Ice and Time: Reading Greenland's Frozen Archive

Somewhere in the middle of Greenland, there is a column of ice three kilometers deep. It has been sitting there, layer by layer, for more than a hundred thousand years — each annual snowfall compressed into a thin band, each band holding a record of the atmosphere above it at the time it fell. This episode is about the slow science of reading that record. About drilling camps on a frozen plateau, about the chemistry of ancient air trapped in tiny bubbles, and about what happens when you shine polarized light through a cylinder of ice from fifty thousand years ago and watch the seasons appear.

The story moves from a 1960s US military research station buried inside the ice sheet to a major international drilling project in the 1990s that reached bedrock after five years of continuous work. Along the way: how volcanic eruptions leave time-stamps in the ice, how sea-salt and ammonium cycles act as an internal calendar for the deeper layers, and what a brief cold episode called the Younger Dryas — beginning roughly 12,900 years ago — looked like from inside the ice. Not dramatic listening. Deliberately not. The ice is patient, and tonight so are we.