Lead author Chloe Gustafson and mountaineer Meghan Seifert install geophysical instruments to measure groundwater listed below West Antarcticas Whillans Ice Stream. Credit: Kerry Key/Lamont-Doherty Earth Observatory
The research study shows the value of electro-magnetic strategies in a new polar environment.
Scientists have actually made the first detection of groundwater beneath an Antarctic ice stream. The discovery verifies what scientists had already thought however had been unable to validate previously.
Scientists require information from all parts of the Antarctic ice sheet to understand how the system works and how it alters in time in reaction to climate. The research study provides a look of a formerly inaccessible and undiscovered part of the Antarctic ice sheet and improves scientists understanding of how it may affect water level.
The researchers measured the groundwater during the 2018-2019 field season by using a ground-based geophysical electromagnetic (EM) approach called magnetotellurics. The approach utilizes variations in Earths electrical and magnetic fields to determine subsurface resistivity. This study was the first time the technique had been utilized to search for groundwater below a glacial ice stream.
” The Empire State Building up to the antenna is about 420 meters high,” Gustafson stated. This is considerable because subglacial lakes in this area are two to 15 meters deep.
” Ice streams are necessary due to the fact that they funnel about 90% of Antarcticas ice from the interior out to the margins,” stated Chloe Gustafson, a postdoctoral researcher at UC San Diegos Scripps Institution of Oceanography. Groundwater at the base of these ice streams can affect how they stream, hence possibly influencing how ice is carried off of the Antarctic continent.
The group imaged only one ice stream, there are many more in Antarctica. “It suggests that there is most likely groundwater underneath more Antarctic ice streams,” Gustafson said.
A group of researchers from Scripps Oceanography and Columbia Universitys Lamont-Doherty Earth Observatory led the task. Gustafson and 6 co-authors reported their findings in the May 6, 2022, problem of the journal Science.
” Its been a hypothesis from our understanding of how the planet works that theres groundwater under Antarctica, however we have not been able to measure it before,” said research study co-author Helen Amanda Fricker, a Scripps glaciologist and co-director of the Scripps Polar.
The researchers measured the groundwater during the 2018-2019 field season by using a ground-based geophysical electro-magnetic (EM) technique called magnetotellurics. The method uses variations in Earths magnetic and electrical fields to measure subsurface resistivity. This study was the very first time the technique had actually been used to search for groundwater underneath a glacial ice stream.
Time-lapse video revealing the field crew installing a magnetotelluric station at Subglacial Lake Whillans in West Antarctica.
” This method typically hasnt been used in polar environments,” Fricker stated. “This is a good presentation of the power of the method and how much it can bring to our understanding of not simply Antarctica, but Greenland and other glacier areas, as well.”
The method has actually been used in Antarctica considering that the 1990s, but those research studies were focused on imaging deep crustal functions at depths well below 10 kilometers (6.2 miles). The studies did have the result, however, of demonstrating that scientists could use magnetotellurics on ice and snow also, Gustafson stated.
” We took their example and applied it to a shallow concern of hydrology, within 5 kilometers (3.1 miles) of the sub-ice environment.”
In the last years, airborne electromagnetic methods have actually been utilized to image shallow groundwater in the upper 100 to 200 meters (328 to 656 feet) below some thin glaciers and completely frozen areas of the McMurdo Dry Valleys. However those methods can just translucent about 350 meters (1,148 feet) of ice.
The Whillans Ice Stream, where Gustafson and associates gathered the data, measures about 800 meters (2,625 feet) thick. Their brand-new data fill in a wide space between those previous deep and shallow data sets.
Chloe Gustafson belonged to a four-person group that spent six weeks camping in the ice and snow collecting data on the Whillans Ice Stream from November 2018 to January 2019. Together they conquered the obstacles of working under Antarctic field conditions, consisting of high winds and sub-zero temperatures.
” We imaged from the ice bed to about five kilometers and even much deeper,” stated Kerry Key, an associate professor of earth and ecological sciences at Columbia University and a Scripps Oceanography alumnus.
” My hope is that individuals will start to view electromagnetics as part of the standard Antarctic geophysical toolkit,” Gustafson stated.
The Science study was based on passively collected, naturally created magnetotellurics signals to determine variations in electrical resistivity.
” This tells us about groundwater qualities because freshwater is going to show up a lot different in our imaging than salty water,” Gustafson stated.
Augmenting the EM measurements was the seismic imaging data provided by co-author Paul Winberry of Central Washington University. That information verified the existence of thick sediments buried under ice and snow throughout the 60 miles that separated the field teams magnetotellurics surveys.
The scientists calculated that if they could squeeze the groundwater from the sediments onto the surface area, it would form a lake that varied from 220 to 820 meters (722 to 2,690 feet) deep.
” The Empire State Building up to the antenna has to do with 420 meters tall,” Gustafson stated. “At the shallow end, our water would go up the Empire State Building about midway. At the inmost end, its almost two Empire State Buildings stacked on top of each other. Because subglacial lakes in this area are 2 to 15 meters deep, this is considerable. Thats like one to four stories of the Empire State Building.”
Groundwater may exist under comparable conditions on other planets or moons that are launching heat from their interiors, Key stated.
” You can picture a frozen cover over a liquid interior, whether its entirely liquid or liquid-saturated sediments,” he said. “You can think about what we see in Antarctica as possibly comparable to what you might discover on Europa or some other ice-covered worlds or moons.”
The presence of subglacial groundwater likewise has implications for the release of substantial amounts of carbon that were previously saved by seawater-adapted neighborhoods of microorganisms.
” Groundwater motion indicates theres potential for more carbon being transported to the ocean than what weve formerly considered,” stated Gustafson, who finished her PhD under Keys guidance at Columbia in 2020.
For more on this research, see Scientists Discover Massive Groundwater System in Sediments Below Antarctic Ice.
Recommendation: “A vibrant saline groundwater system mapped below an Antarctic ice stream” by Chloe D. Gustafson, Kerry Key, Matthew R. Siegfried, J. Paul Winberry, Helen A. Fricker, Ryan A. Venturelli and Alexander B. Michaud, 5 May 2022, Science.DOI: 10.1126/ science.abm3301.
The National Science Foundation and Columbia University Electromagnetic Methods Research Consortium supported this study as part of the Subglacial Antarctic Lakes Scientific Access project. Co-authors consisted of Scripps Oceanography alumnus Matthew Siegfried and Ryan A. Venturelli of the Colorado School of Mines; and Alexander B. Michaud, Bigelow Laboratory for Ocean Sciences, Maine.
