To the editor:

Mr. Smalter (Public Forum, Jan. 8) correctly quotes atmospheric measurements which show that the CO2 content has increased from about 370 to 385 parts per million (ppm) over the past 10 years. He claims that this is a “very minor” increase and scoffs that it is “Ridiculous!” and “Absurd!” for scientists to suppose that this could be involved in global warming.

Exclamation points aside, the concern over a 15 ppm increase in 10 years is neither ridiculous nor absurd. What scientists are most concerned about is the longer historical record and the recent and future trends, of which 1999 through 2008 is just a small, but significant, part.

Since the beginning of the industrial revolution around 1750, CO2 levels have grown from about 280 to 385 ppm. Most of this 40 percent increase has, in fact, occurred during the last 100 years. If the most recent “very minor” 10-year rate of 15 ppm were to continue for another 100 years, the CO2 level would reach 535 ppm in 2109! This would represent an increase of over 90 percent since 1750, which would be truly deserving of the exclamation mark.

It is this latter scenario which worries the climate scientists. Average annual global surface temperatures have increased somewhat over one degree Fahrenheit during the past 100 years. Calculations based upon continued growth in CO2 levels during the next 100 years predict global temperature increases as large as 5-10 degrees. Such a result would have catastrophic global climatic effects.

Marlin Harmony,
Lawrence