What's under the Antarctic ice sheet? Scientists explored for 61 days to depict the subglacial world for the first time

Antarctica is undoubtedly the most mysterious continent in the world, and due to the limited solar radiation it receives, it is covered with ice and snow all year round, and is the only continent without human settlement.

The average thickness of Antarctica's ice sheet reaches 2160 meters, and the thickest place even reaches 4776 meters, making Antarctica the highest continent while containing 90% of the world's ice, which contains 70% of the world's freshwater resources.

Antarctica, Source: Dave Pape

Because of such abundant freshwater resources, any change in antarctica's ice sheet is enough to affect the whole world, so Antarctica has long received widespread attention from scientists, and many scientific expedition teams are stationed here.

Perhaps because of this, Antarctica has become increasingly mysterious, with some theories suggesting that there is an underground world under the Antarctic ice sheet, or that Antarctica has an entrance to the underground world.

One of the supporting points for these claims is the discovery of lakes under the Antarctic ice sheet and the discovery of many living microbes.

Note: Antarctic Research Station

Of course, lakes and microbes under Antarctica's ice sheet do exist. The presence of lakes under the ice sheet is a good explanation, but microbes do bother scientists all the time.

Why are there microbes in such places, and what do they eat?

In a study published In the journal Science on May 5, geophysicist Chloe Gustafson and his team made a "giant nuclear magnetic resonance" to Antarctica after a 61-day expedition to Antarctica and mapped for the first time parts of the area under the Antarctic ice sheet.

Their purpose, of course, is not to explain why microbes exist, but to try to map underground groundwater systems to understand how ice sheets flow into the ocean — because this loss of ice sheets is critical to sea level rise.

Why is there liquid water under the Antarctic?

Due to the movement of the Antarctic ice sheet, it has long been suspected that the Antarctic subsurface has a huge aquifer, because any model that pushes the ice sheet to move is indispensable to liquid water, which requires water to lubricate and form a flat plane.

Antarctic ice sheet flow, Source: NASA

For example, the study focused on Lake Whelanes and its water system (this water system is the size of the entire United States, because it is only about 800 meters under the ice sheet, relatively shallow for easy study), and researchers have long been identified as a liquid water lake with a depth of 2.1 meters.

In fact, the reason why liquid water can exist under the Antarctic ice sheet is simple, because the water here absorbs part of the heat of geothermal heat, and the heat generated by the strong friction between glaciers and rocks is enough to make its temperature close to the level of about 0 degrees Celsius.

In addition, these areas are surrounded by thick ice sheets, are not affected by polar air, and heat is not easily lost, while considering that it is subject to great pressure, the emergence of liquid water lakes is understandable.

But people don't know what kind of water these are — fresh or saltwater — and the study solves this problem, while also solving the problem of its large number of microorganisms.

Because these groundwater systems are deep and limited by technology, it was previously difficult for scientists to collect direct evidence of such deep hydrological systems, but this time the research team used a technique called "geomagnetic imaging" to finally successfully map the Antarctic underwater world.

Set up exploration site, image source: Earth Observatory

What does it look like under the Antarctic ice sheet?

Geomagnetic imaging relies on the electromagnetic field created by the interaction of the solar wind with the Earth's ionosphere (a layer of dense molecules and charged particles in Earth's upper atmosphere).

When the solar wind hits the ionosphere, they excite particles within the ionosphere and create a moving electromagnetic field that can penetrate the Earth's surface.

These moving magnetic fields then induce secondary magnetic fields in ice, snow, and sediment, and the strength of the secondary magnetic fields is related to the degree of conduction of the materials there.

Therefore, by measuring the strength of the secondary magnetic field, a map of the entire subsurface and the substances it fills can be drawn.

In fact, the exploration of oil and gas is similar to this technology, and the prospectors look for the target address according to some conditions, and then start to detect the material underground.

Lakes, rivers, aquifers drawn, source: Earth Observatory

Of course, there is no doubt that there is liquid water under the ice sheet, and that intricate lakes and rivers are formed, as well as water-bearing sediments.

Because freshwater and brine have different conductivities, researchers have first explored that it is salt water rather than fresh water under the Antarctic ice sheet, and since salt water is less likely to freeze (because salt ions move faster in solvents than water molecules), this may also be a reason for the presence of liquid water under the ice sheet.

Source: Earth Observatory

And the researchers also showed that the deeper under the ice sheet, the closer it is to the conductivity of seawater, and the shallowest part near the ice sheet is closer to fresh water, suggesting that groundwater may have interactions.

In addition, from the bottom of liqueous rivers and lakes, they found a thick "sedimentary sponge" that stretched down to about 5 kilometers below, and these sediments contained more than 10 times more liquid water than the shallower lakes and river systems at the bottom of the ice sheet.

Why are there so many microbes under the Antarctic ice sheet?

These facts help scientists understand how the Antarctic ice sheet flows, but what does this have to do with microbes at the bottom of the Antarctic ice sheet?

In fact, the relationship lies in where these seawater come from, if these are seawater, then microorganisms can completely eat the nutrients brought by seawater.

Based on the levels of radiocarbon found in upper sediments in a previous study, scientists estimate that most of this brine reached under the ice sheet in the past ten thousand years.

There is only one reason why seawater is poured inland, that is, the climate was warm enough, the ice sheet melted and the sea level rose and poured into the land.

At last

The existence of life under the Arctic ice sheet is an indisputable fact, but this is normal and does not require the participation of any underground civilization, and their nutrients are derived from "seawater fossils" from 10,000 years ago.

But where there's life, there's a carbon cycle, and under the Antarctic ice sheet, it's consuming nutrients from "seawater fossils" and producing significant amounts of greenhouse gases like methane and carbon dioxide.

Global warming is a fact now, but the causes are really complex, and the earth has been circulating during glacial and interglacial periods during human activities or carbon emissions.