Icebergs Once Drifted as Far South as Florida During the Last Ice Age

It turns out that icebergs may have once drifted all the way to Florida. Using a high-resolution model to describe ocean circulation during the last ice age about 21,000 years ago, scientists have found that icebergs from the North American ice sheet floated as far south as Florida.

In order to better understand how far icebergs and meltwater drifted from the North American ice sheet-and whether there was evidence of it drifting south-scientists analyzed high-resolution images of the sea floor from Cape Hatteras to Florida. By examining these images, the researchers identified about 400 scour marks on the seabed that were formed by enormous icebergs plowing through the mud on the sea floor. These  characteristic grooves provided physical evidence that icebergs drifted south.

"Our study is the first to show that when the large ice sheet over North America known as the Laurentide ice sheet began to melt, icebergs calved into the sea around Hudson Bay and would have periodically drifted along the east coast of the United States as far south as Miami and the Bahamas in the Caribbean, a distance of more than 3,100 miles, about 5,000 kilometers," said Alan Condron, one of the researchers, in a news release.

The scientists then simulated the release of a series of glacial meltwater floods in a high-resolution ocean circulation model at four different levels for two locations: Hudson Bay and the Gulf of St. Lawrence.

"In order to icebergs to drift to Florida, our glacial ocean circulation model tells us that enormous volumes of meltwater, similar to a catastrophic glacial lake outburst flood, must have been discharging into the ocean from the Laurentide ice sheet, from either Hudson Bay or the Gulf of St. Lawrence."

This, in particular, has implications for the climate of today. More specifically, the researchers point out that future studies on mechanisms on abrupt climate change should take coastal boundary currents in redistributing ice sheet runoff and subpolar fresh water into account.

The findings are published in the journal Nature Geosciences.