[Below is the original script. But a few changes may have been made during the recording of this audio podcast.]

Drilling into the rocks off the coast of Antarctica is revealing a more accurate picture of our future climate. That's because about four million years ago, carbon dioxide levels in the atmosphere were roughly 400 parts-per-million—a level we're likely to reach again in the next few years. Already, CO2 concentrations in the atmosphere are 386 ppm, up from 280 ppm just two centuries ago. 

Of course, back in the Pliocene, there were alligators in Tennessee and our distant ancestors the Australopithicenes graced eastern Africa. Plus, sea levels were about 23 feet higher, more in some areas. 

Carbon dioxide levels conspired with cyclical changes in the tilt of the Earth's rotational axis to melt much of the West Antarctic Ice Sheet back then, according to a study published in Nature this week. Scientists drilled a more than 4,000 foot long rock core from beneath the Ross Ice Shelf that revealed this ice sheet waxed and waned in response to these climate cycles. 

Computer simulations predict the same melting will occur sometime in the next 1,000 years, possibly as soon as this century. With even the most optimistic governments aiming to prevent concentrations of greenhouse gases in the atmosphere from going above 450 ppm, today's ocean front property is likely to get a lot wetter.

—David Biello

60-Second Earth is a weekly podcast from Scientific American. Subscribe to this Podcast: RSS | iTunes

60-Second Earth is a weekly Podcast. Subscribe to this Podcast: RSS | iTunes