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10/25/2004 Archived Entry: "Supervolcanoes"

Gordon P. is at it again, providing us with scientific sophistication. It's been suspect for some time that the human species may have suffered a "near extinction" event sometime in the last 100,000 years, because as a species, humans have a remarkably small genetic diversity, which is most easily explained by the hypothesis that in evolutionarily recent times the global human population may have fallen to only a few thousand individuals, and perhaps even as low as a few hundred individuals.

There have been few concrete causes suggested for this hypothetical global "near extinction" event, but a _Discovery Channel_ documentary entitled "Supervolcanoes" airing tonight and tomorrow night seems to hold together fairly well.

The theory is based on the observation that 75,000 years ago, a huge volcanic caldera-forming event or "supervolcano" erupted near present-day Lake Toba, Indonesia, resulting in an explosion roughly 3000 times more powerful than the Mt. St. Helen's eruption. This explosion is estimated to have generated enough sulfur dioxide haze to have lowered the Earth's global temperature by as much as 15 Celsius, resulting in "a decade without any summers." Such an event, coming so abruptly upon an already small human population of as little as 100,000 hunter-gatherers that were still recovering from the last Ice Age would have been utterly devastating, as it would have also nearly wiped out much of the seasonal food- plants and game they depended on for basic sustenance.

One connection the program brought out that I had not realized was that the Toba explosion was only somewhat more powerful than the explosion that created the Yellowstone caldera,
and that Yellowstone, like Mt. St. Helen's, is merely "dormant," _not extinct_. There is evidence that magma is once again pooling under Yellowstone, and that someday it, or another dormant caldera like it, will again erupt as a "supervolcano." The devastation such a supervolcano eruption would produce is almost inconceivable ---
it would rival a major asteroid strike, devastating the surrounding land for about 1000 km in all directions, and producing another "decade without any summers." One geologist interviewed stated "The question is not _whether_ such an eruption will happen again, but _when_ it will happen again; it could be another 100,000 years, or it could happen tomorrow." About the one glimmer of hope is that, unlike a major asteroid strike (which given our current relatively limited "Spacewatch" capability can still sneak up on us), such a massive volcanic event is likely to give us a fair amount of advance warning in terms of earthquakes and such --- much as Mt. St. Helen's has been giving us, lately...

And I have to admit, a "decade without summers" would certainly put an end to complaints about "global warning" for a while !!! :-T

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