Three Simple Facts About Carbon Dioxide

by John Nielsen-Gammon/Climate Abyss/Feb. 2012
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Some things about carbon dioxide in the climate system are so firmly established and fundamentally important, you can use them as litmus tests to determine whether the person you are listening to is honest and knowledgeable. Note that somebody contradicting these facts may be dishonest or ignorant or both, but it’s usually not possible to tell which. And as can be inferred from a previous post, correctly assessing the reliability of your knowledge source is critical.

Fact #1: A small concentration of CO2 is a big deal.

Physics research over the last two centuries have given scientists and engineers the ability to calculate quite accurately the direct effect of CO2 on the exchange of radiation in the atmosphere. We know, for example, that doubling the concentration of CO2 from its preindustrial levels has about the same energy impact as cranking up the total energy output of the Sun by 1%, with a resulting increase of global surface temperature of 1.5-3 °C (if we’re lucky) or 3-6 °C (if we’re not lucky).

How can so little CO2 have a significant effect? The key is that it is absorbing and emitting infrared radiation at wavelengths most other gases don’t. In other words, it occupies a special niche in the electromagnetic spectrum that gases present in higher concentrations don’t fill very well. The same is true of all other Tyndall (greenhouse) gases of importance to the climate system.

Read more at Climate Abyss