Ocean currents and iceberg movements

In this video clip NIWA scientist John Mitchel explains how icebergs are moved by the water currents. He uses a map to further explain the movement of icebergs.

Points of interest for teachers:

• What does John Mitchel mean when he talks about the iceberg graveyard?

Transcript

JOHN MITCHEL

To illustrate the power of ocean currents, the big icebergs that broke off the Ross ice shelf back in, round 1999, 2000, this big iceberg broke off, moved by the currents till it came aground against Ross Island here and Franklin Islands up here. And with time, with the movement of the currents back and forth, broke it into pieces and now we’ve got this small part here, B15J, which is just sitting up, just North of the ice tongue eight years later after it first broke off.

Eighty percent of these bergs are under water so it’s the, the power of the currents rather than the power of the wind which moves them.

This map will probably help explain it better. The natural current flow in the Ross Sea is across the ice shelf here, up along the Western shoreline here and then around the corner here. So bergs broke off, big bergs broke off the Ross ice shelf here, moved by currents until they rotated to be jammed against Ross and Franklin Island, where they eventually broke up. Gradually moved their way North, over quite a long time – you know year or two, until they came round past Cape Adare here and then around into what’s called the iceberg graveyard where they broke up further, and then possibly are still sitting there.

This is a photo I took flying out of the Antarctic, I think it’s from about twenty thousand feet, showing the iceberg graveyard, big bergs surrounded by the sea ice in late October.