I can go as far as to say that everything human beings do is destructive to the environment one way or the other, but some things are more destructive than others. Eating vegetable is also destructive in some way to the environment just as eating meat is. Facts and evidence shows that eating meat is more destructive to the environment than eating vegies, that's my point.+1
Also Sly forgets that veggies are harvested mostly be machines and those have a high CO2 contribution where as cattle and sheep are not "patrolled" by tractor
Also Veggies need to get to the market just like the "meat" and we also clear forests to make room for fields we can plant veggies in
Should we stop eating all together?!
P.S. In case you are interested, read the following from these links