When Emperor Island was first discovered off the coast of Antarctica back in 1948, it was so named for the thriving colony of around 300 penguins that met there each year to breed. Just over sixty years later, however, there's not a single penguin in sight -- and researchers suspect that melting off from global warming may be to blame for the colony's disappearance. Emperor penguins typically return to breed and nest in the same place that they themselves were born, but this is the first time biologists have recorded a complete collapse of a once healthy colony -- though it's not entirely unexpected given recent changes in sea ice levels. The breeding colony on Emperor Island, off the West Antarctic Peninsula, was first observed to be declining in the late 1970s, until a aerial survey conducted in 2009 revealed that no birds were there at all.
Researchers aren't entirely certain what is behind the unprecedented disappearance of the Emperor penguin colony, though a team of scientists studying the phenomenon theorize that rising temperatures in the region may have made the island a less-than ideal breeding ground. "The one site in Antarctica where we have seen really big changes is the West Antarctic Peninsula," says Philip Trathan of the British Antarctic Survey.
A report from LiveScience offers more details on the team's findings:
Data collected from a station about 25 miles (40 kilometers) away shows a marked increase in air temperature; meanwhile, the local sea ice in the area has been forming later and melting earlier. One study published in 2007 in the Journal of Geophysical Research found that between 1979 and 2004 in this region, sea ice began advancing about 54 days later and retreating 31 days earlier. (This trend does not hold for all of Antarctic waters, but, ultimately, Antarctic sea ice is expected to shrink significantly.)
In addition to destroying colony habitat, warming and the loss of sea ice could indirectly affect the penguins by reducing the availability of the fish, krill and squid they eat, or by increasing the presence of predators, such as giant petrels, the authors write.
Because this is the first time such a disappearance has been observed, the research team is reluctant to say that changes in sea ice levels ultimately caused the penguin colony to die-off entirely, or if they simply relocated. "That's one of the big unknowns," says Trathan.
While penguins living in the Antarctic may be the first to be impacted by rising global temperatures and melting polar ice, they certainly won't be the last. Experts predict that sea levels could rise by over four feet by the end of the next century alone. Worse still, if the Western Antarctic Ice Sheet were to melt entirely, the sea levels could rise some 20 more feet, rendering coastal communities across the globe as virtually unrecognizable, devoid of its previous inhabitants -- a bit like Emperor Island nowadays, perhaps.
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