`God-like hammer' falls on Antarctic ice shelves

Strange, titanic news has been emerging from Antarctica in the run-up to the climate protection negotiations in Berlin, writes Nicholas Schoon. Ice shelves covering hundreds of square miles have abruptly crumbled and disappeared.

Cynics will believe that the two events are not unrelated. What better time for environmentalists and journalists to whip up fears about global warming than just before environment ministers from around the world meet to discuss what - if anything - is to be done. But the scientists who study the frozen continent are genuinely startled by the fate of three ice shelves in the Antarctic peninsula. ``Here are things we thought were permanent which have just crumbed away,'' said David Vaughan, a glaciologist with the Cambridge-based British Antarctic Survey. ``It's as if a God- like hammer has fallen on them.''

The ice shelves are where the land-based ice, which covers almost the entire continent, extends out to sea. They are in constant but very slow motion; ice is being squeezed out to sea off the land, while at the outer edge of the shelves icebergs are calving off and drifting out to sea.

The Wordie shelf, which covered 2,000 square kilometres in the Forties, has lost two-thirds of its mass since then. The 900-square kilometre Prince Gustav shelf, which connected the peninsula's tip to James Ross Island, had been retreating since the Eighties and has now disappeared, leaving the island circumnavigable.

More spectacularly, the northern part of the Larsen shelf, covering 2,000- square kilometres, broke up in a few weeks between January and February this year; these shelves are about 100 metres thick.

Mr Vaughan said the break- ups were much more interesting and significant than the much-reported creation of a iceberg the size of Oxfordshire at the northern end of the peninsula. ``That's something that happens every two or three years.'' The demise of the shelves is thought to be due to average temperatures in the Antarctic peninsula rising by 2.5C over the past 50 years.

Climatologists say that the global warming expected as a result of a built-up of pollutants is likely to be highest in the Arctic and the Antarctic.

``We can't say that this is a sign of global warming,'' said Mr Vaughan. ``But it's certainly a very strong regional warming. We don't know anywhere else in the world where there has been such a marked change in temperatures over this time.''

In fact, the climate in this area of Antarctica is highly variable, with changes in the pack ice cover seeming to cause big changes in temperature and vice versa.

There has, however, been a 0.5C rise in average global temperatures over the past century. It seems increasingly likely to have been caused by a build-up of ``greenhouse gases'', although very few scientists would say there is positive proof.