Guest essay by Eric Worrall
Chris Turney, leader of the ill fated 2013/14 Ship of fools expedition to the Antarctic, which got stuck in the global warming while trying to retrace the Mawson Expedition, has been urging people to listen to his expert knowledge of Penguin colonies.
More than 150,000 Adélie penguins have perished in a single colony in Antarctica after the grounding of a giant iceberg.
The penguins used to thrive at Cape Denison in Commonwealth Bay, where strong winds blowing off the ice sheet kept a large area of water open near the shore.
But in December 2010 an iceberg bigger than the ACT grounded in the bay, trapping floating sea ice near the coast. The penguins now have to make a round trip of more than 120km to feed in the sea and since 2011 the population has plummeted from 160,000 to just 10,000.
According to new research co-authored by the University of NSW’s Climate Change Research Centre and published in the journal Antarctic Science, the colony could be wiped out within 20 years unless the sea ice breaks up or the iceberg, with an area of about 2900 square kilometres, moves.
“Iceberg doesn’t really do it justice,” Professor Turney said. “It’s like a small country, it’s enormous.
“As the planet warms you’re going to get more ice melting. The reality is, more icebergs will be released from Antarctica and just embed themselves along the coastline, and make the travelling distances for some of these colonies even further than they have been.”
Adélie penguins usually return to the colony where they hatched and try to return to the same mate and nest. Professor Turney said the Cape Denison penguins could face a grim future. “They don’t migrate,” he said. “They’re stuck there. They’re dying.“
Read more: Sydney Morning Herald
The abstract of Turney’s study;
The arrival of iceberg B09B in Commonwealth Bay, East Antarctica, and subsequent fast ice expansion has dramatically increased the distance Adélie penguins (Pygoscelis adeliae) breeding at Cape Denison must travel in search of food. This has provided a natural experiment to investigate the impact of iceberg stranding events and sea ice expansion along the East Antarctic coast. As part of the Australasian Antarctic Expedition 2013–14, the Adélie penguin colony at Cape Denison was censused to compare to historic counts. Whilst some 5520 pairs still bred at Cape Denison there has been an order of magnitude decline in Adélie numbers in the area in comparison to the first counts a century ago and, critically, recent estimates based on satellite images and a census in 1997. In contrast, an Adélie population on the eastern fringe of Commonwealth Bay just 8 km from the fast ice edge was thriving, indicating the arrival of B09B and fast ice expansion was probably responsible for the observed recent population decline. In conclusion, the Cape Denison population could be extirpated within 20 years unless B09B relocates or the now perennial fast ice within the bay breaks out. Our results have important implications for wider East Antarctic if the current increasing sea ice trend continues.
I have no doubt a natural catastrophe like the Cape Denison Iceberg can have a severe local impact, and I’m not surprised that a lot of birds have died, given the abrupt onset of the disaster. But suggesting penguins “don’t migrate” is ridiculous; if that was the case, there would only be one colony in the whole world, or more likely, there wouldn’t be any penguins at all.