Prehistoric icebergs may have drifted as far south as Florida

Nature : Massive icebergs carried by prehistoric floods may have traveled down the North American coast as far south as Florida, according to a recent study published in Nature Geoscience. Some 20 000 years ago, as the North American ice sheet began to melt, giant icebergs up to 300 m thick appear to have broken off and been carried by the massive flooding not only into the northern Atlantic Ocean but also south along the continental shelf. The researchers’ findings are based on computer models and on the presence of massive seafloor scars believed to have been left as the icebergs scraped the ocean bottom. The meltwater discharge may also have caused a temporary reversal in surface ocean currents. Now that the Greenland ice sheet is in a period of rapid melt, with large icebergs calving off, researchers are working to understand how that influx of cold fresh water will affect present-day ocean circulation patterns and, possibly, global climate.