earths outlook

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Frigid Breakthrough

Scripps geophysicist Helen Amanda Fricker, associate professor in the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics, uses satellite observations to study the effects of climate change on the Antarctic ice sheet and to understand the processes driving these changes. One of the most dramatic consequences of global warming is sea-level rise, and scientists predict that changes of only a few inches in ocean levels can place coastal cities underwater and disrupt entire ecosystems.

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Fricker discovered a complex system of active liquid water lakes that exist beneath the Western Antarctic ice sheet. Only in the last three years have scientists had the necessary tools to detect this complex system of water flowing under the frozen continent.

"We never had data that extended this far south before to make these measurements, and so the lake system went undetected," Fricker said.

As early as the 1970s, scientists had reported seeing subglacial floods but not until Fricker's study last year did anyone know how pervasive the subglacial water system is. These floods were signs of a much more complex ecosystem waiting to be discovered. Using NASA's Ice Cloud and Land Elevation satellite (ICESat), Fricker noticed astonishing changes in the elevation of the ice sheet, up to 10 meters (33 feet) in some locations, signaling a massive movement of flowing lakes beneath.

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Ice sheets are actually glaciers of densely packed snow about 2 kilometers (1.2 miles) thick that cover much of the Antarctic continent, 13.7 million square kilometers (5.3 million square miles) of land. The Antarctic ice sheet holds the majority of the earth's fresh water and plays a vital role in regulating the earth's temperature.

This discovery wasn't easy. Fricker and her research team analyzed hours of datasets by individual tracks, a process many other glaciologists considered a waste of time.

"It was an incredibly laborious technique that we came up with for analyzing these repeat-tracks. People couldn't believe we were looking at data track by track but if we hadn't done it in that way, we would have missed these lakes entirely," said Fricker.

The data that led to this discovery was collected by the ICESat's Geoscience Laser Altimeter System (GLAS). GLAS, operating in a near-polar orbit that reaches 86 degrees South, sends a laser beam to measure changes in the earth's surface. These pulses provide "snapshots" through time of the subtle change in the elevation of the ice sheets from the active draining of the lakes below.

Next page: Opening the Floodgates of Discovery


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