re: #466 AuldTrafford

Two problems: (i) it is not proven that an increase in opacity (or whatever carbon dioxide does) is harmful…

What is well-established science is what carbon dioxide does. The addition of greenhouse gases increase the opacity of the atmosphere to infrared radiation. As everyone knows (or should know) electromagnetic waves travel unimpeded through vacuum. When EM waves come in contact with a material, the behavior of the waves are determined by the dielectric properties of the material and the wavelength of the wave.

The sun emits light over a broad spectrum, but most of the energy in the spectrum is concentrated in the visible wavelengths. At visible wavelengths, the atmosphere is transparent. This means little energy from the sun is lost to the atmosphere and most reaches then ground unimpeded. The soil has different dielectric properties. Some energy is reflected (the light we see illuminating the ground) and some is absorbed which is transformed into heat energy. The soil releases infrared radiation, ie heat rays. However, the atmosphere is not transparent at infrared wavelengths. At these wavelengths, it is an attenuating dielectric. This means as the EM waves pass through it, energy is lost to the material. The EM wave attenuates (becomes weaker) and the dielectric material warms until all of the energy is absorbed or the wave makes it out of the atmosphere into the vacuum of space. This is the basics of the greenhouse effect. The sun warms the earth, the earth warms the atmosphere.

Carbon dioxide is an important greenhouse gas. For comparison, Mars atmosphere is almost totally carbon dioxide. Though Mars is 75 million kilometers father out, and even though its atmosphere is about 0.1% that of earth’s, the temperature at the equator in summer sometimes exceeds the melting point of water. Human industrial output is releasing gigatons of carbon dioxide into the atmosphere every year. Much of this carbon dioxide is from mineral sources that have been out of the carbon cycle for millions of years. In essence, what we’re doing, is restoring a carbon dioxide balance to the atmosphere that hasn’t existed for a very long time. By restoring the carbon dioxide levels in the atmosphere to pre-historic levels, it is not unreasonable to expect a pre-historic climate, when the earth was warmer and wetter than it is now.

The climate is a dynamic system. It is going to change one way or the other. The one thing that is not going to happen is for the climate to stay the same. There’s only two ways it can go. We’re in an interglacial period right now, a periodic time of mild temperatures between cycles of glaciation. Human civilization will either witness global glaciation in a new ice age, or rising seas in a new hot house. I share the skepticism of many regarding the efficacy of the solutions offered by our political leaders. I think they’re asking the wrong questions. They’re asking “how do we stop climate change” when they should be asking “how is human civilization going to cope with the changing climate.”