"Sentinels for a lost world"

A gentoo penguin
_____________________________________
It is ominous for humans, too, that fewer and fewer penguin chicks are being born or are surviving as climate change ruins their environment, writes Andrew Darby.

Some of climate's best canaries are turning out to be penguins. Down the mine, an upturned songbird in a cage was the first warning of a deadly gas seep. Above ground, an age of fossil fuels later, there are different silences.

In the sub-Antarctic, king penguins fledge fewer chicks if the parents must forage in warming seas. Rising waters are swamping limited nesting space for African penguins in Namibia. And because climate change's legacy varies capriciously, little penguins in Bass Strait seem to do better when the water temperature is up.

But it's on the the west coast of the Antarctic Peninsula that the signal is clearest. The raucous cacophony of Adelie penguins has disappeared from the landscape as colonies collapse.

"On top of a single high rock I see an unbearably poignant tableau," recounts the science writer Meredith Hooper, as she witnesses the demise of a colony.

"One fluffy chick is standing, very still, on its pebble nest, with one adult. A skua stands next to them. Waiting. Death openly in attendance."

Ocean temperatures off the peninsula's west coast are up 1 degree in 50 years. Annual mean temperatures on the peninsula have warmed 3 degrees - or 10 times the global rate. There, scientists have discovered that humans are making weather - ozone depletion and greenhouse gases have strengthened the westerly winds.

It was in this part of the world, too, that the 3250-square kilometre Larsen B iceshelf, stable for 12,000 years, collapsed so spectacularly over just eight days in early 2002.

Earlier that summer, 160 kilometres west across the peninsula from Larsen B, Hooper had arrived at the US Palmer station, with longtime Adelie biologist Bill Fraser, who concluded the breeding season at Palmer had gone to hell.

Adelies breed in summer on the few outcrops of Antarctic rock. In 2001-02 on an island cluster near Palmer, the rookeries were at first buried under repeated snowfalls. Then in high summer came the rarest of polar weather: rain.

Hooper, who describes in her book The Ferocious Summer, just published, what happens, watched as the snowstorms belted in. "If birds stand up to shift position, snow falls on the eggs to melt into a puddle. Eggs are crushed or kicked out of nests as birds try to deal with the snow. Or the eggs lie cold, flooded out."

Then after the surviving chicks fledged, the rain came. "Cold doesn't affect the chicks. It's the rain, soaking their down, forcing them to shiver, using up vital calories in an attempt to keep warm."

Reproduction in the Palmer study area collapsed. An average long-term breeding success rate of 1.34 chicks per pair was measured by Fraser as collapsing to 0.55 chicks. On one of the islands, Litchfield, 1000 pairs of Adelies nested 50 years ago. That summer in 2002, 12 chicks hatched - all to be taken by the crowding, predatory skuas.

"There are no sounds but the wash of the sea, the occasional calls of skuas," Hooper observed. "Every penguin is gone, the nests are abandoned. Listen to the silence. The silence of absence. The sound of failure."

Trouble for the Adelies did not end at the breeding colony. These are birds of the pack ice. Underneath it, swimming in meagre twilight, they find their food in winter. But along the western edge of the Antarctic peninsula, there is also a decline in sea ice.

Adelies are being displaced from their former ranges by more adaptable penguins usually seen in the sub-Antarctic: chinstraps and gentoos.

Hooper caught sight of a lone gentoo standing on the stubby station pier at Palmer. "I used to joke that gentoos were estate agents checking out potential property," Hooper ruminated. "Now here is a gentoo. Symbolically waiting."

These are real-time climate changes, not predictions for the future. They are unfolding in a matter of a few years. In Hobart this month at the sixth International Penguin Conference, as more scientists reported their worries, the birds' value as sentinels for climate change became clearer.