23
Apr 10Reassuring words.
On supervolcanoes:
There is perhaps no better recent example of the havoc that a big eruption can cause than that which followed the explosive destruction of Mt Toba, in northern Sumatra, some 72,000 years ago (which, in geological time, is very recent indeed).
…
On the widely used volcanic explosivity index (VEI), Toba is thought to have been an eight – meaning that in the unusually flamboyant official language of vulcanology it was a super-plinian type eruption with mega-colossal characteristics (Eyjafjallajökull is by contrast listed as a strombolian type, with its characteristic regarded as merely gentle, and having a probable VEI rating of just two).About 680 cubic miles of rock were instantly vaporised by the super-eruptive blast of Toba, all of which was hurled scores of thousands of feet into the air. This this is what did the lasting damage, just as Iceland’s high-altitude rock-dust is doing today. But while we today are merely suffering a large number of inconvenienced people and a weakening of the balance sheets of some airlines, the effect on the post-Toban world was catastrophic: as a result of the thick ash clouds the world’s ambient temperature plummeted, perhaps by as much as 5C – and the cooling and the howling wave of deforestation and deaths of billions of animals and plants caused a sudden culling of the human population of the time, reducing it to maybe as few as 5,000 people, perhaps 1,000 breeding pairs. Many anthropologists believe that the event caused a sudden evolutionary bottleneck, with genetic implications that linger to this day. Put more crudely, humanity was nearly wiped out by Toba, and only by the merest hair’s-breadth did our ancestors of 72,000 years ago manage to cling on and bequeath to us our current existence.
…
The newer of the great eruptions that helped form the mountains of today’s Yellowstone national park in Wyoming took place just 640,000 years ago, and all the current signs – from such phenomena as the rhythmic slow rising and falling of the bed of the Yellowstone river, as if some giant creature is breathing far below – suggest another eruption is coming soon. When it does, it will be an American Armageddon: all of the north and west of the continent, from Vancouver to Oklahoma City, will be rendered uninhabitable, buried under scores of feet of ash. (I mentioned this once in a talk to a group of lunching ladies in Kansas City, soothing their apparent disquiet by adding that by “soon” I was speaking in geologic time, and that meant about 250,000 years, by which time all humankind would be extinct. A woman in the front row exploded with a choleric and incredulous rage: “What?” she said. “Even Americans will be extinct?”)
Eat, drink, and be merry, etc. But just in case this doesn’t happen, try to produce a minimum of CO2 with said merrymaking.
Tagged: aaaaaaah, news, reading