens. So far the best we have done to undo damage to the ozone layer has been to slow down production of CFCs except in certain Asiatic countries.

Most oxides of electropositive metals do little to destroy ozone, so, for every chlorine atom removed from the stratosphere, a mildly ozone-harmful atom or compound would forestall hundreds of times more damage. Most of the compounds we consider would react no further with ozone, after once being burnt with the jet fuel. All of them however, would cheerfully react with halogens or their compounds, and scrub them out of the stratosphere while sinking to lower altitudes. What started as atomic or elemental halogens in the high atmosphere would end up as halides in the soil or ocean.

Note that some recent work shows that almost any solid interface is suspect when the catalytic breakdown of ozone is unwelcome. In particular, ozone has been reported to break down catalytically on the surface of certain classes of sulfate particles.

That report led to the usual hysterical reactions, but it does not follow that the release of sulfur compounds is a threat on a par with halogen volatiles. If it were, every major volcanic injection of sulfur into the stratosphere would wipe out the ozone layer, and yet it does not. Consider the contrast with certain halogens, either atomic or as volatiles: they diffuse as gases. Unlike gases, particles tend to sink or rain out rather than ascending through the stratosphere to the ozone layer, which is mainly some tens of kilometres above the lower stratosphere. Dense particles in themselves therefore do not pose much of a practical threat to ozone. Particles that scrub out chlorine, bromine and iodine thereby actively preserve ozone.

Personally I have doubts about the crucial world wide importance of the ozone layer, and accordingly am not deeply concerned about its status in the stratosphere. However, I have little hard evidence and certainly no quantitative evidence to support my views, and I do not at all see the ozone layer itself as harmful, so, to the extent that a good healthy ozone layer is better for our own health and planet's health in general, the halogen-scrubbing bonus of a good dose of cationic particles seems welcome. It should speed the recovery of the ozone layer by a larger factor than any intervention so far.

As for the effect of the metals on the health of living creatures below, all those I mention are practically harmless, and the K, Ca, Mg, Zn, and sometimes Fe are positively beneficial on most soils, though the benefit should be too small to notice anywhere. The other elements are neutral on any plausible scale.

You might doubt the safety of say, Al or Si, but if you find anywhere on dry land where we normally would inhale less aluminium or Si from the earth than he would get from the sky, do let me know. Remember, we are talking about perhaps grams per square km! Aluminium and silicon are among the commonest elements in the Earth's crust, and constituents of nearly all the mineral dust we inhale harmlessly. Only miners, quarriers, and other people with gross, unprotected exposure are at risk from such dust.

Far from "geoengineering" being an ogre, it positively demands implementation for routine control of climate as well as weather. Even if we had no concern about global warming, even if not a calorie of it were due to anthropic causes, we still would need geoengineering. Dr Strangelove would have loved what engineers could do with it. Whether he would love what politicians do with it, remains to be seen.

Note that Dr Strangelove was badly slandered: his views were sound; it was the politicians, maniacs, and military nuts who not only screwed it all up, but did so in grossly contrary ways.

What About Those Picograms?

The three most dangerous things in the world are:
a programmer with a soldering iron,
a hardware type with a program patch,
and a user with an idea.
Traditional wisdom of computer professionals
retailed by Rick Cook

The next point to discuss is parsimony; not so much parsimony in the sense of avoiding expenditure, as in the sense of getting the best possible results by optimal application of resources. For instance: we wish to block or scatter incoming light as effectively as possible, while avoiding interference with the escape of outgoing light.

That suggests that we need one-way mirrors, but mirrors are a problem to work with at stratospheric altitudes, and our resources are tiny particles, so any such idea must seem like wishful thinking.

And yet at least one principle does offer some promise. All the photons represent energy that can heat the planet, but not all photons are equal. A large proportion of the heat radiated from the planet is in the form of infrared photons with wavelengths of the order of micrometres. The energy peak of incoming sunlight in contrast is somewhere in the yellow, with quarter-wavelengths of the order of a tenth of a micrometre. The light that we wish to scatter most strongly ranges from about 800 down to perhaps 200 nanometres: about two octaves.

In other words we want to block mainly visible, near infrared, and ultraviolet incoming light, without blocking medium- to far-infrared on its way out.

When we use particles to block or scatter light for best effect, those particles should span at least one quarter of the wavelength of the light. The particles do not have to be solid blocks: needles, bubbles or platelets measuring say half a micro-meter in their longest dimension, should do very nicely for scattering sunlight.

However most of the radiation outgoing from Earth has much longer wavelengths. That radiation should pass through clouds of such tiny particles with little interference. The net effect amounts to the one-way heat mirror that we had dreamed of.

This sounds so simple that it may be difficult to remember that the devil always hides in the details. It is likely to demand much work to identify the best materials to use, and the best way to use them.

Nonetheless, there is little doubt that our one-way shield could be effective. Let us consider how much material it would be likely to take. One cubic micro-meter of water has a mass of one picogram. If we could produce platelets one micrometre across and a fifth to a tenth of a micrometre thick, they would average less than one picogram in mass. Instead of plates, needles as thin as that might be more like one tenth of a picogram in mass.

On such assumptions a fraction of a gram per square metre should be quite adequate for our purposes. A ton should be enough for several square kilometres. We need to treat millions of square kilometres of course, but another benefit of using very small particles, especially if they are particularly light, is that they should stay up for a long time, even for years. Remember Tambora!

Remember that most cationic particles of interest would be solid. This suggests some intriguing possibilities. It should be desirable to give all particles, whether solid or liquid, the same strong electric charge: negative, I imagine. Particles that repel each other should stay up longer because they would not be prone to coagulate. Solid particles could be made into long-lived microscopic electrets by exposing them to high voltage electrons when creating them. It also seems possible, by producing dipolar particles with distinct properties at opposite faces, to make them scatter photons more effectively and selectively.

This is no more than speculation at present, but it does suggest that there is a lot of scope for development of subtle, economical, and effective tools.

How do we Lift a Picogram?

All those who believe in psychokinesis: raise my hand!
Steven Wright

Apart from the simplistic nature of speculations about which particles to inject into the atmosphere, and the altitudes at which to lift them, there have been several unconvincing ideas of how to hoist the picograms.

Ballistic launching

If it still don't work, I gets a bigger 'ammer
John Winton

Rockets and artillery have figured largely in proposals for how to lift the picograms. That seems reasonable, because plenty of military surplus artillery can shoot higher than the base of the stratosphere, and anything counts as a hit if it goes higher than say, ten kilometres. So no great accuracy is necessary; a smooth-bore weapon should suffice. If the case of the projectile can be designed to combust on exploding, there will be little deadweight, so the fuel bill is not unreasonable; almost the whole shot can be payload.

Still, problems emerge in injecting such material into the stratosphere by artillery. There are two reasons why we do not want the material concentrated in exploding blobs. Firstly, if we want tiny particles, we usually need to disperse the material in a dilute gaseous form. If the payload is liquid, that requires an especially strong shell. The last thing we want is a rain of clotted oxides. We need not even consider the desirability of a rain of shell fragments. One can design the shot to release the payload gradually along the path at the right altitude, but that demands sophistication in avoiding deadweight.

Secondly we do not want minor patches of over-saturated sky while leaving the rest clear. Although we do not mind a fairly uneven distribution, and we accept that to speak of so many particles per square metre is an idealisation, a matter of averages, shell-bursts may be expected to be more granular than we might like.

If each shell's payload were less than say a tonne, we would need a lot of cannon, and the rate of fire would have to be very high. On the other hand, the propellant need not be of military standard; it could be a mix of liquid oxygen with say hydrogen or ammonia, mixed at the appropriate rate to lift the payload out of the barrel without shattering everything.

The payload could be designed to explode as the projectile approaches freefall begins, and it also could be designed to be very hot and take the form of a rising vortex that travels farther up for several kilometres more.

We can't dismiss the idea out of hand; it is nice to think of beating swords into ploughshares.

But don't expect it to be as simple as it sounds.

Vortex launching

For it is not light that is needed, but fire; it is not the gentle shower, but thunder.
We need the storm, the whirlwind, and the earthquake.
Frederick Douglass

A more sophisticated mechanism that deserves serious attention is shooting up gases and dusts in toroidal vortices of the smoke-ring type. Mushroom clouds if you like.

Such vortices remain spectacularly coherent as they travel, and rise powerfully if they are buoyant, especially when simply very hot. As they rise, they spread evenly, which is desirable. The simplest form might be a mass of oxidiser plus reducing agent in an open cylinder, but I doubt that would be satisfactorily efficient.

A more efficient form of launcher might be a suitably designed box, probably a squat cylinder with a hole in the centre of its ceiling. It could be charged with a mix of say, H₂, H₂S, PH₃, SiH₄, atomised metal dusts, metal volatiles such as carbonyls, with a little oxygen, propelled abruptly by a piston or explosion from below, with carefully configured ignition. It should produce a vortex that rises and burns on the way up, easily reaching the stratosphere under suitable circumstances. By the time the mix reaches its maximal altitude it would be spreading out widely. In suitable locations, the products should be distributed by jet streams and other high altitude winds.

How can I be so sure? Think: we know that the most effectively cooling stratospheric injections in recent millennia have been the mushroom clouds of explosive eruptions. They went round and round the planet, creating volcanic winters. Read, in Wikipedia or elsewhere, about Europe's "Year Without a Summer". It happened the year after the 1815 Tambora eruption at the other side of the northern Hemisphere! The battle of Waterloo, presumably coincidentally, followed not long afterwards.

Something of the vortex-launching kind could be an economical means of raising the materials to operational heights, and a device for launching a tonne of payload every few minutes should be easily portable. If it proves practical to manufacture the ammunition in cartridges for ready use, one could probably fire off more than one per minute.

One would aim for a shot to produce particle sizes of half a micrometre or so, so that they would let infrared light through, but scatter or reflect shorter wavelengths.

Some tinkering with recipes and designs would be necessary.

So what else is new?

Balloon launching

Oh, lift me as a wave, a leaf, a cloud!
Percy Bysshe Shelley

An alternative to artillery and vortex generators could be balloons. This too would demand competent design, but superficially it looks surprisingly attractive.

To determine the optimal gas content of the balloon would require research, so the following proposals are speculative. I speculate on the basis of some simplistic gas mixes, though others might be more economical; hydrogen is expensive. Let us assume that the balloon is filled with a mix of hydrogen, oxygen, and H₂S, designed to rise under its own buoyancy, and burn if ignited. The payload is really the H₂S, possibly together with enough O₂ to consume the hydrogen in the mix. but the hydrogen gas would supply the buoyancy.

H₂S should be sufficiently reactive in stratospheric ultraviolet and oxygen, to be released without further treatment. However, it might be worth igniting its mixture with hydrogen and oxygen on releasing it from the balloon, so that the heat would lift the sulfur or SO_x higher into the stratosphere, perhaps as a vortex. A whole range of possible compositions would need comparative evaluations, but the following example would be one of the simplest:

H₂S + H₂ + O₂ Þ S + 2H₂O

That would yield roughly equal masses of sulfur and water. That reaction is too simple to be realistic of course, but might be close enough for practical purposes. If the water condenses as ice crystals, it would scatter and reflect incoming light very effectively, though of course it would not last long under most circumstances; still, it could be absorbed in the formation of long-lived sulfate particles, and anyway, water vapour is buoyant in air. If we wanted more highly oxidised sulfur we could raise the oxygen content of the mix, but we might then have to increase the hydrogen content, and in general reduce the payload. But the extra heat of combustion should cause the sulfur in any form to rise yet higher.

For maximal payload, we could omit the oxygen and simply let the hydrogen raise the balloon till it bursts at high altitude, leaving the H₂S to oxidise at leisure in the surrounding thin oxygen and ultra violet.

H₂S/H₂ balloons would have to be designed to carry the payload up to above 10 km. That is not hard; really high-altitude research balloons go several times as high as that. Still, it does present some problems; we would need hundreds of thousands of the balloons, and could not tolerate so much polymer balloon fabric settling to earth as pollution.

Various responses to that problem suggest themselves immediately. One option would be to design a nitrated polymer for the balloon material (think celluloid variants or polyvinyl nitrate) such that it is easily ignited along with the balloon's gases, even at stratospheric altitudes, so that no significant amounts reach the ground. Another approach is to design a cellulose or amylose fabric that will not burn especially reliably, but will be biodegradable if it reaches either ground or sea afterwards.

Each balloon should carry a self-destruction device, whether to ignite it or shatter it so that whatever else happens there is no way for any payload to be wasted or for any unwelcome pollution, whether toxic, inflammable, or offensive, to reach the surface,.

Here we are not discussing party balloons, nor even weather balloons (though there is no harm to combining the launches with various forms of research; waste not want not!) No — I estimate that balloons something like 10-metres in diameter when fully inflated, would be a reasonable size. That is much smaller than really high-altitude research balloons, but larger than most weather balloons.

Some research and development would be necessary, but there is an embarrassment of choices of options for design of the materials, the gases, the means of assembly, launching, ignition, and destruction.

For example, if they were to be launched so as to pass over the sea when they pop, either they might burn in the sky, probably only when they are at an altitude where there is sufficient oxygen to support combustion, or their fabric could be drawn elastically into a compact, rigid container that prevents turtles from eating them with injurious results. Either the resultant package could be weighted to sink and provide shelter for benthic organisms, or it could float, so that data it could be designed to collect, could be retrieved for their own value, while preventing ocean pollution.

As for popping, I opine that the best option would be to let the bursting or collapse of the balloon when it exceeds its sustainable height, to trigger the ignition, or the packaging, or whatever form of disposal is planned.

I would hope, since the rate of balloon release at any one point would ideally be huge: many balloons released per hour, and from many trucks, or from large installations; that each assembly unit could be supplied with a roll of material that it automatically would form into a sealed balloon before release, inflate with the gas mixture, and equip with a disposable instrument for data recording and communication, and, if appropriate, for triggering destruction of the balloon residue.

A point of interest is that ignition of a disposable balloon can be so designed as to create a vortex that carries the payload even further up and disperse it more widely.

Blimps and return journeys

. . .and again he sent forth the dove out of the ark;
And the dove came in to him in the evening;
and, lo, in her mouth was an olive leaf pluckt off. . .
Genesis 8

Disposable balloons are not the only option for raising those picograms. Reusable vehicles demand more elaborate and costly design, but they offer several striking advantages. Reduction of possible pollution would be one example.

Unmanned blimps offer some advantages for this class of function, though they present various problems too. Possibly they could be solar powered, rather than carrying fuelled motors. They would have to have a massive payload to be worth consideration, many tonnes at least. I suggest hydrogen for the lifting gas, and cylinders of liquid H₂S or CS₂ or a mixture for the payload. With no crew, their payload would be very efficient, and it is quite possible to design them to carry payloads of tens of tonnes to altitudes of over 20 kilometres.

Nothing is simple of course; blimps are not fast, so we had better assume that they could not rely on getting back to their starting position against contrary winds. They had better be sent aloft where they would have time to deliver the load, say over the Rockies of the Pacific Northwest of the USA, and be blown overland for collection where convenient.

But those are matters of detail. A blimp that could deliver tens of tonnes per trip, in a fleet of a few hundred, at say one trip per week, might be a very useful resource in fighting anthropogenic global warming. Certainly worth consideration.

Leash and harness

If you give me enough time, enough leash, I can become pretty reasonable
Michael Shannon

Free balloons have their shortcomings of waste and perhaps of pollution, and free blimps might have great difficulty and delay in getting back to their launching sites. An alternative principle that might be worth examining is that of tethered vehicles that can be drawn down after a flight, recharged with a new payload prepared while they were up, and relaunched with little delay.

I suggest that any such vehicle be unmanned, for reasons of safety, cost, and payload economy. For every crew member we exclude, we can increase the payload by something like 200 kilograms. (Not that crew members need be particularly fat, but that the mass of the human support resources must be reckoned in too.)

The main problem with the blimp, was the reliability and speed of recovery. One option is to haul the blimp in by a tether. However, if we do that, it is not clear why we should use a blimp instead of a balloon, which would be still more economical. The balloon might well be shaped to orient itself conveniently for loading, or to ensure that it behaves well in the air and avoids tangling the tether, but it should be a lot cheaper than a blimp; possibly more reliable as well.

Whatever the nature and engineering of the tethered vehicle, it probably would be desirable to minimise its on-board equipment. As much of the equipment and power as possible should be in the ground vehicles and establishment, rather than in the air.

This principle implies a tether of some ten to forty kilometres long, depending on the design details, so we must bear the tether's mass and material in mind, among other factors. I think the best tether would be a polymer monofilament. Usually one avoids monofilament for fear of its snapping if damaged, but it is cheap, recyclable, compact, and not heir to some of the ills that afflict rope.

After all, if the tether does snap, the vehicle puts no crew at risk. Of course the choice of tether is up to the engineers, but I suggest a monofilament of oriented polypropylene some 3 to 5 mm in diameter. Polypropylene is the only common polymer of acceptable strength that floats in water; this is a major advantage for recovery and recycling after accidents. It also reduces the deadweight of tether that must be lifted. It should contain a suitable pigment to reduce UV or NV (near violet) damage.

The weight of ten to twenty kilometres of such a tether should be of the order of 100 to 250 kg. It would require quite a sophisticated reel powered by a well-designed motor to avoid damage, danger, jamming, or tangling. If damaged, the polypropylene could be recycled with practically 100% efficiency.

You might wonder how such a stingy little filament, a mere fraction of one tonne, could be useful in managing such massive loads; after all, to justify such equipment, it would have to deliver tens or hundreds of tonnes per load.

True. But it does not have to lift the load, nor pull it down against buoyancy of such an order. A mass of one tonne of H₂S in air at the same pressure would have an effective weight of only about a fifth as much. In a mix of with enough hydrogen to lift it, its weight becomes negative, meaning that it floats upwards, and if it is warm, it requires even less hydrogen, say a quarter of the volume of H₂S. For such a light tether, this demands careful control of the load's momentum in the air, and of the effect of wind on the vessels, but nothing like what would be necessary to lift such masses without the support of significant buoyancy.

The configuration of a unit to manage such tethered craft might take many forms. I suspect that a rewarding design might take the form of a string of balloons, say ten to twenty metres in diameter when fully extended at maximal altitude, each attached to a length of tether filament that is connected to one end of say, 50 metres of tether with a coupling connection at each end, and daisy-chained for as long as is desirable in the reigning circumstances. The last, nearest, segment is coupled to the main tether cord, that may be thicker than the balloon connections.

Each balloon is designed to release its contents abruptly from a vent in its upper surface, when instructed, either igniting the gas or releasing it quietly according to need or practicality. Igniting the gas would need a suitably designed vent, but might carry it a few thousand metres higher.

When the string of balloons has reached as high an altitude as is practical, and is about fully extended, then each balloon vents its contents, starting from the balloon nearest to the reel (the last to be connected), while the main tether is reeled in.

As the empty balloons are collected at ground level, they are serviced, then parked on a rail where they get filled for the next delivery.

I repeat: this is just a notional scheme, but the principle attracts me. Good luck to any better-informed designer; my interest is in an effective project, not any particular design or its details.

Hitch-hiking upward

Creativity is the sudden cessation of stupidity.
Edwin Land

As I already have suggested, commercial jet planes on their lawful occasions should be excellent vehicles for disseminating our light-scattering particles. On take-off and landing they could burn their usual fuel, but on reaching their cruising altitude, which preferably would be some thousands of metres higher than current cruising altitudes, they either would switch to tanks of fuel adulterated with the necessary materials, or they would begin to inject the raw material into the fuel stream or into special burners or afterburners designed for the purpose. Jet exhausts could probably be enlisted to aid the dissemination.

The cheapest way to spread most types of fine particles would be to piggyback on routine commercial activity. Persistent airline contrails already have cooled regional climates, thereby hinting at how we may produce deeper and more extensive shade. This teaches us that it really can be done.

One objection is that commercial jet aircraft only go up to the lower stratosphere. It might be better if they could fly higher.

Well actually they can.

The reason they do not already fly higher, is that currently it is not the most economic altitude for standard commercial flight. If jet airliners were subsidised to fly say 1000m higher, they could increase the effectiveness of injection of material into the stratosphere greatly. However I do not promise that it would be worth their while to do so. Some study needs to be done to discover how much it matters just how high which material is released. Current commercial jet engines work most efficiently at the interface between the stratosphere and troposphere.

But such application of commercial flights, whether passenger or cargo, should be cheaper, faster, and safer than designing and building dedicated fleets of specialised dispensing aircraft.

Consider the following as one option: suppose we were to offer suitable incentives, then commercial aircraft on appropriate routes could use normal fuel at take-off, but begin the injection of H₂S, or fine sulfur powder, or sulfur vapour, or sulfur-rich compounds, into the combustion chambers of the jet engines once the aircraft begin to approach the altitudes of the lower stratosphere. The sulfur oxidesproduced would undergo oxidation and hydration to a mist of dilute sulfurous and sulfuric acid, some 3 to 30 times the mass of the sulfur burned.

It seems likely, to avoid engine damage and possible interference with fuel mixes, that the best option would be to inject the adulterant as afterburner fuel.

Sulfur is not the only candidate; there are various ways in which a jet aircraft can burn such fuels. Suitable gaseous or liquid compositions, such as phosphorus dissolved in CS₂, sulfur compounds dissolved in the fuel, or metal soaps in alcoholic solutions, could be injected into the fuel or into the combustion chambers, depending on their effects and natures.

The form in which to burn the particle-producing fuels would depend on practicalities such as what is most economical and easiest to handle. For instance:

we could produce large tonnages of liquid H₂S from coal, water, sulfur, and industrial waste;
for near-stratospheric cruising, we simply could use cheap, very sulfur-rich jet fuel.

If this is not practical, or is in itself insufficient, then simply add H₂S or CS₂, or organic sulfur compounds, or even elemental sulfur to the fuel itself; H₂S in particular is a high-energy fuel. To the (probably slight!) extent that we can afford to burn it in fuel, it could reduce the dependence on oil for commercial aviation; perhaps enough to pay for the extra altitude and course deviations. Most sources of H₂S currently are toxic liabilities, but by burning sulfur ten kilometres up, we could reduce consumption of commercial aviation fuel while improving our heat budget.

The sulfate fallout would hardly affect existing agricultural sulfur budgets, but such as it is, it should be more likely to alleviate growing sulfur deficiencies in agricultural soils than cause further problems.

A typical commercial jet trail might be hundreds or thousands of kilometres long and perhaps effectively a few kilometres wide. That is pretty generous coverage. Though jets follow well-defined routes, it should be perfectly easy and comparatively cheap to deviate each route slightly so as to prevent overlap. GPS-controlled autopilots should do that nicely and into the bargain decrease the risk of aircraft flying in each other’s wakes or colliding.

All the same this obviously would not give optimal coverage. Commercial routes are too limited and rigid. Where piggybacking on commercial services is not practical, there are two options for immediate consideration. The more obvious one is systematic special-purpose scheduling of special-purpose flights of very long-range cargo jets with payloads of the necessary materials.

An alternative to specialised spraying fleets, and hitching rides on commercial flights, would be specially designed cargo drones with no function other than dissemination of the light-scattering materials. This would be cheaper and safer than crewed vehicles. In particular, unmanned craft could be catapulted aloft at near sonic speeds, perhaps accelerated at 20 Gs, far more than humans could stand, thereby saving considerably on fuel. How such drones would land again (parachute?) would be a question for the design engineers, but drones of various designs do such things routinely already.

Although it has little to do with the subject of this discussion, the effective cost of such drones could be mitigated by piggybacking functions such as atmospheric sensing and aerial photography, much as our balloons could. By the nature of their function they would usually fly too high and too far from commercial jet routes to pose much of a hazard.

Controlling Anthropogenic Global Warming or cooling

We cannot solve our problems with the same thinking
we used when we created them.
Albert Einstein

WHY Control Anthropogenic Global Warming or cooling?

The great difficulty in arguing with logic against an irrational argument
is that the irrational argument has no need to make sense.

This essay deliberately ignores all debate on the validity of theories concerning anthropogenic global warming; there is valid work in the field by now, but the hysteria from most sources concerning most aspects is so facilely, virulently hysterical, that I ignore what, in most other fields, would have passed for debate.

One way or another, here are some reasons why I urge work on certain aspects and methods of control.

I accept that there is a lot happening, and much of it should not have been permitted to happen.

I accept that various greenhouse mechanisms are involved and that the whole mechanism is more complex than we have managed to work out.

I accept that certain gases, notably CO₂, H₂O, NO_X, VOCs and mineral dusts play various major roles, whether sourced from industry, agriculture, volcanic action or climatic feedback.

I accept that other aspects are of various degrees of significance, planetary albedo, solar excursions, meteoric impact, for example.

Some of those are beyond our foreseeable ability to do much about, but the worse they are, the rarer.

This essay deals with the ones we could do something about if only we would use our intelligence, such as by enabling the intelligent ones in our population to get down to business, while the rest of us shut our traps.

Personally I regard pat reactions on either side of the slanging matches as equally hen-witted. Not that my opinion proves much. I am left with much to wonder about and with increasingly resigned impatience I await a healthier trend to unprejudiced and intelligent evaluation and perspective. At the time I write, leaders of the most prominent nations, together with their advisers, are running after variously hysterical, crooked, and contradictory demands of opinion makers, like puppies chasing wind-blown scraps of paper. Such are the realities of politics, international power play, and opportunistic corruption. It amounts to a global tragedy. They would do much better to invest a few percent of the effort and resources into sound, independent, and carefully controlled research.

And engineering.

Whatever happened to science, coolly objective, non-reductionistic, conscientious about data, openness, and even courtesy sometimes? Remember science? All that sort of thing seems to have vanished in a storm of flat statement, flat contradiction, personal abuse, accusations of holocaust denialism or worse, and ad hominem attribution of hidden agenda and corruption.

The media love it of course, but I cannot see how anyone but the politicians, the zealots, and the exploiters of the opportunities for corruption gain anything from the whole sordid mess.

Bring back the cat say I; bring back the gallows; make sloganeering a capital offence!

Other people’s sloganeering of course!

However that may be, none of it makes it any easier to disentangle the validity and importance of the various objective concerns.

For what it is worth I suspect that in respect of greenhouse effects carbon dioxide is just one factor, and that there are complex feedback effects, both local and global.

Ever heard of water?

Some people are most immediately concerned by the degree to which increased carbon dioxide in the atmosphere is increasing the acidity of seawater. Acid seawater dissolves the calcium carbonate in the shells and bodies of various sea creatures. This sounds terrible, in some places it even looks terrible, and the forecasts of eco-catastrophe are more terrible still. However I still have not seen a coherent argument to the effect that carbon dioxide at relevant levels, say under 1000 ppm, causes serious trouble. For instance the most dramatic damage that I have seen exhibited by an oceanologist on television, was caused by volcanic carbon dioxide and possibly other acid materials bubbling up through the water far more vigorously than from soda water. As a reasonable indicator of future damage that sort of demonstration is simply ludicrous.

It has long been known that there also are deep layers of ocean water saturated with carbon dioxide. Some of them are so acid that when shells of dead animals from the surface sink down through the water, they literally dissolve before they reach the bottom. This has nothing to do with anthropogenic carbon dioxide; that carbon dioxide has been accumulating for millions of years. In general I am convinced that excursions of oceanic pH have been common in history or pre-history. And of course there is no reason to think that that has stopped. Why should it? Consider Lake Nyos for example. And some other lakes are no less worrying.

I do not say that every change in atmospheric carbon dioxide levels would be harmless, much less desirable, even though I am well aware that some sudden experts in biology keep claiming that because carbon dioxide is a plant food, all must be well. But the shrillness on both sides is equally helpful to mankind and the planet in general. We need more study without preconceptions and a lot less conferencing by big-bugs, limelight-seekers, bandwagonneers, and politicians.

As for carbon trading, there I too grow shrill. Kyoto-style agreements are for gravy trains, not climatic problems. I was stunned that anyone but the opportunists pushed for the agreement.

If atmospheric carbon dioxide really does need controlling, questions remain. This is where earnest enquirers become badly unpopular with the zealots. Zealots hate questions, except the questions that they are primed to answer glibly. They loathe science because science is more about questions than anything else. They particularly loathe people who try to explain this to them. Zealotry demands unquestioning persecution of the unbeliever; the rival unbeliever, that is to say.

So I know already that I am in for it! But the questions do not go away just because people begin to shout.

One question is how important the CO₂ is at its present levels.

Another is how harmful, or even how beneficial, carbon dioxide might be at present levels.

Yet another is where and when it is harmful or beneficial.

Given either that carbon dioxide at its present level is harmful or beneficial, or how much of each, which processes that increase it are the most important to control, and why? For example, I am far more worried about the rate of consumption of fossil combustible material as fuel, than I am concerned by carbon dioxide increase, or its effect on global warming.

One point on which I agree with many of the Green schools is that the best way to reduce increases to the carbon dioxide in the atmosphere is by saving energy. For one thing, that usually implies reduced abuse of our fossil carbon resources. Unfortunately I do not for a moment believe, as some of the Greens seem to, that saving energy is in itself sufficient. If we and our industries all stopped exhaling tomorrow, it still would take a long time for atmospheric carbon dioxide levels to return to say, pre-18th-century concentrations. I therefore applaud any and every rational means of exploiting environmental sources of energy, such as wind, wave, geothermal, or solar, but such details are beyond the scope of this essay.

I do have reservations of course; for example some Greens espouse the idea of power from ocean heat. That strikes me as very dangerous. There is more carbon dioxide dissolved in the ocean than there is gas in the atmosphere; not just more than atmospheric carbon dioxide, please note, but perhaps more than the total amount of air in the atmosphere. This bears thinking about when we talk of pumping up water from the deeps! I don't say don't do it, but to do it before undertaking very, very careful quantitative evaluations of the probability and scale of adverse consequences, and doing so while making loud noises about the evil of producing carbon dioxide from combustion, sounds like straining at gnats and swallowing dung beetles — the large, hard, prickly kinds of dung beetles. (Sorry, no camels; they are all on backorder for the lunar ³He proponents!)

At the other end of the political spectrum there is the weary chorus of the uselessness of all forms of "renewable energy" on the grounds that we cannot store energy. I deal with that canard in other essays.

Another approach is carbon, or carbon dioxide, sequestration. These I regard with reservations bordering on contempt. Elsewhere I point out some of the hazards of carbon dioxide stored as a gas, but before I believe in a competitive fuel-burning industry that absorbs its own carbon dioxide, I will need to see it.

All in all, sequestering carbon dioxide is a sad, sad, idea. It is doubly sad because people of the standard that have been proposing it really should know better. Sequestering carbon dioxide underground as a gas or fluid is beyond sad – in its perversity it approaches the dignity of insanity. For one thing, for how long do proponents want to keep it down there? Until another generation has to worry about it?

As for sequestration of carbon as an element, that sounds wonderful. We can store huge amounts of carbon compactly and at very little cost or hazard. No argument.

However, even if we could do so at zero cost, it would entail sacrifices of more than half the energy that we can get by burning most fossil fuels. To my mind that consideration is already prohibitive even before observing that none of the technology seriously proposed in any detail so far looks in the slightest encouraging.

One of the best, most flexible, and most efficient options along those lines is to react carbonaceous fuels with water, thereby producing hydrogen. Unfortunately, carbon monoxide is a prominent by-product of such processes, that in many ways is more difficult to deal with than carbon dioxide unless you have options for dealing with huge quantities of it.

Still, enthusiasts don't generally need much encouragement. I am inclined to leave them to it, in the hope that the relevant politicians will maintain a healthy scepticism. In practice I already see worrying hints to suggest that in all but the most backward countries, well-meaning politicians routinely stampede in the direction suggested by whomever first gets their ear.

HOW to Control Carbon Dioxide in Particular?

...it came to be accepted for many years as a practical working principle,
by professional engineers, that the technical ignorance
of the American Congressman could safely be regarded as bottomless.
J. E. Gordon: Structures, or why things don’t fall down.

First, let us ask how to increase atmospheric carbon dioxide in case there should be need. Fortunately this question is unpopular because the answer is trivial, so we can easily dismiss the problem. Probably for longer than the existence of Vertebrates on the planet, the deep sea has contained a larger volume of dissolved carbon dioxide than we have free gaseous atmosphere. If we simply drop wide tubes and pump up water from deep enough, that will bring out the gas with such force that we could harness the process for power. Within a year or two of heavy investment we could be releasing far more carbon dioxide from the oceans' accumulated stores into the atmosphere than all our industries produce.

Not that I foresee any such need. Frankly, the very idea of how much CO₂ is down there, waiting to pop up like a super Lake Nyos event, seems to me nightmarish. If we could fix it into organic matter, that could attenuate al least one threat to "higher" life on Earth.

The converse problem, that of getting rid of carbon dioxide by burying it when we have burnt the carbon-rich resources that we destroy, seems to me perversely silly. Some want to pump it into spent oil wells. Some want to pump it into the deep sea. My most charitable forecast for such solutions, evitable or not, is that they won’t pay, at any rate not in terms of material profit to anyone but politicians and other crooks who get onto the bandwagon early enough.

Most such schemes would imply accumulations that threaten disaster whenever they break out. People fuss about storing isotopes that will decay in less than a million years, often in less than a thousand; in contrast, a small compressed store of carbon dioxide, say a few billion tonnes, enough to wipe out New York perhaps, would not even have begun to break down or lose its destructive potential if it miraculously remains intact after a billion years.

As I pointed out, the amount of CO₂ in the deep sea dwarfs that in the atmosphere; the corollary is that if we put our current surplus down there, it would hardly make a dent. If we compressed the CO₂ we collect, and sink it in the form of large slabs of dry ice, it would stay down indefinitely.

But how to collect it and compress it without enormous expense, is a serious problem.

The most attractive option I have seen, still is to grow enough biological tissue to absorb the carbon dioxide we produce. Land crops won’t do it fast enough. At the rate we burn carbon, rainforests have failed to match the pace for perhaps a century or two. Our only hope is to grow enough green stuff in the oceans.

Now, most of the oceanic surface waters are deserts because practically all their biomass sinks sooner or later, taking trace elements with them. Of these trace elements the most prominent is iron. Accordingly there was great excitement when an experiment demonstrated that enriching iron-deficient Pacific water caused immediate growth of green plankton.

If cogent research demonstrates that atmospheric carbon dioxide levels actually are an actual problem, or threaten to become an actual problem, remotely-controlled dispensers of pelleted, biodegradable, floating micronutrients, especially iron salts, could hitch-hike on commercial marine vessels on suitable routes. Suitable units could be designed to dispense trace elements automatically onto the ocean surface, under automatic control via satellites, and without crew intervention.

This should support large-scale plankton growth in the major oceanic deserts, increasing carbon dioxide absorption beyond anything rainforests could do.

If, as some claim, surface vessels are themselves among the major sources of atmospheric carbon dioxide, it would seem tempting to capture most of their exhausts by directing them below the water surface. That should be simpler than capturing coal-burning stations' exhalations, surely? Yes, some of the carbon dioxide would re-surface because most of the exhaust is in fact elemental nitrogen , but if even a modest amount got photosynthesised or subducted beneath the water, that would be pure, cheap gain.

The alternative would be to let the exhaust gases accumulate in the air, where it takes energy and expensive equipment to collect, and can do a lot of anthropogenic global warming before it is retrieved. Scrubbing it by passing it through the surface waters of the open ocean could only be an improvement.

Ocean enrichment was the favourite proposal for carbon dioxide mitigation in recent years. It is in several respects a textbook example of simplistic hysteria latching on to simplistic issues, and oscillating with simplistic evidence as it is published. Major biological systems invariably are enormously complex. Even where it seems simple, that is because of simplistic observation and misinterpretation.

The idea of ocean enrichment originated with a fine bit of thinking and a fine bit of informal, but effective and enterprising, research. The late John Martin noted that lack of assimilable iron is a limiting factor in the so-called "oceanic deserts": unproductive areas in mid ocean. Nothing, certainly not reality, could be simpler. It was an important observation, with more important implications than most discussion that I have encountered in my role as a non-oceanologist. The question of atmospheric carbon dioxide is just one of its aspects; but it is the most immediate in the present context.

Martin notoriously said: “Give me half a tanker of iron, and I’ll give you an ice age” thereby adding yet another instance to the groaning pile of illustrations of how dangerous it can be to make jokes on important matters in public, in particular in public media. Martin's understanding of the matter was more sophisticated either than that quip suggests, or than the popular media understood. Public and journalistic pronouncements on related matters have largely been pathetically ill informed, inaccurate, illogical, irrelevant, and often downright hysterical.

Martin's associates and successors appear to have done impressive work, but their most dramatic demonstration appears to have been inadvertent: the Scottish proverb that "Bairns and fools should not see half done work!" For example a recent iron enrichment experiment failed to demonstrate instant and selective carbon sequestration and sinking. Amazing! It obviously follows that the principle is unsound as well as too dangerous to experiment with.

Yes?

Without going into detail, such pessimism is grossly nonsensical, about as realistic as early euphoria based on the by now proverbial "half a tanker of iron". That not all the plankton produced will sink immediately, does not imply that the carbon in organic matter near the surface is bad news. All combined organic carbon, whether sinking or contributing to the surface biome, thereby encouraging still further carbon fixing, represents more fixed carbon. To demand that emergent, secondary carbon fixing should become established in a single cycle, would be completely unrealistic.

As I have pointed out, in the context of anthropogenic global warming I am not in the short term much concerned with carbon dioxide concentrations. Rightly or wrongly, I am unmoved by invective; however, if we are indeed to remove carbon dioxide from the air, whether for climate control or anything else, then in the long term supplementing ocean trace elements is likely to be the single most powerful tool at our disposal.

Still, complications arise in the use of iron. If you make good one deficiency, then other constraints become operative. An interesting complement to iron enrichment would be to cast strained sewage upon such open-ocean desert waters, not necessarily hoping to find it after many days. Not in its original form anyway...

Sewage could be expected to add other key nutrients such as phosphates and nitrates, and even a little iron; one could expect dramatic plankton blooms where it is sprayed over ocean deserts. For best results the liquid should be somewhat less dense than the local seawater, so that it floats where photosynthetic activity is at its most intense. Such transport of sewage would be expensive, but far cheaper than just spraying iron; and in the long run, far, far cheaper than doing nothing.

Granted, overcome enough of the nutrient constraints, and you risk encouraging eutrophication, toxic blooms, and smothering of ecosystems beneath. None the less, ocean enrichment, in spite of how many complications it may entail, probably is the most effective carbon fixing technology convenient to hand. Personally I suspect that spraying iron, useful though it may be, would at most be a supplement. Recycling sea floor ooze seems to me a more promising long-term option, although the benefit probably will increase disproportionately if that is combined with iron spraying.

There have been many proposals for increased forestry, and for ocean enrichment to encourage plankton, but it seems to me that another obvious expedient is receiving too little attention. There is increasing concern about the worldwide neglect and destruction of mangroves, without enough being achieved. Possibly some mangrove forests will be reinstated or encouraged, but there is scope for more positive action. In appropriate areas of open ocean, floating rafts could be secured and planted with mangroves of suitable species.

The rafts could be made of pumice or foam glass around glass or polymer float bubbles. They would last indefinitely and could be designed to be almost indifferent to swells, hurricanes and changes in load as their forests grow. Units that float too low under growing burdens can be supported by adding floats from below. The porous structure, free of pollutants, would be populated as rapidly as any reef, by wide varieties of animal and plant organisms in a rapidly developing ecology.

A few million square kilometres of floating mangroves could rival the photosynthetic power of most of our existing rainforests. Maintenance would be cheap and simple (as cheap and simple as anything ever is at sea, of course). Wind and wave power could be applied to maintain station in positions over deep ocean, A modest ratio of exposed sea surface between mangrove rafts would be adequate to prevent ecological disasters such as oxygen deficiency in the surface water.

Such a raft area would in fact amount to a unique conservation area. There would be points of ecological resemblance to the Sargasso Sea in the region of the North Atlantic gyre, and, like it, the first open ocean mangrove rafts probably could best be established in major gyres. Apart from anything else, they could contribute to the management and mitigation of the major ocean garbage patches.

Both as a sink and storage buffer for recycled deep sea nutrients or sprayed micronutrient elements, and as a fish nursery, mangrove rafts could feed millions indefinitely, retrieving the carbon from the atmosphere while accumulating it as conserved biomass.

Although no really large enterprise could be initiated as quickly as the iron spraying schemes, the floating forests could remain functional indefinitely with only minor routine maintenance. Depending on the circumstances and the species utilised, a large island could act as a continuously growing buffer, accumulating billions of tons of carbon, and yielding materials of industrial value as well. More likely than not, it would have a beneficially moderating effect on the adjacent climate too, reducing local trends to the development of cyclonic storms.

Imaginative persons, particularly those of a nautical persuasion, certainly could think of many genuine difficulties. However there has hardly ever been a beneficial initiative which did not have to run the gauntlet of critics at its inception. The proverb: "aller Anfang ist schwer" (all beginnings are difficult) should not be taken to mean that no one should ever begin anything.

There also have been surprisingly many proposals, surprising to me at any rate, for extracting carbon dioxide from the atmosphere mechanically or chemically rather than biologically. Never say never. Perhaps someday someone will manage something worthwhile along those lines. Still, for the present I don't believe a word of it. Using standard techniques the volume of air that needs to be processed to remove a trivial amount of carbon dioxide is prohibitive. Without having done any personal calculations, I suspect that the energy expenditure would exceed the energy output from having produced the carbon dioxide in the first place. I even am sceptical about most semi-biological or pseudo-biological proposals, such as the "synthetic trees". They are said to capture CO₂ through plastic leaves, so that it can be disposed of in various ways, My scepticism of its gross benefit is no guarantee of futility, but I nonetheless do not take such proposals seriously in this document.

However effective such schemes eventually prove to be, they are essentially negative in their effect, in contrast to biological schemes that add the CO₂ to the biomass instead of perpetually adding to the threatening burden of waste.

Engineering, Geoengineering, and Realities

Programming today is a race between software engineers
striving to build bigger and better idiot-proof programs,
and the Universe trying to produce bigger and better idiots.
So far, the Universe is winning.
Rick Cook The Wizardry Compiled

I don't have much of a liking for thrillers and horror movies, but as far as I can tell, they are the favourites of most people.

Tastes differ, so what else is new? What worries me is that many people lacking technical competence, seem unable to tell realities that demand sense without indulgence, from self-indulgent fiction. They relish having something to panic about, and they like to sound informed about the problem and its solutions, solutions that only they understand, having obtained them from the current equivalent equivalents of "the woman from over the wall": online or TV re-hashes by pop experts who cannot hardly spell the technical words, let alone discuss the concepts coherently. Never mind those with fish to fry or with political parasitism to subsist on.

The essential features include that they must have an evil to blame, and that the problem is new (meaning that they have just heard of it so no-one else knows about it) and that the right thing to do is forbid doing anything effective about the problem, because that might be too dangerous, doomed to go wrong because no one knows what will happen if you apply anything else because they haven't heard of it and their gurus don't like it.

They fail to understand that things they feed their hysteria on, such as climate change, are engineering problems; and real engineering problems need real engineers to deal with them by real engineering.

Real engineering is beyond the conception of mindless boob-tube addicts. Real engineering deals with characterising and confirming needs or threats, considering their scope, scale, and nature, considering the nature, scope, and scale, of available resources of materials, skills, funds, logistics, politics, and available time. These must be adapted to meet costs, competing needs, and penalties for neglect or disaster. Then engineer selects the course of action accordingly.

Ideally, anyway.

And ideally, that is what is necessary in considering geoengineering (or, more specifically, climate engineering). We have some pretty strong evidence supporting the need for climate engineering to deal with many problems, and global warming in particular.

We have evidence that at least a significant part of our current global warming is anthropogenic.

We have strong evidence that the warming is continuing, and growing fast enough to threaten the planet's habitability, and demand action on our part.

We have pretty well certain evidence that the bulk of the excess heat is incoming from the sun, and that the excess is not just variation in the solar constant.

We have strong evidence that just cutting back on our production of global warming gases will not suffice to mend matters on any acceptable time scale.

We are compelled, accordingly, to contemplate climate engineering and investigate which forms are most appropriate.

So why make so long-winded an issue of the matter?

Because it is one of the forms of research and engineering that irresponsible scientific illiterates demonise.

Which they do because, when one cannot understand something that one cannot control, it comforts the spirit and indulges the ego, to demonise it. After that, any attempt at positive initiatives to correct or mitigate the problems, is equally vilified, because it demands comprehension, and threatens the basis for the comforted ego if it were to work.

Why Think of Climate Engineering?

That which can be destroyed by the truth, should be.
Patricia C. Hodgell

They would not listen, they did not know how
Perhaps they'll listen now
Don McLean

We have a problem.

Whether anthropogenic or not, it remains a problem, and even if it were not at present a problem, it is clear that such things have been problems in the past — very, very serious, even deadly, problems, and will be problems in the future. They will be ecological problems and political problems, problems of life, suffering, famine and death, so we can't afford just to wait till they go away again.

Some zealots argue that we must not interfere, on the grounds that if anything goes wrong it will make matters worse, and if against all odds, anything did work, that would encourage the fossil fuel burners to carry on with business as usual.

Like when a man has a broken leg, refusing to treat it in case the treatment harmed the leg further, and in case the treatment worked, it would encourage him to break it again.

That kind of logic overlooks what happens if we leave the leg untreated, and that we have no choice but to do something about every situation, and that doing nothing is also a choice, so that we cannot escape our consequences or our responsibilities by ignoring them or ignoring our resources and costs.

Among our most vital resources are our available information, and our capacity for extending that information.

And those entail the associated responsibilities.

We know something about the nature of our problem, and how it reacts to circumstances

We know that simply stopping our farming and industrial production of CO₂ would at best take so long to mend the situation, that there would be no end in sight to the situation; we also know that such a complete stoppage will not happen, so there is no guarantee that our best efforts would do better than slow the progress of the disaster.

Furthermore, there is a tipping-point aspect to this problem: certain effects of climate change cannot be reversed within any foreseeable time if they once proceed beyond a given threshold. For example, as one such tipping point, anthropogenic global warming could cause the development of a new desert in a torrid zone; and that desert might be a new stable effect that would not foreseeably reverse itself spontaneously, but in principle we could reverse it within a human lifetime. However, we could not reasonably expect to reverse all the extinctions and similar side effects that occurred during the creation of the desert.

Conversely, if anthropogenic global warming led to the melting of our remaining great ice sheets in say, Greenland and Antarctica, we could not foreseeably recreate either their ecologies or their ice masses, whether we deemed those to be desirable or not.

The corollary is that we cannot simply deal with the threat by stopping the wrong we are doing, even if we could agree what that is. We need to compensate for the existing damage as well as correct the processes that cause it, not to mention dealing with the needs that had prompted us to behave in that way in the first place.

And we need to develop the ability to steer our climate, our ecology, and our conservation, cycling and balance of resources and the consequences of our actions.

We know that our reserves of non-renewable organic fossil materials are finite and already exhausted in places, while also creating the bulk of anthropogenic greenhouse gases. Don't even think of taking seriously anyone moronic enough to speak of "sustainable use of fossil fuels". (And, no, that is not my invention; I have seen the phrase published.)

Meanwhile, progress in harmless renewables, such as wind, solar, wave, and geothermal power, and in energy storage, and in nuclear breeders, has been continuing rapidly and consistently; at this rate it will strangle the coal and oil and possibly even gas industries for all purposes short of industrial chemistry, road paving, and suchlike.

The biggest and stubbornest remaining emitters of CO₂ are industrial chemistry and transport, and yet, even those are making great progress with energy storage and other difficulties.

We know that reducing our incoming solar energy, while reasonably maintaining our output of infrared, would be quite enough to reduce our global warming.

So?

. . .They would not listen, they're not listening still
Perhaps they never will
Don McLean

Then, in summary, we know the threats and the needs and the limitations and the scale and the urgency; we know that doing nothing, or stopping what we are doing so that the problem goes away, simply will not work.

We either could sit down and cry till the problem goes away (and is replaced by something predictably a lot worse) or we could continue business as usual while social parasites batten on international conferences, all of which will replace the situation with much worse consequences much faster, or we can produce whatever is a positive response to a real situation. That is what is called engineering. In this case the subject is the planet, calling for geoengineering, or largely, the climate, calling for climate engineering.

We know that these things, like all engineering, will go wrong. Like most engineering, it will not go as far wrong as it goes right. Unlike much engineering, where it goes wrong, it will be practical to detect whether something is going wrong, and adjust the process.

We have neither rational, nor moral, nor aesthetic, choice: we must stop dawdling, and get down to business.

As for religious choices, well, there is no accounting for that. Whatever some religion says, there is a horde that contradicts it. We can safely ignore any sect that demands that we leave it to divine powers; engineering has no sympathy for any policy that labours for its own destruction or frustration.

Full Duplex

Thursday, September 15, 2022

Selective Climate Engineering

Before reading on, please note: