Emperor penguins' breeding population may shrink by up to 80 percent by 2100 as melting sea ice reduces the emperor's once vast reach.

"Our best projections show roughly 500 to 600 breeding pairs remaining by the year 2100," said Stephanie Jenouvrier, a Woods Hole Oceanographic Institution biologist and lead author of a paper studying the future of the emperor penguin, in a press release.

"Today, the population size is around 3,000 breeding pairs."

Climate scientists and biologists formed an alliance to study the threat to the emperor's frigid domain. Their study focused on a region known as Terre Adélie, where French scientists have observed penguin populations for 50 years. While Terre Adélie’s population may be shrinking, other populations have disappeared entirely. For example, the Dion Islets colony no longer exists, according to the researchers.

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The research team used 20 climate models to foretell the fate of the penguins. The simulations showed a likely decline in sea ice during key times in the emperor penguins' breeding cycle.

The birds breed on sea ice then lay eggs in May-June. The male takes responsibility for the entire 62-66 days of incubation while the female goes to sea finding food.

The scientists warn that after 2040, sea ice will have shrunk below a usable threshold for the birds and their populations may well collapse. The study was published in Global Change Biology.

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Other recent research using satellite images has shown that the emperor penguin's population is larger than previously believed, but it looks like the full size of the bird's Antarctic empire may have been measured just in time to watch it crumble.

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Photo: Emperor Penguin courtship involves trumpeting and bonding of pairs. (Glen Grant, National Science Foundation, Wikimedia Commons)