Penguins: Endangered by Melting Ice
Rising temperatures and loss of snowpack or ice caps endangers a number of alpine and arctic species, including penguins. At the Antarctic, several species of penguins that depend on sea ice are experiencing population changes ; Colonies of Adélie penguins are declining at warmer sites, such as Anvers and King George Island, but expanding at colder sites such as Cape Royds on the Ross Sea. This indicates that populations of Adélie penguin are shifting location.  Emperor penguins also depend on sea ice, and their colony at Point Geologie is declining.
Both Adélie penguins and emperor penguins nest near Point Geologie, but at different times of the year. Temperatures at this site have remained relatively constant over the past 50 years, while the extent of sea ice has diminished 66%.  The date of the penguins’ arrival at the site has remained relatively constant for the two species, whereas the date on which they begin laying eggs is now delayed by a few days. Apparently, the decreased amount of sea ice has reduced the quantity and accessibility of food supplies such as krill, and these penguins need more time to build up the fat reserves necessary for breeding. 
Penguins in Antarctica (A) Locations of Adélie and emperor penguin colonies on Antarctica for which multiyear censuses of population size are available. (B) Number of breeding pairs of Adélie penguins on Anvers Island and King George Island are declining, whereas the colony on Signy Island is highly variable in size, and that on Cape Royds is growing. The colony of emperor penguins on Point Geologie is shrinking. [B after Croxall et al. 2002.]
 Parmesan, C. (2006) Ecological and evolutionary responses to recent climate change. Annual Review of Ecology Evolution and Systematics 37:637-669.
 Croxall, J. P., P. N. Trathan, and E. J. Murphy (2002) Environmental change and Antarctic seabird populations. Science 297:1510-1514.
 Barbraud, C. and H. Weimerskirch (2006) Antarctic birds breed later in response to climate change. Proceedings of the National Academy of Sciences of the United States of America 103:6248-6251.
This is an excerpt from the book Global Climate Change: Convergence of Disciplines by Dr. Arnold J. Bloom and taken from UCVerse of the University of California.
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