Crude from the BP blowout in the Gulf of Mexico has now entered currents that will carry it out into the Atlantic Ocean and up the East Coast. But experts say the worst that beachgoers in Maryland are likely to encounter might be a few sandy tar balls — soft, asphalt-like blobs that can do little more than stain your feet.
Communities along the southeastern coast, especially in Florida, might have a close encounter with the oil, said Jim Carton, chairman of the Department of Atmospheric and Oceanic Science at the University of Maryland.
"But there's good news for us," he said. "The current leaves the continental shelf at about Cape Hatteras [N.C.], and heads northeast. Parts of North America north of Cape Hatteras should be fairly safe from this stuff."
Barring a hurricane or some other storm that blows surface waters and tar balls westward from the Gulf Stream onto Delmarva beaches, Carton said, "it should pass us by."
That's what Ocean City officials expect, too.
"We've certainly been made aware that [the oil] could go out into the Gulf Stream," said Donna Abbott, a spokeswoman for the Town of Ocean City. "But from what I've heard, there would be less than 1 percent, if it even made it this far, that would be of any significance to our beaches."
"We … feel for the people in the gulf who are going through this. Any coastal community would," she said. "But we … have not been led to believe there is any real potential there for harm to the coast."
"If tar balls do appear," Abbott said, "we … have an outstanding public works department and other staff members who can handle any cleanup situation."
Satellite radar imagery released Thursday by the European Space Agency showed a long tendril of the spilled oil reached the gulf's Loop Current on Tuesday.
From there, Carton said, it will surely begin to flow south toward the Florida Straits and then up the East Coast. Moving at about 2 mph, it could reach Maryland's latitudes in less than three weeks.
"Somebody asked whether this Memorial Day could be affected by this, and I figure there's no way," Carton said. "But it could be a summer issue for parts of the East Coast … and Florida would get it before anyone else."
Carton described the Loop Current as the key player in the Gulf of Mexico. Warm water from the Caribbean Sea streams into the gulf between Mexico's Yucatan Peninsula and the western tip of Cuba. The only way out is through the Florida Straits — the passage between the Florida Keys and Cuba.
But while the current's entrance into and exit from the gulf are constrained by geography, the loop itself is not, Carton explained. It moves around. Sometimes it pinches off and sends a ring current drifting westward.
"Some oil may circulate in one of those rings that tend to head west into Texas," Carton said.
But most of the oil the Loop Current picks up is expected to flow with it toward the Florida Straits just north of Havana.
"I think Cuba is a serious issue, and I wonder if it should be part of the U.S. response," Carton said. "It's our oil showing up on their beaches."
From the Straits, the current turns north along Florida's Atlantic coast and becomes the warm Gulf Stream current.
The Gulf Stream follows the edge of the continental shelf from Miami to Cape Hatteras. That brings it quite close to the South Florida beaches, but moves it somewhat farther offshore as it passes Georgia and the Carolinas.
From Hatteras, the Gulf Stream turns more to the northeast, over deeper ocean waters, where its course becomes more variable.
"So you get these rings spinning off the Gulf Stream," he said. Called "warm core rings," they can drift onshore, bringing with them tropical creatures and, conceivably, tar balls. Such events are "rather infrequent" for the Chesapeake region, but Narragansett Bay in Rhode Island and Cape Cod, Martha's Vineyard and Nantucket in Massachusetts "are more at risk for this kind of thing."
Storm systems could also bring tar balls ashore in Maryland on east winds, Carton said. "It's entirely possible."
But an expert at Texas A&M University said there is little in tar balls for Marylanders to worry about.
While the huge volumes of fresh crude oil drifting in the gulf threatens the human economy and all manner of living things in the gulf's fisheries and estuaries, the oil that's beginning to flow into the ocean currents is constantly "weathering," said Wes Tunnell Jr., associate director of Texas A&M's Harte Research Institute for Gulf of Mexico Studies.
"The Gulf of Mexico is really quite resilient," he said. The gulf's floor has natural oil "seeps" that annually release a volume of crude oil into the water that's the equivalent of two supertankers. Over millions of years, Tunnell said, the ecosystem has evolved a "huge population of bacteria and microorganisms that feed upon the oil."
Gradually, the tiny life forms break down the drifting crude. Over weeks and months, the oil loses many of its most volatile, toxic components, leaving only the heavier, asphalt-like tar.
"Probably all you guys would see up there would be tar balls on your beach, and it would be very weathered," he said.
Centuries ago, people considered the tar a resource. Archaeologists have found that Native Americans along the Gulf Coast used it to line and waterproof their pottery, and to decorate it.
Today, Tunnell said, "it's mainly a nuisance." Like grease, it can stain clothing, towels and skin. "In some places, whenever they're having many tar balls come in, the hotels will have cans of stuff for guests to wipe their feet with before they come in."
Tar balls warmed by the sun "can get kind of gooey," and "might impact something right under the ball, like crustaceans or worms." But such effects, Tunnell said, would be "very spotty."
Among the larger unknowns in this vast spill, he said, is what will happen with the huge underwater plumes of crude reported in the BP spill. "It's been predicted that something like this would happen, but it hasn't been studied."
Scientists know bacteria go to work quickly on crude in warm surface waters, he said. But if much of the spill remains in deeper, colder water, those physical and chemical processes might not work well. "These are questions we don't have the answers to for now."
Carton, at College Park, said crude oil lurking deep in the gulf also would not easily be swept up by the Loop Current, which flows through the warmer, upper layers of the water at depths of less than 1,000 feet.
"Eventually that stuff either collects on Gulf of Mexico beaches … or it sinks, or it exits" through the Florida Straits and into the Gulf Stream, he said.
And with the huge volume of oil that's being discharged from the broken wellhead, he said, those processes could continue for years.