Emperor penguins face tragic breeding failures due to sea ice loss

Emperor penguins are facing a breeding failure on a scale never seen before, due to the unprecedented loss of Antarctic sea ice.

Emperor penguins rely on stable sea ice, firmly attached to the shore as “land-fast” ice, for the majority of the year. It serves as their breeding ground from April to January, with eggs being laid during the harsh Antarctic winter from May to June. These eggs hatch after 65 days, and the chicks do not fledge until summer, between December and January.

A study published today in the journal Communications Earth & Environment reveals the catastrophic effects of Antarctic sea ice loss. 

Researchers from the British Antarctic Survey (BAS) say that it is likely that no chicks survived from four of the five known emperor penguin colonies in the central and eastern Bellingshausen Sea.

Displaced chicks

Study lead author Dr Peter Fretwell said: “We have never seen emperor penguins fail to breed, at this scale, in a single season. 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.”

A grim outlook

Since 2016, Antarctica has experienced the four lowest years of sea ice extents in the 45-year satellite record. Between 2018 and 2022, 30% of the 62 known emperor penguin colonies were affected by partial or total sea ice loss.

These colonies have previously responded to such incidents by relocating to more stable sites, but scientists warn that this strategy won’t work if sea ice habitat across an entire region is affected. Uniquely for a vertebrate species, climate change is considered the sole major factor influencing their long-term population change.

The forecast for the emperor penguins is devastating. If present rates of warming persist, over 90% of colonies will be quasi-extinct by the end of this century.

Satellite monitoring

Scientists have discovered the five colonies of penguins studied (Rothschild Island, Verdi Inlet, Smyley Island, Bryan Peninsula, and Pfrogner Point) in the last 14 years using satellite imagery. 

This technology also allows for continuous monitoring. The European Commission’s Copernicus Sentinel-2 satellite mission has kept a watchful eye over Antarctica since 2018, providing crucial data.

By the end of December 2022, sea ice extent was the lowest experienced in the 45-year satellite record. As of August 2023, the sea ice extent was 2.2 million km^2 lower than the 1981-2022 median, a missing area larger than the size of Greenland or around ten times the size of the United Kingdom.

Tumbling sea ice records

Dr. Caroline Holmes, a polar climate scientist at BAS, said: “Right now, in August 2023, the sea ice extent in Antarctica is still far below all previous records for this time of year. 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 modeling 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.”

Ecosystem annihilation 

The loss of Antarctic sea ice, leading to the catastrophic breeding failure for emperor penguins, is a major wakeup call. Climate models show a decline in Antarctic sea ice under current and forecast human carbon dioxide emissions. 

“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,” said Dr. Jeremy Wilkinson, a sea ice physicist at BAS.

“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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