In this week’s show, we question whether national parks can serve as a barrier to slow the sixth mass extinction.

Certainly, the large landscape parks such as Yellowstone and Yosemite and Grand Canyon offer the habitat many species require. But parks are slowly being hemmed in by development, making it harder and harder for species to follow their natural paths across the landscape.

So can they slow the sixth mass extinction? We’re going to be taking a look at that in the coming weeks and months, and today we’ll lay out that proposal in an essay.