Cheers. So the chicks did survive, but then drowned because their feathers weren't waterproof, when they went to swim? Or the ice melted from under them, before they were ready?

Emperor penguins can be breed in captivity, btw. So it can't be that ice is required. It must be that the environment needs to be stable. But then the article says it was the lack of ice that did it, not the changing of the environmental conditions.