Crude oil is a naturally occurring substance. But deliberate or accidental spills on the sea can be very dramatic events, especially those associated with offshore oil and gas production.
Shooting flames, unsightly slicks, oiled birds, and gooey messes onshore are all highly photogenic. Also, most are within an easy commute for protesting environmentalists and the news media. To be sure, these events are harmful for those affected. However, worldwide offshore petroleum exploration and production only accounts for between 2–4 percent of the oil spilled into the sea each year. By comparison, human activity on land is around 11 percent, three times higher than the oil platforms. Considering that globally there are thousands of offshore platforms and tens of thousands of miles of seafloor pipelines, offshore petroleum production is remarkably clean—and getting cleaner each year.
This may seem like heresy; the point is that offshore production activities must be considered in the context of all sources of oil pollution, amounting to a global total of about 350 million gallons per year. Even if the offshore production component was reduced to zero, the worldwide total would remain huge. Reduction of oil entering the sea must focus on the major sources.
By far the largest “polluter” is Mother Nature. A whopping 47.3 percent of oil put into the oceans comes from natural seeps in coastal areas.
Accounting for nearly half of the oil spilled in the world ocean, natural seeps are the most difficult to control. They occur in coastal areas where the sub-seafloor rock structures are porous above a pressurized oil reservoir. The crude oil and gas are forced up through the seafloor, essentially creating a permanent spill event.
One of the largest natural seep areas in the world is near Coal Oil Point, California. Native Americans used the tars to make their canoes watertight. Today those seeps are just a nuisance as southerly coastal currents occasionally carry tar balls to the tourist-populated beaches down the coast.
It appears there is a relatively simple way to cut down on this natural pollution: reduce pressure in the reservoir by increasing offshore oil production in those areas. California could gain millions of dollars a year in tax revenues since the seeps are in state coastal waters.
But while there is a remedy, it may a long time before it is applied. There seems to be a tolerance for natural seeps but very little for drilling activities. People tend to remember the great oil-spill disasters, so there is vigorous opposition to any new drilling operations, even though natural seepage amounts to a vastly greater amount of oil released into the ocean.
There are areas of natural seeps throughout the world. The Gulf of Mexico has many. Remedies about how to reduce those flows are known; it is only a matter of public will.
Dr. Walsh, a marine consultant, is a retired naval officer and oceanographer. During his naval career he served at sea in submarines and ashore in ocean-related research-and-development assignments.