Together the world’s 6.8 billion people use land equal in size to South America to grow food and raise livestock—an astounding agricultural footprint. And demographers predict the planet will host 9.5 billion people by 2050. Because each of us requires a minimum of 1,500 calories a day, civilization will have to cultivate another Brazil’s worth of land—2.1 billion acres—if farming continues to be practiced as it is today. That much new, arable earth simply does not exist. To quote the great American humorist Mark Twain: “Buy land. They’re not making it any more.”
Agriculture also uses 70 percent of the world’s available freshwater for irrigation, rendering it unusable for drinking as a result of contamination with fertilizers, pesticides, herbicides and silt. If current trends continue, safe drinking water will be impossible to come by in certain densely populated regions. Farming involves huge quantities of fossil fuels, too—20 percent of all the gasoline and diesel fuel consumed in the U.S. The resulting greenhouse gas emissions are of course a major concern, but so is the price of food as it becomes linked to the price of fuel, a mechanism that roughly doubled the cost of eating in most places worldwide between 2005 and 2008.