Ever since humans first set sail on the high seas, we’ve been moving plants and animals around and introducing them to new environments. Globalization vastly sped up the process.

The arrival of non-native species often unleashes a chain of unintended consequences, with winners and losers. Scientists and local governments do their best to keep Asian carp out of the Great Lakes. Last week, no Asian carp were discovered after a massive fish kill in the Calumet-Sag Channel, but scientists warn that Lake Michigan remains at risk of an invasion.

To learn more, we’re joined by Reuben Keller of the Program on the Global Environment at the University of Chicago.