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Researchers suggest space dust cools Earth, furthers extinctions

I saw this on the CNN site this morning. Kind of interesting.....note
the name David Kring a la "Gold Basin".

Researchers suggest space dust cools Earth, furthers extinctions

                  May 7, 1998
                  Web posted at: 10:12 p.m. EDT (0212 GMT)

                  WASHINGTON (AP) -- The Earth's orbit causes
                  the planet to encounter more space dust every
                  100,000 years, and this could cause a cooling that
                  may contribute to climate changes and to periodic
                  extinctions of some life forms, two researchers
                  contend.

                  About 30,000 metric tons of space dust, mostly
                  originating from broken-up asteroids, fall into the
                  Earth's atmosphere every year, says Stephen
                  Kortenkamp of the Carnegie Institution of
                  Washington.

                  Particles of the dust reflect sunlight, in effect
                  shading the Earth and causing some cooling, said
                  Kortenkamp, who is co-author of a study to be
                  published Friday in the journal Science.

                  The Earth's eccentric orbit, which changes slightly
                  from a circle to oval every 100,000 years, can
                  double or triple the amount of dust falling onto the
                  planet, perhaps causing a periodic change in
                  climate, the researchers say.

                  Kortenkamp said this climate change could be
                  enough to start the process leading toward
                  extinctions, such as the disappearance 65 million
                  years ago of the dinosaurs. The researcher said the
                  cooling effect of space dust may have put stress on
                  the dinosaurs and that they were finally killed off
                  by the impact of a large asteroid or comet.

                  "Most people in the field believe there was an
                  impact (that killed the dinosaurs), but there are
                  studies that a gradual extinction began before that,"
                  said Kortenkamp.

                  Other researchers said they believe it unlikely that
                  space dust was a major factor in either extinctions
                  or climate change.

                  If Kortenkamp and his co-author, Stanley Dermott
                  of the University of Florida, are correct, "then we
                  would be faced with extinctions on the order of
                  every 100,000 years," said David Kring of the
                  University of Arizona, an expert on the dinosaur
                  demise.

                  Instead, he said, the geologic history of the Earth
                  shows there have been major extinctions at
                  intervals of 100 million years or greater.

                  Kring also noted that the dinosaurs were a highly
                  successful species for 150 million years.

                  "During that time there would have been many
                  cycles of dust increases, but there was no
                  extinction," said Kring.

                  He and Kenneth Farley of the California Institute
                  of Technology also said they doubted that even the
                  greatest amount of dust estimated by Kortenkamp
                  and Dermott would be enough to cause dramatic
                  cooling, such as in an ice age.

                  That amount of dust, Farley said in Science, is
                  "awfully small to do much of anything."

                  Science, which published the study and comments
                  by Farley, is a publication of the American
                  Association for the Advancement of Science.

--
Matt Morgan
Mile High Meteorites
http://www.mhmeteorites.com
P.O.Box 151293
Lakewood, CO 80215-9293
"Nature never breaks its own laws"