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The Journal of Geophysical Research recognized a UT researcher this month for his work in understanding the changes occurring in the bottom layers of the ice in Greenland, a discovery that will inform the debate surrounding greenhouse gases and rising sea levels.

Joe MacGregor, research associate in the Institute for Geophysics, and Mark Fahnestock, a glaciologist from the Geophysical Institute at the University of Alaska-Fairbanks, used 3-D imaging to capture features of the layers of ice scientists had never seen before.  

MacGregor said one of the key discoveries he and Fahnestock made was of the Eemian ice, a layer of ice believed to be 115,000-130,000 years old, at the bottom of the ice shelf. The climate during the Eemain ice period was likely similar to today’s climate, MacGregor said.

The researchers discovered this ice is located in Central and Northern Greenland, where the lack of snowfall causes the ice to move slowly.

According to MacGregor, Fahnestock led the charge in studying the internal layering of ice sheets and found an important discovery in his early work.

“He ended up discovering a spot at the bottom of the ice sheet which was warming very rapidly due to geothermal heating,” MacGregor said. “Essentially, he found a spot under Greenland with a geothermal flux as warm as Yellowstone. With this under an ice sheet, it can cause some unusual behavior.”   

The researchers collected data from the ice using technology from NASA’s Operation IceBridge. Planes flew over Greenland as a radar transmitted electromagnetic pulses, and these pulses reflected off the ice and created signals. NASA was involved in the operation as part of its six-year commitment to using 3-D imaging to capture the changes in Greenland and Antarctic ice.  

Fahnestock said the team was also able to create a system to trace and map the internal layers of Greenland. 

“There are things in the flow field of the ice sheet that suggest there are processes going on at the bottom,” Fahnestock said. “This stratigraphy allows us to map where conditions at the bottom of the ice sheet are different from place to place.”   

MacGregor said 3-D imaging technology has been hugely useful during field studies.

“Before, all we could do was make a sketch and have an estimate,” MacGregor said. “Now with the gridding system, we now have [the layers] to refer to.” 

Tavi Murray, professor of glaciology at Swansea University in Wales, lectured at the SAC on Friday morning on iceberg calving.

Photo Credit: Lauren Ussery | Daily Texan Staff

Tavi Murray, a glaciology professor at Swansea University in Wales, presented her team’s research of iceberg calving as one of the causes of rising sea levels Friday at the SAC.

The lecture was part of Swansea University’s Texas Showcase — a week-long tour presenting the Welsh university’s research with stops at UT, Texas A&M University and the University of Houston.

Murray led an expedition in Southeast Greenland to research how iceberg calving, which is when a piece of ice falls off the front of a glacier, has contributed to a rise in sea levels.

Swansea glaciology professor Tim James said he witnessed the phenomenon while the team videotaped the glaciers.  

“When we heard this really loud banging shooting down the fjord, we knew we had to get the cameras rolling,” James said. “In the case of the calving event that we witnessed this summer, it was 4 kilometers wide, 800 meters high and about 300 meters deep, and it’s more like the size of a small city.”

The team studied the Helheim and Kangerdlugssuaq glaciers, two of the largest glaciers in Southeast Greenland. Murray said the team’s observations helped link the rate at which icebergs fall to the rate at which sea levels rise.

“If we can understand the rates of discharge through the glaciers of Greenland, then we can actually understand the sea level rise which is coming from Greenland,” Murray said.

In 2013, Murray contributed to work published by the Intergovernmental Panel on Climate Change, which provides the most current knowledge on climate change. She said the group’s most recent report used the information her research team found while watching the glaciers.

“The warming of the climate system is unequivocal,” Murray said. “Global warming is evident from increases in global average air and ocean temperatures, widespread melting of snow and rising global Earth sea levels.”

Murray said warming ocean temperatures have increased the melting of glaciers.

“It’s been suggested that changes in the oceans are actually the key to changes in glaciers,” Murray said.  

UT glaciologists have been conducting research in Greenland by focusing on the Northwest region.

“These are really complementary projects, I think,” Murray said. “Both of these regions are characterized by glaciers that terminate in the ocean.”

Both team’s research will continue to unearth more information on rising sea levels.   

“What we really want to know is how much water Greenland is going to contribute to sea level in the future,” Murray said. “The trend for sea level is inexorably upwards.”

Lauren Andrews, geological sciences graduate student, leads a research team that recently discovered a cause of glacial shifts in the northern Atlantic Ocean region.

Photo Credit: Rachel Zein | Daily Texan Staff

Traveling to the icy regions of Greenland, UT researchers, led by Lauren Andrews, a geological sciences graduate student, looked at the country’s glaciers to see how they impact glacial shifts in icy regions of the Atlantic Ocean, including Greenland.

Andrews and her team published their findings in an October edition of Nature. Andrews said the melting water from the tops of ice sheets flows down to the bottom of a glacier’s bedrock during the summer, causing it to slide. 

“The surface water is getting to the bed and is interacting with the bed of the ice sheet, and the ice [melting] speeds up in the summer and starts to melt faster,” Andrews said. “The idea is that the water on top gets to the bed and can act as a lubricating layer between the ice and the sediment of bed rock.” 

Andrews said this process occurs through natural giant holes on top of the glacier, known as moulins, which act as self-sustaining drainage systems. Water drains through moulins and gets to the bed of the ice sheet, which creates what is known as a subglacial system. According to Andrews, learning about the subglacial systems can help scientists better understand how climate change impacts Greenland’s glaciers.

“Our goal with this project was to understand how that water interacts with the bed and how changes in that subglacial hydrology results in changes in ice velocity,” Andrews said. “What is the correlation between the speed of the ice sheet and the volume of water?”

Andrews’ studies include exploring how these subglacial systems evolve over time by drilling bore holes, which act as man-made re-creations of moulins, into the glaciers. Glaciologists are able to measure the subglacial pressure to help understand how the glaciers change over a certain period of time. 

“The ice velocity changes over the course of the season, and that implies and allows us to infer that there are changes within the subglacial hydrology,” Andrews said.

According to Andrews, there is still research to be done in this area of study, and glaciologists are still trying to understand the complexity of subglacial systems.