Major Climate Change Occurred 5,200 Years Ago: Evidence Suggests That History Could Repeat Itself

Glaciologist Lonnie Thompson worries that he may have found clues that show history repeating itself, and if he is right, the result could have important implications to modern society.
Thompson has spent his career trekking to the far corners of the world to find remote ice fields and then bring back cores drilled from their centers. Within those cores are the records of ancient climate from across the globe.