Warmth puts penguins under pressure

Scientists say some penguins are at risk

From Christine McGourty, science correspondent, in Antarctica

New research suggests Adelie penguins may abandon the Antarctic Peninsula if temperatures continue to increase.

If warming continues they would continue to decline in the peninsula and may completely abandon much of it

Professor Steve Emslie, University of North Carolina

Scientists studying fossilised penguin remains near Britain's Antarctic base at Rothera say there were far fewer Adelie penguins here during warmer periods in the past.

Numbers are falling now as the peninsula continues to warm faster than globally averaged rise in temperatures.

Researchers believe this change in the environment may be affecting the penguins' supply of food in an as yet unexplained way.

Complex picture

When you step outside the base here, the penguins are never far away.

They float by on the icebergs, sunbathing side by side with the seals. And on land, these inquisitive creatures are not scared to come up close, perhaps hopeful of finding some food. But if the warmer weather here continues it could be bad news.

Britain's Antarctic base at Rothera

Unlike some other species further north, they thrive in the coldest Antarctic conditions. And here on the Antarctic Peninsula, temperatures are increasing five times faster than the rest of the world, according to Dr David Vaughan of the British Antarctic Survey.

"Most of Antarctica has been warming at about the same rate as the global average, about two thirds of a degree Celsius over the 20th Century," he said.

"The Antarctic Peninsula has been warming much more rapidly.

"The records we have for the last 50 years suggest it's warmed by about two and a half degrees Celsius over that period, so it's much more substantial than global mean warming."

Abandoned colonies

Professor Steve Emslie of the University of North Carolina, US, has been examining fossilised penguin remains in abandoned colonies near Rothera and he has found that in warmer periods in the past, the Adelie penguin numbers dropped.

He believes this is likely to happen again.

"I think if warming continues they would continue to decline in the peninsula and may completely abandon much of it," he said. "It depends how bad the warming gets."

It is a complicated story, however. Adelie numbers may in future also decrease in the Ross Sea area of Antarctica, where many American scientists are based. But for the moment, the Adelie colonies are stable there and even increasing.

"In the short term, warming has been beneficial there in a way because it's removed some of the sea ice blocking some areas where they can set up colonies," said Professor Emslie.

Ancient evidence

Research by Italian scientists in the Ross Sea area showed there was a large expansion of Adelie penguins there between 3,000 and 4,000 years ago, during a warmer period.

"We're in a similar period today," said Professor Emslie. "Though it's probably already reached the point it was 3-4,000 years ago and if warming continues it could be detrimental because it could be affecting their food in ways we don't quite understand yet."

Some other penguin species may benefit though. The chinstrap penguins prefer to breed in areas that are free of ice and their numbers are increasing worldwide.

Professor Emslie said he had seen evidence from the fossil remains that suggested chinstrap colonies in some areas expanded when the climate was warmer.