Antarctic balance skating on thin ice

THE ocean was calm from our deck on the Sea Spirit when I visited in December.

Now there are renewed fears navigation could become more hazardous for ships after one of the biggest icebergs on record, measuring 5800sq/km, calved away from Antarctica’s Larsen C Ice Shelf between July 10-12.

The iceberg was already in play before it broke away so there’s no immediate impact on sea levels.

But it is expected to break up over time, increasing risks for ships, including passenger cruise vessels travelling to and from South America.

The Larsen A and B ice shelves, situated farther north on the Antarctic Peninsula, collapsed in 1995 and 2002, respectively.

And if the Larsen C ice shelf goes the same way, ocean levels could rise significantly.

This latest calving episode has cut the shelf’s area by more than 12 per cent.

It doesn’t rain or snow much in Antarctica, despite the stormy weather. When it does, the snow doesn’t melt because it’s too cold. Instead it builds up over many years to make large, thick ice sheets.

Together, these sheets form a land mass nearly twice the size of Australia, holding 90 per cent of the world’s ice.

In winter, Antarctica is covered by 20 million square kilometres of sea ice. This dramatically reduces to 2.5 million square kilometres over the southern summer.

Still, scientists only have to look at satellite imagery of Antarctica’s sea ice to see the effects of climate change reflected right back at them. Sea ice reflects the sun’s heat, so without it the sea absorbs more sunlight and warms up.

The main concern is global warming impacts will cause Antarctic ice shelves and glaciers to collapse into the oceans, something that’s been happening in the Arctic for some time.