Marathon runners not a source of CO2 to atmosphere -- shocker!

I'm so glad that RSS exists, so that I don't miss stories like "Barton worries that EPA will regulate runners" from Kate Sheppard at Grist. Did you read it yet? Just in case you didn't, let me recap for you. Representative (from Texas) Joe Barton (Republican) is the ranking Republican on the Energy and Commerce Committee, which means he's the most senior Republican on the committee. This committee's role is, from Wikipedia:

The House Committee on Energy and Commerce has developed what is arguably the broadest (non-tax-oriented) jurisdiction of any Congressional committee. Today, it maintains principal responsibility for legislative oversight relating to telecommunications, consumer protection, food and drug safety, public health, air quality and environmental health, the supply and delivery of energy, and interstate and foreign commerce in general. This jurisdiction extends over five Cabinet-level departments and seven independent agencies--from the Energy Department, Health and Human Services, the Transportation Department to the Federal Trade Commission, Food and Drug Administration, and Federal Communications Commission — and sundry quasi-governmental organizations.

Which is to say, this is a pretty powerful committee. They get to advance (or squelch) a lot of potentially important legislation. And Barton, as ranking member, is a powerful guy within this powerful committee. So it matter that he thinks crazy things, like that marathon runners could be considered a source of pollution. Yeah, didn't you read that article? It goes back to the EPA's decision that carbon dioxide can be considered a pollutant, and as such can be regulated. Barton thinks that people are point sources of carbon dioxide, and I guess because marathons are a large group of heavily exhaling people, Joe thinks that means a large source of carbon dioxide to the atmosphere.

The point Barton is trying, and failing, to make is that carbon dioxide is difficult to regulate because it is a naturally occurring substance that is a basic part of all life on Earth. The reason he is trying to make this point is because he doesn't want to believe that the EPA has the right to regulate carbon dioxide. There are two reasons he doesn't want to accept that. First, because he's a Republican, and that party has decided to oppose regulation of nearly any kind. (Examples, regulating financial institutions like AIG or energy brokers like Enron.) Second, as part of Barton's ideology, he can't accept that humans affect the Earth adversely, so he emotionally reacts to climate change by denying it.

The point I want to make is that Barton is wrong about marathon runners. They aren't a source of carbon dioxide to the atmosphere, even though they do exhale carbon dioxide. The reason is that humans are part of the terrestrial biosphere, which is part of the global carbon cycle, which is basically in balance except for the perturbation from burning fossil fuels. To see this, think about that air you just exhaled, which is relatively enriched in carbon dioxide. Note, you don't breathe in pure oxygen, and you don't exhale pure carbon dioxide. How did that CO2 get into your breath? It is a byproduct of your physiology, mostly it come from breaking down sugars, which provides you with energy. So that means we're a source! No, wait a minute, where did those sugars come from? You ate them! This is exactly why we eat, to ingest the nutrients that will supply us with energy. So think about that for a second: we eat foods that have carbon in various organic molecules, which we break down to get energy, and CO2 is made as a byproduct and respired.

But that means humans (and all animals) make CO2 and put it into the air.

Yeah, but it all comes from somewhere. Let's take me as a simple example, or a cow. The point being, the cow and I are vegetarians, so most of the CO2 we respire comes from breaking down plant matter. Where does the carbon in that plant matter come from? Remember what we all learned as kids, plants breathe in CO2 and breathe out oxygen. Yes, plants take the CO2 right out of the air. They take CO2 from the air, water from the soil, and sunlight, and perform photosynthesis, which is to say 6CO2 + 6H2O → C6H12O6 + 6O2. Like magic, isn't it. On the right side are just 6 molecules of oxygen along with a sugar molecule that is holding onto some carbon and oxygen, which I'll eat and break down for energy, releasing CO2. Magic.

So there's a balance... like a cycle of carbon in the biosphere. This is why, in principle, biofuels should be carbon neutral. Breaking down plant matter moves CO2 around, eventually expelling it into the atmosphere, but eventually it is sucked back into the biosphere by autotrophs like plants and phytoplankton.

So what's the problem with burning fossil fuels? Well, that takes carbon from the lithosphere and suddenly introduces it to the atmosphere-biosphere-ocean system. There is normally exchange between the lithosphere and the rest of the climate system, but that is a very slow process, which combustion accelerates. There's no where for that extra CO2 to go because each part of the cycle only has so much wiggle room. The result is a build-up of CO2 in the atmosphere, where it enhances the greenhouse effect, and chaos ensues. Carbon dioxide isn't a pollutant like CFCs, then, but the carbon dioxide emitted by burning fossil fuels is basically the same. Whatever oil, coal, or natural gas is pulled out of the rocks needs to be accounted for, because that is the potentially harmful carbon.

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