The Amazing Disappearing Gulf Oil Spill
Remember the 2010 BP Gulf Oil disaster? For 83 days it dominated news broadcasts in the US and was followed with interest around the world. Ecological activists wailed that the Gulf would never recover, alternative energy advocates demanded all off shore oil production be shut down, and the Obama administration quickly reversed its plans to open up more coastal areas for oil exploration. Now things have gone strangely silent regarding the worst ever US oil spill. A report commissioned by the reparations fund director pronounced Gulf fisheries mostly recovered and a number of scientific reports found that both oil and natural gas released by the spill had amazingly disappeared. Some environmentalists are still howling but the crisis seems to have passed much more quickly than even the most optimistic predictions.
On April 20, 2010, a violent and tragic methane (CH4) discharge severed the Deepwater Horizon rig from its well, killing 11 rig workers in the process. Two days later, the burning rig sank. Oil and natural gas began spewing into the Gulf of Mexico at a depth of ~1.5 km (~1 mile). This continued until July 15, when the well was effectively sealed. Damage to area fisheries and nearby coastal estuaries was severe, with some experts predicting that recovery would take several decades. The reporting, even in scientific journals, verged on the hyperbolic (see “Will Deepwater Horizon Set a New Standard for Catastrophe?”).
Through the media circus din other experts dissented. In a July 29. 2010, interview with Time magazine, Dr. Ivor Van Heerden, a marine scientist formerly at LSU, commented “there’s just no data to suggest this is an environmental disaster. I have no interest in making BP look good—I think they lied about the size of the spill—but we’re not seeing catastrophic impacts,” says Van Heerden, who, like just about everyone else working in the Gulf these days, is being paid out of BP’s spill response funds. “There’s a lot of hype, but no evidence to justify it.” That article by Michael Grunwald identified several reasons that concerns over the spill might be exaggerated:
The scientists I spoke with cite four basic reasons the initial eco-fears seem overblown. First, the Deepwater Horizon oil, unlike the black glop from the Valdez, is comparatively light and degradable, which is why the slick in the Gulf is dissolving surprisingly rapidly now that the gusher has been capped. Second, the Gulf of Mexico, unlike Prince William Sound, is balmy at more than 85 degrees, which also helps bacteria break down oil. Third, heavy flows of Mississippi River water helped keep the oil away from the coast, where it can do much more damage. Finally, Mother Nature can be incredibly resilient.
Part of the accident settlement entailed BP establishing a $20 billion special compensation fund for victims of the Gulf oil spill. Washington lawyer and former 911 victims' fund manager, Kenneth Feinberg was appointed to administer the fund. One of the things that Feinberg did, in order to better judge damage claims, was to commission a study by environmental experts regarding the damage done to Gulf ecosystems and fisheries.
A boat passes through heavily oiled marsh near Pass a Loutre, Louisiana May 20, 2010. Source Lee Celano/Reuters.
The 39-page report, authored by Dr. John W. Tunnell Jr., associate director of Texas A&M’s Harte Research Institute for Gulf of Mexico Studies, concluded that Gulf fisheries would significantly recover in just a few years. The report acknowledges that it is too early for a definitive assessment of the spill’s ecological effects, but Dr. Tunnell concluded that regional 2011 catches for blue crabs, shrimp, oysters and fin fishes should be in line with catches before the spill.
However, areas where oyster reefs were heavily oiled may not recover for 6-8, or even 10 years. Based on the work of environmental scientists, economists and other experts, the report acknowledges that “prediction is not an exact science” but estimates that the gulf should be mostly recovered by the end of 2012. Even so, further drilling and exploration in offshore areas were once again banned by the Obama administration.
Since the accident, the on again off again drilling ban has led to a number of legal actions. Century Exploration New Orleans Inc. is suing the US over changes in offshore drilling rules. The company claims that the government's ever shifting policies have made development of its $23 million Gulf of Mexico lease “commercially impractical.”
Century’s claim is unrelated to two other industry lawsuits challenging the administration’s offshore drilling moratoriums and attendant safety rules. That litigation, which has bounced back and forth between a New Orleans judge and the appellate court, is awaiting a ruling by US District Judge Martin Feldman, who struck down the initial drilling ban as arbitrary and overly broad. According to Feldman, Interior Department regulators acted with “determined disregard” by lifting and reinstituting a series of policy changes that restricted offshore drilling, following the Gulf spill. The Obama administration's regulatory ineptitude evidently knows no bounds.
Perhaps the most interesting report appeared in the journal Science on January 21, 2010. In “A Persistent Oxygen Anomaly Reveals the Fate of Spilled Methane in the Deep Gulf of Mexico,” a team of investigators, led by John D. Kessler from the Department of Oceanography at Texas A&M University, tracked the fate of CH4 released by the the Deepwater Horizon blowout. The magnitude of the gas release is described at the beginning of the paper.
Estimates of the oil emitted during the 83 days of this disaster range from 4.1 × 106 to 4.4 × 106 ± 20% (uncertainty) barrels. The corresponding emission of methane (CH4) could be as great as 1.25 × 1010 moles or as low as 9.14 × 109 moles, depending on uncertainties in the gas-to-oil ratio and net oil emission. This localized CH4 emission is of similar magnitude to the natural release rate of CH4 to the entire Black Sea and provided a unique opportunity to investigate the fate of CH4 released into the deep ocean and to understand the response of cold-adapted methanotrophic bacteria.
Most people do not realize that 75% of the hydrocarbons emitted by the Gulf oil leak were in the form of natural gas: ethane, propane and, most significantly, methane. Beyond the immediate environmental impacts of the leak, this methane release could serve as a stand-in for a rapid and relatively short-term natural release from hydrates into deep water. Large natural methane releases are thought to have caused periods of rapid global warming in the past, such as the PETM, and may even have contributed to mass extinction events.
Sampling stations in the Gulf of Mexico.
When bacteria metabolize methane oxygen is consumed. This leads to oxygen depletion of waters where methane is released. By tracking the distributions of dissolved CH4 and oxygen (DO) at 207 stations in the Gulf, Kessler et al. reached some unexpected conclusions. After all, the conventional scientific wisdom indicated significant, lasting impact from such a large gas leak. “[W]e expected CH4 intrusions from the Deepwater Horizon to persist for years,” the author's state. The results were surprising to say the least:
It is unlikely that CH4 intrusions were simply missed during the survey, because concurrent fluorescence and DO anomalies were identified at most stations in the deep waters, indicative of both the presence of residual oil hydrocarbons and hydrocarbon respiration. On the basis of these results, we hypothesized that methanotrophic bacteria consumed all CH4 from the Deepwater Horizon event by the 18 August–2 September survey.
Dissolved oxygen at depth.
The lifetime of the methane released from Deepwater Horizon was about 120 days, with no measurable CH4 loss to the atmosphere. Once the methane eating bacteria became established their population underwent exponential growth, limited only by the “food” available. Since it has long been known that natural bacteria eat oil released from seafloor oil seeps, it should have come as no surprise that nature had a way of cleaning up natural gas leaks as well.
Even in the face of these reports, some researchers are still trying to flog the Gulf spill for greater funding. Take for example an article entitield “Better Science Needed for Restoration in the Gulf of Mexico,” which appeared in the Fruary 4, 2011, issue of Science. The policy forum article, written by ten researchers led by Karen A. Bjorndal, is really just a plea for more funding.
Bjorndal et al. bemoan the fact that many populations have not been adequately assessed, so their recovery cannot be measured by researchers. But what starts out a warning about lacking critical data in the end becomes a bid for recovery fund money: “It is not too late to invest funds from BP to support teams of experts to develop effective strategic plans that identify, prioritize, and provide methodologies for collecting essential data.”
“Although difficult to set, priorities should be provided to direct funding to address long-term population management needs,” the author's state, noting: “Having funding priorities in place for key species and ecosystems will allow efficient, strategic use of funds that become available after a crisis.”As Rahm Emanuel, President Obama's former chief of staff, once said, “never let a disaster go to waste.”
While the oil slick in the Gulf dispersed much faster than most experts predicted, that does not mean that all scientists agree that the crisis has past. Various articles have warned of “dead zones” being formed by deep oil plumes. Others claim that the disappearing oil has settled into a deadly layer covering parts of the ocean floor.
“Magic microbes consumed maybe 10 percent of the total discharge, the rest of it we don't know,” said Samantha Joye, a marine scientists at the University of Georgia and lead author of a research letter published in Nature Geoscience. That paper disagrees significantly with the paper by Kessler et al. appearing in Science. It should be noted that the Joye et al. paper was submitted before Kessler and colleagues took their survey samples, making the latter's observations more recent.
Obviously, this debate will not subside any time soon and the scientific studies will go on for decades. While the boffins argue and the law suits fly, the people of the Gulf Coast are slowly putting their lives back together. In a few years the worst oil spill in US history will only be a fading memory—out of sight, out of mind.
Nature is more resilient than we know.
The damage caused by the Deepwater Horizon disaster should not be trivialized—it was a massive ecological disaster caused by greed and incompetence. Those responsible should be punished to the greatest extent of the law and prevention mechanisms for offshore drilling leaks enhanced. But, given the choice of burning more coal or nation wide energy shortages, expanded drilling off the US coast will happen eventually.
We can take some small comfort from what science has learned about the Gulf and other offshore environments: oil and gas seeps are a natural part of the environment and whole communities of organisms have evolved to live off the hydrocarbons they release. As usual, nature is more tolerant of man's indiscretions than we thought. Humans stumble, nature cleans up and life moves on, on this Resilient Earth.
Be safe, enjoy the interglacial and stay skeptical.