Emperor penguins are not currently categorized as 'threatened' by the IUCN Red List, but they should be, according to biologists who study the species. They expect that at least 2/3 of Emperor colonies will have lost at least 50% of their populations by the end of the century because of changes in the sea ice caused by global warming.
Why does sea ice matter so much to penguins? It's not as if Antarctica itself will melt, but sea ice cover needs to be just right because too much of it makes for longer trips for the penguins when they go out to find food for their offsprings (their colonies are already 50–120 km/31–75 miles from the open sea), and too little reduces habitat for krill, an important food source for Emperors.
"If sea ice declines at the rates projected by the IPCC climate models, and continues to influence emperor penguins as it did in the second half of the 20th century in Terre Adélie, at least two-thirds of the colonies are projected to have declined by greater than 50 percent from their current size by 2100," said Stephanie Jenouvrier, a biologist with the Woods Hole Oceanographic Institution (WHOI). "None of the colonies, even the southern-most locations in the Ross Sea, will provide a viable refuge by the end of 21st century. We propose that the emperor penguin is fully deserving of endangered status due to climate change, and can act as an iconic example of a new global conservation paradigm for species threatened by future climate change.”
Right now, Emperor penguins are classified as 'near threatened' by the IUCN Red List and are being considered for inclusion to the U.S. list of endangered species under the US Endangered Species Act.
Via The Telegraph