by Yadav Sharma Bajagai
Emperor penguins (Aptenodytes forsteri) are regarded as an icon of Antarctica due to its peculiar appearance and behaviour. These are the largest of all penguins adapted to extreme climatic condition of Antarctica  and are particularly susceptible to environmental changes in southern ocean as a result of global climate change due to being ice-obligate species . Size of the bird also increases its susceptibility to climate change  and its morphology which prevent them to forage up to greater depth and range make the situation even worse . Alteration in sea ice condition, which ultimately affects availability of pray and breeding and moulting of these birds, significantly affects their population .
Increased mortality due to climate change
Average temperature of ocean surface is the most important factor determining survivability of penguins followed by integrity of sea ice .
Mortality of adult emperor penguins in the penguin colony in Terre Adelie was dramatically increased during 1970s . Meteorological data from the site from 1952 to 2000 revealed that ambient temperature during winter was high throughout the 1970s . This association between environmental temperature and mortality rate in emperor penguin clearly depict the impact of global warming on these creatures. Due to impacts of climate change the population of emperor penguins in Terre Adelie have been decreased by 50% during the latter half of 20th century .
Impacts on habitat
Ainley et al. , through a modelling study, have revealed that habitat of emperor penguin will be seriously damaged when atmospheric temperature increases by 20C as compared to preindustrial level. In this study, it has been speculated that 50% of present population of emperor penguin will disappear due to habitat loss if temperature of earth’s troposphere reaches 20C above preindustrial era.
Impacts on distribution and geographical range
Alteration in integrity and extension of sea ice due to global warming has resulted in poleward contraction of range of emperor penguins [2, 4, 5].
Impacts on phenology
Although extension of pack ice has positive effects on survivability of adult penguins, it has negative influence on hatchability of penguin eggs . Some of the scientists have argued that melting of sea ice due to global warming in fact is beneficial for emperor penguins as it will reduce the distance to be travelled by them in search of food but melting of pack ice have other several disadvantages including flooding of colonies with sea water sweeping the chicks into water and mortality of moulting adults .
Impacts on predation
Antarctic krill, silver fish, and crustaceans are major pray for emperor penguins [1, 6]. Availability of oceanic fauna in this type of habitat is chiefly depend up on temperature of ocean water and integrity and extension of sea ice . Therefore, any alteration in temperature of sea surface and sea ice condition affects the availability of krill, fish and crustaceans which in turn affects emperor penguins . Scarcity of preferred food is one of the major reasons of mortality of emperor penguins .
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