Valentin Krassilov

(Inst. Of Evolution, Haifa)




 When two scientists of a field fully agree on a matter of their professional interest, something must have gone wrong in the Danish Kingdom and beyond. When 2500 scientists, no less, sign a petition urging governments of all countries to take immediate measures against global warming, which they unanimously perceive as a major threat to our existence, their motives must have been anything but science. After all, scientific community is not a mob of football fans, or is it?

Yet even football fans are aware of what they are talking, or shouting, about. Only the top politicians can afford talking (shouting) about something they have no idea of. This way it is easier for them to summon the assurance necessary for summoning us for a quixotic fight against windmills (or for the windmills as the case may be).

For the benefit of such politicians and those summoned, let me remind what can and what cannot be done about climate change. First of all, there is ample evidence of cyclic climate changes through at least two billion years of geological history. Let us forget about dinosaurs for a moment, because even the relatively recent, Cenozoic, changes brought palms and crocodiles to the polar circles. The consequences of such a global warming seem to have been less adverse for life than those inflicted by global cooling. Anyway, living beings always responded by adaptation rather than by attempted prevention of climate change.

The energy of the climate machinery comes from the Sun and is distributed over the globe giving rise to latitudinal climatic zonation. Crocodiles wre brought to the poles not by a dramatic increase of incoming solar energy, but by its more equable than now distribution over latitudes that depends upon geological situation in the first place. I skip the details; we can do nothing about geological situation anyway. Let us better turn to incoming solar energy itself. Its fluctuations are periodic, brought about by the solar radiation cycles, a something entirely beyond our power to prevent. Solar cycles are superimposed by cyclic changes in eccentricity of the Earth’s orbit, obliquity of ecliptic, and precession of equinoxes, the so-called Milankovitch forcing. Yet even Milankovitch himself never claimed knowledge of how we can oppose his forcing.

Yet a certain amount of solar energy is reflected, and this is where we can, in principle, enter the play by altering reflectivity of the earth surface and/or atmosphere. The proportion of incident light reflected is called albedo, which includes several dozen variables, such as incidental distribution of land and sea, polar ice caps, snowfall, cloudiness, greenhouse gases, etc., the atmospheric concentration of carbon dioxide among the latter. This gas is emitted by volcanoes and forest fires. The contribution of fossil fuel burning is less voluminous, yet substantial. Although a minor component of a minor variable, it apparently gives us the chance of asserting ourselves as a global power by challenging global climate, so why not?

Alas, of all the chances this is the most slender, because the balance of atmospheric carbon dioxide is maintained by far more powerful agents then anything we can realistically supply, namely by the far greater than atmospheric stores of carbon dioxide in the world ocean, soil pores, vegetation, and silicate rocks, from which it is released by chemical weathering. Both natural and technological emissions of carbon dioxide are compensated this way. Whatever we do about fuel burning would not have a lasting effect and practically would not have any appreciable effect at all. Since chemical weathering and the other sinks of atmospheric CO2 are affected by the ambient temperature, the balance can only be shifted by temperature itself that eventually control CO2, not the other way around.

Human civilization is essentially an adaptation to climate change by using fire, by wearing clothes, by building shelters, by channeling river mouths, by damming the sea, by predicting storms, etc. We were disillusioned in our adaptive competence by Katrina and similar recent climate-generated hazards. Money spent on a summit on illusionary prevention of climate change is almost enough to guard a city from a Katrina. Then let us do what we can instead of trying to do what we cannot.




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