Wednesday, June 16, 2010

The Other Oil Spill

On June 8th, Representative John Culberson of Texas released an open letter to President Obama, criticizing the administration’s six month moratorium on deep water oil drilling put in place after the April 20th sinking of BP’s Deepwater Horizon oil rig. “I am concerned that the decision to impose the moratorium is based more on emotion than fact,” Culberson wrote. “The Deepwater Horizon incident was a terrible human tragedy with devastating environmental consequences, but it must be viewed in the proper historical context as a statistical anomaly. The government’s own records show that since 1985, more than 7 billion barrels of oil have been produced in federal offshore waters with less than 0.001 percent spilled – a 99.999% record for clean operations. That 25-year record of safety should not be ignored in the haste to respond to public discord.”

Culberson represents Texas’s Seventh Congressional District, which includes much of Houston and its western suburbs—the corporate epicenter for the American oil and gas industry. He is understandably concerned about the economic impact of the drilling moratorium. And there’s no doubt that shutting down deep water offshore drilling will have an economic impact. According to the Houston Business Journal, the moratorium has placed 33 rigs in mothballs and risks $1.8 billion dollars over six months, a figure the paper calls “in the conservative neighborhood.”

While small spills—a few barrels or so—in oil production are common, large ones are not. This rarity of spills of Deepwater Horizon magnitude was a central point made Tuesday by oil company executives while testifying before Congress. Exxon Mobil Chairman Rex Tillerson called the spill an “unprecedented accident,” and claimed that “this incident represents a dramatic departure from the industry norm in deepwater drilling.” Or, as John Watson, CEO of Chevron observed, “It’s important to keep in mind that, as tragic and significant as this incident is, it occurred in an industry with a strong record for safety and environmental protection.”

But as tragic and devastating as this spill has been—to the Gulf environment, to livelihoods, to American culture—there’s been little talk about the less visible and entirely routine ways that our use of oil pollutes the world’s waters. Culberson’s focus on pollution from oil production alone takes an overly narrow view of the environmental impacts of our fossil fuel economy and misses the real story.

It’s impossible to know with 100% accuracy how much oil winds up in the world’s oceans, but in 2002, the National Research Council released “Oil in the Sea III,” an update of earlier studies and still the most comprehensive estimate of oil entering marine ecosystems. The results are surprising, and worth bearing in mind in the wake of the current ongoing disaster.

For starters, the total amount of oil believed to enter the world’s oceans is huge—some 9.5 million barrels a year.* For perspective, that’s just a bit more than the total volume of gasoline consumed in the U.S. in a single day, all dumped into the sea. (I’m using the NRC’s “best estimates,” but they actually give a range—and at the high end, they suppose it’s possible that as much as 60 million barrels of oil a year are deposited into global waters. Again, for perspective, that volume is roughly equivalent to a week’s worth of U.S. gasoline consumption.)

Worldwide, a mere 4% of marine oil pollution a year—or 366,000 barrels—comes from productions spills. This number includes spills from both oil rigs themselves and the miles of pipelines that connect them to shore. (This year’s numbers will surely be higher on account of Deepwater Horizon.)

But a much greater contribution comes not from people, but nature itself. About 4.4 million of these barrels—fully 45% of the total—comes from natural seepage. Cracks and fissures under water or near shores have always oozed petroleum, though usually very slowly and in geographically disparate places. These natural spills often have no adverse impact on the environment, and sometimes even help cultivate ecosystems that thrive on digesting petroleum. Natural seepages are not a new phenomenon either—on land, they are the very phenomena that introduced humans—from ancient Persians to Native Americans—to the substance of petroleum in the first place.

The remaining 51% gets more complicated. This volume, plus the 4% from offshore production and pipeline transportation noted above, or 55% of the total volume dumped, is almost entirely due to human activities. This amount of human contributions the NRC estimates to be roughly 5.225 million barrels.

Put that in perspective. On Tuesday, a team of American scientists increased the estimate of how much oil the BP Gulf spill is pumping into the water. It’s now believed to be somewhere between 35,000 and 60,000 barrels per day. With that estimate, since April 20th, this means the disaster has spilled somewhere between 2 and 3.5 million barrels—or between about a third and two-thirds of all the other average yearly human contributions to polluting our oceans with petroleum.

Said another way: every year, we collectively pour more oil than has probably yet leaked from the BP well into the world’s oceans.

Where does the rest of this yearly waste come from? About 32% is related to oil tankers and cargo vessels. Massive tankers often carry water as ballast in the same tanks that hold oil; emptying them out inevitably discharges oily residues. Most ships also dump large quantities of oil wastes from their engines. And of course, leaks and other accidents can release enormous quantities of oil. (Yet in the U.S., where the 1989 Exxon Valdez disaster—spilling 270,000 barrels—has become the iconic oil tanker spill, since 1967, it actually comes in as only the 35th worst in the world. Bigger ones have just taken place far at sea or far from our continent.) But shipping discharges continue, year after year. This is price we now pay for global trade networks that support the importation of cheap oil and manufactured goods from overseas—in short, our modern consumer economy.

But big companies are not solely responsible for oil discharges from vessels. In the U.S. alone, over 40,000 barrels of oil—perhaps a day’s worth of the BP Gulf spill—is dumped into the sea from recreational vehicles like motor boats and jet skis.

Still more oil pours in to the sea from land. The NRC estimates that 11% of the total oil found in global waters—more than a million barrels—comes from runoff. This is all that waste produced by factories, refineries, waste treatment plants, and even those oily patches left by leaky car engines that appear on roads when it rains. It all eventually flows out to sea. And in the U.S., the contribution of industrial and consumer consumption accounts for about a third of the global total.

(It’s worth noting, though, that the contribution from runoff is actually the calculation with the most uncertainty in the whole estimate. I cite above the 11% or “more than a million barrels” as the NRC’s best estimate. The range—much larger than for other estimates, is actually huge. On the low end, they set the figure at 50,000 barrels. But on the high end, it’s a whopping 36 ½ million barrels—alone between 10 and 18 times the size of the BP Gulf spill.)

The balance of oil dumped into the sea comes from a variety of sources: residues from burning wood or fossil fuels, the dumping of fuel by aircraft, and even biological wastes from certain species like planktons. Added up, the impact may be huge.

When Representative Culberson focuses narrowly on oil spilled in offshore production, we are mislead about the broader context of all the other oil that winds up in the oceans. While it’s easy to wag a finger at oil companies (especially when they do appear to have chronic disregards for environmental protection and worker safety), we bear a collective responsibility for yearly deposits of more oil than the Deepwater Horizon leak has yet released.

There is no easy solution, yet recognizing how our daily choices matter is an essential first step. Oil tankers will continue to spill oil as long as there’s a demand for the stuff, and automobiles will leak oil as long as we’re driving with internal combustion engines. A shift away from these technological systems will take decades, and then, only with the creativity of private industry and a strong push from government (and not just this one).

But there are many actions we can take today. Think about the distances your food has traveled (with the help of oil), and consider shopping for locally grown products. If you can, bike to work, or use public transportation. In the winter, don’t overheat your home, and if you are able to, insulate it better. Pressure local factories to use cleaner manufacturing processes, and encourage politicians to put a price on dumping private wastes in public waters.

If we don’t make changes, or if we respond too narrowly to the disaster in the Gulf, we’ll miss dealing with the larger oil spill the modern world produces every year.

*NOTE: throughout this post, I converted the units used in the NRC report from tonnes (= metric tons) to barrels, a more familiar unit to most people. Since tonnes is a measure of mass and barrels of volume, I chose the common conversion factor of 7.33 barrels/tonne, which reflects a reasonable average of oil densities.


  1. Hi Peter,
    I love your blog! I just noticed it via your gchat sig and now I'm subscribing.

    But I have a question about this "size of oil spill" business. If a million barrels are dumped all in one place, isn't that somehow worse than dispersing a million barrels in a fine mist over the entire Atlantic? Because in the second scenario, bacteria can more readily break it down, etc. Or is it simply that the first spill is more noticeable?

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