By 2050, twice as many people will live in cities as do now. We will consume twice as much meat and dairy as we do today. This modern diet, heavy in meat, dairy, and processed food, requires enormous amounts of energy to produce. That energy mostly comes from fossil fuels, which are not renewable. We're also using fossil fuels to clear millions of acres of rainforest each year for planting crops and then to transport the crops to cities around the world. If we don't change the way that food is produced, we will have a serious problem. It will be very difficult to feed everyone.