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Perennial Aquifer Discovered Inside The Greenland Ice Sheet

December 23, 2013
Image Caption: Drill rig used to extract firn cores from within the Greenland firn aquifer. One of the snowmobiles used in the 300 km traverse of the ice sheet to reach the drill site. Pictured, Clément Miège (co-author and PhD student University of Utah), and Terry Gacke (Ice Drilling Design and Operations). Credit: Evan Burgess

redOrbit Staff & Wire Reports – Your Universe Online

An “extensive” new aquifer discovered in the Greenland Ice Sheet by an international team of researchers contains liquid water year-round, according to research published in Sunday’s edition of the journal Nature Geoscience.

According to the researchers, the reservoir fills 27,000 square miles and is known as a “perennial firn aquifer” because water persists inside the firn – layers of ice and snow that don’t melt for at least one season. They believe that it figures significantly in understanding how snow and ice melt contribute to rising sea levels.

“Of the current sea level rise, the Greenland Ice Sheet is the largest contributor – and it is melting at record levels,” said lead author Rick Forster, a geography professor at the University of Utah. “So understanding the aquifer’s capacity to store water from year to year is important because it fills a major gap in the overall equation of meltwater runoff and sea levels.”

He and his colleagues have been conducting research in this region for the past three years in order to measure snowfall accumulation and how it changes from one year to the next. The region they are analyzing covers 14 percent of southeastern Greenland, but receives 32 percent of the entire ice sheet’s snowfall.

[ Watch the Video: Greenland Ice Stores Liquid Water Year Round ]

The team started by drilling core samples in three locations on the ice for analysis in 2010. They then returned the following year to drill at lower elevations in roughly the same areas. Of the four core samples they collected, two returned to the surface with liquid water pouring off the drill, despite air temperatures of -4 degrees Fahrenheit. That water was found at roughly 33 feet below the surface at one hole and 82 feet below in the second.

“This discovery was a surprise. Although water discharge from streams in winter had been previously reported, and snow temperature data implied small amounts of water, no one had yet reported observing water in the firn that had persisted through the winter,” Forster said. The aquifer they discovered is reportedly larger than the entire state of West Virginia, and similar in form to land-based groundwater aquifers that can be used for drinking water.

“Here instead of the water being stored in the air space between subsurface rock particles, the water is stored in the air space between the ice particles, like the juice in a snow cone,” he added. “The surprising fact is the juice in this snow cone never freezes… Large amounts of snow fall on the surface late in the summer and quickly insulates the water from the subfreezing air temperatures above, allowing the water to persist all year long.”

Forster’s team used data obtained from airborne and ground-penetrating radar in order to locate the aquifer prior to collecting the ground-based core samples. Airborne radar images were collected via NASA’s Operation IceBridge climate change monitoring initiative, while ground-penetrating radar and a roving GPS navigation unit were also used to collect data every five seconds.

“Researchers found that the radar images from air and ground corresponded on both the depth of a bright horizon, indicating where there is a change in consistency of the ice, as well as the undulations of the horizon across distance of about 15 miles,” the University of Utah explained in a statement. “This was confirmation that the airborne radar could map the aquifer just as well as the ground-based radar.”

“The consequences of losing the ice sheet could be catastrophic,” the institution added. While it is unlikely that the entire ice sheet could melt, such an occurrence would cause global sea levels to rise by more than 20 feet. The discovery of the perennial aquifer could help climate scientists predict the movement and temperature of the water within the ice sheet, and could “help slow down the effects of climate change,” Forster concluded.


Source: redOrbit Staff & Wire Reports - Your Universe Online



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