The British Antarctic Survey reports on one consequence of thinning sea ice after one of the warmest winters on record. Out of five known breeding colonies in the Belligshausen Sea, four experienced “catastrophic failures,” with in all likelihood no chicks surviving at all:
The scientists examined satellite images that showed the loss of sea ice at breeding sites, well before chicks would have developed waterproof feathers.
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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 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.
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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.
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Over the past seven years, sea ice around Antarctica has decreased significantly. 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 didn’t start to re-form until late April 2023.
Since then, the deviation from the norm has intensified: as of 20 August 2023 the sea ice extent was 2.2 million km2 lower than the 1981-2022 median (17.9 million km2) significantly surpassing the record winter low on 20 August 2022 of 17.1 million km2. This missing area is larger than the size of Greenland, or around ten times the size of the United Kingdom.
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You can read more about the breeding failures here, in Communications Earth & Environment.