For decades scientists have known about the P-T extinction. Formally referred to as the Permian-Triassic Extinction Event and since nicknamed “the great dying,” the event lives up to its alarming moniker. The Earth’s climate went into an overheated death spiral. Huge numbers of plants and animals on land and in the sea died off. One initial trigger appears to be a gigantic volcano complex with calderas the size of Kansas and rife with vents that would have stretched the length of Florida. But as bad as that global outburst was, evidence gleaned in the last few years suggests it may have triggered secondary complications of equally deadly magnitude. And now researchers have the found dramatic remains of more recent examples of one of those very follow-up phenomenon, fueling intense speculation on the role of hidden stores of exotic ices sequestered away deep under the oceans on both past and future changes in climate:
The new paper describes one such event that occurred about 12,000 years ago in what is now the Barents Sea, a region of the Arctic Ocean stretching between Norway and Russia. There, at the bottom of the ocean floor, stands a collection of more than 100 craters, some as much as 3,000 feet wide and nearly 100 feet deep. The researchers believe they were formed by sudden rushes of methane from the seafloor. Methane, although most commonly observed in gas form, can sometimes become trapped at the bottom of the ocean in very deep or cold regions, freezing into a solid substance known as a methane hydrate. It can remain trapped this way indefinitely until something destabilizes it.
That something is warming oceans. And this is important because it may have happened before—many times, in fact. And one of those times it may have happened was the P-T event. It’s only a coincidence that the nexus of the problem was in, you guessed it: Russia!
The details have been patiently teased out of ancient rocks and start about 251 million years ago: soaring global temperatures, plummeting oxygen levels, spikes in ocean acidity, entire clades of living things disappearing from the fossil record. Vast global forests of pine and fern wrapped around lush tropical regions were completely wiped out. It wasn’t just big clunky reptiles or primitive plants either. The P-T remains the only mass extinction event to claim big losses among virtually every major family of insects.
All this carnage may have taken place quickly, as best we can tell while peering from far away, down into the well of deep geological time. And even from our distant perspective, the incident shows signs of unfolding in at least two and possibly three sharp, distinct pulses of death and desolation spread over a few scant millennia.
Researchers have proposed asteroid and comet impacts, nearby supernovas or gamma ray bursts, and even big changes in solar activity. But for now the most cogent explanation is more familiar and closer to home: 300 million years ago the Earth’s surface was super-sized. A single, vast supercontinent called Pangea had formed and stretched from both poles to the equator on one side of the planet, and an even larger super-ocean called Panthalassa covered more than 70 percent of the world, completely dominating the other side. We know very little about what it was like or what could have lived in the latter. But if there was ever a time for giant exotic sea monsters of all kinds, hetefore and former unknown to science, that was surely it.
But Pangea’s days were numbered. A huge plume of red-hot liquid rock and metal rose out of the planet’s fiery interior and turned the surface above into a hellish nightmare. Shield volcanoes that dwarf the Yellowstone calderas erupted for hundreds of thousands of years and released enormous quantities of greenhouse gasses. The planet warmed, that warmth worked its way into the cold ground near the poles, and it eventually seeped in the deepest parts of the great ocean, where it destabilized huge stores of methane trapped as ice called a clathrate. When this “meth ice” is heated, it goes straight to a gas and bubbles out, adding to the greenhouse gas content of the atmosphere, causing more warming, and the cycle may have run away with itself. Or at least that’s the idea behind the P-T clathrate gun model.
One problem with the clathrate model is that even if it did happen on a massive enough scale to tip the ancient climate further toward hell, we don’t know exactly what direct evidence might look like. Panthalassa, and the once great ocean floor beneath it, is lost forever. Those remains have long since subducted under the edges of continental plates and recycled back into the red-hot mantle. But a few years ago people in remote parts of Siberia began coming across strange holes in the ground. Some were hundreds of feet deep, and some looked for all the world like a giant alien parasite had gestated and burst through the frozen surface in the dead of night. But the best scientific explanation is a powerful chemical reaction that comes about when old, methane-laden permafrost thaws out.
That’s why this finding is important. For the first time, we see that methane burps did indeed happen in the past. And more importantly, they happened specifically in the deep ocean when a warming trend had revved up on land. Methane is a potent greenhouse gas, far more powerful than carbon dioxide. And when it breaks down naturally in the air, it usually produces carbon dioxide and water vapor as byproducts, which are themselves greenhouse gases. So it’s sad to say, but this all means the methane gun may be pointed at the head of planet Earth’s biosphere. It’s loaded, the hammer is now cocked and, if it starts going off, future burps will add lots of powerful greenhouses gases to an already warming atmosphere.