“Why should we be concerned with scarcity issues?” asks New York University’s Alex Evans. Beyond general population growth, there is also an expanding global middle class that is shifting to more Western diets and consuming more energy, he explains. The net result is that demand for food, water, oil, and land is outpacing supply. These scarcity issues should be grouped together, argues Evans, because you can’t address one without affecting the others.

The “Pop Audio” series offers brief clips from ECSP’s conversations with experts around the world, sharing analysis and promoting dialogue on population-related issues. Also available on iTunes.