[meteorite-list] Researchers Say Asteroid Impact Could Alter Climate

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:01:35 2004
Message-ID: <200206261615.JAA02581_at_zagami.jpl.nasa.gov>

Researchers Say Asteroid Impact Could Alter Climate
The Associated Press
June 25, 2002

ALBUQUERQUE (AP) _ Here's the scenario: An asteroid slams into Earth,
kicking up a huge plume of debris that settles into a disk around the
planet, like the rings of Saturn.

The ring's massive shadow chills the tropics and sends Earth into a
100,000-year freeze.

University of New Mexico climate researcher Peter Fawcett has found evidence
that something like that might have happened 35 million years ago during the
Eocene epoch. Rocks from that time show a layer of asteroid debris, followed
by evidence of a 100,000-year cold spell.

So Fawcett and Sandia National Laboratories physicist Mark Boslough believe
scientists trying to understand the Earth's hot and cold spells need to
consider rings.

Occasional asteroids hitting Earth just right could kick up a disk which
could stick around long enough to cause major climate changes, the
scientists suggest in a research paper to be published in the Journal of
Geophysical Research.

The pair used a computer simulation of Earth's climate to show what might
happen if Earth had a Saturn-like ring.

Fawcett said similarities between the computer simulation and the Eocene
cold spell are not proof of anything, but the similarities suggest a
ringworld is worth considering.

That one particular event may or may not have been a ring, he said. But
everything in it is consistent.

The idea came from Boslough, a physicist who has spent much of his career
studying what happens when asteroids hit.

The giant gas planets in the outer solar system _ Jupiter, Saturn, Neptune
and Uranus _ have rings.

You've got nine planets, and four of them have rings of some kind, Boslough
said.

He had worked with Fawcett to modify climate simulation computer programs to
run on Sandia's supercomputers, so using those programs to test the ring
hypothesis seemed logical.

Boslough ran the simulation, plugging in data about a hypothetical ring
blocking the sun. He turned the results over to Fawcett, who uses computer
simulations and field studies to try to understand changes in the climate of
ancient Earth.

Fawcett's maps show cold spells in the tropics.

If you've got less heat in the tropics, there's less to export to the poles,
Fawcett said.

Beneath the shadow cast by the ring, average temperatures in the Sahara
desert drop below freezing. Cold spells spread quickly across the planet,
lowering the global average temperature by nearly 20 degrees Fahrenheit. Ice
spreads across the Bering Strait and reaches up from Antarctica to
Australia.
Received on Wed 26 Jun 2002 12:15:14 PM PDT