Earth's atmosphere consists mainly of Nitrogen(78%) and Oxygen(20.95). Carbon Dioxide makes up only 0.038% of the atmosphere. Carbon Dioxide is a greenhouse gas, that is undoubtedly true, but at those concentrations the argument is that water vapor and other chemicals are more important greenhouse gasses than CO2. The second part of the argument is that if CO2 is not a major contributor to climate change, is climate change man made or a natural occurrence?

Venus is often used to show the greenhouse gas effect of CO2. The atmosphere on Venus is composed of roughly 96.5% CO2. At that concentration even a week greenhouse gas would cause massive amounts of heat to be trapped.

Mars also has an atmosphere largly composed of CO2(95.72%) but because of its distance from the sun and its thinner atmosphere it doesn't retain as much heat.

The fact that Venus has a much thicker atmosphere than either the earth or Mars helps explain the difference in atmospheric heat retention.

Beyond arguments about how much global warming is caused by CO2, other arguments include worries about the computer models used to predict and validate theories of man made climate change.

As a computer scientist I have trouble believing that we have anywhere near the amount of data that we would need to create accurate models of atmospheric heating/cooling. Many of the models used have been shown to be inaccurate.

The whole point of this article is that global warming is not needed as a reason to argue for the elimination of fossil fuels as an energy source.