Everybody loves emperor penguins thanks to films such as "Madagascar" and "Happy Feet," but future generations may possibly get to know these cute, cuddly creatures as extinct animals and group them together with other long-gone creatures like the dinosaurs.
By the next century, scientists predict that the global population of emperor penguins will drop by 19 percent and that two-thirds of the 45 colonies found thriving in Antarctica will be reduced by 50 percent if the rate at which temperatures rise continues as predicted by the Intergovernmental Panel on Climate Change (IPCC). This justifies the inclusion of the golden-crowned sea birds into the list of endangered species, according to the study published in the Nature Climate Change journal.
In 2012, the International Union for Conservation of Nature changed the status of emperor penguins from one of "least concern" to "near threatened." It is, however, not yet considered as endangered.
Emperor penguins depend largely on the existence of sea ice, where they get their regular supply of krill to feed their young. Too little sea ice means young penguins will have less to eat and are in more danger of death, but this doesn't mean having more sea ice than usual is beneficial for the sea birds. In recent years, Antarctica has seen record high levels of sea ice despite rising global temperatures. With too much sea ice, adult penguins will have to swim further to catch fish and squid, which means they take more time and energy looking for food and less for taking care of their young.
Lead researcher Stephanie Jenouvrier, a biologist at the Woods Hole Oceanographic Institution, says the study is the first comprehensive look at the long-term projections of the entire emperor penguin population in Antarctica. To arrive at their predictions, the scientists used an algorithmic model that combines data on sea ice and mating, rearing, foraging, feeding and other patterns of behavior gathered from observing a penguin colony at Terre Adélie, a region that lies across the Southern Ocean from New Zealand.
"Our models take into account both the effects of too much and too little sea ice in the colony area," says Jenouvrier. She also says that although only the Adélie penguins were observed, the researchers have direct satellite observations of 44 other colonies in the area.
The researchers predict global populations will actually rise, at least initially, especially in the colonies found on the southernmost Ross Sea. Currently, colonies off the western coast are on the rise thanks to the break-up of large glaciers in the area. But the population increase is only going to be temporary, according to Jenouvrier, and colonies will start seeing a decline in numbers starting in 2040. By 2080, the researchers say all 45 colonies will see a decrease and, by 2100, approximately two-third of the 45 colonies currently present will be reduced by 50 percent.
The colonies living off the coast of the western Indian Ocean and the eastern Weddell Sea will be the hardest hit, while nine other colonies will be "quasi-extinct," according to the researchers. Currently, only the Adélie, chinstrap and king emperor penguins are seeing a population increase, although the Adélie and chinstrap penguins are susceptible to global warming due to their size.
"When a species is at risk due to one factor -- in this case, climate change -- it can be helped, sometimes greatly, by amelioration of other factors," says co-author Hal Caswell. "That's why the Endangered Species Act is written to protect an endangered species in a number of ways -- exploitation, habitat, disturbance, etc. -- even if those factors are not the cause of its current predicament."