The loss of sea ice in Antarctica has caused unprecedented breeding failure for emperor penguins, researchers say.

According to British Antarctic Survey (BAS) scientists, the penguin colonies experienced unprecedented breeding failure in a region of Antarctica where there was total sea ice loss in 2022.

They say the discovery supports predictions, based on current global warming trends, that more than 90% of emperor penguin colonies will be quasi-extinct by the end of the century.

In the new study, researchers 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.

They examined satellite images that showed the loss of sea ice where the animals go to have their young, well before chicks would have developed waterproof feathers.

Emperor penguins need stable sea ice that is firmly attached to the shore from April through to January.

Once they arrive at their chosen breeding site, the animals lay eggs in Antarctic winter – from May to June – which hatch 65 days later, but chicks do not have waterproof feathers until between December and January.

According to the study, 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.

Lead author of the study, 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.”

Since 2016, Antarctica has seen the four years with the lowest sea ice extents (areas of ice that cover the ocean) 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, the experts say.

Although it is difficult to immediately link specific extreme seasons to climate change, a longer-term decline in sea ice extent is expected from the current generation of climate models.

In the past, emperor penguins have responded to incidents of sea ice loss by moving to more stable sites the following year.

However, scientists say that this will not work if sea ice habitat across an entire region is affected.

The five colonies of penguins studied were all discovered in the last 14 years using satellite imagery – Rothschild Island, Verdi Inlet, Smyley Island, Bryan Peninsula and Pfrogner Point.

All five colonies had been shown to return to the same location each year to breed, with only one previous instance of breeding failure at Bryan Peninsula in 2010.

According to the findings, by the end of December 2022, sea ice extent was the lowest experienced in the 45-year satellite record.

In the Bellingshausen Sea, the home of the penguin colonies in this study, sea ice did not start to re-form until late April 2023.

And the trend has continued.

As of August 20 2023, the sea ice extent was 2.2 million square kilometres lower than the 1981-2022 average (17.9 million square kilometres) significantly surpassing the record winter low on August 20 2022 of 17.1 million square kilometres.

This missing area is larger than the size of Greenland, or around 10 times the size of the United Kingdom.

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 Nino-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.”

The study, published in Communications Earth & Environment, used images from the European Commission’s Copernicus Sentinel-2 satellite mission, which has continuously monitored the area in Antarctica since 2018.