Via Adam and Abe comes this literally chilling Fortune article about catastrophic, abrupt climate change caused by the failure/change in established global climate mechanisms like the North Atlantic Conveyor [diagram, wikipedia entry]:

“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.

… The changes relentlessly hammer the world’s “carrying capacity”—the natural resources, social organizations, and economic networks that support the population. Technological progress and market forces, which have long helped boost Earth’s carrying capacity, can do little to offset the crisis—it is too widespread and unfolds too fast.

As the planet’s carrying capacity shrinks, an ancient pattern reemerges: the eruption of desperate, all-out wars over food, water, and energy supplies. As Harvard archeologist Steven LeBlanc has noted, wars over resources were the norm until about three centuries ago. When such conflicts broke out, 25% of a population’s adult males usually died. As abrupt climate change hits home, warfare may again come to define human life.”

Sitting in Helsinki airport about to fly to San Diego for Etech, this feels close to home:

“Europe, hardest hit by its temperature drop, struggles to deal with immigrants from Scandinavia seeking warmer climes to the south.”

Yup.

» Fortune: The Pentagon’s Weather Nightmare