Some lakes form under the ice because the ice acts as a barrier that prevents heat from escaping, thus promoting the formation of a layer of liquid water below.
Water under the ice seems strange, right? Yet, it happens when the glacier rests on a rocky base with natural hollows and depressions. These depressions allow meltwater to accumulate rather than flow away. The presence of impermeable rocks, such as clay or unfractured hard rocks, helps retain this water under the glacier. On top of that, a warm rock or minor geothermal activity beneath the ice can locally increase melting and keep the water in a liquid state. Not to mention that the enormous pressure exerted by the mass of ice above helps keep the water liquid, even at negative temperatures. All these little geological ingredients create the perfect spot for hidden lakes to form beneath the ice.
Climate change is causing an acceleration of the surface melting of glaciers. This melted water seeps through cracks and crevices until it reaches the base of the glacier, where it accumulates, sometimes forming significant pockets. Certain periods of rapid warming thus create massive surpluses of liquid water beneath the ice. Conversely, frequent temperature variations alternating between hot and cold further weaken and crack the ice, facilitating even more the arrival of water to the lower parts. When these subglacial lakes become too large, they can trigger sudden events called jökulhlaup, sudden releases that unleash huge amounts of water in a short time.
Under a glacier, water accumulates primarily because the base of the glacier melts due to the combined effects of two things: the pressure exerted by the weight of the ice and the natural heat from the ground called geothermal flux. The thicker the ice, the greater the pressure, which slightly lowers its melting point. As a result, even if the temperature remains close to zero or negative, the ice still melts right at its base. This process is called pressure melting. Then, the water created accumulates in underground pockets or circulates through channels between the ice and the bedrock, thus creating hidden lakes beneath the ice. Sometimes, friction caused by the glacier moving over its rocky bed generates enough heat to accelerate this phenomenon.
It's surprising, but yes, humans can modify the formation of lakes under the ice. With greenhouse gas emissions, we heat the air and the ice melts faster. This excess water can slide under glaciers and form pockets of water, creating lakes that didn't exist before. Drilling or scientific research conducted on-site can also sometimes facilitate the flow of subglacial water. And then there is also melting related to industrial pollutants: the dark particles deposited on the ice absorb heat, further accelerating its melting and influencing this phenomenon of lake formation hidden beneath the glaciers.
Some subglacial lakes have become particularly famous, like Lake Vostok beneath Antarctica. It impresses because it is buried under nearly 4 kilometers of ice, completely isolated from the rest of the world for probably millions of years. Its liquid water comes from the geothermal heat released by the Earth at depth. Another well-known example is Lake Whillans, also in West Antarctica. More accessible, this one fascinates because scientists have discovered tiny living organisms beneath a thick layer of ice, demonstrating that life can exist even in super extreme conditions. In Iceland, there are also subglacial lakes, often located beneath active glaciers like Vatnajökull. These Icelandic lakes, by merging with the volcanoes below, can cause sudden floods called jökulhlaups, which are rapid and very powerful.
Scientists estimate that there are several hundred lakes hidden beneath the Antarctic ice sheet; these bodies of water significantly influence the stability of the glacier above them.
The waters of subglacial lakes are sometimes kept liquid due to the combination of the extreme pressure exerted by the ice and the heat released from the underlying Earth's crust.
Some subglacial lakes may harbor unique extremophilic microbial life forms capable of surviving without sunlight through complex chemical processes known as chemosynthesis.
The phenomenon of lake formation under ice is not exclusive to Earth: scientists strongly suspect the existence of vast oceans hidden beneath the ice on the surface of Europa, one of Jupiter's moons.
Indeed, subglacial lakes often act as a lubricant between the glacier and the bedrock, thereby facilitating the glacier's mobility. This lubrication can lead to a temporary or permanent acceleration of its movement forward.
Yes, exploring these fragile and isolated environments poses a serious risk of biological or chemical contamination from the equipment and technologies used for ice drilling. As a precaution, very strict sterilization and environmental safety protocols are employed to prevent any disturbance or contamination of the isolated subglacial ecosystems.
Indirectly yes, because the subglacial dynamics influence the stability of ice sheets. If these lakes drain suddenly or connect with the ocean, it can accelerate the melting or sliding of glaciers, potentially affecting sea levels and global climate.
Sure! Here’s the translation: "Yes, when average temperatures rise, glaciers melt more. This meltwater seeps into the lower layers of the glacier, facilitating the formation or expansion of subglacial lakes and potentially increasing the risks associated with sudden flooding."
There are lakes beneath the ice whose depth can be significant. Lake Vostok, in Antarctica, is one of the deepest discovered to date, with a maximum depth of about 1000 meters, located approximately 4000 meters beneath the ice sheet.
Scientists primarily use geophysical techniques such as ice-penetrating radar, gravimetry, and magnetic measurements to identify and map the presence of liquid water beneath the ice. Radar waves penetrate the ice, bounce off the surface of the liquid water, and thus indicate the exact location of subglacial lakes.
Subglacial lakes are most often detected using radar remote sensing, which allows the identification of liquid water layers beneath glaciers. Radar waves penetrate the ice and return specific signals when they encounter different interfaces, such as ice and liquid water.
Yes, some extremophilic organisms adapted to harsh conditions can survive and even thrive in subglacial lakes, despite total darkness, cold temperatures, and high pressure. Studies, for example in Lake Vostok in Antarctica, have indicated the presence of microorganisms adapted to these extreme environments.
The main risks are glacial lake outburst floods, which are sudden and massive floods that occur when a subglacial lake empties rapidly. This can cause significant damage to infrastructure and threaten human lives downstream.
Yes, some isolated subglacial lakes that have been cut off for a very long time harbor microorganisms capable of surviving in extreme conditions, in the absence of light and under high pressure. These organisms have adapted their biological mechanisms to withstand very cold and nutrient-poor environments.
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