Millions of moviegoers fell in love with penguins in the recent box office hits, March of the Penguins and Happy Feet. The plucky, flightless birds are well adapted to aquatic life in some of the world harshest climate, but some species can also be found in equatorial ecosystems. Penguins can swim up to 35 km/hour and dive to depth of 520 meters or more to search for food. They mate and raise their chick on dry land or sea ice. Probably the best known species, the Emperor penguins of Antarctica, can endure temperatures down to 60C below zero and winds of 195 km/hour.
Eighteen penguin species inhabit a wide range of habitats in the Southern Hemisphere. The International Union for Conservation of Nature reports that 11 or these species are currently in decline and at risk for extinction. Climate change is a major factor in these population declines, affecting different species in different ways, depending on the type of ecosystem in which they live. For nearly all penguin species, global warming has reduced the available food supply, threatened penguin nesting grounds, and decreased the survival rates of chicks.
A recent study of the small population of Victoria's little penguins inhabiting Phillip Island found severe declines in average birth weight, with fewer chicks surviving to adulthood. The change appears to be related to stronger storms, which make it more difficult for the adults to find food. Warmer weather is also breaking up the penguin's feeding spots and disrupting their breeding habits.
A World Wildlife Fund-commissioned study on Antarctic Penguins and Climate Change showed that higher ocean temperatures have reduced Antarctica's sea ice by 40% from 26 years ago. The warmer waters have also greatly reduced the krill population, which is the main food for penguins. The krill population has declined by up to 80% since 1970, and further warming could kill off another 95% of the krill. With the warmer winters and more severe storms, some Emperor penguin colonies have been cut in half over the last 50 years.
While climate change is already affecting many ecosystems, the Antarctic is warming at a rate five times faster than the average global warming. This has shortened the sea ice season, threatening the entire food web of the area as well as the survival of the penguins. If the sea ice breaks up before the chicks have grown their waterproof feathers, they are likely to die in the ocean. The declining food supply also threatens the survival of adults.
IWWF Director-General James Leap warns that carbon emissions in industrialized countries will need to be cut by 30% by 2020 to stop prevent the destruction of the penguins habitat and threatening their extinction. During an unusually warm period in the late 1970s, the Emperor colony featured in the March of the Penguins fell by over 50%. Another colony has plunged from 250 to just 10 pairs since 1960 because of the rapid loss of sea ice.
Adelie penguins build pebble nests along the Antarctic shoreline, but the increased the amount of snow in the region (warmer air holds more moisture, resulting in more snowfall) has made it increasingly difficult for the Adelies to find snow-free ground to raise their chicks.
Researchers believe that a 1.3C rise in temperature (by mid-21st century) will threaten up to 40% of the Emperor penguins and 70% of the Adelie penguins. The continued loss of sea ice could bring the Emperor penguins to the brink of extinction before the end of this century. The Macaroni penguin population has already dropped by 50%, and Indian Ocean species in New Zealand and Marion Island have declined by 50 to 94% as ocean temperatures have warmed. The King penguins of the southern Indian Ocean are now considered at risk of extinction if the trend continues.
Species living along the Equator - at the Galapagos Islands and off the coasts of South America and Africa - depend on colder ocean upwellings to bring nutrient-rich waters, and these ecosystems are negatively affected by El Nino events. Climate scientists predict global warming will bring stronger El Nino events in the future, causing more frequent food shortages for these penguin populations. In addition to the threat of starvation, many adults will have to abandon their eggs or chicks as they travel further to find food. Galapagos penguin populations fell by 77% during the 1982-83 El Nino, and only 2,000 birds remain today.
Two other threats that are likely to result from greenhouse gas pollution are rising sea levels and ocean acidification. Rising seas will threaten penguins' coastal nesting sites, and acidification will further decrease the food supply. Reports indicate that the entire Southern Ocean food web is nearing disaster. The pteropod, a vital part of the ocean's food chain, could be completely wiped out as early as 2030.
Links
http://www.abc.net.au/lateline/content/2008/s2677370 .htm
http://www.actionbioscience.org/environment/wolf.htm l
http://www.biologicaldiversity.org/about/staff/index .html
http://www.penguinscience/com/education/