Emperor penguins are closer to extinction than ever due to ‘catastrophic’ breeding failure caused by the loss of sea ice ten times the size of Britain, warns new research.
Colonies of the tallest and heaviest of all living penguin species suffered an ‘unprecedented’ failure to breed in a region of Antarctica where there was total sea ice loss last year, say scientists.
The worrying discovery supports predictions that more than 90% of emperor penguin colonies will be quasi-extinct by the end of the century, based on current global warming trends.
Researchers from British Antarctic Survey (BAS) discussed the high probability that no chicks had survived from four of the five known emperor penguin colonies in the central and eastern Bellingshausen Sea.
The scientists studied satellite images that showed the loss of sea ice at breeding sites, well before chicks would have developed waterproof feathers, enabling them to survive in the icy waters.
Emperor penguins are dependent on stable sea ice that is firmly attached to the shore for the majority of the year, from April through to January.
Once they arrive at their chosen breeding site, penguins lay eggs in Antarctic winter from May to June. Eggs hatch after 65 days, but chicks do not fledge until the Antarctic summer, between December and January.
At the beginning of December 2022, the Antarctic sea ice extent had matched the previous all-time low set in 2021.
The most extreme loss was seen in the central and eastern Bellingshausen Sea region, west of the Antarctic Peninsula where there was a 100% loss of sea ice in November 2022, according to the study published in the journal Communications Earth & Environment.
‘We have never seen emperor penguins fail to breed, at this scale, in a single season,’ said lead author Dr Peter Fretwell.
‘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.’
Since 2016, Antarctica has seen the four years with the lowest sea ice extents in the 45-year satellite record, with the two lowest years in 2021/22 and 2022/23.
Between 2018 and 2022, 30% of the 62 known emperor penguin colonies in Antarctica were affected by partial or total sea ice loss.
A longer-term decline in sea ice extent is expected from the current generation of climate models.
Emperor penguins have previously responded to incidents of sea ice loss by moving to more stable sites the following year. However, scientists say that strategy won’t work if sea ice habitat across an entire region is affected.
Emperor penguins have never been subject to large scale hunting, habitat loss, overfishing or other local human-made interactions in the modern era.
Unusually for a vertebrate species, climate change is considered the only major factor influencing their long-term population change.
Over the last seven years, sea ice around Antarctica has decreased significantly.
By the end of December last year, sea ice extent was the lowest experienced in the 45-year satellite record. In the Bellingshausen Sea, the home of the penguin colonies in the study, sea ice didn’t start to re-form until late April.
Scientists say that, since then, the deviation from the norm has intensified.
As of Sunday, August 20, the sea ice extent was 2.2 million km2 lower than the 1981-2022 average – surpassing the record winter low on the same date last year.
The researchers said the missing area is larger than the size of Greenland, or around ten times the size of the United Kingdom.
‘Right now, in August 2023, the sea ice extent in Antarctica is still far below all previous records for this time of year,’ said Dr Caroline Holmes, a polar climate scientist with BAS.
‘In this period where oceans are freezing up, we’re seeing areas that are still, remarkably, largely ice-free.
‘Year-to-year changes in sea ice extent are linked to natural atmospheric patterns such as El Niño-Southern Oscillation, the strength of the southern hemisphere jet stream, and regional low-pressure systems.
‘We’ll need years of targeted observations and modelling to know precisely how much the current conditions are being influenced by these phenomena and by natural ocean variability.
“However, the recent years of tumbling sea ice records and warming of the subsurface Southern Ocean point strongly to human-induced global warming exacerbating these extremes.’
Dr Jeremy Wilkinson, a sea ice physicist at BAS, added: ‘This paper dramatically reveals the connection between sea ice loss and ecosystem annihilation.
‘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.
‘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.’
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