With news of potentially destructive volcanoes and exploding calderas, are we headed toward another major extinction event? Dr. Janet Asimov examines various scientific theories that may just bring about the end of the world as we know it.
Twenty years ago I wrote a science article on what was, and still is, the extinction event. About 252 million years ago at the end of the Permian period in Earth’s history, 95% of life in the ocean died (including my favorite critter, the trilobite) and 70% of life on land died (including eight orders of insects—the only time insects have lost members since they evolved 390 million years ago).
Because we humans were not involved, either as perpetrators or as victims, my article then had the title, “At Least We Missed the Permian Catastrophe.”
Extinction events fascinate scientists, who have pursued much research into all of them, especially the Permian one, which has been labeled “The Great Dying.” Theories about this event touched on everything from incoming space missiles to a greenhouse effect from organic matter sinking to the bottom of the sea, reducing atmospheric CO2 and causing planetary cooling.
Oh, and also volcanoes. There are so many bad ones recorded in history—most people know about the eruption of Tambora in 1816 that caused “the year without a summer,” or the one in 1883 when Krakatoa killed 36,000 people, or the famous eruption of Vesuvius in AD 79. All of them were tiny compared to what happened at the end of the Permian.
New research indicates that volcanoes are probably the answer, or certainly the main answer to the puzzle of the Permian catastrophe.
Notice that I do not say “proves.” Evidence of what happened to life 252 million years ago is not an algebraic proof. The theory for which new evidence has turned up has always been a possibility, and now it’s a probability. That’s the way science works—with words like “possibility” and “probability,” “maybe” and “seems likely.”
The extinction of all dinosaurs except birds 65 million years ago was, numerically speaking, small potatoes (“only” 50 percent of life died) compared to the Great Dying. However, we can say that it is quite probable that our favorite media stars went belly-up mainly because an asteroid landed on the Yucatan peninsula.
There’s still some argument about this, however, with various other theories claiming that their solution is perhaps an additional cause. I personally think that an asteroid as big as that one would cause a rebound effect on the other side of the planet, accounting for volcanism.
But you wanted to know about the Great Dying, didn’t you? And without having to click on Wikipedia—although it’s a very good summary, which did not exist when I first probed into the Permian. (Support Wikipedia—it’s one of the much better efforts of the electronic age.)
To begin with, the Permian period in Earth’s history owes its name to a British geologist named Sir Roderick Impey Murchison who, in 1841, studied rocks in the Russian town of Perm, near Lake Baikal. Remembering the ancient kingdom of Permia, Murchison applied “Permian” to the third geological period in the Upper Paleozoic Era, the time preceding the famous dinosaur-filled Mesozoic Era.
The entire Paleozoic Era—Upper and Lower—lasted about 352 million years, during which first the sea and then the land were colonized by a diversity of invertebrates and vertebrates. By the time of the Paleozoic’s last period, the Permian, reptiles had replaced amphibians as the rulers on land. (By the way, always keep in mind that the true conquerors and rulers of both sea and land were and are microorganisms.)
During the Permian there were remarkable developments in land vertebrates. Scientists once thought that most Permian land vertebrates were carnivorous until they discovered the fossil of a 280 million year old reptile that had pointy teeth but also stones in its stomach to help grind plant food. Twenty million years later came Suminia getmanovi, whose teeth were clearly capable of shearing and shredding tough land vegetation like conifers, ferns and cycads. As herbivores like this became bigger and more plentiful, so did the reptilian carnivores that preyed upon them with sharp teeth.
Plants did their own evolving during the Permian. While modern flowering plants (which appeared in the age of dinosaurs) have sperm that is not motile, those of the ancient (but still with us) Gingko trees reach the ovules by swimming up tubes, much the way human sperm swims up the Fallopian tubes. The Permian seed fern, Glossopteris, also had motile sperm, each bearing a spiral pattern of tiny wavy appendages called flagella that function to propel the sperm along. Lots of biological inventions are very old.
The complex ecosystems of the early Permian existed on the supercontinent of Pangea (with our familiar continents stuck together), surrounded by the ocean Panthalassa. Both the ocean and the supercontinent teemed with life. However, this balmy wonderland did keep changing, for 60 million years. By the time of the disaster at the end of the Permian, Pangea was tearing apart. This may have contributed to the volcanoes and earthquakes.
The internet site on the latest world earthquakes is addictive, especially when you look at those associated with “the ring of fire” of volcanoes in the land circling the Pacific Ocean. This land is moving, and when land moves there are numerous earthquakes and lots of volcanoes, some of them very dangerous.
There wasn’t a simple ring of fire at the end of the Permian. There was fire—immense volcanism over a huge northern area, resulting in the famous two million square kilometers of hard lava called the Siberian traps (meaning “stairs” in Swedish). Since the various continents had not separated as much as they have today, this Permian volcanism affected much more of the planet than any current volcano could.
Geologists have now succeeded in dating the Permian volcanism that caused the Siberian traps, as well as the age of fossils from the Great Dying. It seems quite probable that the volcanism came before, and not after, the extinctions.
Furthermore, computer modeling shows that when the Siberian volcanism occurred, the amount of sulfur dioxide probably injected into the atmosphere would have acidified rain to, as the article in Science magazine says, “pH 2, about that of lemon juice.” Ever squeezed lemon juice on a plant?
Further, geologists have found mercury-toxic debris in fossilized ash from the P-T boundary (that’s the time of the extinction, the end of the Permian and the beginning of the Triassic). It was altogether a nasty event.
All this better evidence produces a smoking gun effect, cheering to people who enjoy the solution of puzzles. I was thrilled, but not exactly cheered, because I tend to worry about the possibility of modern volcanism doing us in.
There are many possibilities for truly nasty volcanism. If the caldera known as Yellowstone National Park decides (excuse the anthropomorphism) to blow, it won’t cause a Permian-like extinction event, but it might contribute heavily to crushing a good deal of our civilization—although we often seem to be tinkering with that job ourselves.
The point is that planet Earth is alive, not just with living organisms, but geologically. Land masses move, hot spots of upwelling magma exist, and we are not safe.
Accepting the dangers of volcanism will make it more likely that research will go on, for right now we can’t prevent or even cope with the kind of disaster that ended the Permian. There will be other episodes of volcanism that may not be so extreme but will nevertheless endanger us. We can’t just forget about this and hope it never happens, because some day, it will.
Safety is not assured by knowledge, research, and technology, but it is more likely. We are currently helpless about extreme volcanism, but we already have the knowledge and technology for finding threatening asteroids and for pushing them out of the way. There’s no excuse for Homo sapiens going the way of the dinosaurs.
For us, some extinction events are more probable than others. Let’s hope that if a possibility of one lurks in our future, we’ll know about it and do what we can to survive. If we’re faced with something like the Permian catastrophe, won’t we be sorry we didn’t build underground homes on the moon and Mars?