You can see from the graphs above that when dealing with only CO2 there is a marginal increase in how much worse chicken or fish are compared to alternatives which aren't as nutrient rich.
A 3x increase isn't nearly as high as people would like you to believe. Let alone milk which is more eco friendly than many of your common calcium alternatives.
Not only that but dairy plans to be carbon neutral in the USA as of 2050.
You can paint eco-friendly husbandry practices terribly as much as you want, but real progress is constantly being made. These same industries are the ones actually investing in lab grown meat.
Yes but co2 isn't everything. How much space it uses, which could be used to keep biodiversity high is also very important and actually the bigger factor in the question of human civilization surviving. We can deal with hotness, but we can't deal with no insects
The common thing there is that they're smaller animals. When you raise a large animal like a cow you need to sustain that extra size for the entire time they grow.
You can see from the graphs that the smaller animals don't matter. It's per kg of consumed food per kg of CO2.
That also means that meats which are more nutrient rich and bioavailable are often as good as plant alternatives. This only gets better with time and eventual lab grown alternatives.
Altering diets for husbandry has made huge strides in lowering emissions too.
Vegans can Doomer emissions as much as they want to but it's already solved lol. The market will get there just like every other green intiative because turns out people and money DOES care about the future.
The biggest issue with eating meat currently is their shit poor living conditions and treatment. Even separating calves early for dairy isn't nearly as bad for yields as people previously thought too. Like any industry it takes time to make change.