Mark Fahnestock

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.”