Letter: Refuting letter skeptical of climate change - Quad-City Times

Letter: Refuting letter skeptical of climate change

I read Don Erbst's letter questioning climate change on July 23, but was surprised no one responded. He argued that the climate has fluctuated throughout the ages, so "warming" depends on when you start your comparison (no argument there, it's a tautology), and also that carbon dioxide could not be responsible for the current warming because it's a very small percentage in the atmosphere.

I am not a climate scientist, but his numbers look about right, although they seem to be for dried air without particles. (Note that water vapor can be up to 4% of the air — skewing the other percentages — and actually has a larger "greenhouse" effect than carbon dioxide: think of how clouds act like a blanket reducing radiation of heat back into space.)

As for how carbon dioxide can affect a large change in the atmosphere, consider two things. First, Freon, which had an even lower percentage, had a major effect on ozone in the atmosphere that has been reduced since we switched refrigerants. Second, in complex systems with many components interacting with each other, a small change in one will often make a large impact on the whole — this is the basic meaning of the so-called "butterfly effect."

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Finally, NASA's satellites measuring this have shown about a 50% increase in carbon dioxide levels in the 60 some years they have been in operation. I can personally testify to the weather changes during that time: although correlation does not necessarily mean causation, does Mr. Erbst have another explanation?

Dennis Ewoldt

Davenport