subglacial lake
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What is a subglacial lake?
A subglacial lake is a sizable body of liquid water situated beneath a glacier or ice sheet, typically at the intersection of the ice mass and the bedrock. These lakes may be interconnected by channels or exist as isolated systems, holding approximately 15% of the Earth’s liquid freshwater, with the majority found in Antarctica.
Subglacial lakes were first detected in the 1960s using airborne radio-echo sounding (RES). Satellite altimetry helps differentiate open systems from closed ones by tracking ice elevation changes, with elevation changes suggesting an open network connected by meltwater rivers that may lubricate the ice sheet above. Lake Vostok is the largest known subglacial lake.
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Where are subglacial lakes usually found?
Subglacial lakes are commonly found where glaciers or ice sheets meet the bedrock below. Most known subglacial lakes are in Antarctica, but they can also be found beneath the Greenland Ice Sheet, ice caps in Iceland, the Canadian Archipelago, and mountain glaciers. These lakes can be connected by channels or exist as isolated systems, holding a significant amount of Earth's freshwater. They are detected using airborne radio-echo sounding (RES) equipment.
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How do subglacial lakes form beneath glaciers or ice sheets?
Subglacial lakes are large bodies of liquid water that exist beneath a glacier or ice sheet, typically at the intersection of the ice and bedrock. These lakes can form as closed systems, isolated from each other, the atmosphere, and meltwater sources, or they can be interconnected by channels.
The origin of subglacial lakes can be traced back to the accumulation of snow that turns into crystalline ice over long periods. Over time, continued accumulation causes ice to move downhill. Subglacial lakes are detected using airborne radio-echo sounding (RES) equipment. Satellite altimetry studies are often used to separate open systems from closed ones. Fluctuations in water movement through the system cause repeated filling and draining of the lakes, which in turn causes rapid short-term changes in their elevation.
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What makes subglacial lakes different from other types of lakes?
Subglacial lakes are unique because they exist beneath ice masses, typically where a glacier or ice sheet intersects with bedrock. Unlike other lakes, they can be connected by channels or exist as isolated systems, cut off from the atmosphere and meltwater sources. These lakes contain a significant portion of Earth’s liquid freshwater, with a majority found in Antarctica.
Satellite altimetry helps differentiate open systems from closed ones by tracking elevation changes, which indicates filling and draining patterns. This interconnectedness can lubricate the ice sheet above, increasing its velocity towards the oceans. Hydrologically isolated systems are of interest because they may contain unique life forms that have been separated from surface ecosystems for millions of years.
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How do scientists study subglacial lakes if they are hidden under ice?
Scientists study subglacial lakes using methods like airborne radio-echo sounding (RES) that sends radio waves from an aircraft that reflect off the interfaces between materials to create a cross section of a glacier or ice sheet. In data analysis, subglacial lakes appear as flat or smooth areas or as regions where radio waves reflect strongly.
Satellite altimetry studies, using lasers to track differences in ice elevation, help differentiate open from closed systems. Subglacial lakes whose elevations undergo frequent changes are considered part of an open network of lakes joined by meltwater rivers.
The Russian drilling project at Lake Vostok penetrated 3,769 meters of ice to reach liquid water.
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Why are subglacial lakes important for understanding Earth's past climate and possible life forms?
Subglacial lakes are important for understanding Earth's past climate because their sediments contain records of climate change, such as ripple marks, carbonaceous layers, and fossil species, offering insights into the history of the lake basin and climate. They can also contain unique life forms because they are isolated from other ecosystems for long periods, potentially harboring extremophiles that provide information about the possibilities for life in extreme environments. Analysis of ice cores obtained from these lakes can reveal past atmospheric composition and volcanic eruptions, further linking greenhouse gas levels to climate and identifying historic eruptions.
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subglacial lake, any large body of liquid water that exists below an ice mass. Typically, subglacial lakes form where an overlying glacier or ice sheet intersects with the bedrock below. These water bodies may be connected to one another by a system of channels, or they may exist as closed systems that are isolated from one another as well as from the atmosphere and a meltwater source above. They contain a substantial portion of Earth’s liquid freshwater stocks, some studies noting that some 15 percent of the planet’s supply (some 10,000 cubic km [2,400 cubic miles]) occurs beneath Antarctica’s ice. Some 773 subglacial lakes had been identified by 2022. Of these, the overwhelming majority occur in Antarctica, with an additional 64 sitting beneath the Greenland Ice Sheet, 2 beneath the ice cap on Devon Island in the Canadian Archipelago, 6 beneath the ice caps in Iceland, and 26 beneath mountain glaciers.
Subglacial lakes in Antarctica were first detected using airborne radio-echo sounding (RES) equipment during the 1960s and early ’70s. Australian glaciologist Gordon de Quetteville Robin and British glaciologist and researcher Charles Winthrop Molesworth Swithinbank, working with British Antarctic Survey staff and using RES, in 1970 became the first researchers to show evidence of subglacial lakes. Since then, RES has revealed the locations of hundreds of subglacial lakes. The process operates by sending out radio waves from an aircraft. The radio waves are reflected off the interfaces between different materials (such as those that occur between air-ice, ice-water, and ice-sediment boundaries) to create a cross section of a glacier or ice sheet. In the data analysis, subglacial lakes appear as flat or smooth areas or as regions where radio waves reflect strongly.
Satellite altimetry studies, which use lasers to track differences in ice elevation from one period to the next, are often used to separate open systems from closed ones. Subglacial lakes whose elevations undergo frequent changes are thought to fill and drain, which suggest that they are part of an open network of lakes joined by meltwater rivers. Since these networks occur at the base of the ice, they may play a role in lubricating the ice sheet above and increasing the velocity of its movement toward the oceans. Hydrologically isolated systems are of interest to the scientific community because such extreme environments—some of which have been separated from ecosystems located at or close to Earth’s surface for millions of years—may contain unique forms of life (see also extremophile).
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Lake Vostok, which is located approximately 4 km (2.5 miles) beneath Russia’s Vostok Station on the East Antarctic Ice Sheet, is the largest known subglacial lake. It is roughly elliptical in shape, running more than 240 km (150 miles) long with a maximum width of about 50 km (31 miles), and it holds approximately 5,400 cubic km (1,300 cubic miles) of water. In contrast, the smallest water bodies still considered to be subglacial lakes have volumes that are roughly 0.0001 cubic km (3.5 million cubic feet, or about 26.4 million gallons).