Beneath a fast-flowing ice stream in West Antarctica, scientists have discovered a vast aquifer filled with seawater that may have been locked down for thousands of years.
This is the first time that scientists have found water beneath an ice stream in the frigid region, and it could change our understanding of how climate change affects the region.
The new underground system can be thought of as a giant sponge, made up of porous soil and water, according to the lead author of the study.
She told Live Science that the Sponge is anywhere from half a kilometer to two kilometers thick.
The report was published in the journal Science on Thursday. Lake Whillans is a subglacial lake that sits at a depth of 2,625 feet under the ice.
Winnie Chu, a glaciergeophysicist at the Georgia Institute of Technology's School of Earth and Atmospheric Sciences, was not involved in the study.
The shallow system of lakes and rivers at the base of the ice shelf hold less than a tenth of the volume of water found in the enormous aquifer. Lake Whillans is 20 square miles (60 square kilometers) in size and is 7 feet deep.
The diversity of life discovered beneath the ice shelf is unbelievable.
Chu said that scientists have long speculated that huge aquifers could be hidden beneath the ice because of the glaciers and ice streams that carry water over a bed of permeable soil.
She explained that until now, technological limitations prevented researchers from gathering direct evidence of deep hydrological systems. Instead, the research focused on lakes and rivers located at or near the base of glaciers and ice shelves.
To peer beyond the shallow systems into the hidden depths below, Gustafson and her colleagues used a technique called Magnetotelluric imaging. The Whillans ice stream is a moving belt of ice that moves about 6 feet per day in its flows towards the Ross Ice Shelf.
The ionosphere is a dense layer of molecules and charged particles in the upper atmosphere.
The particles within the ionosphere are excited by the solar winds and generate moving fields. Secondary fields in the ice, snow and sediments are what the magnetotelluric instruments measure. The team buried the instruments in shallow pits in the snow and gathered data from many different locations on the ice stream.
The secondary fields are very tightly coupled to geology and hydrology, which means that ice looks very different from the rest.
She said that the signal from the sun interacting with the Earth's magnetic field was similar to taking an MRI of the Earth.
Massive iceberg narrowly avoided a collision with the ice shelf.
The studies of Earth's crust and upper mantle started as early as the 1990s, according to a review in the journal.
The team took the measurements from a deeper depth, which was 3 miles (5 km) down. There, they found a thick, salty sponge at its deepest depths and freshwater near its shallowest part, where the sponge approached the ice stream.
The shallow, subglacial systems link up to the deep-seated aquifer, and that both likely influence the flow of ice above.
It isn't clear if the aquifer can exchange water from time to time with the subglacial hydrology or if it is a one-way transfer, where water from the ice stream trickles down and then remains stored in the aquifer for some time.
The flow of the ice stream above may be affected by either injecting water into the subglacial system or removing water from the system.
The exchange of water between the deep system and shallow system could affect the growth of life beneath the ice stream. The flow of liquid water through the aquifer and the lakes and rivers above drives the flow of nitrogen through the system. There are different types of microbes that can survive in each environment.
Microbes that feast on crushed rocks thrive in the ice covered lakes.
The authors theorize that the water in the deepest part of the underground system may have come from the ocean during a warm period in the mid-Holocene.
As the ice sheet readvanced, the presence of thick ice cut off ocean access to the bed, and the remnant seawater was sealed as underground water beneath the Whillans ice stream, Chu wrote in a commentary of the study.
The Whillans ice stream is the first to be detected, but the research team suspects that there are other systems beneath the ice streams. The ice sheet interior is likely to be extended by hundreds of kilometers by these groundwater systems. The next step is to compare what they found at Whillans to what they found elsewhere on the continent.
How do the deep systems beneath the Thwaites glacier differ from the ones under Whillans? The current models of ice flow don't factor in the aquifers, so that will be an interesting area of research going forward.
There is still so much we don't know about the relationship between the ice sheet's hydrogeology and climate change, so we can't say anything concrete about how it will change.
There are related content.
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The collapse of the ice shelf could be a sign of things to come.
A giant crack frees a huge ice cube in the middle of the ocean.
The article was published by Live Science. The original article can be found here.
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