"Even here, however, population growth is not the most immediate issue: another sector is expanding much faster. The UN's Food and Agriculture Organisation expects that global meat production will double by 2050 - growing, in other words, at two and a half times the rate of human numbers. The supply of meat has already trebled since 1980: farm animals now take up 70% of all agricultural land and eat one third of the world's grain. In the rich nations we consume three times as much meat and four times as much milk per capita as the people of the poor world. While human population growth is one of the factors that could contribute to a global food deficit, it is not the most urgent."
Classic Monbiot, a great read.