But is it possible the world could run out of food entirely? Barring a doomsday scenario in which the planet becomes temporarily or permanently unable to host plant life (say following a major meteor strike like the one believed to have wiped out the dinosaurs), then the question really boils down to this: Could a reduction in arable land and fresh water lead to a massive drop in food levels, creating a worldwide famine?
Unfortunately, increased desertification and water use are serious threats to future food production. Perhaps not enough to cripple the entire human race, but certainly enough to cause serious problems if everybody plans to keep eating on a regular basis. Add in factors like increased competition from biofuels, an impending population explosion, crop failures and climate-related drought, and you have a perfect storm for severely decreased food production.
But perhaps the larger part of the problem is that agriculture accounts for 70 percent of the planet's water use, and while you can reuse fresh water, there's just not that much of it to go around. Using conventional (and unsustainable) agricultural methods, it takes nearly 400 gallons (1,500 liters) of water to grow just 2 pounds (1 kilogram) of wheat. Meat-eaters cause even more of a problem. To get that 2-pounds-worth of meat, it takes a whopping 4,000 gallons (15,000 liters) of water [source: FAO].
And while people definitely need to eat, drinking water is also definitely a must. Because an extreme amount of water goes into food production, and because climate change could increase the acreage of nonarable land and melt our remaining freshwater glaciers, it's becoming more difficult to ensure that everyone gets the proper amount of water to drink -- 1.5 gallons (2-5 liters) a day. So the even more critical question could be: Will we run out of water?