Several years ago, Tal Ezer, an oceanographer at Old Dominion University in Norfolk, Va., was jogging through flooded streets, even though the sun shined and the weather had been nice for days. Government tidal predictions were off by a foot and he wondered why.
His curiosity took him to data generated by an abandoned undersea telephone cable strung between South Florida and the Bahamas. Scientists had figured out a way to measure the Gulf Stream’s velocity by analyzing changes in the cable’s voltage.
Ezer and his colleagues took data from the cable and compared it to tides in Norfolk and other areas on the East Coast. The results were clear: The sea level isn’t really level.
Thanks to the earth's rotation and other factors, the Gulf Stream pulls water from the coast and creates a slope; higher in the stream, lower by the shore. When the current slows, the sea level rises.
Oceanographers knew this on a theoretical level, but only in recent years, in part because of Ezer's work, scientists now have proof of this phenomenon.
In several studies, he and his colleagues found that storms such as 2016's Hurricane Matthew disrupted the flow of the Gulf Stream. As the flow decreased, tides north of the disruption increased and caused flooding in low-lying areas, including the streets where he jogs.
Such findings, he said, will help forecasters predict sunny-day flooding along the southeast coast.
For a deeper dive into the Gulf Stream and the amazing and disturbing things happening to it, visit our new special report: Into the Gulf Stream.