I think to a first approximation eating fish and chicken is much worse than eating beef—the CO2 from the beef equivalent to replacing one chicken or fish is unlikely to lead to anywhere near the suffering the chicken or fish experience. 1kg of beef (approx weight of one chicken or fish) ~100kg CO2e; 100GtC extra emissions would have to do damage equivalent to 1 trillion units of factory farmed chicken / fish lives worth of suffering for it to be comparable. This doesn’t seem likely to me (but I guess it plausibly could be if you think that worst case climate scenarios are likely and the damage lasts 100s or 1000s of years).
Intuitively I agree with you for farmed chicken and farmed fish vs beef. I’m just not actually sure how to do the comparisons.
For wild fish matters may differ because it’s not obvious what the welfare and CO2 impacts of eating them are but FWIW I haven’t looked into this closely
Offsetting the carbon cost of going from an all-chicken diet to an all-beef diet would cost $22 per year, or about 5 cents per beef-based meal. Since you would be saving 60 chickens, this is three chickens saved per dollar, or one chicken per thirty cents. A factory farmed chicken lives about thirty days, usually in extreme suffering. So if you value preventing one day of suffering by one chicken at one cent, this is a good deal.
I think to a first approximation eating fish and chicken is much worse than eating beef—the CO2 from the beef equivalent to replacing one chicken or fish is unlikely to lead to anywhere near the suffering the chicken or fish experience. 1kg of beef (approx weight of one chicken or fish) ~100kg CO2e; 100GtC extra emissions would have to do damage equivalent to 1 trillion units of factory farmed chicken / fish lives worth of suffering for it to be comparable. This doesn’t seem likely to me (but I guess it plausibly could be if you think that worst case climate scenarios are likely and the damage lasts 100s or 1000s of years).
Intuitively I agree with you for farmed chicken and farmed fish vs beef. I’m just not actually sure how to do the comparisons.
For wild fish matters may differ because it’s not obvious what the welfare and CO2 impacts of eating them are but FWIW I haven’t looked into this closely
See also