Despite large differences in farming practices across the world, plant-based protein sources still have a lower footprint than the lowest-impact meat products.
  • EE
    3•10 months ago

    And remember, biking or walking is no more environmentally sound - per person-km travelled, using a typical western diet - than a fuel-efficient automobile with a single passenger

    Because of the extra calories you burn? Do you have a source for that?

    • Overzeetop
      2•10 months ago

      Sure. This paper in Nature, estimates walking and cycling to generate 0.26 and 0.14kg CO2, respectively, given the diet in the most economically developed areas (I noted “typical western”, not world wide or average) in my post). The EPA calculates gasoline at 8887g CO2 per gallon, so a car which gets 39mpg (note I mentioned fuel efficient - not average) is around 0.14 kg CO2 per km (8887/39mpg/1.628km) and a car which gets 21 MPG is around 0.26 kg CO2/km (which actually is close to the average vehicle).

      Nature bases their estimates on full-replacement calories for the energy burned. YkmMV based on style, location, traffic, weather, and a bunch of other factors. Walking and biking is healthier for you and will likely extend your life and increase your resting metabolic rate (=the CO2 you create just lying about), but I’m not counting that against the walkers/bikers in this equation ;-)

      Note: I walk quite a bit for fun - logged about 250km on my vacation last fall - and I bike when the weather is nice - often not even to go anywhere I need to; I’m just adding to the carbon problem for personal health and entertainment purposes.

      • EE
        1•10 months ago

        You’re comparing apples to oranges. The Nature paper includes all associated emissions for the food (using “air-freighted asparagus” as an example) while the EPA explicitly excludes non-CO2 greenhouse gas emissions and emissions from production and distribution of both the fuel and the car. On top of that you compare the most efficient car of 2022 in a mixed (city+highway) environment (yes you mentioned efficiency) to the upper limit of what the Nature paper estimates (if all additional energy expenditure was compensated by additional food intake), while the realistic estimate is 0.15 and 0.08kg CO2 per km for walking and cycling respectively.

        So there might well be a factor of 10 between cycling to the supermarket and taking your car in terms of GHG emissions. We just can’t tell from the sources you linked. And while it’s an edgy position to take “I’m just adding to the carbon problem for personal health and entertainment purposes” your claim might well convince people that moving away from a car based society would not have any impact on CO2 emissions. I also think you could make your point that rich people have a way outsized impact without all choices of normal people being exactly the same.