Tyler Cowen passes along this nugget from Heart of Dryness:
For every newly converted vegetarian, four poor humans start earning enough money to put beef on the table. In the past three decades, the earth's dominant carnivores have tripled our average per capita consumption; in the next four decades global meat production will double to 465 million tons.
Ezra Klein adds:
Keep in mind that livestock production is a larger contributor to global warming than transportation. But there's been virtually no progress in persuading rich or poor countries to worry much about this fact.
The Dish 