For decades scientists working in Antarctica document subglacial lakes, water buried under miles below the ice. They spotted more than 400, and even drilled into a few and found evidence of living and long dead life forms.
But despite their omnipresence at the bottom of the world, no one really looked to see if the subglacial lakes were widespread beneath the Greenland ice sheet. So far.
Only four subglacial lakes were previously documented in Greenland. This week, impressive research published in Zagreb Nature Communications added another 56 new lake candidates.
Furthermore, researchers behind this research believe it is just the beginning. Like in Antarctica, subglacial lakes can be a key feature of the Greenland subterranean. Some of them can even affect the ice movement up until it is full and drain.
"I'm sure this is the tip of the iceberg in terms of what can be found," co-author Stephen Livingston, a glaziologist from Sheffield University, told us.
Machines spying on the hidden lakes of Antarctica
The solar panels stood tall with ice space while the team for four people approached motor sledges. The GZ20 did not visit visitors for a year after another brutal winter of Antarctica had passed since the last time the human caretakers had been reported.
You would not see the obvious signs of walking in the ice, but there are several ways researchers can detect subglacial lakes.
Many have been observed in Antarctica by satellite, such as NASA ICESat (and recently initiated replacement, ICESat-2), which repeatedly flew through the same ice sections to measure small changes in surface height – interpreted as a result of filling and draining underground Lakes.
Where the lakes are less active, so to speak, scientists have other means to detect them. They can, for example, record radio waves through the ice and use their reflections to produce the background image below. Thus, in the mid-1990s, the researchers succeeded in verifying the presence of Lake Vostok, a surface of 10,000 km2 subglacial lake buried near the southern half.
This latter approach helped scientists discover the majority of new – though much smaller – subglacial lakes in Greenland.
The authors discussed a huge database of radio echo probe (RES) collected by the IceBridge operation, captured in the air in the Earth's Polar Regions under the guidance of NASA, from 1993 to 2016. waves that fend off produce a "lighter" signal that points to the accumulated water on the ice cover.
Eleven such lakes could be observed during at least a decade of RSE data, increasing the confidence of researchers that the lakes are persistent.
"At least for decades, these lakes seem relatively stable," Livingston said.
Two more active lakes were observed by investigating topography maps of the high density of the ice surface of Greenland. Taken together, these 56 lake candidates range from 0.2 to 5.9 km. With the exception of two active lakes in the southwest, most of them fell into three characteristic clusters in the central, eastern, northern and northwestern Greenland.
Those in central eastern Greenland mostly coincided with geothermal focal points, indicating that the heat from the interior of the Earth had a role in their formation.
A small number of active lakes, which are documented by scientists, meanwhile are closer to the ice sheet, where significant surface melting occurs in the summer months, suggesting that it can be filled up while the muddy water flows from the surface to the rock.
This raises questions as to whether climatic changes, which accelerate melting on the surface of Greenland, may affect the activity of some of these lakes and then move the ice above them.
Livingston said it was too early to say, but understanding the link between lakes and ice movements above them is an important area for future research.
There is more work to be done simply by documenting the existence of these lakes. Livingston noticed that although the IceBridge operation data is extensive, he still covers only a "small percentage" of the ice cover of Greenland. He suspects that many lakes can be found closer to those topographic maps, which researchers continue to do.
Finally, scientists can now begin more detailed studies of some of the lakes found. It may take several years to prepare for drilling in one, as the team recently worked in Antarctica. Who knows what they could discover in his waters.