METHANE EXTINCTION SCARE: "COULD IT HAPPEN AGAIN?"

San Diego Union-Tribune ^ | 12 November 2003 | Richard A. Lovett

[Mike Darancette]

A geologist thinks methane releases nearly caused the end of Earth; could it happen again?

By Richard A. Lovett

Two hundred fifty million years ago, at the end of a geological epoch known as the Permian, the Earth went through an environmental upheaval so severe that life nearly ended. At least 90 percent of the planet's plant and animal species were wiped out - and some estimates put the figure much higher.

"It was the mother of all extinctions," says Gregory Retallack, a geologist from the University of Oregon who has traced the event across narrow bands of rock in places as remote as South Africa and Antarctica.

Scientists have long been puzzled by what might have caused such a massive die-off, posing theories that range from catastrophic volcanism to a wallop from a large asteroid, similar to the one believed to have wiped out the dinosaurs 185 million years later.

But, in a study published in the September issue of the Geological Society of America Bulletin, Retallack proposed a new explanation: The denizens of the Permian died of altitude sickness caused by a drastic decline in atmospheric oxygen.

That's right: altitude sickness - the problem that leaves you gasping for breath in the thin air of Denver or Mexico City. At higher elevations it produces headaches, nausea, dizziness, and, if you go high enough, deadly fluid buildups in the lungs and brain.

Retallack bases his theory in part on the fact that of the few land animals that survived, one of the most abundant was a reptile called Lystrosaurus. A burrowing creature, Lystrosaurus had a barrel chest, short, squat legs and a flat face. These characteristics helped it live underground, but Retallack says that they would also aid survival in a world of reduced oxygen. The animals' barrel chests allowed strong chest muscles for powerful breathing. Short limbs reduced the workload on the heart as it pumped oxygenated blood to the muscles. A flat face facilitated rapid, unobstructed breathing. In addition, Lystrosaurus' nasal passages were designed like those of humans, allowing the animals to breathe and chew at the same time.

Other Permian reptiles were like modern-day alligators, which must hold their breaths while eating, a disadvantage if oxygen is in short supply.

Methane key

Lystrosaurus isn't the only Permian survivor that showed traits that would be important in a reduced-oxygen environment. In the ocean, surviving mollusks were muscular varieties that could pump large volumes of seawater through their bodies for the most efficient extraction of oxygen. On land, surviving plants tended to be those that grew in dry, well-aerated soils, where oxygen could easily get to their roots.

All these factors help build a case that the ability to live on reduced oxygen was important for surviving the Permian extinction. But the theory would be little more than an exercise in speculation if there were no way to explain what happened to all that oxygen.

Retallack believes the answer can be found in vast, seabed reservoirs of methane, a chemical comprised of a single carbon atom linked to four atoms of hydrogen.

On the seabed, methane is continuously formed by the action of bacteria on buried organic matter. Methane is a gas, but instead of percolating to the surface, it remains beneath the ocean, trapped by the pressure of the overlying water in a form called methane hydrates.

These hydrates can lie dormant for millions of years, until something disturbs them and frees the methane to bubble to the surface and enter the atmosphere.

"Several things could have done the trick," Retallack says. "A meteorite impact or volcanic eruption right into a big methane reservoir, a volcanic eruption, volcanic gases warming the Earth, a submarine landslide triggered by an earthquake. Or, all of these could have happened together."

Once it reached the atmosphere, the methane would have reacted with oxygen to form water and carbon dioxide. Plants would then have used the carbon dioxide to form stems, roots and leaves, but not without a net loss of atmospheric oxygen throughout the process.

One of the many mysteries of the Permian extinction is that fossil soils from that era are unusually low in the heavier of carbon's two stable isotopes, carbon-13. For that to have occurred, the atmosphere's usual mix of carbon must have been diluted by a large admixture of the other isotope, carbon-12.

Some scientists have proposed that this carbon might have been belched out of volcanoes, which were known to have been extremely active at the end of the Permian. But volcanoes can't account for the isotope ratios seen in end-Permian soils, says Robert Berner, a geochemist from Yale University.

"Carbon dioxide from volcanoes could not give you that carbon isotope spike," he says. "You have to do it with something isotopically light, and the best candidate is methane."

Berner, who published his results last year in the Proceedings of the National Academy of Sciences, adds that the most likely source of methane is from the rapid release of methane hydrates from the seabed.

The soils from the end-Permian era are so heavily enriched with light carbon, however, that a truly enormous amount of methane must have been released into the atmosphere - enough to contain nearly twice as much carbon as is currently contained in every living thing on the surface of the earth, Retallack says.

Before the extinction, the Permian was an era when swamp-dwelling plants were forming large amounts of coal and, as a byproduct, jacking up the oxygen content of the atmosphere substantially beyond that which we know today. Geologists estimate that during this era, the air was comprised of 35 percent oxygen, compared with today's 21 percent.

The methane hydrates, Retallack calculates, would have consumed enough oxygen to reduce the atmospheric content all the way to 12 percent - roughly equivalent to the amount found today at an elevation of 16,500 feet. For creatures adapted to the high oxygen levels of the Permian, the effect would have been comparable to being lifted from sea level to the summit of Mount Everest.

Such a change would certainly have been a severe stress for many types of animals, says Dr. John West, a professor of medicine and physiology at UCSD, who studies human adaptations to high elevations. Andean miners can live indefinitely at elevations as high as 19,000 feet, West adds, but it's anyone's guess how well animals would adapt.

West notes that few animals live that high today, due to lack of food. But most of those that do, he says, have adaptations that wouldn't show in fossils, such as blood hemoglobin with an unusually high affinity for oxygen. Interestingly, he says, burrowing animals adapted to poorly ventilated tunnels show the same trait, a characteristic that he thinks might be more important to their survival than the barrel chests and short limbs observed by Retallack.

Future energy source

Retallack's theory has drawn cautious interest from some geophysicists, who regard it as intriguingly innovative. Others are more dubious.

Most scientists agree that the end of the Permian was accompanied by a rapid drop in atmospheric oxygen, but among geologists, "rapid" is a relative term. Berner thinks it took at least a million years, far too long to account for the rapid die-off that marked the Permian extinction.

But Retallack believes that while methane releases might have occurred in several stages spread across several thousand years, each one occurred quickly.

"I don't see any way to get (the methane) out slowly," he says. "I'm inclined to think of a catastrophic release within days or months."

Another question is whether the seabeds could have released enough methane to knock the atmospheric level of oxygen down by the amount proposed by Retallack.

Retallack says yes, but another methane hydrate researcher, Gerald Dickens of Rice University in Houston, thinks that Retallack's theory takes about 10 times too much methane.

Perhaps Retallack's use of the term "altitude sickness" has inadvertently polarized the debate. To most people, altitude sickness is an ailment that strikes quickly, when one ascends too far, too fast. Retallack admits that he himself was once struck down by the condition on an ill-fated attempt to climb Africa's 19,340-foot Mount Kilimanjaro.

Permian species may not have suffered sudden death from altitude sickness. Most could have been out-competed by the few that best adapted when the atmosphere changed.

More disturbing is the question of whether something similar could happen again. The Permian isn't the only time when geophysicists believe that large volumes of methane were released from the seabed. Something similar appears to have happened during the Eocene, 52 million years ago, although the amount of methane involved was considerably smaller.

And, methane hydrates exist today on the seabed, where in theory they could be released by another earthquake, volcanic eruption or asteroid impact similar to whatever event it was that may have triggered their release at the end of the Permian.

More importantly, humans are looking at methane hydrates as potential sources of energy. Before progressing too far, we'd better be sure that our extraction methods won't trigger large-scale releases. "The possibility for environmental catastrophe is a bit of a worry," Retallack says.

Richard A. Lovett is a freelance science writer in Portland, Ore.

© Copyright 2003 Union-Tribune Publishing Co.

[Mike Darancette]

One more thing to worry about.

[Mike Darancette]

PING

[farmfriend]

Rights, farms, environment ping.

Let me know if you wish to be added or removed from this list.
I don't get offended if you want to be removed.

For real time political chat - Radio Free Republic chat room

[Ingtar]

If there had been that much methane in the atmosphere, I would think that the first lightning strike would solve the problem. Of course, there would be other problems.

[richardtavor]

I wouldn't worry about it too much...

[Uncle George]

KENNEDYGAS will lead to the extinction of all the LIB SLIME.

[Aracelis]

Only a "Ping!"...no rude noises. :^)

[js1138]

methane extinction ping

[mewzilla]

It's all the herrings' fault.

[Aracelis]

Thought you might enjoy this...

[Centurion2000]

bump for a mother of all farts from the ocean.

All hail the Cthulu fart .... it killed the Permians ... whoever they were ;-)

[geopyg]

As a land geophysicist, I sometimes consult for a local marine geophysical firm. They're working on ways to locate the methane hydrates. Perhaps they'd have a better market trying to sell it as a way TO STOP THE NEXT EXTINCTION OF EVERYTHING rather than an alternate power source.

[almcbean]

When I grow up I want to be a geologist or paleontologist. Then I can say whatever I want and no one can disprove it.

[eastsider]

Retallack bases his theory in part on the fact that of the few land animals that survived, one of the most abundant was a reptile called Lystrosaurus. A burrowing creature, Lystrosaurus had a barrel chest, short, squat legs and a flat face. These characteristics helped it live underground, but Retallack says that they would also aid survival in a world of reduced oxygen. The animals' barrel chests allowed strong chest muscles for powerful breathing. Short limbs reduced the workload on the heart as it pumped oxygenated blood to the muscles. A flat face facilitated rapid, unobstructed breathing. In addition, Lystrosaurus' nasal passages were designed like those of humans, allowing the animals to breathe and chew at the same time.

[Gorjus]

"We'd better not do "X", because 'The possibility for environmental catastrophe is a bit of a worry.'"

Wow! Who'd'a thunk it? A possible environmental catastrophe! Stop all attempts to develop new energy sources immediately! Immediately, do you hear?! After all, we've never, ever heard anything like this before, on anything else.

(Okay, so sarcasm is impolite. And I know my argument is not really with you. But I do get a bit tired of ecofreaks crying wolf, though I appreciate that you posted it.)

[finnman69]

End of the Wold Fart.

[sheik yerbouty]

We will have to ban chili, beer, and cole slaw! Matches will also be forbidden lest someone get the urge for a "blue flame special"!

[sheik yerbouty]

We will have to ban chili, beer, and cole slaw! Matches will also be forbidden lest someone get the urge for a "blue flame special"!

[Chancellor Palpatine]

METHANE EXTINCTION SCARE: "COULD IT HAPPEN AGAIN?"

According to my wife, after I've walked out of the bathroom, the answer is a resounding "yes".

[Yeti]

On land, surviving plants tended to be those that grew in dry, well-aerated soils, where oxygen could easily get to their roots.

Huh?