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He cites recent studies of ocean floor sediments that indicate a sudden warming trend at the end of the Mesozoic era, about 60 million years ago.
The rising temperatures coincided with what McLeans calls “catastropic extinctions at the end of the Mesozoic. It all happened in a million years or less, which to a geologist is a very short time.”
But what caused the earth to become warmer after temperatures had been declin*ng for some 20 million years?
McLean believes extinctions of several species of plankton (tiny ocean plants) caused a reduction of the photosynthesis process by which plants consume carbon dioxide from the atmosphere and produce oxygen. Carbon dioxide allows incoming solar radiation to pass through, but traps part of the warm infrared energy radiated from the earth. The more carbon dioxide there is in the earth's atmosphere.
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