PARIS • Global warming is on track to wipe out 70 per cent of the world's king penguins by century's end, putting the regal birds on a path towards extinction, researchers have warned.
As climate change drives away the fish and squid upon which the flightless creatures depend, the penguins must swim further afield to find sustenance for their hungry hatchlings on land.
"For most colonies, the length of the summer trips by parents to get food will soon become so long that their offspring could starve while waiting," said Dr Celine Le Bohec, a population ecologist at the University of Strasbourg/CNRS in France and co-author of a study in Nature Climate Change. "If global warming continues at its current pace, the species may disappear," she told Agence France-Presse.
Dr Le Bohec and her colleagues calculate that 1.1 million king penguin couples will be forced to abandon their current breeding grounds - mainly on the islands of Crozet, Prince Edward and Kerguelen - within a matter of decades.
On current trends, the planet will heat up 3 deg C or 4 deg C compared with mid-19th-century levels by 2100. Even if humanity caps the rise of Earth's surface temperature at 2 deg C - the target set in the 197-nation Paris climate treaty - up to half of the iconic birds could be forced into exile without a clear destination.
The problem is that there are few suitable alternatives, creating a no-win, feed-or-breed dilemma.
"There are only a handful of islands in the Southern Ocean, and not all of them are suitable to sustain large breeding colonies," said lead author Robin Cristofari from the Centre Scientifique de Monaco.
At just under a metre tall, king penguins - whose black-and-white tuxedos are accessorised with orange bands around the neck - are "serially monogamous", meaning they stay faithful to one mate each year. The female bird produces a single egg, which incubates for nearly two months. Male and female take turns keeping it warm.
King penguins are picky about where they settle: they need year-round tolerable temperatures, no winter sea ice circling the island, and a smooth beach of sand or pebbles. Above all, they need an abundant, nearby source of food. For thousands of years, that came from the Antarctic Polar Front, an upwelling from the Southern Ocean teeming with fish, squid and other comestibles.
With climate change, however, this conveyor belt of nutrition has been drifting southwards.
Analysing the king penguin genome, the researchers reconstructed fluctuations in their population over the last 50,000 years. Past episodes of natural climate change, they found, also shifted marine currents and the distribution of sea ice, and the birds always managed to adapt.
"King penguins were able to move around quite a lot to find the safest breeding ground," explained senior author Emiliano Trucchi, an evolutionary geneticist at the Universities of Ferrara and Vienna in Italy. But this time, he added, man-made climate change is too abrupt and rapid. To make matters worse, king penguins are also dealing with competition from industrial fishing boats that scoop up fish by the tonne, and other species of penguins.