Going to extremes

摘要

YOU'RE never short of superlatives describing Antarctica. The highest, driest, coldest and windiest continent on Earth, 58 times the size of the UK, capped by an ice sheet over 4km thick and surrounded by some of the stormiest seas on the planet, it is the world's last great wilderness. It's also an important natural laboratory, which is why British Antarctic Survey (BAS) and many other nations maintain scientific facilities there. It was at Halley, one of BAS's five Antarctic research stations, that the hole in the ozone layer was first discovered in 1985, and much of our knowledge of climate change comes from analysing the ancient bubbles of air trapped in Antarctic ice cores. Completed in 1992, the current research station at Halley is the fifth facility to be built on the Brunt Ice Shelf. Constructed on jackable legs, Halley V has lasted twice as long as its predecessors (see box below) because it has been able to rise above the ever-accumulating snow. But being built not on solid ground but on floating ice flowing away from the continent, Halley V is now too near the edge of the ice for comfort and needs to be replaced.