What's the environmental impact now of meat production? I read frances moore lappe and want an update.

Ask others but... Political correctness aside, in today's world there are many more total people, mostly much better nourished, and eating much more meat than in the 1970's of "diet for a small planet." is it sustainable? My reading makes me think it is, and that most world malnutrition (africa, china, etc.) is due to evil / stupid social policies. I would pay much more for meat raised humanely. Hear from others?