Can we feed the world without destroying the planet?

With Earth's population expected to reach 9 billion by 2040, the question of how to feed the world has never been more pressing. During a 20 February symposium on global food security at the 2010 AAAS meeting in San Diego, researchers discussed how an increasing population, rising incomes, and a warming, unpredictable climate system are likely to place unprecedented demands on the planet's food systems.

Speakers reported that increased yields are not likely to fill this gap. In a business-as-usual scenario, that could mean a dramatic expansion of the farmed area on the planet, on the order of the entire arable land of the United States. There's a problem, researchers said: This suitable new farmland doesn't exist.

Feeding the world has always been a challenge. Even though farmers produce enough food today to theoretically feed every person on the planet, about one billion people don't have the money they need to purchase that food. Two billion more teeter on the edge of having food on the table from one day to the next.

"We have the availability, but not the access," said David Lobell, a food systems scientist from Stanford University. "But that may not be true in the future."

Ecologist David Tilman, an ecologist at the University of Minnesota, warned that increasing population is only part of the anticipated food scarcity. As incomes increase, preferences shift toward more meat-based diets. Such diets require a lot more calories to produce, leading to "surprising increases in demand for food around the world," Tilman said.

Given ongoing trends of increasing incomes in developing nations, Tilman estimated that in fifty years global crop demand may increase by 120 to 140 percent. That's almost two times faster than current projections from the United Nations Food and Agricultural Organization.

New strategies will be needed to keep up with this demand, speakers stated. "The area used to grow food has been decreasing since 1970," said agronomist Kenneth Cassman of the University of Nebraska. "All major cities are located on our best farmland."

During that time, increasing yields have made it possible to maintain the expansion of food systems. However, Tilman estimated that even if those increases persist, farmers would produce just 66 percent more yield by 2060. That's about half of what he expects society will need.

The only other way to produce enough food will be to drastically expand the farmed area of the planet. That could mean converting 40 percent of the remaining tropical forests and savannas to farmland, he said—a devastating blow to stressed ecosystems.

Climate change will make the challenge of crop expansion even more difficult. Assessing historical climate and crop report data in various regions around the world, Lobell found that higher temperatures almost always lead to decreased yields. With projected warming scenarios, he said, "It is plausible that even by 2030, average cereal prices could rise by 30 percent because of climate change."

Despite these challenges, the panelists noted that there are ways of addressing these problems. The most promising possibility is to help developing nations increase their food production to the levels of developed countries, which Tilman said argued could be done by using nitrogen fertilizer more wisely and more equitably throughout the world.

Implementing such solutions is a steep challenge, speakers agreed. As symposium organizer Jonathan Foley of the University of Minnesota stated, "Feeding the world while preserving the environment is maybe the greatest challenge we will ever face."

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Jess McNally is a pursuing a master's degree in Earth Systems from Stanford University, specializing in environmental communication and education. Her undergraduate degree is also in Earth Systems, with a focus on biological oceanography. She is coauthor on an academic paper on butterfly population biology, and is a contributor to the Sound Advice for Green Earth Column for Stanford Magazine online. She is pursuing a career in science writing. Reach her at jessmcn@gmail.com.

Feb. 24, 2010

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