June 10, 2014
West Antarctica’s Thwaites Glacier Is Melting Due To Geothermal Heat
Gerard LeBlond for www.redorbit.com - Your Universe Online
Researchers from the Institute for Geophysics at The University of Texas at Austin (UTIG) have discovered that Thwaites Glacier is being eroded by the ocean, as well as being melted from geothermal heat. Their findings are published in the current edition of the Proceedings of the National Academy of Sciences (PNAS).
Accurate information from beneath the West Antarctic Ice Sheet has previously been inaccessible, but new findings of the conditions below the glacier help the researchers better understand the severity of the glacier’s rapidly depleting ice.
The Thwaites Glacier has gained attention as researchers recently discovered the ice sheet is collapsing. However, more data needs to be gathered and computer modeling is needed to determine a more accurate time frame and how much the sea level will increase.
By the use of radar techniques to show water flow below the ice sheet, researchers were able to estimate the rate at which the ice is melting and identify its cause. The geothermal heat under the glacier is found to be much hotter and on a wider scale than previously presumed.
The increase in heat under Thwaites Glacier is believed to be from magma associated with volcanic activity caused by fissures opening in the Earth’s crust below the ice sheet. This is rapidly melting the underside of the glacier and could cause it to slide, affecting its stability and contribute to rising sea levels.
This information is crucial, as the researchers can now accurately determine how the glacier will respond to the warming ocean. The current ice sheet models assumed the heat flow is uniform under the ice and it is distributed evenly below.
Lead author Dusty Schroeder explains that the new findings show that the heat distribution is like a stove top distributing the heat differently at different locations.
“It's the most complex thermal environment you might imagine. And then you plop the most critical dynamically unstable ice sheet on planet Earth in the middle of this thing, and then you try to model it. It's virtually impossible,” co-author Don Blankenship, a senior research scientist at UTIG and Schroeder's PhD adviser, stated.
The glacier is the size of Florida and is 2.5 miles thick in certain areas. Understanding how the distribution of the thermal heat flows is crucial information in determining what may happen to the glacier and predicting the rise of global sea levels. The glacier is considered to be unstable because the interior is more than a mile below sea level, but it is very shallow near shore.
This instability could cause the collapse of the glacier and global sea levels could rise by 6.5 feet while the West Antarctic Ice Sheet could rise twice that.
Previous research used ice-penetrating radar sounding data to gather information which formed the foundation for the new study. Schroeder used the information in both studies and has determined the minimum geothermal heat flow is about 100 milliwatts per square meter. Some hotspots are over 200 milliwatts per square meter. The average heat flow of the Earth is less than 65 milliwatts per square meter.
“The combination of variable subglacial geothermal heat flow and the interacting subglacial water system could threaten the stability of Thwaites Glacier in ways that we never before imagined,” Schroeder said.