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The decline of sea ice in Antarctica because of global warming is presenting penguin colonies with a "double whammy" through declining food stocks and increasing competition from commercial fishers, says the WWF.
In a report presented at the Bali climate change conference yesterday, the WWF said the penguin
population of Antarctica was threatened by global warming.
Anna Reynolds, deputy director of WWF's global climate change programme, said the literature review showed the four populations of penguins that bred on the continent were under growing pressure.
She said the penguins faced a double whammy as the declining sea ice reduced krill numbers while also opening up the way for more commercial fishing.
That was affecting penguins in the northern parts of Antarctica, such as Chinstraps and Gentoos, which were normally more resilient to climate change. There was also a problem of global warming taking away precious ground on which penguins raised their young.
"Now it seems these icons of the Antarctic will have to face an extremely tough battle to adapt to the unprecedented rate of climate change."
Ms Reynolds said the Antarctic Peninsula was warming five times faster than the global average. The vast Southern Ocean had warmed all the way down to a depth of 3000m.
Sea ice, the ice that formed from sea water, covered 40 per cent less of the area than it did 26 years ago off the West Antarctic Peninsula.
"This decrease led to reduced numbers of krill, the main source of food for Chinstrap penguins. The number of Chinstraps decreased by as much as 30 to 66 per cent in some colonies, as less food made it more difficult for the young to survive."
It was a similar story for Gentoo penguins, which were increasingly dependent on the declining krill stocks as overfishing killed off their usual food sources.
Ms Reynolds said some of the Emperor penguin colonies had halved in size over the past half century. Warmer winter temperatures and stronger winds meant the penguins had to raise their chicks on increasingly thinner sea ice.
On the northwestern coast, populations of Adelie penguins had dropped by 65 per cent over the past 25 years and Gentoos and Chinstraps had invaded the region.
Ms Reynolds said warmer temperatures meant the atmosphere could hold more moisture, which in turn brought more snow.
"Scientists are worried for the Adelie penguin, which need land that is free of snow and ice to raise their young."