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To fry? To freeze? To freeze perchance to steam?
Aye, where’s the tub?

A discussion of some options for dealing with climate change & climate scares.

First things first: I am fully aware that the suggestions in this note are not half-baked (yet), that they deal with vast and possibly unmanageably complex systems, whose current behaviour has not been soundly characterised, and that even the available data are nothing like satisfactory as yet.

So why don’t I just shut up?

I don’t do shutting up.  Not so’s you’d notice, anyway.

Besides, I regard hubris as one of Humanity’s signal virtues and I do not think that Humanity’s global problems, whether anthropogenic or adventitious, will be satisfactorily resolved without Humanity’s energetic and active contribution.

And if questions and suggestions always must wait till everything were resolved, there would no need for questions and suggestions, would there?

And OK, the world would be a quieter place.  So, all right, blame me; blame, blame, blame!

Good, now we have that done, let’s get back to the hopefully not so real world.

We live on a planet on which temperature and heat supply are crucial and are delicately, even precariously, balanced.  Everyone in this list will know that a one percent change in our solar flux could have drastic effects on the entire planetary ecology and climate; favourable effects in some places, disastrous elsewhere.  Earth has spent some four or five billion years alternately freezing, sweating and dithering, and our climatic fundis or would-be fundis have spent decades panicking about or pooh-poohing predictions of imminent ages of fire or ice, drought or drowning.  Facile catastrophists and uniformitarian zealots have perished on the battlegrounds of prehistoric weather and climate, their explanations, their implications for our future, if any, and the significance of putative human contributions to potential climatic change.

But to me that is all backdrop.  I hold no brief for most views on the subject, except to agree that it is very, very important.  My point here is far more limited.  As Twain said, everyone is always talking about the weather, but no one does anything about it.  Maybe it is time to change that, and not merely by driving gas guzzlers.

Until our planet runs out of water, heat is the key factor in our climate.  Our most natural source of really large scale warmth is the sun and our most natural sources of coolth are shade and thermal radiation: exclusion or shedding of solar heat.  If we could increase the capture of sunlight by just a few percent or increase its exclusion or shedding by a few percent, there is hardly an area on Earth whose climate we could not change during the next billion years or so.  In fact, I bet that if we could change the solar absorption of some marine areas, we could change the rainfall of some land areas too.  Fancy changing the Sahara or the Great Australian Desert back to savannah, or even just reversing the current trend to desertification in some major areas!

Just a modest increase in the reliability of the climate of some bread-basket areas would in itself be a major, major benefit.

Now what sort of engineering would that take?  It would depend on the area, of course.  Let’s consider a few examples.  If we could hasten spring snow melt, or discourage extensive seasonal snow cover or turn permanent snow cover to seasonal snow, that would already be something dramatic.  Even warming the snow without melting it during the cold weather, so that it melts more quickly in spring, could be useful.

What would work?  I reckon that darkening the snowscapes should do the trick.  Does anyone know whether any work has been done along those lines?  Or whether anyone has calculated what sort of area would need to be darkened and by how much and for how long,  if the effect is to be worth it?

And how do we darken snowscapes? I am no snow expert myself, and I do appreciate that every possible method that shows any promise would need intelligent experimentation to see whether it would work at all, and if so, under which circumstances it would be appropriate.   But I can think of a few approaches.

• Soluble dyes to darken the snow itself.  There are some compounds of very modest cost that could be sprayed over snow at rates of about a milligram per square meter, or a tonne per thousand square kilometers.  Even fairly toxic compounds would be acceptable at that concentration, though of course only harmless biodegradable compounds need be considered in practice.  Melting would be from the top and the first melt would soak into snow beneath, rendering that in turn more absorbent to heat.  Note that though they would work best in bright sunlight, such heat absorbers would also have a beneficial effect in gathering energy from light diffused under cloud cover.   Even dyes covered by fresh snowfalls would be useful once they were exposed by the melting of layers above them, possibly themselves melted by subsequent spraying.  Each melting deferred by burial of the dye, could be seen as meltwater in the bank.
• Pigments on the snow.  Similar in principle to dyes, but possibly a bit trickier to manage.  Many pigments would be suitable, even dark clay, though for really large scale work one would want something like carbon black or sooty oil or tarry material.  Some grades of carbon black are at least as absorbent as dyes, though perhaps they would wash away more easily.  Some experimentation would be necessary to find the best medium and techniques.
• Heat absorbent objects and heat pumps.  It is doubtful whether any fancy mechanism would be suited to such a large-scale job, but it might be that black plastic or Al threads or bubbles or cube corners designed not to blow or float away would suit some applications better than pigments or dyes.
• Biological heat traps or “pigments”.  Particularly promising options might be to spread spores of suitable strains of algae or photosynthetic bacteria in tiny drops of gel doped with mineral nutrients.  They would absorb light and heat and propagate themselves, thereby amplifying the absorption as they grow.  If something suitable could be concocted, it might be more cost-effective than spraying a synthetic pigment.
• Possibly marine or lacustrine ice sheets could be broken up by pumping a stream of water against their undersides, possibly just by redirecting natural currents.  Suitable placement of surface darkeners could help the dissection.  Freed ice sheets could then be floated to regions where they would melt more easily, or (long-standing dream!) where their water and cold could be put to use.

Any substance that can be effective at rates of milligrams per square meter could be distributed by aircraft.  A modest fleet of large cargo planes carrying say ten or twenty tonnes of payload could cover a million square kilometres  in a week or two.  The effect need not be limited to snow fields. Even plant cover, such as boreal forest or tundra, could benefit from the warming effect of improved absorption or accelerated melting of snow cover on their leaves.  Adding plant nutrients would slow the rate of coverage because of the increased mass to be distributed, but where given nutrients are limiting, could increase the long-term benefit of leaf cover and increased metabolism.  A related concept is the spraying of iron into iron-limited oceanic waters, to stimulate phytoplanktonic growth.

Let’s not get too facile.  Not all attractive options would work everywhere or be economical everywhere.  The point is that intelligent application and modest investment in established technology could have large scale effects on fairly short time scales.  I don’t see much risk of a new ice-age for as long as humanity maintains its technological capabilities and keeps its wits (or develops some...!)

Another form of climatic tailoring that I should expect to show promise, is by colouring soil either to heat up in patches or fail to heat in patches, either by darkening or lightening it.  The idea in this case could be to convert cold soil from permafrost to forest or cropland (or crop swamp; how about converting tundra to paddy fields?)  Or perhaps we could even create updraft areas that would cause rain in selected areas or act as windbreaks.

But where is the atmospheric water to come from?

From adjacent tracts of sea, suitably chosen.  It should not be difficult to design floating grids confining shaggy black mats or pellets of foam glass or plastic that are barely buoyant and retain a thin layer of water.  Given suitable design, the increased absorption of heat should increase evaporation by a large factor.  The land breeze or suitable prevailing winds could carry the vapour inland and suitable updrafts could precipitate the water.  Chimney-type power plants could even precipitate it as useable water  instead of just general rain, I bet!  The sea-going structures could be combined with wave- and wind-power installations.

I am not convinced that further increase in atmospheric CO₂ would have a gross effect on the atmospheric greenhouse effect, but on the assumption that it would, we could get a lot of CO₂ far more cheaply than by burning fuel.  A vast amount of CO₂ is dissolved in the deep ocean, far more than is at present in the atmosphere.  We could release a fraction of a percent of the dissolved gas by simply lowering neutrally buoyant pipes, each some tens of metres in diameter and a few km long, into suitable areas of open ocean, then starting a CO₂-driven siphon.  As the gas in the rising water column bubbled up, we could actually use the stream to drive power turbines at a profit, while building up a respectable greenhouse effect without burning fossil fuel.

One experiment I should love to see, is to fill a valley with a pool of CO₂ and see whether the greenhouse effect is noticeable!

All right; so we could use increased solar absorption to increase local temperatures, control weather patterns and increase precipitation.  What about reducing insolation to counteract global warming?

Since it would be difficult, not to say rash, to induce an increased rate of explosive volcanism or install orbital sunshades, the main lines of attack would probably be to reflect incoming sunlight in the stratosphere, at cloud level or at ground or sea level.  Possibly there might be some merit to trapping more of the energy photosynthetically, but I doubt that the increased energy consumption would be significant.

Excluding the extra heat by increasing reflectivity in the stratosphere sounds attractive, but I am unsure what the best medium would be.  I don’t see how to get that much ozone up there and in any case the behaviour of ozone is very complex.  It is not clear that increasing it would lead to cooling.  Possibly injecting a few million tonnes of SO₃ aerosol would do the trick, especially near the equator, but perhaps shading the horse latitudes would have a more beneficial effect on rainfall patterns.

Pollution from the SO₃ would be no problem, because we are talking of minuscule amounts of a plant nutrient in rather short supply in some regions.  Of course, getting SO₃ up there would be a demanding exercise, even if it were desirable, which is not yet certain.  My bet is that the best method would be to send up sulphur vapour or H₂S.

Possibly simply injecting water into the stratosphere would be worth while.  Very modest amounts should be disproportionately effective, freezing to microscopic ice crystals.  The question is what the best way would be of getting it up there.  I suspect that we could do a great deal by sending up large numbers of hydrogen- or methane-powered or even H₂S-burning aircraft designed to fly at perhaps 20 km instead of the normal 9 km of commercial jets.  Whether they should be combined with commercial flights or should be specialised for the purpose, is a question for the people charged with the design and the tasks.

The next option is more promising, I think.  Encourage more cloud formation in the troposphere.  This could be done on a large scale by tuning the techniques for heating sea water and creating updrafts.  A few tens of million square kilometres of extra cloud cover at strategic latitudes should have a significant cooling effect, and the more desperately it is needed, the better it should work.

Another approach would be to spread light-coloured material over available land and sea.  This is more controllable, but I am not at all sure what material to use, that would be sufficiently effective and cheap.  It would be hard to aluminise the Sahara and the Pacific.  How cheaply could we produce titania in billion-tonne quantities, I wonder?  Personally I prefer the cloud idea.

As I said, I have little faith in the photosynthetic absorption of energy to reduce insolation, but increased plant cover might be a good way to induce increased cloud cover.

All right.  No need to labour the point before there is any prospect of serious interest in the options, let alone clarity on the need for any such scheme.  What I have been wondering for the last thirty years or so, is why so little discussion has gone into any such options, instead of bewailing first the imminence of the next ice age, and then the threat of global warming, even unto converting our planet into a second Venus.

Suggestions anyone?  Personally I am more interested in terraforming Venus.  Earth is not challenging enough and Mars looks too unpromising.

Cheers,

Jon Richfield

jonrichfield@telkomsa.net

CCCMENU CCC for 2000