I heard something to do with Nitrogen and …cow farts(?) I am really unsure of this and would like to learn more.
Answer -
4 Parts
- Ethical reason for consuming animals
- Methane produced by cows are a harmful greenhouse gas which is contributing to our current climate crisis
- Health Reasons - there is convincing evidence that processed meats cause cancer
- it takes a lot more calories of plant food to produce the calories we would consume from the meat.
Details about the answers are in the comments
Take a look at the global human population chart over the last few millenia. Things can seem sustainable when there are a million people on the planet. When there are 8 billion things are a bit different.