Why is meat production bad for the environment?

The production of most meat requires great amounts of resources that could be better used in making food directly for humans. The environmental impact from growing the feed for cattle is up to 20 times that of growing food for human consumption.

Cattle release large amounts of methane from their digestive system and from their poop which is bad as methane is many times worse than most other gases for the greenhouse effect (although carbon dioxide is - in total - a greater problem)