To: WSFAlist at keithlynch.net
Date: Sun, 6 Oct 2002 21:49:46 -0400
Subject: [WSFA] Fw: a coming ice age?
From: ronkean at juno.com
Reply-To: WSFA members <WSFAlist at keithlynch.net>

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http://nationalpost.com/financialpost/story.html?id={B7052CCD-012B-43B6-9
65D-817642A34738}

Rumble of a coming ice age

Margaret Munro

National Post

Toronton, Ontario

Friday, October 04, 2002

A remarkable change in the waters of the North Atlantic has thrown what
one leading oceanographer is calling a "curve ball" into thinking that
the planet will gradually warm due to greenhouse gases in the
atmosphere.

Instead, there is a real possibility that global warming may soon
trigger the sudden onset of an ice age that could last hundreds of
years.

"In just the past year, we have seen ominous signs that we may be headed
toward a potentially dangerous threshold," says Dr.  Robert Gagosian,
president and director of the Woods Hole Oceanographic Institution in
Massachusetts.  "If we cross it, Earth's climate could switch gears and
jump very rapidly -- not gradually -- into a completely different mode
of operation.

Gagosian bases his comments on a growing body of evidence that
significant changes are underway in the North Atlantic, threatening the
ocean current that moderates temperatures in northern climes.  Without
it London, which is almost as far north as Edmonton, would have much
longer, colder winters.  And Prince Edward Island potatoes might become
a thing of the past.

Talk that climate change might one day trigger the sudden onset of an
ice age is not new.  But Gagosian believes there is a new urgency,
warning that the changes could occur in our lifetime.

And once the changes start, the cooling could be rapid, reducing
temperatures by several degrees Celsius over much of the United States,
Canada and Europe within a decade.

Gagosian warns rivers, harbours and shipping lanes would freeze much
earlier, and transportation, agriculture and fishing would be disrupted.

"In short, the world, and the world economy, would be drastically
different," Gagosian says.

His controversial predictions, which he has been making in speeches and
has posted on the Wood Hole Web site, are based largely on information
garnered from the North Atlantic, where the water is becoming fresher
and sinking more slowly.

Igor Yashayaev, at the federal Bedford Institute of Oceanography in Nova
Scotia and his colleagues in Britain, the United States and Germany,
have found the entire water column of the Labrador Sea has undergone
radical change over the past three to four decades.

Data collected during annual spring trips across the Labrador Sea and in
waters between Greenland, Iceland and Europe show the North Atlantic, at
depths up to 4,000 metres, has become less salty, especially in the last
decade.

Scientists are not sure where all the fresh water is coming from.  But
they suspect much of it is coming the Arctic, where ice has been melting
and thinning at an usually high rate.

Gagosian and his colleagues say the flood of fresh water could shut down
the so-called Great Ocean Conveyor, the ocean's main heat-circulating
system.  It drives the Gulf Stream, which carries heat from the tropics
north.

By the time water from the Gulf Stream reaches the Labrador and
Greenland seas, it is so cool and dense that it sinks into the deep
ocean, creating a void that pulls more warm tropical waters north.

Fresh water is more buoyant and less able to sink.  Scientists worry
that fresher water flowing into the North Atlantic could slow the Gulf
Stream or push it south.  Or, even worse, shut the conveyor system down
completely.

Already, surface water in the Greenland Sea is sinking 20% more slowly
that in the 1970s, according to evidence gathered by European
scientists.  This decreased salinity "is arguably the biggest and most
dramatic change in ocean property that has ever been measured in the
global ocean," Gagosian says.

"At what per cent will the Ocean Conveyor stop?  25%?  40%?  60%?  This
is not like a dimmer switch, but more like a light switch.  It probably
goes from 'on' to 'off,' " he says.

Not everyone, however, is so sure the conveyor is in danger.

"The jury is still out," says Eddy Carmack, an oceanographer at the
federal Institute of Ocean Sciences in Sidney, B.C., who is studying
changes in the polar and subpolar seas.  He is not convinced freshening
in the North Atlantic will lead to an abrupt climate change.

"But the stakes are so high, it can not be dismissed," he adds.  One
thing that can be said with certainty is that the climate is becoming
less predictable.

Allyn Clarke, a senior scientist at the Bedford Institute, also cautions
against reading too much into the data.  He heads the Canadian team that
monitors the Labrador Sea.

He says the evidence of freshening in the deep waters of the North
Atlantic has been "shocking" to many oceanographers.  But like Carmack,
he says not enough is known to predict if and when the ocean conveyor
could stop.  But he says it is a possibility, and one that could trigger
an ice age.

Clarke is not as outspoken as his U.S.  colleagues, but he says he is in
"full sympathy" with Gagosian's report, which stresses the need for
better understanding of the changing oceans.

"We are presently doing a global experiment on our climate system with
little understanding of which of a number of possible outcomes will
result," Clarke says.

Changes in ocean temperatures have been linked to ice ages in the past.
About 12,800 years ago, North Atlantic waters cooled dramatically and so
did the North Atlantic region.

It took only about a decade to move into a cold spell that lasted close
to 1,300 years, Gagosian says.

The most recent shutdown in the North Atlantic circulation is believed
to have occurred 500 years ago, wiping out established Norse settlements
and vineyards that once thrived in Greenland, he says.

A recent U.S.  National Academy of Sciences report, entitled "Abrupt
Climate Change: Inevitable Surprises," notes that climate changes have
occurred with "startling speed" in the past.  And next time, the report
said, the cost to agriculture alone could be in the $100- to
$250-billion range.

Perhaps the most sobering realization is there will be little anyone can
do about it -- short of adapt.

"The climate system can and has moved to new climate states in a matter
of decades," Clarke says.  "If the system undergoes such a change, we
have virtually no idea of how to attempt to stop or reverse the system."

.

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