Contrary to what Michael Ivey wrote [“Climate-change Believers Betray Their Naiveté,” July 8, Xpress] in response to Anne Craig’s letter [“Local Group Lobbies for Climate Change Action,” June 24, Xpress], climate science is not “kindergarten stuff.” It is actually a very complex matter, and even a trained scientist could be forgiven for not understanding important aspects of long-term global climate dynamics.
One of the sources of complexity has to do with feedback mechanisms. Ivey points out that water vapor is the most prevalent greenhouse gas, and he’s right, though I’m unsure about his numbers. But more important than what percentage of all the greenhouse gases water vapor comprises is what percentage of the greenhouse effect is attributable to water vapor. Apparently it does contribute more than CO2 to the total effect: around 50 percent.
However, CO2 contributes as well, and the more CO2 we add, the more we increase the greenhouse effect. And the hotter these changes in CO2 make the planet, the more water is vaporized globally, further increasing the greenhouse effect. So the water-vapor effect is a positive feedback mechanism that is not under our control, which makes it that much more important to curb carbon emissions, which are.
I don’t understand all of the finer points of climate science, but there are some general principles that should guide us even in the face of uncertainty. One general principle that is clear from geological history is that complex systems like the atmosphere are not necessarily stable and are prone to “tipping points” due to positive (and negative) feedback mechanisms. In the distant past, such tipping points have led to several sudden changes that caused mass extinctions.
For this reason, we should take the path of caution and cut carbon emissions. The carbon fee and dividend system promoted by the Citizens Climate Lobby seems like a good way to do that.
— Jake Greear