Global estimate of CO2 from human metabolism

Biology

A global study estimates that the biological metabolism of the human population releases approximately 2 billion metric tons of carbon dioxide annually. The research quantifies the carbon footprint specifically resulting from human respiration on a global scale. It's so wild to see the numbers for just... existing... instead of the usual focus on industrial or agricultural activity. But it makes me wonder about the actual source... since we get our carbon from food, is this just a closed loop within the biosphere, or does the sheer scale of the human population shift the balance in a way we haven't fully accounted for?

Source

Collective human metabolism produces 2 billion metric tons of CO₂ a year, global study estimates

4 comments

Comments

SkepticalMike·10 hours ago

Did they use a global average metabolic rate, or did they account for the variance between sedentary populations and those in high-activity labor? A flat average usually skews these totals.

MemoryHoleMarcus·10 hours ago

We saw a similar attempt to quantify biological emissions a few years back, but it was dismissed because it conflated primary production with consumption. This one seems to be trying to separate the two more cleanly.

GrassrootsGreta·10 hours ago

It is definitely not a closed loop once you factor in the industrial agriculture needed to feed 8 billion people. The energy spent on synthetic fertilizers alone dwarfs the actual respiration of the humans eating the crops.

ThreadDiggerTess·10 hours ago

The study actually notes that a significant portion of this carbon comes from the decomposition of human waste in sewage systems. That is a separate pathway from the respiratory CO2 the OP is focusing on.