A worldwide switch to vegetarian diets could allow the planet's estimated 2050 population of 9.7 billion to feed themselves without cutting down any more forests.
Karl-Heinz Erb and his colleagues at the University of Klagenfurt in Vienna created a model of the global agricultural system that forecasts the next 34 years, based on predictions of crop output per hectare, cropland expansion, efficiency of raising livestock, changes in the human diet and other variables. The team reports that given greatly increased crop yields and grazing intensity, global diets could stay much as they are without deforestation. A switch to a vegan or vegetarian diet could, however, allow sufficient expansion of even organically grown crops into former grazing land, without the need to boost yields.
Increased trade between areas of high production and high food demand will be needed to make any of these scenarios feasible.