http://en.wikipedia.org/wiki/Younger_Dryas
"The Younger Dryas saw a rapid return to glacial conditions in the
higher latitudes of the Northern Hemisphere between 12,900–11,500
years before present (BP)[5] in sharp contrast to the warming of the
preceding interstadial deglaciation. The transitions each occurred
over a period of a decade or so.[6] Thermally fractionated nitrogen
and argon isotope data from Greenland ice core GISP2 indicate that
the summit of Greenland was ~15°C colder during the Younger Dryas[6]
than today. In the UK, coleopteran (fossil beetle) evidence suggests
mean annual temperature dropped to approximately 5°C,[7] and
periglacial conditions prevailed in lowland areas, while icefields
and glaciers formed in upland areas.[8] Nothing of the size, extent,
or rapidity of this period of abrupt climate change has been
experienced since.[5]"
"There is evidence that a theorized Younger Dryas impact event,
12,900 years ago in North America could have initiated the Younger
Dryas cooling and population bottleneck or near extinction of the
Clovis people.[13]"
The gulf stream carries tropical water right up close to and along
the US coast, all the way up through the Canadian coastline, and then
over to Greenland. If Greenland dropped ~15°C, then the coastal
areas of the US likely did too. There were populations of Clovis
People along the US coast which disappeared. Some archaeologists
subscribe to the hypothesis a meteor event caused the Younger Dryas
extinction event though. There was a Public Broadcasting System NOVA
show on this here recently. The two events could be related. A comet
impact could have caused fresh water release. Here is an interesting
paper, even though it may be amateur:
http://webpages.charter.net/tsiolkovsky/Clovis_Comet_Crater.pdf
On Aug 3, 2009, at 8:32 PM, [email protected] wrote:
In reply to Horace Heffner's message of Mon, 27 Jul 2009 10:28:03
-0800:
Hi,
Horace Heffner wrote:
It may also permanently disappear too fast to avoid the loss of
power by other means.
What do you mean by that? Are you suggesting that the Gulf Stream
may stop or shift locations?
Yes. Disruption of the thermohaline circulation may have already
happened somewhat in the past, making for cold weather year round in
the Northern Hemisphere. Melting of the polar ice could produce a
new (but probably short!) ice age, even though global temperatures
increase.
I remember seeing a show on TV about this a few years back. I seem
to remember
that they suggested that the European end of the Gulf Stream would
shift south
to Africa, but I don't think there was much change in the US end.
Regards,
Robin van Spaandonk
http://rvanspaa.freehostia.com/Project.html
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
