Saturday, November 11, 2006

Greenland and Antarctica Ice Caps Linked By Ocean Current

by Staff Writers
Paris (AFP) Nov 8, 2006
Greenland and Antarctica are at opposite ends of the planet but their climate systems appear to be linked by a remarkable ocean current, according to a study appearing Thursday. The paper, coincidentally published as a key UN conference on climate change unfolds in Nairobi, also sheds light on man-made climate change, for it implies that Antarctica's ice could eventually start to melt because of localised warming in the far North Atlantic.

The evidence comes from a 2,500-metre (8,125-feet-) deep ice core, drilled in blood-freezing chill by European scientists at Dronning Maud Land, on the part of Antarctica that faces the South Atlantic.

With its compacted layers of ice and telltale concentrations of methane in trapped air bubbles, the core yields a compelling picture of snowfall and atmospheric temperatures going back 150,000 years.

Even better than that, it can be matched with cores of similar amplitude drilled in the Greenland icesheet.

Put together, the cores provide the first solid evidence to back a theory that millennial scale climate changes that have unfolded in the far north and south of the Atlantic are not isolated, local events, but linked.

The glacial climate in the Northern Atlantic can swing extraordinarily rapidly, with temperatures rising by between eight and 16 C (14.4-28.8 F) within the space of a few decades at the end of each Ice Age and falling back, albeit more slowly, when the next Ice Age beckons.

Antarctica, though, has far smaller temperature shifts, of between only one and three C (1.8-5.4 F), and these unfold over millennia.

But the two sets of ice cores point to what the EPICA (European Project for Ice Coring in Antarctica) scientists, reporting in the British journal Nature, describe as a "bipolar seesaw."

In short: what happens at one end of the Atlantic has a huge effect on the other, although at different timescales and in different ways.

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