Our planetary footprint

We forget that "as we multiply, so do the things associated with us, including our livestock. At present there are about 1.5 billion cattle and domestic buffalo and about 1.7 billion sheep and goats". It is likely to be even higher for pigs and poultry which are reared more intensively.
The report continues, "Global livestock grazing and feed production use '30 percent of the land surface of the planet'. Livestock – which consume more food than they yield – also compete directly with humans for water. And the drive to expand grazing land destroys more biologically sensitive terrain, rain forests especially, than anything else."
As if that were not enough, "even more striking and alarming, is that livestock are responsible for about 18 percent of the global warming effect, more than transportation's contribution". The principal culprit is methane produced by all ruminants, a more effective greenhouse gas than carbon dioxide.

Source: International Herald Tribune, December 28th, 2006. quoting the "Livestock's Long Shadow" by the Food & Agriculture Organization of the United Nations.