Welcome to Quantum Magazine's podcast.

Each episode, we bring you stories about developments in science and mathematics.

I'm Susan Vallage.

On a 1987 voyage to the Antarctic, paleoceanographer James Kennett and his crew dropped anchor in the

wet-all sea, drilled into the seabed and extracted a vertical cylinder of sediment.

In an inch thick layer of Plinkton fossils and other organic remains buried more than 500

feet deep, they found a disturbing clue about the planet's past that could spell disaster for the

future.

Lower in the sediment core, Kennett's crew found fossils from 60 plankton species. But in that thin

cross-section from about 56 million years ago, the number of species dropped to 17.

And the plankton's oxygen and carbon isotope compositions had dramatically changed.

Kennett and his student Lowell Stott deduced that carbon dioxide had flooded the air, causing the ocean to rapidly

acidify and heat up. It's a process similar to what we're seeing today. Around the same time,

those 17 kinds of Plinkton settled into the Antarctic seabed, a taper-like creature died in what's now

Wyoming.

It deposited a tooth in a bright red layer of sedimentary rock in the Big Horn Basin's badlands.

In 1992, the person who found that tooth fossil, Phil Gingrich, and collaborators Jim Zackos and Paul Koch,

reported the same isotope anomalies in the toothed enamel that Kennett and Stott had presented in their ocean findings a year earlier.

The prehistoric mammal had also been breathing carbon dioxide flooded air.

More data points surfaced in China, then Europe, then all over. A picture emerged of a brief

cataclysmic hot spell 56 million years ago, now known as the Paleocene-Eocene Thermal Maximum.

That's P-E-T-M for short. Heat-trapping carbon leaked into the sky from an unknown source. The planet, which was already

...