Gulf Oil Threat to Florida Waning Fast

Dick writes about Earth and planetary science for Science magazine.

No one is lowering their guard just yet, but the chances are diminishing that significant amounts of oil from the ongoing Deepwater Horizon spill will soon make it to southern Florida. In part, it is the behavior of the Gulf of Mexico's increasingly infamous Loop Current that could lower the threat.

"The oil is in the Loop Current," says physical oceanographer Robert Weisberg of the University of South Florida (USF) in St. Petersburg, but that does not mean Florida is doomed. The Loop Current flows north past the Yucatán Peninsula into the gulf, reverses and heads south out of the gulf, and exits eastward into the Atlantic Ocean through the Florida Strait at the tip of Florida. As some of the spilled oil drifted in recent days southeastward into a northward-extended loop, the specter of oil spreading along the Florida Keys, hard past Miami, and up the East Coast raised alarm.

But Weisberg's forecast model of eastern gulf currents as well as other forecast models he runs at USF are showing the oil entraining in what looks increasingly like an eddy. The Loop Current sometimes extends so far northward that it forms a closed loop that pinches off from the main current and becomes an independent, clockwise-rotating eddy out in the middle of the gulf. "That's the best thing that could possibly happen," says Weisberg. "It would stay in the eddy. It would be a sort of a valve to drain some of the oil away without it going to Miami."

Failing a cooperative Loop Current, the amount of oil being entrained in it is looking to be small. In a teleconference with reporters today, Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration (NOAA), noted that there "is only a very small amount in the Loop Current." She described it as a sheen—NOAA's smallest characterization—with possible subsurface tarballs. "By the time [the oil] makes it to the Florida Strait, it likely will have transformed into tarballs and streamers, and that may not make it to the beach." NOAA scientists will know more about the Loop Current's future behavior after a P-3 "Hurricane Hunter" aircraft flies over it tomorrow and drops instrumented probes of the subsurface.

For more on the gulf oil spill, see our full coverage.

Posted in Climate, Policy Gulf Oil Spill, oil fate