Emperor penguins suffer ‘unprecedented’ breeding failure as sea ice disappears

90 percent of Emperor penguin colonies could go quasi-extinct by 2100.
Two Emperor penguin chicks standing on sea ice in Antarctica.
Climate change is the biggest threat to Emperor penguin populations. Peter Fretwell/British Antarctic Survey

The Earth’s South Pole is at a climate change crossroads, with Antarctica’s quickly melting ice and expected consistent ocean heat waves. Now, one of its signature species is in trouble. A study published August 24 in the journal Communications Earth & Environment found that some Emperor penguin colonies saw an unprecedented breeding failure in a region of the continent that experienced a total loss of sea ice in 2022.

[Related: The East Antarctic Ice Sheet could raise sea levels 16 feet by 2500.]

Four out of five Emperor penguin colonies in the Bellingshausen Sea on the western side Antarctica did not see any chicks survive to successfully fledge in the spring of 2022. Emperor penguin chicks typically fledge at four months old, when they’ve developed their first set of waterproof feathers. 

All of the colonies in this study have been discovered in the last 14 years using satellite imagery, and there has only been one previous instance of breeding failure among these penguin populations. 

“We have seen the occasional colony have bad sea ice and early break up, but this most unusual thing in this study is that a whole region has had extremely poor sea ice,” Peter Fretwell, a remote sensing expert and environmental scientist with the British Antarctic Survey and co-author of the study, tells PopSci

Similarly, the Halley Bay penguin colony, which was not included in this study and lives in a different part of Antarctica, failed to raise any chicks between 2016 and 2019. That failure was also attributed to sea ice loss. 

From April to January, Emperor penguins depend on stable sea ice that is firmly attached to the shore or ‘land-fast’ ice. Once they arrive at their chosen breeding site, penguins will lay eggs during the Antarctic winter (May to June) in the ice. Eggs will hatch after 65 days, but the chicks do not fledge until December to January during Antarctic summer. 

“This year the ice in the Bellingshausen Sea did not form until late June–when the birds should already be on their eggs. It may be that in future this region could be one of the first to become unsuitable breeding habitat,” says Fretwell.

Between 2018 and 2022, 30 percent of the 62 known Emperor penguin colonies living in Antarctica were affected by partial or total sea ice loss. The British Antarctic Survey said that it is difficult to immediately link specific extreme seasons to climate change, but a longer-term drop in sea ice extent is expected based on current climate models.  

[Related: The march of the penguins has a new star: an autonomous robot.]

By early December 2022, the Antarctic sea ice matched the previous all-time low set in 2021. The central and eastern Bellingshausen Sea region saw the worst of it, with 100 percent sea ice loss.

“Right now, in August 2023, the sea ice extent in Antarctica is still far below all previous records for this time of year,” Caroline Holmes, a British Antarctic Survey polar climate scientist who was not involved in the study, said in a statement. “In this period where oceans are freezing up, we’re seeing areas that are still, remarkably, largely ice-free.”

Previously, Emperor penguins have responded to this sea ice loss by moving to a more stable site the next year. However, this strategy won’t work if the loss of sea ice habitat extends to an entire region. 

These populations have also not been subject to large scale hunting or overfishing and other direct interactions with humans, and climate change is considered to be the only major influence on their long-term population changes. More recent efforts to predict Emperor penguin population changes paint a bleak picture, showing that if the present rate of warming persists, more than 90 percent of colonies will be quasi-extinct by the end of this century.

Daniel P. Zitterbart, a physicist by training and an Emperor penguin remote sensing expert from Woods Hole Oceanographic Institution who was not involved in the study called it a very important and timely investigation. 

“The sad part is we had all been expecting this, but we expected this later. It happened for so many colonies in just one year, just because of changing weather patterns,” Zitterbart tells PopSci. “Peter points out that this is likely due to La Niña and change in wind patterns, but the study can show us how increased extremes can have an immediate impact on those colonies that are further up north.”

As their habitat is expected to shrink over the next century, scientists are unsure if the areas that they are moving to will have enough resources to host all of the penguins coming in. Studies like this one continue to ring the alarm that Antarctica and its wildlife remain vulnerable to extremes.

“Hopefully, this is a one year thing for now and with the weather pattern changing back to El Niño, the sea ice in this location this year and next year will grow back to what it normally is,” says Zitterbart. “But we all know that this year we had the first 6.4 Sigma event, which means that the sea ice in Antarctica is very low.”