Chris D Thomas, Jack Hatfield, and Katie Noble in The Conversation:
Fortunately, a whole raft of new technologies is being developed that make a system-wide revolution in food production feasible. According to recent research by one of us (Chris), this transformation could meet increased global food demands by a growing human population on less than 20% of the world’s existing farmland. Or in other words, these technologies could release at least 80% of existing farmland from agriculture in about a century.
Around four-fifths of the land used for human food production is allocated to meat and dairy, including both range lands and crops specifically grown to feed livestock. Add up the whole of India, South Africa, France and Spain and you have the amount of land devoted to crops that are then fed to livestock.
More here.