"The impacts from food production for a vegan diet reflect the least GHG emissions when compared with that of a meat-based or vegetarian diet. As per Table 10, vegan diets produce carbon dioxide emissions of 1,798 g/person/day, showing the lowest amount of emissions, versus 7,891 g/person/day from a meat-based diet, demonstrating the highest emissions (Table 10). Vegetarian diets produce slightly higher emissions than a vegan diet, totaling 2,622 g/person/day. The largest individual food group contributor is red meats within the meat-based diet in the amount of 5,153 g/person/day. At the opposite end in a vegan diet, the lowest contributor to GHG emissions is potatoes."
Every study I am aware of is clear that a vegan diet is less carbon intense than a carnivore diet. Beef especially, which is reported as 49% of the total for meat eaters.
I think the people suggesting that "in the US it would raise CO2 emissions" is like a third-order effect people imagined up by drawing a box around the US and saying emissions from cattle grown in other countries for our consumption somehow emit carbon that doesn't get to the US while simultaneously assuming land use conversion in the US to increase agricultural output of plants which would increase emissions locally. Maybe. A lot of our crops go to feed those cattle.
I would be extremely skeptical of any claim like this that flies in the face of 3rd grade science class where we learned that at each step up in the food chain 90% of the energy is lost to support systems like... being alive... while only 10% remains as biomass to eat. This is basically thermodynamics in action with edge effects that contrarians want to focus on.
The definition of "meat-based" in that thesis is interesting:
>> Meat-based diets presume consumption of a combination of plant-based foods in combination with differing kinds of meats and fish and can include milk products, honey, and eggs.
So "meat-based" is any diet that includes any amount of meat. A person who eats a beef steak every day and a person who eats a chicken leg twice a week are both counted under "meat-based" and their environmental impact is calculated as one, and compared to vegan and vegetarian diets'.
I find that dodgy to say the least.
Also, I don't see where the bit you quote agrees with, and so is a likely source for, the bit of the OP's comment I quoted.
I'll re-emphasize the table I linked before, though I agree with one of the other responses that the OP meant that the benefits are marginal on an overall basis so my response wasn't strictly addressing the comment.
They absolutely distinguish between poultry and beef, though they don't distinguish steak from hamburger. They specified exactly what that breakdown was in the table and I doubt that it's random.
137gm red meat, 57gm poultry, 22gm fish per day on average per person using the "meat-based diet" model.
Assuming that pork and beef are both "red meat", the USDA availability chart (couldn't find consumption) is here:
and what I see is about 100 pounds of red meat, 65 pounds of poultry, and 15 pounds of fish per person per year available. 100 pounds of red meat per year is 124gm/day, and the ratios are a little off but not by a ton. They definitely report what their diet assumptions were though... my guess is they had a more robust model diet from USDA they used than the chart of clearly not quite the right dataset I took that from.
>> 137gm red meat, 57gm poultry, 22gm fish per day on average per person using the "meat-based diet" model.
There's a big gap between that and a vegetarian or vegan diet. There is definitely a lot of room in between for plant-based diets with a reasonable amount of meat (say chicken or fish twice a weak and a Sunday roast once or twice a month). I'm willing to bet that this kind of diet is much more common than one including a hearty portion of meat every day and that comparing this diet to vegetarian or vegan diets would yield a much less significant difference in terms of environmental impact.
This seems unlikely to have escaped the author? Of course a hybrid diet would be in between, I'm just saying that the diet breakdowns they chose to present are almost certainly model diets from literature rather than arbitrarily chosen to make meat eaters look bad. It's a thesis, not PETA marketing material, there are some standards for rigor and they would have needed to cite and justify why they chose what they chose.
That said, I honestly do not think that your diet suggestion is common for Americans, I rarely see people go a meal without meat. The total of 216gm/day is only 7.6 ounces of meat, and I remember getting weird looks ordering only a 6 ounce steak as an adult. And burgers are frequently about a half pound too. Or a chicken breast. It seems totally believable to me that this is average even accounting for less frequent consumers of meat.
I take efforts to rarely eat it so I'm probably barely different from vegetarian. Obviously hybrid diets will fall somewhere in between? I'm not presently an advocate for no-meat product diets because I don't like extremes but I am an advocate for using substitutes when there's little difference. Like taco bell meat could be soy-based meat-substitute ground and literally no one would notice.
>> This seems unlikely to have escaped the author? Of course a hybrid diet would be in between, I'm just saying that the diet breakdowns they chose to present are almost certainly model diets from literature rather than arbitrarily chosen to make meat eaters look bad. It's a thesis, not PETA marketing material, there are some standards for rigor and they would have needed to cite and justify why they chose what they chose.
Why assume so much? The thesis is in the link you provided. You can easily check whether what you suppose in this comment is true or not.
>> That said, I honestly do not think that your diet suggestion is common for Americans, I rarely see people go a meal without meat.
So this "meat-based" diet is only relevant to Americans? That makes sense- but in that case, the comparison with vegetarian and vegan diets is also only relevant to Americans. i.e. it's American "meat-based" diets that are more environmentally wasteful compared to American "vegetarian" diets etc.
I guess it depends on the definition of 'a few percent' in what they said but I think you're misinterpreting it. They don't seem to be saying it wouldn't lower your emissions, they're claiming it's a small part of your emissions.
The change in that paper is ~2 tons/year, and average use in America is ~16 tons/year so about 1/8th. It depends if you think ~12% is 'a few percent' or not.
>It depends if you think ~12% is 'a few percent' or not.
I find that people have no consistency in such matters. What counts as enough of a difference to care about seems to change upon the issue and just so happens to generally align with an individual's view of if an issue is worth worrying about or not.
This pic does not say if it's talking about the total or the total per unit consumed, nor does it give a measure of what the total is. The chart is unfortunately not especially helpful in a vacuum. Which is not to say you're interpreting it wrong, I just cannot tell if your conclusion there is actually valid. Or if it's post-consumer (i.e. table scraps) or industrial (i.e. animal feed that goes bad) which dramatically changes the interpretation if animal production and cereal grain waste are correlated.
This doesn't really make sense, though. You have to grow grain in order to raise livestock. Without seeing how these numbers were calculated, it's hard to say exactly what this graph is showing.
The drop from vegan to average is about 1 ton of CO2 annually. Americans are 15-20 tons annually. China’s CO2 emissions growth was 2-3% last year: https://unearthed.greenpeace.org/2019/02/28/china-coal-renew.... 3% on 9 gigatons is a 270 megatons increase. That’s somewhat under a ton per American.
I can believe that but could you please source it?