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Nature_and_Environment.7

Global Climate Change

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{Nature_and_Environment.7.2}: Kai Hagen {kai} Tue, 24 Feb 2004 01:12:14 CST (HTML)

CLIMATE COLLAPSE
The Pentagon's Weather Nightmare

The climate could change radically, and fast. That would be the mother of all national security issues.

FORTUNE Magazine

Monday, January 26, 2004

By David Stipp

Global warming may be bad news for future generations, but let's face it, most of us spend as little time worrying about it as we did about al Qaeda before 9/11. Like the terrorists, though, the seemingly remote climate risk may hit home sooner and harder than we ever imagined. In fact, the prospect has become so real that the Pentagon's strategic planners are grappling with it.

The threat that has riveted their attention is this: Global warming, rather than causing gradual, centuries-spanning change, may be pushing the climate to a tipping point. Growing evidence suggests the ocean-atmosphere system that controls the world's climate can lurch from one state to another in less than a decade*like a canoe that's gradually tilted until suddenly it flips over. Scientists don't know how close the system is to a critical threshold. But abrupt climate change may well occur in the not- too-distant future. If it does, the need to rapidly adapt may overwhelm many societies*thereby upsetting the geopolitical balance of power.

Though triggered by warming, such change would probably cause cooling in the Northern Hemisphere, leading to longer, harsher winters in much of the U.S. and Europe. Worse, it would cause massive droughts, turning farmland to dust bowls and forests to ashes. Picture last fall's California wildfires as a regular thing. Or imagine similar disasters destabilizing nuclear powers such as Pakistan or Russia*it's easy to see why the Pentagon has become interested in abrupt climate change.

Climate researchers began getting seriously concerned about it a decade ago, after studying temperature indicators embedded in ancient layers of Arctic ice. The data show that a number of dramatic shifts in average temperature took place in the past with shocking speed*in some cases, just a few years.

The case for angst was buttressed by a theory regarded as the most likely explanation for the abrupt changes. The eastern U.S. and northern Europe, it seems, are warmed by a huge Atlantic Ocean current that flows north from the tropics*that's why Britain, at Labrador's latitude, is relatively temperate. Pumping out warm, moist air, this "great conveyor" current gets cooler and denser as it moves north. That causes the current to sink in the North Atlantic, where it heads south again in the ocean depths. The sinking process draws more water from the south, keeping the roughly circular current on the go.

But when the climate warms, according to the theory, fresh water from melting Arctic glaciers flows into the North Atlantic, lowering the current's salinity*and its density and tendency to sink. A warmer climate also increases rainfall and runoff into the current, further lowering its saltiness. As a result, the conveyor loses its main motive force and can rapidly collapse, turning off the huge heat pump and altering the climate over much of the Northern Hemisphere.


This excerpt is only about a fifth of this informative article. Read the rest here:
http://www.fortune.com/fortune/print/0,15935,582584,00.html

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