Poor physics



To the Editor:

In his letter to the editor on June 18, John Fehlauer “welcome[s] the opportunity to discuss climate science with anybody honestly interested in it.”

One difficulty with his discussion on basic physics is that his take on “how greenhouse gases warm the planet,” at least in the case of CO2 from burning fossil fuels, is unfortunately incorrect.

Yes, CO2 can be considered a greenhouse gas. And yes, CO2 has contributed to global warming. But, the relationship between temperature and CO2 is not linear, but a reverse logarithm.

This means the first 20 ppm of CO2 had a greater impact on temperature than the next 400 ppm. CO2 quickly reaches its saturation point in the atmosphere, and at 385-390 ppm, it is already a spent force. Any further increase will do next to nothing to global temperatures.

Climate sensitivity thus decreases with increasing CO2 concentration.

While Fehlauer claims that “The basic physics of how greenhouse gases warm the planet hasn’t changed since the 19th century,” the devil is in the details. In the case of CO2, Arrhenius reworked his calculations in 1906 and reduced the degree of warming by a doubling of CO2 to only 1.6 degrees centigrade. And more recent calculations have revised this theoretical temperature increase downward even further to less than 1 degree centigrade increase.

A good resource for this is a recent book by J. Fone, “Climate Change: Natural or Manmade.” It includes a good illustration of the reverse logarithmic effect. This is not original with him, so it isn’t just made up.

As I have pointed out previously, global atmospheric temperatures have not been rising with increases in CO2 from burning fossil fuels for over 18 years, even though CO2 levels have increased steadily.

CO2 isn’t a pollutant, and if anything, it’s a nutrient essential for human and plant life.

We can use more of it.

Tom Rolfes

Somesville

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