Parts of Antarctica are warming rapidly, and this is affecting snowfall, snowmelt, sea ice distribution and thickness, and ice shelves. Different species are affected in different ways by these processes.
Emperor penguins are often cited as one of the most vulnerable animals. Over the past 50 years, the population of Emperors in Terre Adelie has decreased by 50% because of a decrease in adult survival during the late 1970s, when there was a prolonged warm period with decreased sea-ice extent (Barbraud and Weimerskirch, 2001).
Across the Western Antarctic Peninsula, winter temperatures are increasing and sea ice extent is decreasing, both of which profoundly affect the ecosystem. This has affected the krill population in the area, as krill are dependent on winter sea ice. Krill forms the basis of the Antarctic food chain and is a staple food for both Chinstrap and Adelie penguins. As krill abundance decreases, Adelie and Chinstrap penguin populations continue to decline (Trivelpiece et al., 2011).
Antarctic krill. By Øystein Paulsen – MAR-ECO, CC BY-SA 3.0
Barbraud C, Weimerskirch H. Emperor penguins and climate change. Nature 411, 183-186 (2001).
Trivelpiece WZ, Hinke JT, Miller AK, Reiss CS, Trivelpiece SG, Watters GM. Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica. Proceedings of the National Academy of Sciences 108, 7625-7628 (2011).