I write a column for the Pollution Engineering magazine every two months. My August 2009 column was posted on my blog here. Apparently I touched a raw nerve out there with some of my readers. And that’s a good thing. Here is what one reader wrote to me in an emal:
“You end your What is Cap-and-Trade article in the current Pollution Engineering with the question… Why should carbon emission control be treated any differently? My answer… BECAUSE CO2 IS NOT A POLLUTANT OF CONSEQUENCE.
At less than 400 ppm, CO2 is merely a trace component in the atmosphere and constitutes only about 4% of greenhouse gases. Human-emitted CO2 is only 3% to 4% of total atmospheric CO2 and the remainder comes from natural sources (and, incidentally, produces lots of vegetation). Human-emitted CO2, therefore, is at most less than 0.0016 of greenhouse gases. To suppose that tweaking that figure down some with cap-and-trade could possibly affect the Earth’s climate is an obvious absurdity. Something like 90% or more of the greenhouse effect is cause by water vapor. Furthermore, the effect of CO2 is logarithmic—i.e., as quantity increases, the greenhouse effect gradually levels off. ”
The same reader followed up with another email a day later:
My email reply to him follows: