Reducing Greenhouse Gases: The Problem

In the previous post, I looked at the prospects for helping combat global warming by decreasing the solar input to the planet, mainly by reflecting light back to space. The basic problem is the size of the planet: to reduce solar input by 1% you have to totally reflect one per cent of the incoming radiation, which involved ideal reflectors of area somewhat greater than 4 x 10^11 square meters.

Superficially, option two, which is to increase heat output, is easier. All you have to do is to reduce the amount of greenhouse gases in the atmosphere. However, that is something of a problem because we are adding almost 9 billion tonne of carbon as greenhouse gases per year. So, to improve the current situation we have to devise a means of taking out more than 9 Gt of carbon, or over 33 billion tonne of carbon dioxide per annum. Worse, much of the carbon is in the form of methane, which is a much worse greenhouse gas, so a target of 50 billion tonne per annum of carbon dioxide is probably a minimal “hold the current state”. Again, the size of the problem is basically the problem.

Carbon dioxide is naturally removed from the atmosphere by weathering certain rocks. To oversimplify, silicates come in two main classes: granitic and basaltic. The granitic rocks have a much lower density than the basaltic, so they tend to float, and our continents are largely granitic, which, having a large fraction of their composition as aluminosilicates, and since aluminium does not form a stable carbonate, these rocks weather mainly to clays and not carbonates. Thus the main rocks of our continents are not going to help.

The basaltic rocks mainly comprise olivines or pyroxyenes, which are two families of iron/magnesium silicates, the former being nominally “salts” of silicic acid, and the latter salts of chains of polysilicic acid. These will weather to form silica and carbonates of their metals, but at varying rates. One of the proposals is to crush peridotite, one of the fastest to weather, into dust and incorporate it into soils. Powdering it increases surface area, thus increasing the rate of reaction because the reaction is limited to where the carbonic acid in water can get at something to react. It will still be slow, and the energy to crush the rock has to come from somewhere, and might be better used to substitute for the worst other means of producing energy. Another problem is that while peridotite is one of the most common rocks on the planet, that is because it is essentially an upper mantle rock, with only odd visits to the surface. Reacting the gaseous carbon dioxide with basalt is nature’s way of taking it from the atmosphere, but with all the basalt on the planetary surface, it will take centuries to remove the excess there now. This is not going work, although it would make sense to bury carbon dioxide if it were already isolated, but preferably into some basaltic zone.

A better way of removing carbon dioxide is to grow more forests, and in particular to permit the equatorial rain forests to regenerate. A further alternative is to grow massive amounts of algae, which would require ocean fertilization. Some marine algae are extremely rapid growing plants (with a microscope you can watch continuous cell division!). For macroalgae, in the 1970s the US Navy showed how such algae could be grown in open ocean water (as opposed to near coastlines) by growing on rafts and fertilizing with bottom water raised by wave power. The experiment succeeded until a rather unfortunate storm wrecked things, but that, to me is a design and engineering problem that could be solved. In short, the technology for growing plants is more or less available.

The algae could then be used to make synthetic fuels, and while that would merely cycle carbon dioxide, it is better than producing more. We could also bury carbon, as any such processing makes some carbon deposited as char. The growing of algae has one further possible advantage; it takes energy entering the oceans and stores it as chemical energy rather than as heat, and it also emits mercaptans, which should make more clouds after absorbing more ultraviolet light.

To be clear, neither of these will solve the problem, but growing plants will at least contribute to a solution.

So, why don’t we? Quite simply, economics. There are two main problems: the tragedy of the commons, and politicians. The first problem is that unless everyone contributes, the problem cannot be solved, but some, of course, will not mind climate change, or, alternatively, decide nothing will affect them, so why should they pay to fix it? Unfortunately, the expense is so great. This is part of why I favour the algal response. The growing of such algae will also support greater fish life, and hence improve the food supplies, and can be used to make liquid fuels, provided the right technology is used, and there is some chance it may increase cloud cover. By addressing three problems, two of which have money-making prospects as well, makes it more likely it would be successful. At first, of course, such algae could be grown near the current coastlines, and we know how to do that.

Politicians are a more intractable problem. An example: in New Zealand politicians were determined that an emissions trading scheme would be its response. Some New Zealanders began planting trees to get credits, but then Ukraine and Russia produced mountains of such paper credits, there price crashed, and while the current trees might be absorbing carbon dioxide, nobody is in a rush to plant more. If you have travelled the world, you will see vast area where forests have been removed and nothing done with the resultant land. Forests could be regrown, especially tropical ones. The problem then is, who pays for them? Why should Brazil, say, spend a lot of money to plant forests to benefit everyone else? It is politics and governance again.


12 thoughts on “Reducing Greenhouse Gases: The Problem

  1. We are a greedy and short-sighted species, unfortunately. Optimistically, though, the algae solution may be the one, especially if it creates profits. Your previous post about blocking solar energy reminded me of the “year without a summer,” 1816, following the eruption of Mt. Tambora. Of course, volcanoes cannot be made to erupt, and even though the effect could be simulated by introducing particles of some sort, it might work too well in the short term. Truly an intractable problem.

    • Yes, volcanoes make a great answer when they work, although they are somewhat destructive in other ways. The contrails proposal is like that, putting up dust in a slightly more orderly fashion.

  2. There is only one mitigation solution for the GHG (Greenhouse Gas) asphyxiation problem: a massive carbon tax. Mitigations such as synthetic fuels, growing algae, or forests… would help. A bit.

    A caveat: today’s species are not made to function with 500 ppm GHG we have now. We are within ten years of a doubling of the old concentrations. Watch the Great Barrier Reef die.

    So what happens? Species die, indeed, or do not live too well. This is what recent studies on the Amazon forest show: trees are aging faster than they used to. So much for growing plants.

    A generalization of synthetic fuels, is to mimic trees, and directly synthetize from CO2 the material we need: artificial cellulose/wood…

    Long term solution? Terraforming thermonuclear fusion plants to mechanically refrigerate CO2 out of the atmosphere, and then inject it tectonically in sinking oceanic plates…

    • Dear Patrice, Yes, a carbon tax would help, BUT you still need energy, and I believe you will still need liquid fuels. Reasons I shall leave for another post. And yes, species die. Even now, here, paua (a variant on abalone) are in severe trouble because the young shellfish need aragonite for their shells, and the pH of the oceans is now reaching a point where this version of calcium carbonate is having difficulty precipitating. And while evolution tends to protect species, evolution cannot cope with the current rate of change we are imposing.

      Aging trees is not necessarily a problem, as long as they are replaced. If they rot and convert carbon into soil components, than can be good. And yes, thermonuclear offers a potential solution, except we cannot do much with that now because we haven’t got it.

      And thanks for the intelligent comments.

      • Another problem is Sea Level Rise
        A solution would be to pump (using electricity from windmills feeding 100 large pumps as used in New Orleans) the ocean into the middle of Antarctica, where it would freeze. Windmills could be used for the electricity. Studies show that would neutralize the present 3mm rise. However, that’s augmenting…

        Carbon tax would accelerate enormously the switch to solar and wind, and ocean waves, by bringing the pain now, instead of tomorrow.

        Something else: a power thermonuclear reactor is probably feasible, NOW.

      • I must agree with you on sea level rise, although I am not sure pumping sea water will do it. Pumping melt would be preferable because you don’t really want a concentration of salt there. If there were a way, I would prefer to get clouds to deposit snow in the interior, but I concede I am not sure how to pull that one off.

        Your link to the thermonuclear reactor said a plant should be ready by 2037. I do not consider that to be now 🙂 However, apart from details, I am in general agreement with you.

  3. What would be feasible would be to start on a power reactor (“DEMO”), now (making it slightly bigger than ITER. Initial ITER was supposed to be much bigger. BTW, you should check my entanglement essay… That was really now.

    • I am trying to find a directly intuitive version of the Bell Inequality. (Although the initial EPR is intuitive, it leads all too naturally to Many-Worlds…)

      • This is what my post will be about. If you take the known properties of the photons, and accept the condition of entanglement, then it is easy to derive a Bell inequality from those properties, which means there cannot be any violation unless one of the premises is wrong, or the associative law of sets is violated, the latter meaning all of mathematics is rubbish. My view is all is well, and there are no violations. I have published why not in my ebook “Guidance Waves” and have shown the proof to various physicists who teach the topic, and to one who wrote a book on Bell’s inequalities, and they all avoid me like the plague, but none can find a fault. (And knowing physicists, if there were a fault that they could see, they could never resist pointing it out!) The reason for my slowness is I want to try and get the point in the post as easily comprehensible as possible, and that is not easy. (The reason there are no violations is that in the rotating polariser type experiment there are silly insufficient true variables to put into the inequality.) Incidentally, this says nothing about locality, and is equally valid for local and non-local.

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