During the summer months, Adélie penguins represent the dominant biomass of terrestrial Antarctica. Literally millions of individuals nest in ice-free areas around the coast of the continent. Hence, these modern populations of Adélie penguins have often been championed as an ideal biological indicator of ecological and environmental changes that we currently face. In addition, Adélie penguins show an extraordinary record of sub-fossil remains, dating back to the late Pleistocene. At this time, temperatures were much lower than now. Hence, this species offers unique long-term information, at both the genomic and ecological levels, about how a species has responded to climate change over more than 40 000 years.