I can just tell you: they did some looking at each production process and the inputs and outputs, then extrapolated it out to global scale.
The problem is that inputs and outputs vary wildly from place to place, that’s why some places are all corn and beans and others are cattle and yet others are something else. Given those differences are because of the economic inputs varying as opposed to the environmental inputs and outputs varying.
You can’t just go around to all the beef producers in the county and figure out how their operation works then multiply it by however much to fit the world scale because the rest of the world might be doing it wildly differently.
Although while I see the criticism of their methodology I think it means things are actually way worse, not better in terms of the environmental impact of beef.
The original paper says that they weighted each measure to the country's national production and then weighted those by the country's share of global production. They didn't just average each result they got for beef with no regard for location.
I think their point is that scaling to the volume of beef production of other countries isn't correct because the methods of production vary widely enough to produce much different results. As in, some countries likely produce more or less CO2/kg of beef so it makes no sense to simply scale the number they got from a single county to global scales.
Not the guy you're replying too though, so I'm not certain.
Right, but they didn't do that. It's a meta-analysis, so they took the value that each study got for a given crop in a specific country and then weighted all of the values by the share of global production that that country is responsible for. So if we pretend that the only three countries are Estonia, Latvia, and Lithuania, they did the following:
Found three studies from Estonia, two from Latvia, and two from Lithuania
Averaged the values of the three Estonian studies
Did the same for the two Latvian ones and the two Lithuanian ones
Found that Estonia is responsible for 60% of the world's beef, Latvia 25%, and Lithuania 15%
Took their three national averages and weighted them 0.6 for Estonia, 0.25 for Latvia, and 0.15 for Lithuania to get the final value for beef
Repeat for each other crop
The dataset was 1530 studies across 39,000 farms in 119 countries
Yes I was wildly oversimplifying the methodology using a hypothetical intended to help people who might not have a background in either research or beef production understand.
they take a myopic view of the inputs and outputs for food sources, not considering, for instance, that much of what is fed to animals would otherwise be wasted. the beef doesn't produce all that CO2, poore & nemecek were calculating all the co2 that goes into the inputs. i mentioned elsewhere cottonseed, but frankly i know that only takes up a minute portion of what they're calculating. instead, they are also counting soy, and that's almost as dishonest as you can get. nearly all soy is pressed for oil, and after that, the waste product is what is fed to cattle and other livestock. technically, you could eat it, but most people don't and don't want to. feeding it to livestock actually reclaims waste products. and even the calculation for the soy itself is skewed since it often also counts the deforestation that has already taken place as an emission source, regardless of whether that particular plot of land has been deforested for decades.
Yeah that seems like it's pretty flawed. Even just going down the soybean oil byproduct rabbit hole the Internet says most of it is "acidulated" to prepare it as an ingredient in lubricants and plastic. So beef production isn't even the main use of the byproduct.
Do we have any better studies? Or is this like the infamous self defense with a handgun study, bad science and all we have at the same time?
I'm afraid they're straight up lying. The paper doesn't mention cotton even once. See for yourself in the paper here or the database here. It doesn't even specify one type of feed for the beef cattle, because it is a meta-analsyis of hundreds of others papers about specific practices in specific areas. It takes a weighted average of those depending on how much of the world's production the area studied in each one accounts for.