Quote:
Originally Posted by IamIan
Jamesqf then referenced the Triassic extinction event as an example to support his predicted extinction event .. and suggested that it was the ~2,000 ppm CO2 of the Triassic that was the primary cause of that extinction event ... thus correlating it back to his CO2 based predicted extinction event.
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One thing you seem to be overlooking here is rate of change. Life can, given enough time, evolve to survive a wide range of conditions. Consider for instance those ocean floor hydrothermal vent communities, with animals living at temperatures up to 80C, and dependent on chemosynthetic bacteria for their food supply. So it seems quite possible (though I don't know of any conclusive evidence) that pre-Cambrian life had evolved, over tens to hundreds of millions of years, to live in a high-temperature, high CO2 environment. The Cambrian 'explosion' (which took some 40 million years - a pretty slow explosion :-)) might thus be in part a response to having to evolve to survive at lower temperatures.
You could look even further back in geological time, to the "great oxygenation event" (
Great Oxygenation Event - Wikipedia, the free encyclopedia ) for a similar drastic change in atmospheric composition and hence temperature. But note that this 'event' took something like a billion years, giving life plenty of time to evolve adaptations to the new conditions.
By contrast, the changes causing the P-T extinction took something like a few hundred thousand years, and the current changes are happening within a few hundred. So how does life evolve to adapt in that short a time? Note also that what's relevant here is not absolute time, but reproductive generations. If you're a single-celled organism reproducing in a few hours, or even a insect producing several generations a year, you have a lot more evolutionary range than something that takes 10-20 years to reproduce.