Dead penguin chicks from sea ice loss

Dead penguin chicks from sea ice loss

Emperor penguins depend on stable sea ice to raise their young. © British Antarctic Survey

In four Antarctic emperor penguin colonies, premature melting of Antarctic sea ice killed chicks in the past year, researchers report. This emerges from satellite observations in the Bellingshausen Sea. The discovery reinforces fears that projected warming in the Antarctic region could wipe out most of the emperor penguin populations by the end of this century, the scientists say.

In the cold half of the year, the sea ice spreads and in the summer half of the year it shrinks: This seasonal development occurs in both polar regions of the world. But climate change is eroding the sea ice. This is particularly drastic in the far north of the world and can be clearly linked to the Arctic warming trend. But even in the waters around Antarctica, minimum records have been recorded in recent years in the satellite recordings of sea ice extent going back 45 years. However, it is still unclear to what extent this has to do with special cyclical fluctuations and what role climate change plays in this. Basically, however, climate models show that the southern polar region of the earth is also affected by a warming trend with a melting effect.

These are bad prospects for the symbolic animal of Antarctica. Because the emperor penguins depend on stable sea ice that is connected to the coast for their reproduction. Once arrived at their ancestral breeding grounds, the animals lay their eggs during the Antarctic winter of May to June and warm them on their feet while standing on the sea ice. The chicks then hatch after 65 days. They are then fed by the parents until they fledge in the Antarctic summer. Only then do they develop waterproof plumage that enables them to swim. So until then they need the floating ice.

Outer space view of brood losses

As the research team from the British Antarctic Survey (BAS) in Cambridge reports, this has now led to a sad end to the 2022/23 breeding season for the emperor penguins in the Bellingshausen Sea in western Antarctica. Since 2018, the researchers there have been observing the developments in five emperor penguin colonies using satellite images. You are in front of Rothschild Island, Verdi Inlet, Smyley Island, the Bryan Peninsula and Pfrogner Point. The animals that keep returning there are clearly noticeable on the satellite images by the brown stains of their droppings on the ice. Colony sizes range from about 630 pairs on Rothschild Island to about 3500 pairs on Smyley Island.

As the researchers report, the sea ice around Antarctica reached its smallest extent in the 45-year history of satellite recordings at the end of December 2022. The region of the five observed penguin colonies in the Bellingshausen Sea was particularly affected by this decline. The satellite data showed that four colonies lost sea ice well before the penguin chicks fledged. Only the Rothschild Island colony was spared. It also became apparent that the affected breeding sites were being abandoned by the adult penguins. According to the researchers, it seems clear that there was a total loss of the young animals. “We have never seen emperor penguins fail to reproduce to this extent,” says lead author Peter Fretwell from the BAS.

Bad prospects for the symbolic animal of Antarctica

According to the team, this observation illustrates how severely threatened the emperor penguins are by thermal anomalies and long-term warming processes. Previous observations show that the animals can react to brood losses due to sea ice loss by moving to more stable locations in the following year. However, even this strategy cannot work in the long term if the sea ice habitat is affected in an entire region, say the scientists.

However, it is not clear how the climate and the loss of sea ice in the Antarctic region will continue to develop. This is because annual changes in sea ice extent are related to natural atmospheric patterns in the southern hemisphere and regional low-pressure systems. “We need further research and modeling to capture how much current conditions are affected by these phenomena and the natural variability of the oceans,” says Caroline Holmes of the BAS. “However, recent years of negative sea ice records and warming of the Southern Ocean strongly suggest that human-caused global warming is exacerbating these extremes. Climate models also predict a decline in Antarctic sea ice below both current and projected human carbon dioxide emissions.

In conclusion, BAS’ Jeremy Wilkinson said: “The current discovery is another warning sign for humanity. The connection between sea ice loss and ecosystem destruction becomes clear in a drastic way,” says the scientist.

Source: British Antarctic Survey, Article: Communications Earth & Environment, doi: 10.1038/s43247-023-00927-x

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