Was looking into this because of that recent Paul McCartney article that was shared, and wanted to share what I found:

Here’s a good breakdown of differences between vegan & vegetarian diets in terms of climate impact: https://www.nature.com/articles/s43016-023-00795-w

Emissions:

  • Vegan:............. CO2: 2.16, CH4: 04.39, N2O: 0.71
  • Vegetarian:........ CO2: 3.33, CH4: 20.21, N2O: 0.98
  • medium meat-eaters: CO2: 5.34, CH4: 40.88, N20: 1.73
  • high meat-eaters:.. CO2: 7.28, CH4: 65.40, N2O: 2.62

So vegans have 30% of the emissions as high-meat-eaters, and the differences between vegans and vegetarians are significant with regards to their emissions, particularly methane emissions due to the significantly higher consumption of cheese by vegetarians.

(EDIT: it has been suggested it’s worth clarifying that vegan diet having 30% CO2 emissions means that there was a 70% reduction in CO2 emissions, and that methane emissions were reduced by 93% going from high-meat to vegan.)

Vegetarians ate significantly more cheese (30 g / day) than even meat-eaters (19 g / day), despite eating less dairy overall otherwise.

Also should be noted that there is a big gap between biodiversity impact between vegans and vegetarians, with vegetarian diets causing nearly double the number of species extinctions per day than vegan diets.

I was surprised that water use was so similar between vegans and vegetarians considering how much cheese vegetarians eat.

I still would recommend a vegetarian diet to meat eaters, as it’s still a massive improvement (and in my experience, it’s easier to become vegan once vegetarian), just thought it was interesting to actually quantify differences between veganism and vegetarianism in terms of climate impact.

  • dandelion (she/her)@lemmy.blahaj.zoneOP
    1·
    5 days ago

    I think I’m confused by your response … the original article says a vegan diet has 70% fewer carbon emissions than a high meat-eater diet (it’s 30% of the meat diet) …

    If you have $100 and I have $30, I have 70% fewer dollars than you, I have 30% of what you have. That’s a dramatic reduction, I don’t think the even more dramatic reduction in methane emissions will be any more convincing - to be honest I don’t think any of this data will convince anyone to become vegan, most likely. Changes to diet like that are usually more emotionally motivated than rational.

    I couldn’t tell, but it seemed like you were implying that the carbon emissions are only a 30% reduction or something, I’m not sure how else to interpret your seeming belief that this isn’t a significant enough reduction in emissions …

    I do think a car is more impactful than a diet in terms of emissions created - an efficient, new gas car will emit 400 g CO2 / mile, which means even a mile of driving will far strip the 7 g daily CO2 emissions from a high meat diet.

    • ProdigalFrog@slrpnk.netEnglish
      2·
      5 days ago

      I believe they are suggesting that people may see your statement at the end of your OP where you say a vegan diet has only 30% of the emissions as total emissions, not just the co2 emissions.

      The other user is suggesting making it more clear that there is also a 90% reduction in methane gasses, which can be missed by a user who is not carefully examining the data.

      I myself would suggest phrasing the lower emissions of vegan diets in terms of their total reduction instead of the percentage they use in comparison, as the reduction percentage is a bigger number, which sadly I would consider more psychologically effective despite it being the same information shown in a different way.

      I.e, 70% less feels like higher impact compared to only using 30% as much.

      • dandelion (she/her)@lemmy.blahaj.zoneOP
        2·
        5 days ago

        that’s a good suggestion - I edited the OP to make that clarification; I agree that “30% of emissions” is harder to immediately understand than “70% fewer emissions”. We can’t ignore psychology if we are trying to be persuasive.

        It’s not clear to me how we should think about the impact of methane gases - on the one hand they have a greater warming effect, but on the other hand they stay in the atmosphere for much less time (12 years) and overall contribute less to global warming than CO2 (which stays in the atmosphere for hundreds of years). It actually looks like nitrous oxide is an even bigger source of warming, and fertilizer inefficiencies by growing crops to feed animals is a major source of released N2O, though this is comparing CO2, CH4, and N2O tonne-to-tonne, it might be better to know how each contributes according to the actual amount being emitted …

        Either way, it should be abundantly clear that a vegan diet does reduce greenhouse gas emissions of all kinds significantly and is something actionable anyone can do if they want to reduce their footprint (esp. important for Americans and people living in developed countries where over-consumption is real).

        Though I personally think individuals deciding to become vegan to solve climate change is like asking individuals to make donations to end poverty - it’s not enough and won’t solve the problem, we need much larger social and structural changes so that by default everyone is making healthy climate choices because it’s the easiest, cheapest, and most preferable option.

        For comparison, it’s very hard to live without a car if there is not sufficient public transportation infrastructure. Demanding someone in a car-centric city to live without their car and just take the bus obviously misses the point: we need public transportation infrastructure, the problem isn’t that Bob isn’t willing to hop on a bike and risk his life cycling 10 miles to work every day on a stroad because it’s faster to cycle 10 miles than to wait several hours for the bus.

        If Bob wants to do that, power to him - but we should be realistic and recognize we aren’t going to solve climate change this way (nor is it particularly kind or reasonable to Bob, even if his behavior is considered morally exemplary).