University of Nebraska, Lincoln: Global Warming
From beneath Antarctica's Ross Sea scientists retrieve pristine record of the continent's climate cycles - 04/16/07
Frequent climate fluctuations on the world's southernmost continent have been so extreme over the past 5 million years that Antarctica's Ross Ice Shelf, a floating slab of ice the size of France, oscillated in size dramatically, and perhaps even disappeared for periods of time when the West Antarctic Ice Sheet may have been smaller, according to scientists engaged in an unprecedented international geologic drilling project.
Researchers with the Antarctic Geological Drilling (ANDRILL) Program, which concluded its first field season in January, say long cores of sedimentary rocks that they recovered from below the bed of the Ross Sea beneath the ice shelf allow them to peer deeply into the past to a time when Antarctica was a warmer, more inviting place.
They were surprised, for example, to find such large volumes of fossil diatoms -- microscopic single-celled algae that live in surface or shallow waters -- in the cores. The presence of the fossilized one-cell creatures, some of them previously unknown to science, confirms that large areas of the Ross Ice Shelf have previously melted and were replaced with highly productive open waters.
Studies of the cores may provide scientists with glimpses into the planet's future if predictions of global temperature increases are accurate. Either way, they say, data from the cores will help create more accurate climate models for predicting future trends.
Powell and Tim Naish, of New Zealand's Victoria University of Wellington, served as co-chief scientists for the first season of the $30-million ANDRILL Program. A second drilling operation will begin at another location next fall (during the Antarctic spring) under co-chief scientists David Harwood of the University of Nebraska-Lincoln and Fabio Florindo of Italy's National Institute of Geophysics and Vulcanlogy
