Geoengineering: to do or not do?

For those interested in science, and in global warming, a recent issue of Nature (vol 516, pp 20 – 21) showed some of the problems relating to geoengineering, which involves taking action to change the climate. Strictly speaking, we are already doing it. By burning fossil fuels we are warming the planet through the additional carbon dioxide in the atmosphere. The question is, can we reverse this warming in a controlled fashion? The argument behind geoengineering is simple: we can either try it or not try it. If we do, we have the potential to create massive new problems; if we do not, sea levels will eventually rise somewhere between 20 – 50 meters, drowning all our coastal cities, destroying a surprising amount of some of the most productive farmland, and altering rainfall distributions quite dramatically. Then, of course, there are more violent storms. So, what are the options?
One is to try to increase the amount of light reflected to space, which can be achieved by forming more clouds. One way to do this is to spray salt water into the air. This has the advantage of being easy to do, and easy to stop doing. It is harder to know the consequences, but we should be able to predict to some extent because volcanic eruptions will do something similar to what is being proposed. Climate scientists, however, complain that this may reduce rainfall in some regions and possibly worsen ozone depletion. Of course they also warn that rainfall will be reduced anyway. Meanwhile, a computer simulation produced results that indicated changes in rainfall consequent to geoengineering “could affect 25 – 65% of the world’s population”. Charming! No comment that the changes could be beneficial. No comment either about the fact that any given model has consistently failed to predict details of weather.
However, from my point of view, the most bizarre outcome came from the proposal to seed the oceans to grow microalgae, which grow very rapidly and take up carbon dioxide in doing so. When the algae die, they should sink to the ocean floor and trap carbon. Trouble was, in some of the few experiments, it seems they did not, possibly because the algae did not die, or possibly because the experimenters did not count it properly. One other outcome might be that they get eaten by fish, thus improving the world’s food supply, and another might be that they give off dimethyl sulphide (and use up quite a bit of solar energy in doing so) which goes to the atmosphere, gets oxidized by absorbing more light, and then forms clouds, which reflects light. Ideal?
As a potential means of fighting climate change, I admit to liking this idea, nevertheless there is a problem, but not what you might think. Or maybe you would. Yep, it is financial embarrassment. Entrepreneurs decided to seed the oceans this way to generate large volumes of carbon credits, which could be sold to those who wanted to burn more coal, a sure way of reducing greenhouse gases! Yeah, right! Anyway, that was headed off by an international treaty, in which this activity was stopped by labeling it “ocean pollution”, and no further experiments have taken place. Talk about useless politicians!
The problem is as I see it that the politicians cannot seem to recognize that a technical problem needs a technical solution. The economists cannot solve this, as shown by that response to an emissions trading scheme noted above. The problem is, changing the prices of forms of energy cannot in themselves generate energy. Conservation may be encouraged, and that is good, but ultimately our lifestyle requires a very high fraction of what we currently use. Worse, there is no point in denying the fact that the planet is warming, and the only solution is to cool it. Cutting emissions is definitely desirable, but it is not enough to retain our previous climate because the gases currently there produce net warming, and this extra warming would continue for at least a hundred years if no further gases were emitted during that time. If we do not want to do something, who pays the price for what happens?

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