What is hydrogen sulfide? It smells like farts and rotten eggs. You can find it in swamps, sewers, landfills, volcanic and natural gases, and pretty much everywhere there is a petroleum refinery. Unfortunately, you can also usually find it whenever and wherever you've got mass extinctions.
In fact, it is hydrogen sulfide, rather than killer asteroids or some other interstellar death-bringer, that has possibly become the go-to kill-shot of most mass extinctions in Earth's history.
"It doesn't take much hydrogen sulfide to kill off anything," Gerry Dickens, professor of earth science and paleoceanography at Rice University, explained to AlterNet by phone.
He should know: It was Dickens' work with methane hydrates that completed the puzzle of the Permian-Triassic extinction event, more aptly known as the Great Dying, in the 2002 BBC Horizon documentary The Day the Earth Nearly Died.
During the Great Dying, over 250 million years ago, flood basalts in the Siberian and Emeishan traps unleashed hell on Earth, spewing titanic walls of lava, ash, debris and greenhouse gases into the sky, blotting out the sun and surrounding hundreds of thousands of miles in a biblical inferno for which there is no contemporary analogue, at least in reality.
But even that wasn't enough to wipe out the 96 percent of Earth's marine, terrestrial and plant species claimed by the Great Dying. A growing scientific consensus explains that the death stroke was probably delivered from Earth's anoxic oceans, whose resultant out-of-whack pH balance, once literally defined as the "power of hydrogen," released catastrophic stores of either methane hydrate or hydrogen sulfide into the atmosphere.
Whichever one it was, hydrogen had the power to bring Earth to its knees. And it could happen again.
"It's unannounced stealth nastiness," Peter Ward, professor of biology and paleontology at the University of Washington, declared by phone to AlterNet. "My new book ends with a hydrogen sulfide extinction."
That book, The Medea Hypothesis, posits not one but five hydrogen sulfide extinction events, including the Great Dying, throughout Earth's history. Going further, it flips the Gaia hypothesis on its head by suggesting -- with increasing persuasion, given our current climate crisis of too much carbon dioxide in the air and too little oxygen in the oceans -- that Earth is not seeking an optimal physical and chemical environment for its life.
In fact, Ward argues, its multicellular life is actually suicidal in nature, whose doom will eventually return Earth to the microbes that have dominated most of its history.
Although the truth probably lies somewhere between Gaia and Medea, Ward seems to be right about one thing: Hydrogen sulfide is an unheralded executioner.
"If ancient volcanism raised CO2 and lowered the amount of oxygen in the atmosphere, and global warming made it more difficult for the remaining oxygen to penetrate the oceans, conditions would have become amenable for the deep-sea anaerobic bacteria to generate massive upwellings of hydrogen sulfide," Ward wrote in a Scientific American clarion call titled "Impact from the Deep."Virtually no form of life on the earth was safe."
Ward -- who has also written the books Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future; Rare Earth: Why Complex Life is Uncommon in the Universe; and the forthcoming Our Flooded World -- concludes his Scientific American piece with the obvious question: Could it happen again?
All the pieces seem to be moving into place. Global warming is a runaway train, carbon dioxide levels are exponentially rising, and oceans are subsequently losing oxygen. There are even hydrogen sulfide blooms being found in Namibia and other places where industrial pollution is spilling waste into the water.
The good news? We know that in the Permian and other mass extinctions that it took levels of around 1,000 parts per million of atmospheric carbon dioxide to rob the oceans of oxygen and kill off most life on Earth. The bad news? We're closer to that devastating concentration than we think.
With CO2 hovering around 385 ppm, but increasing at an annual rate of 2 to 3 ppm, it doesn't take a math teacher to realize that we could hit 900 ppm by the end of next century. Or earlier, given the exponential nature of climate change.
"It's not quite linear," Dickens explained. "As you make the system worse, less carbon gets taken up by the oceans, which are sinks on a global scale. When that has happened in the past, suddenly a whole bunch of carbon has come out of the ocean fast. The magnitude is extraordinary. And there's also a temperature component: As things get warmer, the process amplifies."
Currently, it's amplifying at a fearsome rate. For his part, Ward believes we're headed toward a penultimate moment in Earth's history, one we should be ashamed of.
"We're way beyond anything from the Pleistocene, and heading towards the Cretaceous," Ward told AlterNet. "If we hit 800-1,000 ppm, we're in trouble. The sun is also getting warmer, so 1,000 ppm is really going to be like 2,000 ppm. We're talking about the second-hottest period in the planet's history."
Right now, Ward and other scientists who have proposed parallels between the mass extinctions of the past and the one we could be experiencing now, known as the Holocene extinction event, are lost in the wilderness of geopolitical machination and rampant global consumption. But interest in their destabilizing theories are growing.
"NASA called me about three months ago, and the administrator at Ames Research Center said, 'You've got to be kidding about this stuff!' " Ward said. "So myself and several other scientists put together a white paper on hydrogen sulfide, because this is a matter of national security. Just because its longer-term than other problems doesn't mean it's any less deadly. Our species is going to be in trouble in a hundred to a thousand years from now. What happens if the oceans go anoxic, within this century or by the end of next century? You'll have conditions that might be irreversible for a very long time."
Ward says that the Obama administration has been cool to the possibility of anoxic oceans and the various hydrogen terrors that lie in wait on its floors or its chemical processes.
And for his part, even Dickens is not as worried about mass extinction at the hands of climate change as he is about terrors closer to home.
"I've got more important things to keep me up at night," the good-natured scientist wisecracked over the phone, "like finding the next grant so I can go study this stuff."
But time, and probably not a lot of it, will tell which terror is more worthy of our immediate attention, expense and innovation. But whatever may come and whatever we decide, Ward warned, we better get our lazy asses in gear.
The worst that could supposedly happen is that we could be wrong and lose trillions of dollars to saving the planet, and thereby ourselves, rather than throwing them down the black hole of credit-default swaps and hyper-real derivatives.
But the worst that could really happen is that anthropogenic global warming could throw the planet's pH balance into chaos, as the combination of CO2-choked skies and anoxic oceans release the mother of all mass-extinction farts into the atmosphere, a killing joke we could never recover from. And who wants to go out like that?
"There's bad stuff before you even get to hydrogen sulfide," Ward concluded. "And there's not much you can do about any of it, in terms of geoengineering. The simple solution is to reduce global greenhouse-gas emissions, and do it now. Here's the scary thing that can happen: Human extinction. Let's get serious."