What can seabed cores tell us?

To learn how the Earth responded to climate change 50 million years ago, and how it may react to future warming, scientists are plumbing the seafloor to unlock ancient secrets. Here's how they're doing it.

Imagine holding a very long drinking straw from the top of the Empire State Building and using it to drill into the sidewalk below—that's about the scale. Then imagine that straw weighs 600,000 pounds and requires a 2000-hp engine to lift it.

The barrel of this straw captures a 2.5-inch-wide cylinder of layered mud and, with the tug of a winch cable, it starts its long trip back to the surface inside the drill pipe, through a "moon pool" hole in the center of the ship and onto the deck. Here the sediment core is delivered to geologists, ready to probe the climate record it holds. Meanwhile, another core barrel is lowered inside the pipe. Each successive barrel drills steadily deeper into the seafloor, recovering older and older parts of the sediment sequence.