Massive Icebergs Once Floated to Florida

Usually, travelers flock to Florida as means of garnering a typical beach holiday—tans, mojitos, and coastal adventures. But icebergs? In ice age Florida, yes.

According to Nature Geosciences, mammoth chunks of ice once floated down the East Coast to parts of South Carolina and southern Florida during the last ice age, creating deep grooves and furrows into the Atlantic seafloor. At the time – 21,000 years ago – a crystalline blanket known as the Laurentide Ice Sheet covered a large portion of Canada, but as climate began to warm, chunks of the sheet snapped off in the Hudson Bay. The massive pieces then drifted thousands of miles south on the East Coast—at times, even landing amid Caribbean islands.

Led by oceanographer Alan Condron of the University of Massachusetts Amherst and team, the findings involved a high-resolution numerical model used to chronicle ocean circulation during the last age. Condron and crew found an estimated 400 extensive grooves on the ocean floor. Presumably left by the jagged bottoms of ice chunks, the grooves illustrate just how large the ice formations were. “The depth of the scours tells us that icebergs drifting to southern Florida were at least 1,000 feet, or 300 meters, thick,” Condron says. “This is enormous. Such icebergs are only found off the coast of Greenland today.”

The observations made with regard to past meltwater and iceberg movement suggest that future ice sheet melting may be more complicated that previously thought. “We can’t simply make the assumption that all of the cold, fresh water from ice sheet melting stays in the North Atlantic,” explains lead study author Jenna Hill, a geologist at Coastal Carolina University in Conway, South Carolina. “Determining how far south of the subpolar gyre icebergs and meltwater penetrated is vital for understanding the sensitivity of North Atlantic Deep Water formation and climate to past changes in high-latitude freshwater runoff.”

However, iceberg sailing parades down the Atlantic didn’t happen too often; the coastline showings were more like forceful but spaced-out floods.

Overall, the new finding assists in further molding climate research today. “This new research shows that much of the meltwater from the Greenland ice sheet may be redistributed by narrow coastal currents and circulate through subtropical regions prior to reaching the subpolar ocean. It’s a more complicated picture than we believed before,” Condron says.