The Hot Zone

In deep waters

Posted by Alison Hawkes on July 19, 2010
Category : The Oceans

Antarctic Bottom Water sounds like it’s frigidly cold, and it is. It’s the densest water in the ocean, made from open ocean water that’s cooled by surrounding polar ice that then sinks.

As it’s replenished, the bottom water spreads northward like an icy chill and drives the ocean conveyor belt. It’s been thought that it would take centuries for warming surface waters to penetrate such depths. But new research published in the recent journal Science finds that climate change could reach these cool waters a whole lot sooner.

Using computer simulation, researchers led by the Research Institute for Global Change in Japan found that the deep ocean is far more sensitive to the surface than previously thought.

As surface waters warm in the Southern Ocean, the layers of Antarctic Bottom Water thin. This weakens the deep water current that transports the cool water across the ocean floor. The researchers conclude that within four decades, bottom warming can occur.

Assuming that these deep waters will remain a regulator of the Earth’s climate “must be revisited,” they say.

“… the multicentennial to multimillenial developmental time scales currently envisaged in the predicted oceanic response to climate warming are probably too long.”

What that means for the ocean conveyor belt is a bit frightening. We’re in deep waters.

-Alison Hawkes

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