For decades, Antarctic sea ice seemed to be immune to climate change – growing in places and staying steady in others – while Arctic sea ice has seen serious decline. But this came to an end in 2016, with significant decreases to the sea ice. In fact, 2017 has a historic low, at nearly 30% below average. A sharp decline in Antarctic sea ice observed from 2016 – 2020 was equivalent to 30 years of ice loss in the Arctic! So, what’s the big deal with sea ice? It’s important because it acts as a mirror for solar radiation. Once it’s gone, that reveals dark ocean water below, which, instead of reflecting sunlight, absorbs it, leading to ocean warming. In late 2022, satellites recorded the early loss of sea ice in western Antarctica along the Bellingshausen Sea which led to the catastrophic loss of an estimated 10,000 emperor penguin chicks. The chicks didn’t have the time to shed their baby down feathers and develop waterproof feathers needed for swimming in the ocean.


As the climate continues to warm, it’s estimated that more than 90% of emperor penguin colonies will be extinct by the end of the century. Unlike other species of penguins that lay their eggs on land, the emperor penguins depend on sea ice. The colonies are even visible from space, given the guano (poop) they leave behind stands out against the white ice. The chicks normally set out to sea around December/January (spring/summer in Antarctica). But because the sea ice fragmented early, in November, the chicks weren’t yet ready.


Not only did sea ice break up earlier last season, the new ice floes have also been slow to form. This means the colonies will probably not be producing chicks for at least another year. The maximum sea ice extent is normally reached in September and it’s tracking far below where it should be. Anomalously warm ocean water and a particular pattern of winds has pushed ice back towards the coast, making it difficult to spread. Changes are expected – but, so rapidly? That’s unprecedented and a harbinger of things to come.


#sciencewednesdays #summitssongsandscience


Photo by Ulyana Peña: This penguin was spotted near the Ukrainian Antarctic Akademik Vernadsky station on Galindez Island, Antarctica, 65˚15’S, 64˚16’W, February 2020. Emperors are almost always found between the 66º and 77º south latitudes, so this was unusual to see.