Friday, November 9, 2007

As taken from

The Arctic: Losing Its Cool

The Arctic is warming up faster than any other region. Because
it plays a vital role in cooling the rest of the globe, the effects of this warming will be felt worldwide, not just on remote tundra.

Nineteenth-century explorer Fridtjof Nansen called the Arctic "nature's great ice temple," a place teeming with roaming polar bears and a forbidding landscape frozen since "the earliest dawn of time."

But today, one cannot venture far enough north to escape global warming. The region has heated up nearly twice as fast as the rest of the globe over the past 50 years, according to a 2004 study assessing climate change in the Arctic.

Land-based ice such as glaciers, ice sheets and permafrost and floating ice are vanishing, and the ongoing thaw has profound ramifications for the rest of the world.

Arctic Powers the "Heat Pump"
The Arctic is critical to the globe's climate and influence temperatures everywhere.

It sounds counter-intuitive, but the Arctic plays a primary role in distributing heat around the world through what is known as the "heat pump." The ocean's currents circulate heat throughout the world, through a system known as the "great conveyor belt."

Two main forces keep the conveyor moving: winds and ocean density differences. The Arctic is key to the density differences.

The conveyor belt's critical points are where surface waters plunge into deep waters. This happens only in a few places, two of which are in the North Atlantic.

As the ocean surface waters cool in the far north, they become denser and sink toward the bottom of the ocean. There, the cold water flows toward the equator. This combination of sinking and flow helps drive the ocean conveyor.

Because the cold waters that flow south must be replaced, warm surface currents flow farther north and deliver warmth to places far north. Without the ocean conveyor's heat pump, Europe's temperate climate would be much colder.

Global warming is changing that key spot in the North Atlantic where the surface waters plunge. A mix of increased precipitation, river run-off and melting ice—all related to climate change—is making surface waters in the north less salty and dense, weakening this major pump in the ocean's natural circulation.

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