Global warming gets blame for breakaway Antarctic ice slabs

A slab of ice that would stretch from Dublin to Drogheda, in a strip five kilometres wide, has broken free from the Antarctic ice shelf due to global warming, according to new satellite images.

The 200 sq km chunk, now melting apart and drifting off into the south Atlantic, is as thick as five Liberty Halls end to end.

This is a mere ice-cube, however, compared to the 12,000 sq km Larsen B ice shelf, almost the area of Northern Ireland, that is now expected to disintegrate as the centuries-old shelf thins and loses its stability.

But we will have to hold on a few months for this spectacular ice show, according to Dr Ted Scambos, a research scientist at the US National Snow and Ice Data Centre at the University of Colorado in Boulder. The break-up "has probably shut down for most of 1998", he said, as the Antarctic enters its southern hemisphere winter.

Come the Antarctic summer the shelf instability is expected to return, with the Larsen B shelf possibly disappearing into the ocean by the end of the year or early in 1999.

All this ice will have no impact on ocean levels, Dr Scambos explained. The Larsen B extends 60 miles out into the ocean, floating like an ice cube in a gin and tonic but still connected to the ice mass on the shore. Yet its going could open the way to rising sea levels. With this enormous plug out of the way the massive glaciers that build the ice shelves could begin to flow more quickly, dumping huge quantities of formerly landlocked ice into the sea.

The shelf loss is linked to a warming trend at the South Pole. The regional climate has climbed by 2.5C since the 1940s, prompting a rapid retreat of ice at the continent's northernmost tip.

Larsen B was the "biggest ice shelf yet to be threatened", Dr Scambos said. "The total size of the Larsen B is more than all the previous ice that has been lost from Antarctic Peninsula ice sheets in the past two decades."

"This may be the beginning of the end for the Larsen ice shelf," Dr Scambos said. It sits "on the front end of the warming trend" and once gone it will be gone for good, unless we enter another round of climate change and see a return to colder rather than warmer conditions.