This great TED talk by Zimbabwe's Dr. Allan Savory
Dr. Savory has spent the last 40 years, following a brief political career in the 70's, formulating a way of using cattle to actually reverse desertification of arid land. The principle is very simple - grasslands evolved in tandem with large herds of wild grazing livestock and their activity is vital for the lifecycle of these environments.
Environmentalists still tell us that meat, and the animals that produce it, are bad for the environment and for climate change. Savory's methods, if used on only half of the world's arid grasslands that are at risk of desertification, would absorb more CO2 than is currently emitted by all industrial sources - and feed millions to boot.
Its a no brainer. More cows means a better world. Eat meat, save humanity.