[meteorite-list] Younger Dryas Onset Marked by Dramatic Environmental and Biotic Change, James Kennett talk, INQUA 2011 Bern, Switzerland: Rich Murray 2011.07.27

From: Rich Murray <rmforall_at_meteoritecentral.com>
Date: Wed, 27 Jul 2011 17:33:09 -0700
Message-ID: <CAHqJ8pYhk6+b+4Rr8p7JOAWt73AfjNkEKPwqb4viTbhdt16-pA_at_mail.gmail.com>

Younger Dryas Onset Marked by Dramatic Environmental and Biotic
Change, James Kennett talk, INQUA 2011 Bern, Switzerland: Rich Murray
2011.07.27

http://www.inqua2011.ch/?a=programme&subnavi=abstract&id=1666&sessionid=60

[ click on Next Abstract for next talk in this session ]

Abstract Details

ID: 1666
Title: Younger Dryas Onset Marked by Dramatic Environmental and Biotic Change

Content:
The onset of the Younger Dryas (YD) episode was marked by a complex
array of abrupt and potentially linked changes in the Earth's
environmental and biotic systems.
We will broadly review YD changes in atmosphere and ocean circulation,
ice sheets, North American continental hydrosphere, biosphere
including extinctions, and human culture.
The cause of the YD is controversial and currently debated, yet any
causal hypothesis needs to account for these changes.
,Such cooling episodes with YD characteristics and timing in earlier
Terminations appear more affiliated with terminal glacial episodes.
YD onset is also outstanding because of close collective association
with major, abrupt continental-scale ecological reorganization,
megafaunal extinction and human adaptive shifts.
The YD climate onset was remarkably abrupt (~one year) suggesting
atmospheric climate response preceded oceanic change.
Maximum cooling was atypically early, near the YD onset and associated
with an abrupt increase in atmospheric dust.
A major North American hydrographic reorganization, apparently
associated with destabilization of ice sheet margins, was marked by
abrupt switch in flow from the south to northern oceans.
This outburst flooding may have coincided with major drainage of Lake Agassiz.
Associated outburst floods affected widely separated areas of the Arctic.
The ocean responded by major change in meridional overturning.
On land, responses include widespread evidence of biomass burning;
change in sediment deposition including a layer with exotic materials
interpreted to be of cosmic impact origin;
broad continental vegetation disruption;
abrupt megafaunal extinction;
and genetic bottlenecks reflecting population declines and/or animal migrations.
The North American human record suggests abrupt disappearance of the
Clovis culture;
a human genetic bottleneck;
and a widespread archeological gap during early YD centuries.

Session: 60 The enigmatic Younger Dryas climatic episode
Authors: James Kennett
Presenter: James Kennett
Type: oral
Received on Wed 27 Jul 2011 08:33:09 PM PDT