Also: animal ag uses 80% of all arable land with most of it destined for grazing land (which a lot of (rain-)-forest had to be razed for) while only producing 17% of global calories and 38% of global proteins. The rest comes from human edible plants. A global switch to a plant based diet would reduce land usage from 4 to 1 billion. It's still possible to re-wild grazing lands.