April 4, 2010
ECONOMIST
25 St. James Street
London SW1A 1HG
UNITED KINGDOM
Sir:
I read your article “We All Want to Save the World” with rising alarm, not so much about what is planned, which is going nowhere, but about what they will think up next. A group met at Asilomar, California, to continue taking steps to introduce a haze high in the atmosphere to shade us from the sun and reduce global warming.
Basic physics makes clear that an object in a box at 100 degrees will, at equilibrium, be at 100 degrees, whatever the temperature scale. It is also clear that any object in space at our distance from the sun will at equilibrium come to about 70o Fahrenheit, where we feel comfortable. Thirdly, as air rises in the atmosphere it expands and cools, so there is a normal lapse rate such that higher altitudes are generally cooler. If you spray an opaque cloud high enough so that the ambient temperature is now minus 70o F, that cloud must, at equilibrium, come to room temperature. There will of course be a transient cooling, which may last for years, as the lack of sunlight at the surface causes local cooling and the system mixes. But in the end, room temperature it must be.
Unless the lapse rate fell, and it would almost surely rise, surface temperatures would rise to something like 210o F. Only then would it be possible to radiate energy into space. The experts hoping to cool the earth that way are depending on a perpetual motion machine. Shame on them.
Sincerely,
M. Linton Herbert MD
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