Saturday, June 23, 2007

Close the Carbon Cycle

This is part of my general musings on the environment.

I have come across a lot of proposals for what to do about greenhouse emissions. There is also a lot of debate the relative merits of different options trying to consider how every aspect of the technology will impact greenhouse gas emissions. Ethanol, for example, burns quite cleanly, but you have to use a lot of energy to produce it, and if that energy comes from fossil fuels itself, you need to take those emissions into consideration. There are other proposals like putting chalk in asphalt making it gray instead of black. This is actually a good idea, as it will increase the amount of solar radiation reflected back into space, and so reduce surface warming (this is known technically as increasing the earth's albedo). In the discussion that I've seen, however, (although I must say my research to date has not been extensive) what I think the central objective of our efforts must be, is being missed.

The ultimate objective, with regards to greenhouse emissions, needs to be to close the carbon cycle. That is, we need to get to a point where the amount of carbon emitted into the atmosphere in the form of CO2 each is less than or equal to the amount of CO2 drawn from the atmosphere each year. Plants growing, oceanic algae, a host of other activities, pulls CO2 from the atmosphere each year. Great. Respiration from animals and human activities like burning fossil fuels adds CO2 to the atmosphere. Currently we put a lot more in than gets taken out. So keep in mind that we won't solve the greenhouse gas problem, until we close the carbon cycle.

The upshot is that nuclear power, which I'm not opposed to, is an aid to the greenhouse gas issue only to the extent that it replaces the burning of fossil fuels. It does not help the issue if it simply adds capacity and people simply use more power. Likewise, the chalk in the asphalt, or other techniques to raise the earth's albedo, will put off the day that increasing CO2 levels will have devestating effect. And that is a good thing. However, it does not help close the carbon cycle, which ultimately we must do.

More on these ideas in a future post.

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