He walks through the timeline of the Younger Dryas, a period lasting nearly 1,300 years that ended abruptly around 11,700 years ago. Marine geologists identify this termination as Meltwater Pulse 1B, a sudden catastrophic warming accompanied by a massive influx of glacial meltwater into the oceans. An earlier event, Meltwater Pulse 1A, occurred around 14,600 years ago and may have triggered the Older Dryas cooling period. These pulses represent some of the most dramatic climate shifts in recent geological history, moments when vast ice sheets destabilized and reshaped both sea levels and global temperatures in geologically instantaneous timeframes.