re: Is going vegan the only ethical option?

There are definite benefits to going vegetarian, like a few have said, and it's not overly difficult. Vegan is tougher to do well and stay healthy. A lot of produce has morphed (GMO) to be less nutritious than it used to naturally be.

A good way to transition if interested is to do mostly vegetarian and try to make the meats you eat organ meats. Organ meats tend to be more nutritious (that's why old school body builders ate liver & liver pills as much as they did). And perhaps supplement with bone broth.

Regarding environmental impact of farming in general, and of livestock especially, I think big agricultural companies (Monsanto, ADM, etc.) have made things worse than they need to be. Don't know if they initially knew the problems they were causing; the control they have and $ they make are the obvious reasons they're reluctant to improve things.

But I think it can be done better. Joel Salatin is a rather interesting figure and pioneer in terms of farming livestock more naturally. Pioneer is probably a funny way to say it... it's undoubtedly riffing on old ways, at least in part. He has a way of rotating animals (I think chickens being rotated into areas where cows were to eat insects, or similar, is an example) that results in healthier animals without antibiotics, and the land is cleaner and not depleted the way it becomes in standard big farms.

Hard to do his ideas justice in a post without writing a novel. Here's a couple of fascinating (imho) podcasts with Joel Salatin for those interested:

Joe Rogan show 479

with Ben Greenfield (episode titled, The Pigness of Pigs)