Around 14,500 years ago, at the end of the last ice age, the collapse of a large chunk of ice, likely from the Laurentide Ice Sheet covering North America, initiated an event known as Meltwater Pulse 1A. Sea levels rose more than a foot—and more than a mile of coast disappeared—per decade, displacing those living near shorelines. The earth’s human population was then roughly three million, 0.04 percent of what it is today.