23:43 03Dec2004 How global warming can lead to a big chill

WASHINGTON, Dec 3 (Reuters) - Global warming could lead to a big chill
in the North Atlantic, at least if history is anything to go by, researchers
reported on Friday.
They published evidence to support a popular theory that rising
temperatures caused a big melt of polar ice 8,200 years ago, causing a
freshwater flood into the salty North Atlantic.
This would have changed the flow of the balmy Gulf Stream and in just a
few years, average temperatures plummeted, ushering in a deep freeze that
lasted a century or more, researchers have proposed.
Writing in the Dec. 11 issue of Geophysical Research Letters, Torbjorn
Tornqvist, an assistant professor of earth and environmental sciences at the
University of Illinois at Chicago, says he has evidence that this happened.
"Few would argue it's the most dramatic climate change in the last
10,000 years," Tornqvist said in a statement. "We're now able to show the
first sea-level record that corresponds to that event."
Tornqvist and some graduate students found the evidence along the Gulf
of Mexico off the southern U.S. coast.
They found peat deposits that would have been formed under rising sea
levels. Working with researchers in the Netherlands, they dated the material
to 8,200 years ago.
Their composition suggested they were made when a sal****er marsh was
abruptly flooded and turned into a lagoon.
"Climatologists urgently need this type of information to run their
climate models in order to understand the conditions that can produce such
an abrupt climate change," Tonrqvist said.

"Brendan DJ Murphy" wrote in message
...

23:43 03Dec2004 How global warming can lead to a big chill

WASHINGTON, Dec 3 (Reuters) - Global warming could lead to a big chill
in the North Atlantic, at least if history is anything to go by,
researchers
reported on Friday.
They published evidence to support a popular theory that rising
temperatures caused a big melt of polar ice 8,200 years ago, causing a
freshwater flood into the salty North Atlantic.
This would have changed the flow of the balmy Gulf Stream and in just a
few years, average temperatures plummeted, ushering in a deep freeze that
lasted a century or more, researchers have proposed.
snip

Is this serious? This is post-YoungerDryas. Sea-level continued to
rise erratically from the end of the Younger Dryas till about 2500BC
as polar ice (in both hemispheres, but mainly in the north) receded.
One would expect there to have been relatively sudden upward
surges in sea-level during this period and it is good to have this
confirmed, but this newspaper summary does not seem to offer any
*evidence* that it was associated with a dramatic cooling.

Or is this a journalist "merely [adding] corroborative detail intended
to give artistic verisimilitude to an otherwise bald and unconvincing
narrative"?

Philip Eden

Philip, there was an abrupt cooling even at around 8,200 years ago, so there
is at least the possibility that the two may be related. Even the Hadley
Centre run not just one climate model but many. One of their scenarios is a
rapid cooling of the North Atlantic region, especially Northwest Europe.
OK, maybe it's an unlikely event but so is the temperature rising by 5c over
the next 100 years.

Shaun Pudwell.


"Philip Eden" philipATweatherHYPHENukDOTcom wrote in message
...

"Brendan DJ Murphy" wrote in message
...

23:43 03Dec2004 How global warming can lead to a big chill

WASHINGTON, Dec 3 (Reuters) - Global warming could lead to a big
chill
in the North Atlantic, at least if history is anything to go by,
researchers
reported on Friday.
They published evidence to support a popular theory that rising
temperatures caused a big melt of polar ice 8,200 years ago, causing a
freshwater flood into the salty North Atlantic.
This would have changed the flow of the balmy Gulf Stream and in just
a
few years, average temperatures plummeted, ushering in a deep freeze
that
lasted a century or more, researchers have proposed.
snip

Is this serious? This is post-YoungerDryas. Sea-level continued to
rise erratically from the end of the Younger Dryas till about 2500BC
as polar ice (in both hemispheres, but mainly in the north) receded.
One would expect there to have been relatively sudden upward
surges in sea-level during this period and it is good to have this
confirmed, but this newspaper summary does not seem to offer any
*evidence* that it was associated with a dramatic cooling.

Or is this a journalist "merely [adding] corroborative detail intended
to give artistic verisimilitude to an otherwise bald and unconvincing
narrative"?

Philip Eden