Antarctic melting sea ice may doom emperor penguins, according to scientists

The world's largest penguins could be pushed to the brink of extinction by the end of this century due to the melting of Antarctic sea ice caused by global climate change, according to scientists.

Emperor penguins, the species of these aquatic flightless birds featured in the Oscar-winning 2005 documentary March of the Penguins, breed on Antarctic sea ice and dive from the sea ice to feed on krill, fish and squid.

Researchers led by biologists Stephanie Jenouvrier and Hal Caswell of the Woods Hole Oceanographic Institution in Massachusetts used mathematical models to predict how climate warming and the resulting loss of sea ice would affect a big colony of emperor penguins at Terre Adelie, Antarctica.

Their models on average forecast a decline of 87 per cent in the colony's population - from the current 3,000 breeding pairs to 400 breeding pairs by 2100. But some models predicted the colony's population would plummet by at least 95 per cent, placing the birds there at risk of extinction.

Terre Adelie is one of roughly 40 colonies of emperor penguins. The researchers viewed the fate of this colony as a possible example of what could happen to the entire species, now estimated at about 200,000 breeding pairs in all.

"Presumably, similar kinds of effects will happen in other colonies and other locations around Antarctica," said Dr Caswell, although he added that some colonies could be affected less dramatically by climate change.

"This is another example of the way in which climate change affects various factors of the habitat of animals adapted to live in really extreme conditions and puts populations at risk. It's very similar to the situation with the polar bears in the Arctic," Dr Caswell said.

Polar bears, the world's largest bear species, also rely heavily on sea ice, albeit on the opposite end of the planet.

Emperor penguins live in some of the coldest conditions on Earth. They are the largest of the world's penguins, weighing up to about 40 kilogrammes and standing up to about 1.15 metres tall. They dive to depths of 550 metres and hold their breath for up to 22 minutes.

"I hope people will be sensitised by the effect of climate change on such a charismatic species and realize there are strong ecological consequences of climate change," Dr Jenouvrier, whose findings appear in the journal Proceedings of the National Academy of Sciences, said in a telephone interview.

The researchers used climate projections by the UN Intergovernmental Panel on Climate Change, and also took into account how emperor penguins were affected by past fluctuations in their sea ice environment.

Since the 1960s, the number of emperor penguins in his colony already has dropped by half, Dr Caswell said.