Monday, November 12, 2007
The idea that the Earth had been a frozen sphere for about 10 million years, a long time ago, is relatively recent, about 15 years old. The theory is called Snowball Earth. Clever, no?
No one is sure what caused the worse extinction event ever but there are plenty of theories and most of the recent ones have seemed to coalesce around the Siberian Traps and what's called a mantle plume, when hot lava destined to become basalt pours out over a vast region. In the worst extinction, the P-T extinction, basalt covered about a 5th of Siberia. Remember the basalt. The Siberian Traps theory replaced the asteroid strike theory. Oh, and the mantle plume heated the world and nearly everything died.
OK, back to the shows. How the Earth Was Made was relatively straightforward and appeared to want to show the latest in scientific knowledge about Earth history. Here's a paraphrase of how it described the cause of Snowball Earth--a supecontinent of all the present continents pressed together, called Rodinia, stopped the convection of warm currents north and south so the poles got colder, the white snow and sea pack ice at the poles grew, thus the albedo increased, further cooling the Earth (they made a really big deal of albedo--the whiteness of the snow and ice) and it went positive feedback until even the tropics on land were a mile deep in ice and the oceans at the equator near frozen solid. Volcanoes and the break-up of Rodnina caused the ice and snow to melt. As a 'good out of bad' thing that followed, the Cambrian explosion of life forms happened next and all the current phyla, orders and families of animals and plants, and many others no longer with us, evolved in short order, including us chordates.
The same show then said that the P-T extinction was caused when another supercontinent, Pangea, had the mantle plume in what is now Siberia and it got really hot, less oxygen in the sea and nearly everything died. (OK, the explanation was longer but that's the basic story).
The agenda driven show, Global Warning, said of a frozen Earth that there was a big eruption of basalt creating lava on Rodinia, which reacted with the rain and stripped out all the CO2 and it got cold. Some rocks do react with CO2 and strip it out, but there was no mention in the show of ocean currents or albedo. CO2 keeps us warm; without it the planet freezes, was the message conveyed.
Global Warning on the P-T extinction was different too, and, to my way of thinking, self-contradictory. The massive eruptions in Siberia put CO2 into the atmosphere, the show explained, it got hot because of all the CO2 and nearly everything died. No mention of basalt on Global Warning. Now, if a vast expanse of basalt 650 million years ago stripped out the CO2 from the atmosphere and froze the Earth, why didn't the even bigger expanse, millions of square miles of basalt in the central Siberian section of Pangea, do the same thing 250 million years ago? Ha! Riddle me that, batman.
Either the massive volcanic eruptions put enough CO2 into air to change things or they didn't. Either the basalt, with rain, leached the airborne CO2 out into bicarbonate or it didn't. Volcanoes producing CO2 and basalt can't be the same explanation for opposite effects--for both freezing and boiling. Well, they can't if you're a scientist serving the truth, but they seem to be able to if you are pushing an agenda, namely, that CO2 is the only greenhouse gas that matters (it's not--invisible water, vapor and clouds are 28 times more important than CO2); and when you're pushing the idea that if there is too much CO2 in the air (nod, nod, wink, wink), we'll all cook and croak. If you're rewriting ancient history to support the current scientific fraud/fad, then any ancient event can certainly be enlisted to do double (and opposite) duty.
I love this sort of show, I just wish that politics didn't make them so unreliable
Labels: Science; Global Warming