The rate of increase in food production is lagging behind the rate of increase in population in many parts of the world, and the total crop area is shrinking, by 5 percent since 1981. An area the size of Colorado is abandoned each year because it's no longer viable to farm. A lot of people say the real problem is distribution, that the food surpluses in the rich nations could feed the world. If we raise that to the equivalent of a relatively good SouthAmerican diet, with about 15 percent of calories coming from animal products, you could feed 4 billion. At a North American standard, with about 35 percent coming from animals, you could only feed 2.5 billion.
Critics say that there are vast tracts of unused land.
We struggle to find areas to study the functioning of natural systems, and it's impossible to find one square centimeter that hasn't been impacted by humans. Personally, I've been unable to escape cows. Even Colorado wilderness areas above 10,000 feet have cows all over them. It's cows or condos. One of my sites in Costa Rica is even named Vaca Vaca.