I think things would be markedly better with eating only fish and eggs, although I think the fishing is out of hand already, and egg chickens can be kept in just as horrible of conditions as meat chickens.
that’s conflating ideas though… climate change may very well be an extinction level event… animal cruelty is upsetting, but by far the lesser of 2 issues here
They go hand in hand, the meat industry is so polluting because of the commercial scale which is also why its so inhumane.
I think many would settle for just a much smaller meat industry. Maybe a more careful one.
hand in hand implies intrinsically linked - if we could solve the climate crisis tomorrow by stopping the consumption of beef and lamb, and switching to poultry which is treated much worse, then that’s good for one and bad for the other