Climate News Network

Warming worries for south polar penguins

July 6, 2016, by Tim Radford

Adélie penguins on an iceberg in the Antarctic. Image: Jason Auch via Wikimedia Commons

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Scientists say that temperature rises in the Antarctic region could lead to serious decline in two-thirds of Adélie penguin colonies by the end of the century.

LONDON, 6 July, 2016 – A little climate change could be good for polar penguins, but too much could be very bad indeed, according to researchers in the US researchers.

They predict that, by 2060, almost a third of all Adélie penguin colonies in the Antarctic region could be in decline. By 2099, almost two-thirds could be in trouble.

In yet another future forecast based on a closer look at climates past. Megan Cimino, a marine biologist at the University of Delaware’s College of Earth, Ocean and Environment, and colleagues suggest in Scientific Reports journal that climate variation plays an integral part in Adélie numbers. Over the millennia, as glaciers have expanded, colonies have dwindled.

When the south polar climate mellows a little, the Adélie (Pygoscelis adeliae) return to the rocky nesting grounds they favour, and their numbers grow. Right now, according to a study two years ago, the species is thriving as never before. But there can be too much of a good thing, the latest study suggests.

Charismatic predator

“It is only in recent decades that we know Adélie penguins’ population declines are associated with warming, which suggests that many regions of the Antarctic have warmed too much and that further warming is no longer positive for the species,” Dr Cimino says.

The Adélie may be doing well for the moment. Other species of the region’s most charismatic predator face more immediate perils. One report suggests that the mix of rigid behaviour patterns and climate change puts all seven species of Eudyptes – the rockhoppers and crested penguins – at risk.

Long-term change in the Antarctic region poses a real hazard for the emperor penguin, and Magellanic penguins on the Argentine coast are threatened by increasing rainfall – which soaks the down of chicks while they are at their most vulnerable – and by hyperthermia as average temperatures rise.

“Studies like this are important because they focus our attention on areas where a species is most vulnerable to change”

The Delaware study used massive amounts of data to model habitat suitability. The researchers also looked at high resolution satellite images from 1980 to 2010, and at direct counts of populations in the breeding season.

That helped them work out where Adélies breed, and where they don’t, and how populations have changed over recent decades.

They started with evidence that the species has moved in and out of the West Antarctic Peninsula intermittently over the last 6,000 years, has made itself comfortable in East Antarctica at intervals for 14,000 years, and in the Ross Sea for at least 45,000 years.

Then they put their information into projections of change in the southern polar region to make estimates of what could happen between 2011 and 2099. They found that, when sea surfaces are warm, the species doesn’t flourish: a 30% colony decline – which adds up to about a fifth of all Adélie numbers – by 2060 and 60% by the century’s end.

Dramatic decline

The West Antarctic Peninsula is one of the most-rapidly warming regions on Earth. And penguin colonies there have declined dramatically.

But it doesn’t mean the end of a species. Antarctica is vast, and implacably icy, and although there is evidence that sea ice and glaciers may be in retreat, it is for the moment happening slowly around much of the mainland. So the Adélie would have somewhere to go.

Dr Cimino says: “The Cape Adare region of the Ross Sea is home to the earliest known penguin occupation and has the largest known Adélie penguin rookery in the world. Although the climate there is expected to warm a bit, it looks like it could be a refugia in the future. And if you look back over geologic time, it was likely a refuge in the past.” said.

“Studies like this are important because they focus our attention on areas where a species is most vulnerable to change. The results can be used for management, and they can have implications for other species that live in the area and for other ecosystem processes.” – Climate News Network

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