[coryrc]

Methane emissions, I assume. (Solvable with 2% seaweed in the diet)

Also possibly rainforest destruction for crops, but I'm not as sure about that.

[trollbridge]

Rainforest in Argentina?

Argentina beef are raised in pasture. About as eco friendly as it gets. Converting pasture to row crops is far more devastating to the environment (topsoil loss, GHG emissions from loss of biomatter in topsoil, fossil fuel derived fertiliser and more.)