2011-12-04 22:14:41Does breathing contribute to CO2 buildup in the atmosphere?


Does breathing contribute to CO2 buildup in the atmosphere?

I think we need to rethink this one. It is essentially the same argument that 1st generation biofuel manufacturers used before they came under criticism for saying ' CO2 emitted from a vehicle is replaced by the CO2 absorbed by the feedstock, so the biofuel is carbon neutral', but we know this is misleading.

We criticise Spencer as well.

"It is a little known fact that the extra carbon dioxide (and methane, an especially potent greenhouse gas) emitted by joggers accounts for close to 10% of the current Global Warming problem."
20 June 2005 (Source)
By breathing out, we are simply returning to the air the same CO2 that was there to begin with.

The premise of the rebuttal to Spencer is that breathing shouldn't be taken in isolation from the entire chemical cycle.  However, on this basis we must include the nutrients and planting of the crops which of course include the GHG emissions released by fertilisers, tilling and possibly deforestation, such as N20 and CH4. 

The bottom line is that breathing increases with exercise which requires more food, and food (particularily those involving meat production) does indeed generate significant net GHGs to the environment.

According to these calculations walking at 3mph generates almost a quarter of life cycle emissions per mile than that of driving, assuming the typical US diet.  Obviously this could be drastically reduced by eating vegan foods.

It is based on this calculator

2012-01-04 02:19:18


I think the core argument being refuted here is that the CO2 that we exhale does indeed directly increase CO2 in the atmosphere. When Rush Limbaugh screams “CO2 is what you and I breathe out!” I don’t think he is expressing his concern over the high fossil energy demands of modern agriculture. I think he is just trying to trick people into thinking that billions of people putting CO2 into the atmosphere with every breath (trying to get an emotional response to the idea of such a big number) since the dawn of humanity didn’t have an effect, therefore nothing else is probably going to have an effect.

Maybe a sentence about the footprint of industrial agriculture would fit well at the end, just to remind people today’s means of producing food is not carbon-neutral like it once was. But I think the carbon footprint of agriculture is an independent topic from the question of whether our exhaled CO2 has an effect. I exhale the same CO2 from an apple regardless of how that apple was grown. It’s really just a coincidence that the waste product from the energy source we use to grow most of our food is the same waste product that we create when we eat the food, and so I'm not sure the two topics need to be lumped into the same article.