Cow's generate green-house gases
Did you know that a cow's digestive system generates per year the same amount of green-house gas like a car running 20'000 km?
Wow, that's weird.
This means that eating less meat allows to reduce green-house effect and global warming.... in addition of health benefits I mean. :)
BTW, remember, to "build" a cow you need grass, to "build" grass you need space and so there is also a deforestation effect jumping in here.