Ceilidh

Michael Zey
futurist3000@aol.com

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Authors:                  Sharon Begley

Pagination:               B.1

ISSN:                     00999660

Subject Terms:            Global warming
                         Environmental impact
                         Ice ageGreenhouse effect
                         Ocean currents
                         Motion pictures -- Day After Tomorrow, The

Classification Codes:     1530: Natural resources

Personal Names:           Broecker, Wallace S


Abstract:

Compared with the movie's timetable, "abrupt" climate change in real life
is downright pokey, with radical swings into disaster mode taking not days
but a decade or so. Someplace between science and cinema, as oceanographer
Raymond Schmitt of Woods Hole Oceanographic Institution, of Woods Hole,
Mass., puts it, "the word 'abrupt' got lost in translation."

Well before its May 28 opening, "Day After" is making waves on all sorts
of fronts. Last month, a scientist leaked to the New York Times a NASA
memo forbidding agency researchers, who have done pioneering work on climate
change, from discussing the movie with reporters. Outside theaters showing
"Day After," members of the activist group MoveOn.org plan to distribute
fliers explaining how the greenhouse effect could trigger abrupt and catastrophic
climate change. Skeptics, meanwhile, are pointing to the film as proof
of enviros' supposed tendency toward Chicken Little-ism.

"Whether Europe freezes after the conveyor shuts down depends on whether
sea ice re-forms in the North Atlantic," says Dr. [Wallace Broecker]. Adds
Woods Hole's Dr. Schmitt, "Without the amplifier of sea ice, it's hard"
to freeze Europe, let alone Manhattan.
Copyright (c) 2004, Dow Jones & Company Inc. Reproduced with permission
of copyright owner. Further reproduction or distribution is prohibited
without permission.

Full Text:

FROM THE MOMENT the gigantic ice shelf breaks off Antarctica at the beginning
of "The Day After Tomorrow," Fox's $125 million disaster flick about abrupt
climate change, it takes (according to the script I read) only four months
before killer hail pelts Tokyo, tornadoes devastate Los Angeles, and a
deep freeze turns Manhattan into a jagged ice cube, with Lady Liberty half-buried
in snow.

Compared with the movie's timetable, "abrupt" climate change in real life
is downright pokey, with radical swings into disaster mode taking not days
but a decade or so. Someplace between science and cinema, as oceanographer
Raymond Schmitt of Woods Hole Oceanographic Institution, of Woods Hole,
Mass., puts it, "the word 'abrupt' got lost in translation."

Well before its May 28 opening, "Day After" is making waves on all sorts
of fronts. Last month, a scientist leaked to the New York Times a NASA
memo forbidding agency researchers, who have done pioneering work on climate
change, from discussing the movie with reporters. Outside theaters showing
"Day After," members of the activist group MoveOn.org plan to distribute
fliers explaining how the greenhouse effect could trigger abrupt and catastrophic
climate change. Skeptics, meanwhile, are pointing to the film as proof
of enviros' supposed tendency toward Chicken Little-ism.

AS IT HAPPENS, the movie arrives at a pivotal moment in research into whether
the current global warming caused by the greenhouse effect could, paradoxically,
trigger a deep freeze in some regions.

It is now 17 years since geochemist Wallace Broecker of Lamont- Doherty
Earth Observatory, Palisades, N.Y., first suggested that a greenhouse-induced
shutdown of a current in the Atlantic Ocean called the thermohaline circulation
-- the "conveyor," to its fans -- could trigger abrupt climate change and
plunge much of Europe into a mini- ice age. The current carries warmth
north from the Gulf of Mexico, giving Europe balmier weather than its latitude
otherwise would provide. Since Dr. Broecker's initial work, studies of
ancient climates have left no doubt that abrupt shifts from tepid to frigid
have been the norm.

"Temperature swings of eight to 10 degrees Celsius [14 to 18 degrees Fahrenheit]
in a decade have occurred in Greenland and the North Atlantic many times
in the last 100,000 years," says climate scientist Richard Alley of Pennsylvania
State University, State College, Pa.

More important, new data link these sudden deep freezes to shutdowns of
the conveyor, just as Dr. Broecker proposed. In one clever bit of sleuthing,
oceanographers discovered that the ratio of two elements produced from
the decay of radioactive uranium in the ocean reveals whether the conveyor
is flowing at full force. When it is, the element protactinium gets swept
south, explains Woods Hole's Jerry McManus. But when the conveyor shuts
down, protactinium stays put, and more of it (relative to the other decay
element, thorium) winds up in ocean sediments. In a study published last
month, Dr. McManus and colleagues used the Pa/Th ratio in sediment cores
to conclude that a near-total and "instantaneous" shutdown in the conveyor
coincided with a deep freeze in Europe 17,500 years ago.

This and other data leave little doubt that "changes in ocean circulation
are correlated with sudden temperature changes," says Prof. Alley.

WHETHER GREENHOUSE warming could shut down the conveyor and trigger "Day
After"-like climate catastrophes is another matter, however. In the past,
the conveyor seized up when a huge influx of fresh water, as from melting
ice sheets, poured into the North Atlantic near the end of ice ages. Today,
extra fresh water is also arriving, thanks to increased rainfall (in our
warmer world, there is more evaporation and hence rain) and more river
runoff. But increased rainfall and river runoff, even if it lasted decades,
might not be enough to shut off the conveyor the way the sudden catastrophic
influx of fresh water did 12,700 years ago.

"I just can't foresee that these kinds of freshwater inputs could even
approach the amount that was discharged in the past, and that seems necessary
to shut down the conveyor," says geoscientist Andrew Weaver of the University
of Victoria, British Columbia.

Also, even if a shutdown of the conveyor chilled Europe, for the cold to
snowball (sorry) into a mini ice age seems to require abundant sea ice.
In our warming world, that commodity is decreasing. Arctic sea ice has
shrunk almost 40% in the past few decades, the National Academy of Sciences
said in a 2002 report on abrupt climate change.

"Whether Europe freezes after the conveyor shuts down depends on whether
sea ice re-forms in the North Atlantic," says Dr. Broecker. Adds Woods
Hole's Dr. Schmitt, "Without the amplifier of sea ice, it's hard" to freeze
Europe, let alone Manhattan.

Still, the climate has sprung enough surprises that it's foolish to rule
out anything. Even a cooling of the North Atlantic that stops short of
shutting down the conveyor could disrupt the monsoons, bringing drought
to Asia, and make for deadly European winters, says Prof. Alley.

"Do I expect a catastrophic shutdown of the conveyor?" he asks. "No. Can
I guarantee it won't happen? No."