Download 20 Mar 2004

Abrupt Climate Change, the Pentagon, and the President
by Art Hobson
[email protected]
http://physics.uark.edu/hobson/
President Bush's ideologically-driven distortions of reality might soon come
home to haunt him. There have been documented reports of all sorts of manipulations
of scientific findings, but Bush's visceral refusal to take global warming seriously is
arguably his most dangerous delusion.
Faith-based opposition to global warming has taken many forms, including
ignoring a National Academy of Sciences review that was requested by Bush himself,
disdaining his own administration's global warming report as "a report put out by the
bureaucracy," removing a section on climate change from a 2002 Environmental
Protection Agency (EPA) report, tampering so blatantly with a 2003 EPA report that
EPA director Christine Whitman opted to delete the entire climate change section, and
pressuring the United Nations to replace scientist Robert Watson as head of the
International Panel on Climate Change because big oil didn't like his conclusions.
Now comes a report taking global warming seriously indeed, and from a
source that the administration never ignores: the Pentagon.
The report was commissioned by the influential Pentagon mover and shaker
Andrew Marshall. The 22-page report was withheld from the press for four months,
was finally released on 23 February, and is available at
http://www.ems.org/climate/pentagon_climate_change.html. Its authors are Peter
Schwartz, CIA consultant and former head of planning at Royal Dutch/Shell Group,
and Doug Randall of Global Business Network.
The report was stimulated by a series of recent scientific reports on the
possibility that global warming could cause large and abrupt climate change. For a
riveting account of the science, read The Two-Mile Time Machine: Ice Cores, Abrupt
Climate Change, and Our Future by Richard Alley.
The study looked at the most-discussed scenario for abrupt climate change: a
shutdown of the so-called "conveyor belt" that circulates heat and salt through the
world's oceans. Here's how it works.
The Gulf Stream carries surface water, warmed in the tropics, up the eastern
U.S. coast and across the north Atlantic toward northern Europe, warming both
regions. Some Gulf Stream water evaporates, making the remaining water
saltier. When it reaches the vicinity of Iceland, it meets Arctic water and cools. At
this point, the Gulf Stream water becomes heavier than the surrounding water, both
because it is overloaded with salt and because it is cold (cold water is more dense than
warm water). This causes the Gulf Stream to sink to the ocean floor near Iceland, and
this sinking gives an enormous "push" to the deep water in this region, pushing it
southward. This powers a complete global circulation of deep ocean currents that
move south to Antarctica, then eastward to the Pacific where it finally rises to the
surface and flows back westward into the Atlantic and northward again as the Gulf
Stream. It takes a given parcel of water 1000 years to complete one global cycle.
But global warming is melting the north polar ice cap, Greenland, northern
Canada and northern Russia, releasing lots of new fresh (non-salty) water. This
freshens the Arctic ocean and the northern reaches of the Gulf Stream, making it
lighter and less apt to sink. At some point the sinking will cease, stopping the global
conveyor belt at its source. Northern Europe and the eastern U.S. will cool abruptly,
throwing them into a new ice age, while tropical and southern regions will continue to
warm.
This chain of events is commonplace in Earth's history. Conveyor belt stops
and starts are thought to have occurred naturally and repeatedly each time the planet
slipped into or out of an ice age. Ice cores drilled deep into Greenland's glaciers yield
evidence of numerous large, abrupt climate changes caused by conveyor belt shifts
that have jumped the planet's temperature by up to 20 degrees.
It's impossible to predict when the conveyor will switch from "on" to "off." It's
like pressing a light switch slowly with your finger. As you gradually increase the
pressure, there is no way to predict when it will switch from "on" to "off." That last
little bit of pressure makes a big difference. As geochemist Wallace Broecker puts it,
"The Earth's climate system is an ornery beast which overreacts to even small
nudges," adding that "we are poking it."
The Pentagon's scenario is modeled on a conveyor shutdown that actually
occurred 8200 years ago, triggering a relatively modest but abrupt shift from warm to
cool conditions. North European temperatures dropped precipitously, and severe
winters in Europe and elsewhere caused glaciers to advance, rivers to freeze, and
agriculture to decline.
The Pentagon study plays out the social consequences of this
scenario. Conveyor belt collapse is assumed to begin in 2010. During 2010-2020,
drought persists in Europe and eastern North America, while temperatures drop by 5
degrees over the northern hemisphere and rise by 4 degrees in the south. Storms and
winds intensify, hitting interior regions of northern Asia and North America with
weather extremes. Megadroughts begin in key regions of China and northern
Europe. By 2020, Europe's climate is more like Siberia's.
Monsoon rains become unreliable across south Asia. Massive emigration
becomes a problem everywhere. Crop yields decline. Numerous shortages of food,
water and energy (the latter two are already stressed today) develop. Oil prices go
through the roof.
2020-2030 sees unrest and wars over immigration, food, water, energy, and
other natural resources. Many nations acquire nuclear weapons.
You can see why the Pentagon might be concerned. It will be interesting to see
how our president responds to this challenge to his own ideological preconceptions.