In a recent letter (“Honor Lac- Megantic by reining in use of fossil fuels,” July 28), the author suggests that “over the last century, the fossil fuel-related carbon dioxide content of Earth’s atmosphere has gone from under 300 to more than 400 parts per million.”

When discussing climate change, it is to everyone’s advantage to report factual data. A recent research paper finds only about 4 percent of the atmospheric carbon dioxide can be attributed to burning fossil fuels. The research was published in the journal Atmospheric Chemistry and Physics.

This indicates that of the increase in carbon dioxide of 160 ppm since the year 1860, only about 5 ppm can be attributed to fossil fuels.

The core of the carbon dioxide debate comes from the International Panel on Climate Change. By comparing apples to oranges, the IPCC compares today’s instrument readings to air bubbles compressed in ice for hundreds of thousands of years. While today’s instrument readings are instantaneous, the ice core readings are not and therefore called approximate data or “proxy” data.

Why is it called “approximate”? Because it is extracted from old compressed ice and the readings are then averaged over the course of 1,000 years. When you take an average, it eliminates any high points.

For example: Take a day last week with a high temperature of 80 and a morning low of 50. This gives a mean of 65. What happened to the 80?

This is what happens when we take a 1,000-year mean for carbon dioxide: The mean of 300 ppm eliminates the 400 ppm peak that occurs on all global warming cycles. This is why the IPCC says that atmospheric carbon dioxide has never been above 300 ppm.

David Dilley

CEO, Global Weather Oscillations Inc.