thousands of years ago, icebergs broke off of glaciers in Canada, rafted into the ocean, and deposited rocky debris that settled to the ocean floor as they melted. Heinrich envisioned that this armada of icebergs was set in motion by the breakup of glaciers. The more scientists analyzed ice cores and the seafloor, the stranger these iceberg-glacier breakup events became. The glacial breakups, involving the separation of hundreds of large icebergs from an ice sheet in northern Canada, happened over the course of less than 250 years. And just as rapidly, each one of these events elevated global
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