Thursday, April 4, 2019

Climate change

From a comic strip by Quino:
Mafalda, her little brother Guille, and their friend Felipe, are sitting on a doorstep during a very hot day.
Felipe: Bother! It’s really hot!
Guille: It’s the fault of the government, right?
Mafalda: No, it's the fault of the summer.
Turning toward Felipe, she adds:
Mafalda: He’s a small boy, he still can’t put the blame right.
Listened in a radio station news in June 2017, on a very hot week:
Announcer: The cause of the heat we are experiencing is the climate change.
Like Guille, this announcer (or the person who wrote what she said) can’t put the blame right.
Nobody doubts that climate change is a fact. In recent decades there have been some evident changes in the global climate: the average temperature of the planet is rising; the glaciers are receding; the polar ice is melting; the distribution and intensity of extreme weather events (storms and hurricanes) is changing. What we must discover is the cause of these phenomena. Regarding this, there are two main theories:
  1. The current situation is the result of a combination of natural cycles in the evolution of the climate of our planet. Among these cycles, the following can be mentioned:
    • Milankovitch cycles, consequence of periodic alterations in the orbit of the Earth that modify the amount of solar radiation it receives. These changes, which affect the eccentricity of the orbit, its obliquity and its precession, take place over periods of thousands of years, but the combination of several cycles with different periods can give rise to perceptible changes in much shorter periods.
    • Solar cycles, which affect the amount of energy that the sun emits, and therefore the amount we receive. The best known is the 11-year cycle of sunspots, of very short duration, but there are other overlapping cycles. A curious fact: the almost total disappearance of sunspots between 1650 and 1700 happened at the same time as the peak in an epoch of abnormal cold, which is called the little ice age.
  2. The current situation is a consequence of human activity. Among these causes, the following can be highlighted:
    • The concentration of CO2 in the atmosphere, which has gone up from 290 to 370 parts per million between 1850 and 2000. It is well-known that carbon dioxide is one of the gases that can cause a greenhouse effect, by absorbing and accumulating in the atmosphere part of the solar energy that in its absence would be ejected into outer space. A spectacular example of this effect is the planet Venus, whose atmosphere, composed mainly of nitrogen and carbon dioxide, has a surface pressure 90 times greater than that of the Earth, and a temperature of about 470C, higher than that of Mercury and able to melt lead. (See my science fiction novel Descent into the hell of Venus, which can be downloaded free from my website).
    • The continuous and growing consumption of energy. In another post in this blog I pointed out that this increase has turned, from exponential, to approximately linear. In other words, we are already in the linear part of the logistic curve, as is also the case with the world population. The UN forecasts indicate that the increase in population will probably reach a maximum between 2050 and 2100. We can expect, therefore, that the increase in energy consumption will also slow down around the same dates.
CO2 concentration in the atmosphere
What is the most likely cause of the climate change? In my opinion, a combination of both. In any case, if our action could be one of the causes of the phenomenon, we should do something about it. We have the very recent example of the hole in the ozone layer, which was considered a consequence of the massive use of chlorofluorocarbons (CFCs) in industrial and domestic applications. Their almost total ban since 1989 (in the Montreal Protocol) has managed to put at least a partial brake on the deterioration of the ozone layer.
A different question is whether the use of renewable energies will serve to stop the possible effects of human influence on climate change. The answer to this question is yes and no. If the consumption of fossil fuels stops, the amount of CO2 that we are sending to the atmosphere will decrease. But renewable energies, by themselves, would also cause an increase in the global temperature of the planet. It has been calculated that, if all the energy consumed now in the United States came from wind power installations, the temperature on the surface would increase by 0.24C. One cannot get something for nothing.

The same post in Spanish
Thematic Thread on Politics and Economy: Previous Next
Extended version published in Journal of Global Issues & Solutions
Manuel Alfonseca

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