Pien Huang

Brian Lapointe, a research professor at Florida Atlantic University's Harbor Branch Oceanographic Institute, has spent his career studying corals at the Looe Key Reef, in a National Marine Sanctuary in the Florida Keys.

Over that time, he's witnessed an alarming trend. In the past 20 years, half of Florida corals have died off.

Updated at 5:45 p.m. ET

Three summers ago, Ayse Tenger-Trolander, a graduate student at the University of Chicago, ordered a batch of monarch butterflies from a breeder, and made an accidental discovery: the butterflies had likely lost the ability to migrate.

The world's glaciers are melting faster than before, but it still takes decades to see changes that are happening at a glacial pace.