sisyphean numbersCross-posted from Yale Environment 360.

In a mere half-century, the number of people on the planet has soared from 3 billion to 7 billion, placing us squarely in the midst of the most rapid expansion of world population in our 50,000-year history — and placing ever-growing pressure on the Earth and its resources.

But that is the past. What of the future? Leading demographers, including those at the United Nations and the U.S. Census Bureau, are projecting that world population will peak at 9.5 billion to 10 billion later this century, and then gradually decline as poorer countries develop. But what if those projections are too optimistic? What if population continues to soar, as it has in recent decades, and the world becomes home to 12 billion or even 16 billion people by 2100, as a high-end U.N. estimate has projected? Such an outcome would clearly have enormous social and environmental implications, including placing enormous stress on the world’s food and water resources, spurring further loss of wildlands and biodiversity, and hastening the degradation of the natural systems that support life on Earth.