Posted 2 years ago on April 4, 2014, 3:08 p.m. EST by LeoYo
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The Perp in the Greatest Mass Extinction on Earth? Methane
Friday, 04 April 2014 10:47
By Gaius Publius, AMERICAblog | News Analysis
In the past, when I’ve written about climate and mass extinctions, I generally single out two of them — the one 65 million years ago that ended the dinosaur era, and the one about 250 million years ago that killed off almost everything then alive and made room for the dinosaurs to develop.
The dinosaur-killing extinction is called the “Cretaceous–Paleogene (K–Pg) extinction event” since it occurred between the Cretaceous Period and the Paleogene Period. The earlier extinction, also called the “Great Dying,” is the “Permian–Triassic (P–Tr) extinction event” and occurred between those two geological periods.
But starting from the first explosion of life on earth, some 540 million years ago, all geological periods are grouped into just three “eras” — the era of Old Life (Paleozoic Era), the era of Middle Life (Mesozoic Era, or the age of dinosaurs), and the era of New Life (Cenozoic Era, or the age of mammals and man).
The Paleozoic Era lasted over 290 million years. The Mesozoic Era lasted 185 million years. We’re in the Cenozoic Era now, and it’s lasted 65 million years.
Just three major divisions since life first exploded. And guess what divides these eras? The two mass extinctions I mentioned above. Here’s what that looks like in one handy chart:
Mass Extinctions since the Cambrian Period (540 million years ago) Mass Extinctions since the Cambrian Period (about 540 million years ago)
So yes, mass extinctions — certainly mass extinctions of this size — matter. As I argued here and here, we may not using our little climate problem just to exit the Holocene (our current 12,000-year geological division). We may be exiting the entire Cenozoic Era. Now that’s a world-historical event.
The Great Dying Was Probably Caused by Atmospheric Methane
So the first part of today’s piece to keep in mind is the major geological divisions. And make no mistake, the Great Dying was a great dying, the mother of all great dyings (my emphasis everywhere):
It is the Earth’s most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years. [Other sources say 30 million years.]
Now the second part of this discussion. People have been puzzled about the cause for a long time, and how it managed to be so … effective. Turns out that researchers at MIT may have found the answer — atmospheric methane. It’s the only explanation that fits the facts, and there’s much evidence to support it. Given the factual data that’s been assembled about the event, all of the other, previously-thought-plausible explanations have to be dismissed. Not one of the others could explain the combination of facts now known.
Let’s look at this from two sources, MIT and a separate write-up of their research. The MIT publication is informative, but the other is more clear for the lay reader. First, from the MIT news office:
Methane-producing microbes may be responsible for the largest mass extinction in Earth’s history.
Evidence left at the crime scene is abundant and global: Fossil remains show that sometime around 252 million years ago, about 90 percent of all species on Earth were suddenly wiped out — by far the largest of this planet’s five known mass extinctions. But pinpointing the culprit has been difficult, and controversial.
Now, a team of MIT researchers may have found enough evidence to convict the guilty parties — but you’ll need a microscope to see the killers.
The perpetrators, this new work suggests, were not asteroids, volcanoes, or raging coal fires, all of which have been implicated previously. Rather, they were a form of microbes — specifically, methane-producing archaea called Methanosarcina — that suddenly bloomed explosively in the oceans, spewing prodigious amounts of methane into the atmosphere and dramatically changing the climate and the chemistry of the oceans.
Volcanoes are not entirely off the hook, according to this new scenario; they have simply been demoted to accessories to the crime. The reason for the sudden, explosive growth of the microbes, new evidence shows, may have been their novel ability to use a rich source of organic carbon, aided by a sudden influx of a nutrient required for their growth: the element nickel, emitted by massive volcanism at just that time.
The new solution to this mystery is published this week in the Proceedings of the National Academy of Science by MIT professor of geophysics Daniel Rothman, postdoc Gregory Fournier, and five other researchers at MIT and in China.
Now William Costolo at the Guardian Liberty Voice:
The ocean swarm of micro-organisms was the byproduct of volcanic eruptions which threw off the substance nickel. The nickel from the volcanoes provided the metabolic fuel necessary for the bloom to occur. Scientists previously suspected that the volcano eruptions themselves caused the horrific killing, but the MIT researchers determined that the volcanoes alone would not have created enough atmospheric carbon dioxide to cause the mass extinction. The carbon dioxide must have come from another source.
Further research indicated to the scientists that the source of the carbon dioxide was derived from a biological source. The carbon dioxide levels would have receded faster if derived only from the volcanoes. The rich source of nickel available from the volcanos was just the right fuel for the tiny methane producing killing machines to consume the carbon in the ocean floors and proliferate in rapid fashion.
The analysis of genome material provided the necessary clues to the researchers. The Methanosarcina acquired a genetic trait from another microscopic organism which allowed them to quickly produce the poison gas under the right conditions. The vast store of carbon in the oceans together with the volcanic nickel provided the perfect storm of material required for a gigantic methane plume. The tiny organisms followed their genetic programming to reproduce quickly and throw off a massive amount of poison gas.
Except for his use of the term “poison gas” (living things weren’t “poisoned”), this is a clear explanation of the relationship between the massive volcanoes, the nickel, the microbes, and the methane. The killing happened in relatively short order, driven by the massive volcanoes.
The mass kill off, known as the Permian extinction, had its roots in the volcanoes of the Siberian Traps. The lava flows were so large they would have covered a land area larger than the United States. The atmosphere remained poisoned for over 100,000 years. The earth did not regenerate diverse life for another 30,000,000 years. The length of time the atmosphere remained poisoned was a clue to the researchers that the volcanoes alone could not have caused the killing catastrophe.
Why does methane have such a powerful effect? Read on.