They're fat and happy today, but emperor penguins may have had too much of a good thing during the last ice age. (Barbara Wienecke)

A new genetic analysis of emperor penguins suggests that even the kings of the cold can get too chilly for their own good. In fact, the current emperor oasis of Antarctica may have been too icy to support them during the last ice age.

Emperor penguins can thrive at temperatures of -22 degrees Fahrenheit. But from around 26,500 to 19,000 years ago (during the time when Earth's glacial sheets where at the most widespread they've been since), populations were as much as seven times smaller than today.

Researchers from the universities of Southampton, Oxford, Tasmania and the Australian Antarctic Division traced modern emperor penguins back to three distinct genetic groups that survived the colder period. They believe that the three groups broke into small populations of refugees, then became more prominent again once the world warmed up. Their work was published this week in Global Change Biology.

One of these distinct groups can currently be found by the Ross Sea of Antarctica, which the researchers believe may have served as one of the three safe havens during the ice age.

Even though emperor penguins need glacial sheets -- they do their breeding on the ice -- they also need access to the open ocean for feeding. In most parts of Antarctica, it seems, the ice coverage proved too widespread for sufficient access to food.

With temperatures too cold to maintain proper ice-to-ocean ratio, the researchers suspect that penguins relied on polynyas -- places where the wind and currents were strong enough to keep sea ice from forming -- to survive.

Just because the planet is warming doesn't mean that emperor penguins are safe from climate change. In the Ross Sea, wind pattern changes associated with climate change are causing an increase in ice. This trend is expected to reverse within the century, but the new research suggests that we'd be wise to keep an eye on how our feathered friends down there manage through the shift.

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