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Hurricane, Oil Spill Could Be Troubling Mix

Phil Radford, executive director of Greenpeace USA, inspects oil-covered reeds along the Gulf of Mexico while visiting the disaster site on May 20. (Getty Images)

If a hurricane encounters the oil slick now covering parts of the Gulf of Mexico, the result could be devastating, scientists say. Not only could any hurricane increase the damage that oil does to coastal wetlands, but the presence of oil could lead to a more powerful hurricane, they say.

Nobody knows for sure, though, because there's no record of a hurricane ever crossing paths with a large oil spill.

Trouble Brewing

The Atlantic hurricane season begins June 1, and forecasters expect it to be busier than usual. Meanwhile, oil continues to gush into the Gulf of Mexico from the site where the Deepwater Horizon rig exploded on April 20 and sank two days later in 5,000 feet of water.

Since then, oil has been accumulating at the surface. And that could be raising the temperature of the surrounding water, says Kerry Emanuel, a hurricane expert at the Massachusetts Institute of Technology.

"You have this black surface, and it's doing two things," Emanuel says. "First of all it's absorbing sunlight. And secondly, it is curtailing evaporation from the Gulf."

Evaporation normally helps cool the Gulf waters, Emanuel says.

"So theoretically, the Gulf underneath this oil slick should be getting hotter than it normally would be." And hotter water helps create more powerful hurricanes.

It's hard to know if the water is actually getting hotter, though, because oil prevents satellites from taking accurate temperature readings.

Impact On The Environment

Environmental scientists are already predicting that oil from the spill will damage the vegetation in coastal marshes. And the damage could be worse if a hurricane pushed oil deep into a wetland, or into currents that would carry it down Florida's west coast.

"That's a big concern," Emanuel says. "Hurricanes would be pretty effective at dispersing [the oil] and pushing it around."

Other scientists say the amount of damage may depend on timing.

A hurricane might even be beneficial if it arrives before oil has a chance to damage coastal marshes, says Irving Mendelssohn, who studies coastal plant ecology at Louisiana State University.

"It's very possible that the hurricane will tend to both dissipate and break up the oil faster," he says. That could dilute the toxic substances and result in minimal damage to plants, he says.

But Mendelssohn says there could be more damage if the hurricane arrived after oil had reached the coast.

"Then the hurricane results in greater erosion of the wetland," he says, "because the wetland has already lost its vegetation and is already in a degraded state."

Marsh plants are hardy, and usually recover from a single encounter with oil, especially the less toxic type involved in this spill, Mendelssohn says. His great fear is that some combination of hurricanes, ocean currents and the ongoing spill will cover the same marsh plants with oil repeatedly.

"That type of re-oiling will completely kill the plant," he says, destroying the wetland, and leaving the coast without a key defense against hurricanes.

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Transcript

ROBERT SIEGEL, host:

From NPR News, it's ALL THINGS CONSIDERED. I'm Robert Siegel.

There is no record of a hurricane ever encountering a major oil spill, but that could change in the next few months. The Atlantic hurricane season begins in less than two weeks, and forecasters say it's likely to produce more storms than usual. Meanwhile, oil continues to gush into the Gulf of Mexico from the site where the Deepwater Horizon rig exploded and sank.

As NPR's Jon Hamilton reports, scientists believe the combination of oil and hurricane could make the damage caused by each even worse.

JON HAMILTON: Back in the 1960s, researchers wondered whether an oil slick might actually stop a hurricane. So, a few years ago, Kerry Emanuel, a hurricane expert at MIT, tested the idea in his lab. He used fish oil, a tank of water and a hurricane powered by a fan.

Dr. KERRY EMANUEL (Professor of Meteorology, MIT): The net result was that when you get up to moderately high wind speeds, the film on the surface just breaks apart as you might guess it would.

HAMILTON: Suggesting that an actual hurricane wouldn't even be weakened by an oil slick.

And in Emanuel's experiment, the swirling winds seem to sweep up the oil. So, a hurricane in the Gulf might suck up oil along with sea spray and deposit it on land. Emanuel says it's all speculation because it's never happened before.

And recently Emanuel has been speculating about ways an oil slick could actually make a hurricane more powerful.

Dr. EMANUEL: Right now, sitting out there as it is in the Gulf, you have this black surface and it's doing two things. First of all, it's absorbing sunlight. And secondly, it is curtailing evaporation from the Gulf right now.

HAMILTON: Emanuel says both of those things tend to trap heat in the water.

Dr. EMANUEL: So, theoretically, the Gulf underneath this oil slick should be getting hotter than it normally would be.

HAMILTON: And hot water is one factor that drives small hurricanes to become big ones. It's hard to know for sure if the area near this lake is getting hotter because the oil makes satellite temperature readings unreliable.

Emanuel says not only is it possible that the oil spill could make a hurricane worse, the reverse might also be true. For example, the hurricane could magnify the effects of the spill by pushing oil into coastal wetlands.

Dr. EMANUEL: That's a big concern. Hurricanes would be pretty effective at dispersing it and pushing it around.

HAMILTON: Other scientists say the amount of damage depends on timing. Irving Mendelssohn, who studies coastal plant ecology at Louisiana State University, says a hurricane might even be beneficial if it occurs before oil has a chance to damage coastal marshes.

Dr. IRVING MENDELSSOHN (Professor of Oceanography, Louisiana State University): It's very possible that the hurricane will tend to both dissipate and break up the oil faster and then, of course, move it over a larger area, more or less diluting it, so that the effect may be minimal.

HAMILTON: But Mendelssohn says there might be more damage if the hurricane arrived after oil had reached the coast.

Dr. MENDELSSOHN: And then the hurricane results in greater erosion of the wetland because the wetland has already lost its vegetation and is already in a degraded state.

HAMILTON: Mendelssohn says marsh plants usually recover from a single encounter with oil, especially the less-toxic type involved in this spill. He says his greatest fear is that some combination of hurricanes, ocean currents and the ongoing spill will cover the same marsh plants with oil repeatedly.

Dr. MENDELSSOHN: That type of re-oiling will completely kill the plant because all these underground reserves that are used to produce new plants will be used it, and then you can get complete death.

HAMILTON: Destroying the wetlands and leaving the coast without a key defense against hurricanes.

Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.

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