[meteorite-list] New "Big Impact" Theory

[Sterling K. Webb]

New "Big Impact" theory. In case you find the
references to a "new Ice Age" puzzling, I'll remind
you that it's the Ice Age that we in right now. Yes,
friends, we are in an Ice Age, at 5-7 C. below the
long-term norm.

The full text of the article follows.


Sterling K. Webb
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http://www.sciencedaily.com/releases/2012/09/120919103612.htm

Did a 'Forgotten' Meteor 
Have a Deadly, Icy Double-Punch?

ScienceDaily (Sep. 19, 2012) - When a huge 
meteor collided with Earth about 2.5 million 
years ago and fell into the southern Pacific 
Ocean it not only could have generated a 
massive tsunami but also may have plunged 
the world into the Ice Ages, a new study suggests.

A team of Australian researchers says that because 
the Eltanin meteor -- which was up to two kilometres 
across -- crashed into deep water, most scientists 
have not adequately considered either its potential 
for immediate catastrophic impacts on coastlines 
around the Pacific rim or its capacity to destabilise 
the entire planet's climate system.

"This is the only known deep-ocean impact event on 
the planet and it's largely been forgotten because 
there's no obvious giant crater to investigate, as there 
would have been if it had hit a landmass," says Professor 
James Goff, lead author of a forthcoming paper in the 
Journal of Quaternary Science. Goff is co-director of 
UNSW's Australia-Pacific Tsunami Research Centre and 
Natural Hazards Research Laboratory.

"But consider that we're talking about something the 
size of a small mountain crashing at very high speed 
into very deep ocean, between Chile and Antarctica. 
Unlike a land impact, where the energy of the collision 
is largely absorbed locally, this would have generated 
an incredible splash with waves literally hundreds of 
metres high near the impact site.

"Some modelling suggests that the ensuing mega-tsunami 
could have been unimaginably large -- sweeping across 
vast areas of the Pacific and engulfing coastlines far inland. 
But it also would have ejected massive amounts of water 
vapour, sulphur and dust up into the stratosphere.

"The tsunami alone would have been devastating enough 
in the short term, but all that material shot so high into 
the atmosphere could have been enough to dim the sun 
and dramatically reduce surface temperatures. Earth was 
already in a gradual cooling phase, so this might have 
been enough to rapidly accelerate and accentuate the 
process and kick start the Ice Ages."

In the paper, Goff and colleagues from UNSW and the 
Australian Nuclear Science and Technology Organisation, 
note that geologists and climatologists have interpreted 
geological deposits in Chile, Antarctica, Australia, and 
elsewhere as evidence of climatic change, marking the 
start of the Quaternary period. An alternative interpretation 
is that some or all of these deposits may be the result of 
mega-tsunami inundation, the study suggests.

"There's no doubt the world was already cooling through 
the mid and late Pliocene," says co-author Professor Mike 
Archer. "What we're suggesting is that the Eltanin impact 
may have rammed this slow-moving change forward in an 
instant -- hurtling the world into the cycle of glaciations 
that characterized the next 2.5 million years and triggered 
our own evolution as a species.

"As a 'cene' changer -- that is, from the Pliocene to Pleistocene -- 
Eltanin may have been overall as significant as the meteor 
that took out the non-flying dinosaurs 65 million years ago. 
We're urging our colleagues to carefully reconsider conventional 
interpretations of the sediments we're flagging and consider 
whether these could be instead the result of a mega-tsunami 
triggered by a meteor."