Vanishing sea ice led to an unprecedented breeding failure among Antarctica’s iconic emperor penguins – adding to fears climate change could leave nine in 10 colonies quasi-extinct this century.
The world’s tallest and heaviest penguin, and featured in everything from Happy Feet to Antarctica New Zealand’s own logo, the emperor has long been the white continent’s best-known ambassador.
Over recent times, however, gradual shifts in their icy habitat have left scientists increasingly concerned about their long-term survival.
One major US study forecasted a potential 87 per cent decline in their population – falling from some 3000 breeding pairs to just a few hundred – by 2100, while another projected all of their colonies would be declining by century’s end, mostly due to habitat loss.
Now, a team led by a prominent UK scientist, currently based at the University of Canterbury, has delivered more bad news about the famous species.
In four of five known colonies in the central and eastern Bellingshausen Sea, Dr Peter Fretwell and his British Antarctic Survey (BAS) colleagues found it highly likely no chicks had survived.
The scientists examined satellite images that showed the loss of sea ice at breeding sites, well before chicks would have developed waterproof feathers.
Stable sea ice – namely “land-fast” ice that’s firmly attached to the shore for most of the year – was critical to the penguins, which laid eggs throughout winter, with chicks fledging over early summer.
Since the start of December, however, sea ice around Antarctica has shrunk to extraordinary lows – and the most extreme loss happened to be where those five colonies were located.
“We have never seen emperor penguins fail to breed, at this scale, in a single season,” said Fretwell, an award-winning cartographer and author of the 2022 book Antarctic Atlas.
“The loss of sea ice in this region during the Antarctic summer made it very unlikely that displaced chicks would survive.
“We know that emperor penguins are highly vulnerable in a warming climate - and current scientific evidence suggests that extreme sea ice loss events like this will become more frequent and widespread.”
Between 2018 and 2022 alone, an estimated 30 per cent of the 62 known emperor penguin colonies were affected by partial or total sea ice loss.
While it was difficult to immediately link specific extreme seasons to climate change, the latest models pointed to a longer-term decline in sea ice extent.
For the emperor – a species that’s never been plighted by large-scale hunting, habitat loss or over-fishing – climate change was considered the only major factor threatening their existence.
“This paper dramatically reveals the connection between sea ice loss and ecosystem annihilation,” BAS sea ice physicist Dr Jeremy Wilkinson said.
“Climate change is melting sea ice at an alarming rate. It is likely to be absent from the Arctic in the 2030s - and in the Antarctic, the four lowest sea ice extents recorded have been since 2016,” he said.
“It is another warning sign for humanity that we cannot continue down this path, politicians must act to minimise the impact of climate change. There is no time left.”
Permanent loss of sea ice also posed catastrophic implications for the rest of the world.
As white, frozen ocean water around Antarctica receded, heat absorption could accelerate surface warming and destabilise ice shelves.
Ultimately, this could lead to the rapid and potentially unstoppable loss of up to one third of Antarctica’s ice sheets, which together stored tens of metres of equivalent global sea level rise.
Today’s study, published in the journal Communications Earth and Environment, comes days after another paper described a range of recent extreme events in Antarctica, while hundreds of international scientists urgently called for more science in the Southern Ocean.
Jamie Morton is a specialist in science and environmental reporting. He joined the Herald in 2011 and writes about everything from conservation and climate change to natural hazards and new technology.