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SALT LAKE CITY — Researchers at the University of Utah were recently surprised to discover a water aquifer roughly the size of Ireland in the Greenland Ice Sheet.
The findings will allow researchers to more accurately predict how much melt water is entering the ocean, lead author Rick Forster said. The Greenland Ice Sheet is contributing more to sea level rise than any other mass of ice and his team was studying the accumulation of snow there when they discovered this new mechanism for storing water.
“At slightly lower elevations where we expected the accumulation to be higher, instead of pulling up cores when they got to the 10-meter depth, when they pulled that core up water was just gushing out of it,” he said. “(In a video) you can hear the excitement in their voices.”
The drilling occurred in April, which is long before any surface melt occurs for the year. He said it was well below freezing temperatures when they brought the watery cores up.
The water was able to stay in liquid form because after the ice would melt, it would fill void spaces in the ice and then be insulated by the high snow level. Four or five meters of snow falls every year in this area, he said.
"The fact that they found water in these still winter conditions meant that the water existed throughout the entire winter," Forster said. "That was a big surprise — all of this water had persisted through this brutally cold Greenland winter."
The drill they were using was designed to only work in dry snow conditions, so they didn't have the right equipment to keep drilling at the time. However, they also had a ground-penetrating radar with them, which they discovered could be driven across the ground with a snowmobile to find a bright layer of water on the radar.
The bright layer of water on their radar corresponded with 10 meters, which is exactly the level where the wet cores had been drilled. In another spot, the bright layer appeared to be 25 meters below the surface. When they went to the location and brought up the 25th one-meter segment, water came gushing up again.
"That really confirmed that it wasn't just in one place and it confirmed that this ground-penetrating radar could trace it out very accurately," he said.
NASA had a radar system flying over Greenland at the same time, so researchers at the University of Utah used their images to map the aquifer once they confirmed the water levels were mapped at the same level.
When Forster presented his findings at a scientific meeting, he met a group from the Netherlands who had developed a sophisticated model to predict how much mass the Greenland Ice Sheet is losing every year. The group's model showed water was being retained in the same places. They were able to make a comprehensive model by combining data.
Using the model, they could find evidence of the layer of water as far back as the 1970s. Data before that time is not available.
"We don't think it's a very recent phenomenon — we think it's probably been there for decades," Forster said. "But the model does show, if you look at the amount of water, that it has been increasing during that time, which would be consistent with global warming and increased melting."
He said there are groundwater dating techniques that could be used to date the water in future studies to answer the question of how long it has been going on.