You don't have to care about animals to find reasons to stop eating them. From Vegan Porn we learn of a UN Food and Agriculture Organization report finding that cattle-rearing produces more greenhouse gases than all the cars on the road.
Your hamburger and steak are responsible for 9% of human carbon dioxide production, 65% of nitrous oxide production, 37% of methane production, and 64% of ammonia production. In addition, raising livestock uses 30% of the entire land surface area of the Earth. The study finds that "the environmental costs per unit of livestock production must be cut by one half, just to avoid the level of damage worsening beyond its present level."
But a roast beef sandwich is more important than all that, right?