Natural oil seeps: Not proof oil spill worries are overblown


Forbes and Mississippi Governor Haley Barbour say we shouldn't really worry much about the Deepwater Horizon oil spill—after all, natural oil seeps are constantly leaking hundreds of thousands of barrels of oil into the Gulf of Mexico and everything is fine. So, are they right?

As you might guess, there's a bit of distortion going on here.

Natural seeps are real—kind of the underwater oil deposit equivalent of a natural spring of water popping up through the ground on land. They really do release a lot of oil into the world's oceans—as much as 14 million barrels per year. But, as Cutler Cleveland, Professor in the Department of Geography and Environment at Boston University, wrote on the Oil Drum blog, they do that at a much slower rate than man-made oil spills.

The Deepwater Horizon site releases 3 to 12 times the oil per day compared to that released by natural seeps across the entire Gulf of Mexico. By May 30, the Deepwater Horizon site had released between 468,000 and 741,000 barrels of oil, compared to 60,000 to 150,000 barrels from natural seeps across the entire Gulf of Mexico over the same 39 day period.

Natural seeps also don't run constantly or consistently. They stop and start, and put out more or less oil over time. And most of the seeps have been seeping for a very long time.

Why does all this matter? I've said it before and I'll say it again: Dose makes the poison.

Smaller amounts of oil, released a slower rate, into a local ecosystem that has evolved in tandem with the ongoing natural seep isn't as big of a deal as a whole metric crap-ton of oil dumped quickly into a larger area of ocean. (Just like smaller amounts of Corexit oil dispersant can be legitimately safe, even though we don't know anything about the toxicity of the product when used in huge quantities.)

The existence of natural oil seeps is not a legitimate argument against the very real need for concern about the effects of a massive oil spill. Tell your friends. And maybe Gov. Barbour, if you get a chance.

Oil Drum blog writers Gail Tverberg and Prof. Dave Summers were instrumental in answering my questions about oil seeps. For more details on the seeps, read Cutler Cleveland's full post, and this follow-up by Summers.

Tar ball on the beach in Alabama. Tar balls can be cause by both natural seeps and spills. It's impossible to know which without testing. Photo by Flickr user EveMBH, via CC