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AN UNCERTAIN CLIMATEIn the 1990s, technological advances continued to give Kooyman and Ponganis - both participants in International Polar Year research that began in March - new tools for their investigations. A collaboration with Greg Marshall, a National Geographic biologist, allowed them to attach miniaturized cameras in backpacks on the animals, providing the first live footage of emperor penguins hunting for fish under the Antarctic ice (the "Crittercam" segments were subsequently featured in "March of the Penguins"). Kooyman initiated research concerning the ecology of emperor penguins by using U.S. Geological Survey aerial photographs to compile census data. Counting penguin populations was never easy, partly due to the remoteness of the colonies and the difficulty in counting individual penguins during the surveys. Advances in satellite technology emerged as a possible solution to these problems and since 2002 has augmented the value of aerial census studies. Kooyman has tracked the booms and busts of populations at six colonies based around the Antarctic's Ross Sea. At times breeding success drops precipitously, such as in cases when sea ice disintegrates more quickly than usual. In these cases chicks can perish when they are not ready to fledge. On the other hand, when everything goes according to their breeding schedule, numbers can swell. But since 1962, his first trip to Antarctica, Kooyman had never seen anything like he did in 2001.  
In January of that year, a gigantic section of the Ross Ice Shelf calved. Half became known as B15A, the largest iceberg ever recorded at 290 kilometers (180 miles) long and 39 kilometers (24 miles) wide. It drifted at sea and eventually collided with another portion of the Ross Ice Shelf at Cape Crozier, home to one of Kooyman's study sites. In the months that followed, B15A destroyed the penguins' nesting habitat. As noted in a research paper published this year by Kooyman, Ponganis and colleagues, the collision caused adults who had been incubating eggs to be crushed, trapped in ravines, or to abandon the colony. The researchers found that chick production plummeted to less than half of the levels prior to the event. In a 2006 survey researchers counted a third as many chicks as there were before the collapse. B15A knocked another iceberg, C16, from the ice shelf and the two leviathans, the researchers found, blocked a colony at Beaufort Island from its traditional molting and feeding areas. But according to Kooyman, the main threat of climate warming for emperor penguins may not come from extreme cases such as B15A and C16, but rather from gradually thinning ice. The most scientifically accepted report on global warming, the Intergovernmental Panel on Climate Change Fourth Assessment Report issued earlier this year, estimated that the planet's temperatures will rise by the end of the century by between 1.8 and 4 degrees C (3.2 and 7.2 degrees F). The report raised serious questions about threats posed by the thinning of Greenland and Antarctic ice sheets. 
"Emperor penguins are dependent on sea ice for about 10 months of the year," said Kooyman. "If it starts to fail on them, they may have a major problem." Foraging areas may be reduced. Fish prey availabilities may change or decline due to altered sea currents. Key molting destinations may disappear. Penguins could join polar bears two-thirds of which could disappear by 2050, according to a recent federal report among the unfortunate recipients of climate change-related alteration of their habitat. Kooyman is concerned about these issues, but at the same time he knows that penguins have survived through the millennia by overcoming the extreme conditions of the Antarctic. They may find a way to overcome a warming climate as they have done in the past. "Emperors are a resilient species," Kooyman says. "Everything is changing so fast in their environment that the question now is: Can emperor penguins adapt fast enough? That's an open question at this point." |
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:: © 2009 Scripps Institution of Oceanography, University of California, San Diego. All Rights Reserved.
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