Is BP’s Oil Volcano An Extinction Level Event?

While much is being made of the catastrophic environmental and economic effects the oil being released from BP’s Macondo well, perhaps an even greater problem is the huge amounts of methane that accompanies it. Accounting for some 40% of the total volume, the methane is moving in vast underwater plumes at concentrations 10,000 that of normal.

The man featured in the clip above, Dr. Gregory Ryskin (Department of Chemical Engineering, Northwestern University) wrote a paper titled Methane-driven oceanic eruptions and mass extinctions, published in the September 2003 issue of  Geology.  The Abstract reads as follows:

Focusing on the Permian-Triassic boundary, ca. 251 Ma, I explore the possibility that mass extinction can be caused by an extremely fast, explosive release of dissolved methane (and other dissolved gases such as carbon dioxide and hydrogen sulfide) that accumulated in the oceanic water masses prone to stagnation and anoxia (e.g., in silled basins). The mechanism of the explosive release is the same as in the Lake Nyos disaster of 1986, i.e., a watercolumn eruption caused by the interplay of buoyancy forces and exsolution of dissolved gas. The eruption brings to the surface deep anoxic waters that cause extinctions in the marine realm. Terrestrial extinctions are caused by explosions and conflagrations that follow the massive release of methane (the air-methane mixture is explosive at methane concentrations between 5% and 15%) and by the eruption-triggered floods. This scenario accounts well for the available data, and may be relevant to other phenomena.

Nicknamed “The Great Dying”, the Permian-Triassic event was, according to Wikipedia:  “Earth’s largest extinction [that] killed 57% of all families and 83% of all genera (53% of marine families, 84% of marine genera, about 96% of all marine species and an estimated 70% of land species) including vertebrates, insects and plants.”

For those unfamiliar with Lake Nyos event, here’s an account from How Stuff Works:

Dead cattle surround compounds in Nyos village Sept. 3, 1986, almost two weeks after the lake’s explosion.

[O]n the evening of Aug. 21, 1986, farmers living near the lake heard rumbling. At the same time, a frothy spray shot hundreds of feet out of the lake, and a white cloud collected over the water. From the gro­und, the cloud grew to 328 feet (100 meters) tall and flowed across the land. When farmers near the lake left their houses to investigate the noise, they lost consciousness.

The heavy cloud sunk into a valley, which channeled it into settlements. People in the affected areas collapsed in their tracks — at home, on roads or in the field — losing consciousness or dying in a few breaths. In Nyos an­d Kam, the first villages hit by the cloud, everyone but four inhabitants on high ground died.

The valley split, and the cloud followed, killing people up to 15.5 miles (25 kilometers) away from the lake. Over the next two days, people from surrounding areas entered the valley to find the bodies of humans and cows lying on the ground.

By Aug. 23, the cloud had mostly blown away, and the silence had lifted. After being unconscious for up to 36 hours, some people revived to find, horrifically, that their family members, neighbors and livestock were dead.

The lake had changed, too. It was now shallower; plants and leaves floated in it; and its formerly picturesque blue hue had darkened into rust.

Again ignoring the methane component,  most of the discussion in the media about possible air borne fallout from the “spill” concerns the possibility of strong winds picking up the oil and depositing it inland as an oily rain. (Highly unlikely, since oil is heavier than rainwater.) More likely is the movement of misty clouds of deadly methane  and hydrogen sulfide moving over the landscape and descending like something from a Stephen King novel.

While Ryskin cites earthquakes, continental drift,  internal gravity waves, and an underwater volcanoes as possible triggering mechanisms for large methane releases, he didn’t mention the possibility of a greedy, cost cutting oil company ripping a gash in the ocean floor sitting atop a huge deposit of highly pressurized methane.

To get some idea of the explosive power of methane gas, consider that it a prime component in fuel air explosives that have the destructive power of small tactical nuclear weapons. (A fuel air explosive was seen in the movie Rambo II and and simulated in Outbreak).  Ryskin does the calculations in the section of his paper titled:

OCEANIC ERUPTION AS A CAUSE OF MASS EXTINCTION

The consequences of a methane-driven oceanic eruption for marine and terrestrial life are likely to be catastrophic. Figuratively speaking, the erupting region ‘‘boils over,’’ ejecting a large amount of methane and other gases (e.g., CO2, H2S) into the atmosphere, and flooding large areas of land. Whereas pure methane is lighter than air, methane loaded with water droplets is much heavier, and thus spreads over the land, mixing with air in the process (and losing water as rain). The air-methane mixture is explosive at methane concentrations between 5% and 15%; as such mixtures form in different locations near the ground and are ignited by lightning, explosions and conflagrations destroy most of the terrestrial life, and also produce great amounts of smoke and of carbon dioxide.

Sounds like anybody not wearing a respirator and slathered in a million SPF sunblock is going to have a very bad day (to borrow a line from another movie, The Terminator). Ryskin continues:

Firestorms carry smoke and dust into the upper atmosphere, where they may remain for several years (Turco et al., 1991); the resulting darkness and global cooling may provide an additional kill mechanism. Conversely, carbon dioxide and the remaining methane create the greenhouse effect, which may lead to global warming. The outcome of the competition between the cooling and the warming tendencies is difficult to predict (Turco et al., 1991; Pierrehumbert, 2002).

Evidence for the global warming possibility is contained in the NASA study cited here by Gavin Schmidt (who blogs at RealClimate.org):

Methane Explosion Warmed the Prehistoric Earth, Possible Again

December 10, 2001

A tremendous release of methane gas frozen beneath the sea floor heated the Earth by up to 13°F (7°C) 55 million years ago, a new NASA study confirms. NASA scientists used data from a computer simulation of the paleo-climate to better understand the role of methane in climate change. While most greenhouse gas studies focus on carbon dioxide, methane is 20 times more potent as a heat-trapping gas in the atmosphere.

In the last 200 years, atmospheric methane has more than doubled due to decomposing organic materials in wetlands and swamps and human aided emissions from gas pipelines, coal mining, increases in irrigation and livestock flatulence.

However, there is another source of methane, formed from decomposing organic matter in ocean sediments, frozen in deposits under the seabed….

Back to Ryskin:

Upon release of a significant portion of the dissolved methane, the ocean settles down, and the entire sequence of events (i.e., development of anoxia, accumulation of dissolved methane, the metastable state, eruption) begins anew. No external cause is required to bring about a methane-driven eruption—its mechanism is self-contained, and implies that eruptions are likely to occur repeatedly at the same location. Because methane is isotopically light, its fast release must result in a negative carbon isotope excursion in the geological record. Knowing the magnitude of the excursion, one can estimate the amount of methane that could have produced it. Such calculations (prompted by the methane-hydrate-dissociation model, but equally applicable here) have been performed for several global events in the geological record; the results range from ;1018 to 1019 g of released methane (e.g., Katz et al., 1999; Kennedy et al., 2001; de Wit et al., 2002). These are very large amounts: the total carbon content of today’s terrestrial biomass is ;2 3 1018 g. Nevertheless, relatively small regions of the deep ocean could contain such amounts of dissolved methane; e.g., the Black Sea alone (volume ;0.4 3 1023 of the ocean total; maximum depth only 2.2 km) could hold, at saturation, ;0.5 3 1018 g. A similar region of the deep ocean could contain much more  (the amount grows quadratically with depth ). Released in a geological instant (weeks, perhaps), 1018 to 1019 g of methane could destroy the terrestrial life almost entirely. Combustion and explosion of 0.75 3 1019 g of methane would liberate energy equivalent to 108 Mt of TNT, 10,000 times greater than the world’s stockpile of nuclear weapons, implicated in the nuclear winter scenario (Turco et al., 1991).

Nature had a very good reason, and a very good solution, for sequestering the methane that seeps through the ocean floor from deposits deep within the earth. I hope to address the particulars in a future post. Suffice it say for now that BP has brought home to all of us the warning that it’s not nice to fool with Mother Nature.

Any discussion that BP might just have precipitated an extinction level event wouldn’t be complete without mention of the tsunami scenario. David Corn in Mother Jones relates something he found on a winger web site, so take it with a mountain of salt:

At some point the drilled hole in the earth will enlarge itself beneath the wellhead to weaken the area the wellhead rests upon. The intense pressure will then push the wellhead off the hole allowing a direct unrestricted flow of oil, etc.The hole will continue to increase in size allowing more and more oil to rise into the Gulf. After several billion barrels of oil have been released, the pressure within the massive cavity five miles beneath the ocean floor will begin to normalize.

This will allow the water, under the intense pressure at 1 mile deep, to be forced into the hole and the cavity where the oil was. The temperature at that depth is near 400 degrees, possibly more.

The water will be vaporized and turned into steam, creating an enormous amount of force, lifting the Gulf floor. It is difficult to know how much water will go down to the core and therefore, its not possible to fully calculate the rise of the floor.

The tsunami wave this will create will be anywhere from 20 to 80 feet high, possibly more. Then the floor will fall into the now vacant chamber. This is how nature will seal the hole.

Depending on the height of the tsunami, the ocean debris, oil, and existing structures that will be washed away on shore and inland, will leave the area from 50 to 200 miles inland devoid of life. Even if the debris is cleaned up, the contaminants that will be in the ground and water supply will prohibit re-population of these areas for an unknown number of years.

In a footnote, Ryskin cites written historical accounts that may refer to such methane/water column eruptions:

A number of smaller-scale eruptions may have occurred after the acquisition of language by humans and inspired the flood myths, common all over the world except Africa. See, in particular, Diodorus Siculus 5.47.3–5. The Epic of Gilgamesh (XI, 96–112) describes the land set ablaze, ‘‘shattered like a [clay] pot’’, plunged into darkness, and flooded. In Genesis 7:11, ‘‘All the fountains of the great deep burst forth . . . ’’, etc.

During the financial crisis precipitated by the Wall Street meltdown in the fall of  ’08, I heard am investment adviser answer the question: “What positions are you taking now?” His answer:  “Cash, and fetal.”

Cue Mr. Barry McGuire.