Emperor penguins and climate change

Variations in ocean-atmosphere coupling over time in the Southern Ocean(1-3 ) have dominant effects on sea-ice extent and ecosystem structure(4-6), but the ultimate consequences of such environmental changes for large marine p redators cannot be accurately predicted because of the absence of long-term data series on key demographic parameters(7,8). Here, we use the longest t ime series available on demographic parameters of an Antarctic large predat or breeding on fast ice(9,10) and relying on food resources from the Southe rn Ocean(11). We show that over the past 50 years, the population of empero r penguins (Aptenodytes forsteri) in Terre Adelie has declined by 50% becau se of a decrease in adult survival during the late 1970s. At this time ther e was a prolonged abnormally warm period with reduced sea-ice extent. Morta lity rates increased when warm sea-surface temperatures occurred in the for aging area and when annual sea-ice extent was reduced, and were higher for males than for females. In contrast with survival, emperor penguins hatched fewer eggs when winter sea-ice was extended. These results indicate strong and contrasting effects of large-scale oceanographic processes and sea-ice extent on the demography of emperor penguins, and their potential high sus ceptibility to climate change.