[aerohead]

Last week, PBS NOVA aired, 'DINOSAUR APOCALYPSE', which had to do with the mass extinction event, 66-million years ago, which took out 75% of all species on Earth, including all, non-avian dinosaurs.
Something which stood out had to do with 'Impact-Winter,' created by 3-trillion tonnes of sulfur-based rock, from the Yucatan Peninsula being vaporized, and ejected into space.
Earth's gravity pulled the vaporized rock back into the atmosphere, where it gave its heat up, allowing the vapor to cool into glass spheroids, which rained down, while turning the air into a hot-air broiler, incinerating most terrestrial and oceanic life forms.
Earth was dark for about a decade, all food systems collapsed.
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The interesting part was that, the sulfate aerosols created by the asteroid impact, remained in the stratosphere long enough to cool the whole planet by 48-degrees-F. This phenomena was first discussed by Benjamin Franklin, who coined the term ,'parasol effect', which is used in today's general circulation climate models.
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Today's 'cooling' is associated with coal-fired power plant emissions, which are keeping the troposphere about 1-C cooler than it would be without the aerosols. In effect, the Earth has already warmed 2.1-C, we just won't 'feel' it, until all these plants are taken offline, and the aerosols have a couple months to precipitate out.
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If you haven't seen the show, it's worth a look. The paleontologists have reasonably demonstrated that dinosaurs were present right at the time the 'Mount Everest'- sized asteroid came in at 45,000-mph.
None, except the 'chickens' existed afterwards.