Bike vs. Roadster

[Nuboatwork]

Originally Posted by bolosky

I...
Again, recall that I never have been arguing that it's better to drive the Roadster than to bike (especially for me since I ride an exercise bike pretty regularly). Rather, I'm just trying to figure out the relative carbon footprint of the two, and I was surprised that it came out so close. ...

I think you need to step back from the equations and think about what "Carbon footprint" is trying to measure -- the increase of atmospheric CO2.

Burning coal raises atmospheric CO2 because it is returning Carbon to the atmosphere which was sequestered millions of years ago. When this is done on a worldwide industrial scale it changes the atmosphere because we are burning thousands or millions of years worth of CO2 sequestration in the course of a single year.

Metabolizing a banana releases CO2, but the Carbon in the banana was only just recently removed from the atmosphere when the plant took in CO2. So this represents a fairly "closed loop" and there is no net increase in atmospheric CO2.

Of course, this doesn't take into account any fossil fuels burned in the growing, processing or transportation of the food. But human metabolism of CO2 shouldn't be part of the equation, imho.

[bolosky]

Originally Posted by Nuboatwork

I think you need to step back from the equations and think about what "Carbon footprint" is trying to measure -- the increase of atmospheric CO2.

Burning coal raises atmospheric CO2 because it is returning Carbon to the atmosphere which was sequestered millions of years ago. When this is done on a worldwide industrial scale it changes the atmosphere because we are burning thousands or millions of years worth of CO2 sequestration in the course of a single year.

Metabolizing a banana releases CO2, but the Carbon in the banana was only just recently removed from the atmosphere when the plant took in CO2. So this represents a fairly "closed loop" and there is no net increase in atmospheric CO2.

Of course, this doesn't take into account any fossil fuels burned in the growing, processing or transportation of the food. But human metabolism of CO2 shouldn't be part of the equation, imho.

That's exactly what I was trying to do. The numbers I used for carbon footprint of food are (I think) based entirely on the production and distribution of the food, not the carbon in the food itself.