Antarctica. Why is Antarctica a source of fresh water? Inland waters of Antarctica

If the water from these lakes seeps under the glacier, it will not last long.

From 2000 to 2013, nearly 8,000 blue lakes with melt water appeared on the Langhowde Glacier in East Antarctica, the likes of which have never been seen in this area before. British experts from the University of Durham, who have studied this phenomenon, express concern that the complete disappearance of this glacier is a matter of time.

Experts studied more than a hundred and fifty satellite images and analyzed other data previously collected about 7,990 blue lakes, after which they came to the conclusion that they were formed under the influence of warm air. At the same time, it is possible that the melt water found in some of these lakes can seep under the glacier, significantly accelerating its melting and making it irreversible.

Similar in essence, but even larger-scale phenomena are currently observed in Greenland, where, among other things, for this reason, more than a trillion tons of ice melted from 2011 to 2014. It cannot be ruled out that in the future something similar awaits the Langhovde glacier, the researchers, who published their work in the scientific Geophysical Research Letters, note.

In May of this year, the attention of specialists was attracted by another Antarctic glacier called Totten, which, as it turned out, was. The researchers expressed concern that the melting of this glacier could potentially lead to an increase in world sea levels by more than two meters (although this, in all likelihood, will take at least several centuries).

Although scientists occasionally report the melting of individual glaciers in Antarctica, in general, its ice is considered to be pretty well protected from melting due to climate change. One of the explanations for this was recently in the so-called Southern Ocean at a depth of more than three kilometers, water that does not participate in circulation and remains one of the most “untouched” by global warming in the world.

Read: Antarctica

Antarctica has an extremely harsh cold climate. The absolute pole of cold is located in East Antarctica, where temperatures down to -89.2 °C were recorded (the area of the Vostok station).

Another feature of the meteorology of East Antarctica is katabatic (katabatic) winds due to its dome-shaped topography. These steady southerly winds occur on rather steep slopes of the ice sheet due to the cooling of the air layer near the ice surface, the density of the near-surface layer increases, and it flows down the slope under the action of gravity.

The thickness of the air flow layer is usually 200-300 m; due to the large amount of ice dust carried by the wind, horizontal visibility in such winds is very low. The strength of the katabatic wind is proportional to the steepness of the slope and reaches its greatest strength in coastal areas with a high slope towards the sea. The katabatic winds reach their maximum strength in the Antarctic winter - from April to November they blow almost continuously around the clock, from November to March - at night or when the Sun is low above the horizon. In summer, during the daytime, due to the heating of the near-surface air layer by the sun, katabatic winds near the coast stop.

Data on temperature changes from 1981 to 2007 show that the temperature background in Antarctica has changed unevenly. For West Antarctica, as a whole, an increase in temperature is observed, while for East Antarctica, no warming has been detected, and even a certain negative trend has been noted. It is unlikely that in the 21st century the process of melting of Antarctica will increase significantly. On the contrary, the amount of snow falling on the Antarctic ice sheet is expected to increase as temperatures rise. However, due to warming, a more intensive destruction of ice shelves and an acceleration of the movement of outlet glaciers of Antarctica, which throw ice into the World Ocean, are possible.

Inland waters

In the 90s of the XX century, Russian scientists discovered the subglacial non-freezing Lake Vostok - the largest of the Antarctic lakes, having a length of 250 km and a width of 50 km; the lake holds about 5400 thousand km³ of water.

In January 2006, geophysicists Robin Bell and Michael Studinger from the American Lamont-Doherty Geophysical Observatory discovered the second and third largest subglacial lakes, with an area of 2000 km² and 1600 km², respectively, located at a depth of about 3 km from the surface of the continent. They reported that this could have been done sooner if the data from the Soviet expedition of 1958-1959 had been analyzed more carefully. In addition to these data, satellite data, radar readings and measurements of the force of gravity on the surface of the continent were used.

In total, in 2007, more than 140 subglacial lakes were discovered in Antarctica.

Why is Antarctica called a source of fresh water? Where is most of the fresh water on Earth, you will learn from this article.

Why is Antarctica a source of fresh water?

The substance without which life on our planet is impossible is water. Its importance cannot be overestimated. Fresh water plays an especially important role in our life.

To date, the largest source of fresh water on the planet is Antarctica. Of course, they are not in a liquid state, but in icebergs, which cover 93% of the mainland.

ice sheet Antarctica contains about 80% of all fresh water on the planet.; if it melts completely, global sea levels will rise by almost 60 meters

Scientists have reported that in the summer, when the ice begins to melt, it would be possible to obtain more than 7 thousand km3 of this resource. And this is several times higher than its world water consumption. In addition to the ice sheet, on the territory of the mainland there are also ice shelves with preserved fresh water, which are a continuation of the glacial, upper cover. In total, there are about 13 ice shelves in Antarctica, and they contain more than 600 thousand km3 of such necessary fresh water.

Shelf and sheet glaciers form icebergs. They periodically break off and go on a free voyage across the ocean. Very often, having moved to warmer waters, icebergs begin to melt and become a source of fresh water.

Antarctica is a continent located in the very south of the Earth, the center of Antarctica approximately coincides with the geographic south pole. Antarctica is washed by the waters of the Southern Ocean.

The area of the continent is about 14,107,000 km² (of which ice shelves - 930,000 km², islands - 75,500 km²).

Antarctica is also called the part of the world, consisting of the mainland of Antarctica and adjacent islands.

Climate of Antarctica:

Antarctica has an extremely harsh cold climate. In East Antarctica, at the Soviet Antarctic station Vostok on July 21, 1983, the lowest air temperature on Earth in the entire history of meteorological measurements was recorded: 89.2 degrees below zero. The area is considered the cold pole of the Earth. The average temperatures of the winter months (June, July, August) are from -60 to -75 °С, summer (December, January, February) from -30 to -50 °С; on the coast in winter from -8 to -35 °С, in summer 0-5 °С.

Another feature of the meteorology of East Antarctica is katabatic (katabatic) winds, due to its dome-shaped topography. These steady southerly winds occur on rather steep slopes of the ice sheet due to the cooling of the air layer near the ice surface, the density of the near-surface layer increases, and it flows down the slope under the action of gravity. The thickness of the air flow layer is usually 200-300 m; due to the large amount of ice dust carried by the wind, horizontal visibility in such winds is very low. The strength of the katabatic wind is proportional to the steepness of the slope and reaches its highest values in coastal areas with a high slope towards the sea. The katabatic winds reach their maximum strength in the Antarctic winter - from April to November they blow almost continuously around the clock, from November to March - at night or when the Sun is low above the horizon. In summer, during the daytime, due to the heating of the near-surface air layer by the sun, katabatic winds near the coast stop.

Relief of Antarctica:

Antarctica is the highest continent of the Earth, the average height of the surface of the continent above sea level is more than 2000 m, and in the center of the continent it reaches 4000 meters. Most of this height is the permanent ice sheet of the continent, under which the continental relief is hidden, and only 0.3% (about 40 thousand km²) of its area is free of ice - mainly in West Antarctica and the Transantarctic Mountains: islands, coastal areas, etc. n. "dry valleys" and individual ridges and mountain peaks (nunataks) rising above the ice surface. The Transantarctic Mountains, crossing almost the entire continent, divide Antarctica into two parts - West Antarctica and East Antarctica, which have a different origin and geological structure. In the east there is a high (the highest elevation of the ice surface is ~4100 m above sea level) ice-covered plateau. The western part consists of a group of mountainous islands connected by ice. On the Pacific coast are the Antarctic Andes, whose height exceeds 4000 m; the highest point of the continent - 5140 m above sea level - the Vinson Massif in the Ellsworth Mountains. The deepest depression of the continent, the Bentley Basin, is also located in West Antarctica, probably of rift origin. The depth of the Bentley depression, filled with ice, reaches 2555 m below sea level.

Underwater relief of Antarctica:

The study using modern methods made it possible to learn more about the subglacial relief of the southern continent. As a result of the research, it turned out that about a third of the mainland lies below the level of the world ocean, the research also showed the presence of mountain ranges and massifs.

The western part of the continent has a complex relief and large elevation changes. Here are the highest mountain (Mount Vinson 5140 m) and the deepest depression (Bentley trough −2555 m) in Antarctica. The Antarctic Peninsula is a continuation of the South American Andes, which stretch towards the South Pole, slightly deviating from it to the western sector.

The eastern part of the mainland has a predominantly smooth relief, with separate plateaus and mountain ranges up to 3-4 km high. In contrast to the western part, composed of young Cenozoic rocks, the eastern part is a projection of the crystalline basement of the platform that was previously part of Gondwana.

The continent has relatively low volcanic activity. The largest volcano is Mount Erebus on Ross Island in the sea of the same name.

Ice sheet of Antarctica:

The Antarctic ice sheet is the largest on our planet and exceeds the nearest Greenland ice sheet in area by approximately 10 times. It contains ~30 million km³ of ice, that is, 90% of all land ice. Due to the gravity of the ice, as studies by geophysicists show, the continent sank by an average of 0.5 km, as evidenced by its relatively deep shelf. The ice sheet in Antarctica contains about 80% of all fresh water on the planet; if it melts completely, global sea levels will rise by almost 60 meters (for comparison: if the Greenland ice sheet melted, ocean levels would rise by only 8 meters).

The ice sheet is dome-shaped with an increase in the steepness of the surface towards the coast, where it is framed in many places by ice shelves. The average thickness of the ice layer is 2500-2800 m, reaching a maximum value in some areas of East Antarctica - 4800 m. The accumulation of ice on the ice sheet leads, as in the case of other glaciers, to the flow of ice into the coast of the continent; ice breaks off in the form of icebergs. The annual volume of ablation is estimated at 2500 km³.

A feature of Antarctica is a large area of ice shelves (low (blue) areas of West Antarctica), which is ~10% of the area that rises above sea level; these glaciers are the source of icebergs of record size, much larger than those of the outlet glaciers of Greenland; for example, in 2000, the largest iceberg B-15 known at the moment (2005) with an area of over 10 thousand km² broke away from the Ross Ice Shelf. In winter (summer in the Northern Hemisphere), the area of sea ice around Antarctica increases to 18 million km², and in summer it decreases to 3-4 million km².

Seismic activity in Antarctica:

Antarctica is a tectonically calm continent with low seismic activity, manifestations of volcanism are concentrated in West Antarctica and are associated with the Antarctic Peninsula, which arose during the Andean period of mountain building. Some of the volcanoes, especially island ones, have erupted in the last 200 years. The most active volcano in Antarctica is Erebus. It is called "the volcano guarding the way to the South Pole".

Inland waters of Antarctica:

Due to the fact that not only the average annual, but also in most areas even summer temperatures in Antarctica do not exceed zero degrees, precipitation there falls only in the form of snow (rain is an extremely rare occurrence). It forms an ice sheet (snow is compressed under its own weight) with a thickness of more than 1700 m, in some places reaching 4300 m. About 80% of the entire fresh water of the Earth is concentrated in the Antarctic ice. Nevertheless, there are lakes in Antarctica, and in the summer, rivers. The food of the rivers is glacial. Due to the intense solar radiation, due to the exceptional transparency of the air, the melting of glaciers occurs even at a slight negative air temperature. On the surface of the glacier, often at a considerable distance from the coast, streams of melt water are formed. The most intense melting occurs near oases, next to rocky ground heated by the sun. Since all streams are fed by the melting of the glacier, their water and level regime is completely determined by the course of air temperature and solar radiation. The highest flows in them are observed during the hours of the highest air temperatures, that is, in the second half of the day, and the lowest - at night, and often at this time the channels completely dry up. Glacial streams and rivers, as a rule, have very winding channels and connect numerous glacial lakes. Open channels usually end before reaching the sea or lake, and the watercourse makes its way further under the ice or in the thickness of the glacier, like underground rivers in karst areas.

With the onset of autumn frosts, the flow stops, and deep channels with steep banks are covered with snow or blocked by snow bridges. Sometimes almost constant snow and frequent blizzards block the channels of the streams even before the runoff stops, and then the streams flow in ice tunnels, completely invisible from the surface. Like crevasses in glaciers, they are dangerous as heavy vehicles can fall through them. If the snow bridge is not strong enough, it can collapse under the weight of a person. The rivers of the Antarctic oases flowing through the ground usually do not exceed a few kilometers in length. The largest is R. Onyx, over 20 km long. The rivers exist only in the summer.

Antarctic lakes are no less peculiar. Sometimes they stand out in a special, Antarctic type. They are located in oases or dry valleys and are almost always covered with a thick layer of ice. However, in summer, a strip of open water several tens of meters wide is formed along the banks and at the mouths of temporary streams. Often, lakes are stratified. At the bottom there is a layer of water with increased temperature and salinity, as, for example, in Lake Vanda (English) Russian .. In some small closed lakes, the salt concentration is significantly increased and they can be completely ice-free. For example, oz. Don Juan, with a high concentration of calcium chloride in its waters, freezes only at very low temperatures. Antarctic lakes are small, only some of them are larger than 10 km² (Lake Vanda, Lake Figure). The largest of the Antarctic lakes is Lake Figurnoe in the Bunger oasis. Bizarrely meandering among the hills, it stretches for 20 kilometers. Its area is 14.7 km², and the depth exceeds 130 meters. The deepest is Lake Radok, its depth reaches 362 m.

There are lakes on the coast of Antarctica, formed as a result of water backwater by snowfields or small glaciers. Water in such lakes sometimes accumulates for several years until its level rises to the upper edge of the natural dam. Then excess water begins to flow out of the lake. A channel is formed, which quickly deepens, the flow of water increases. As the channel deepens, the water level in the lake falls and it shrinks in size. In winter, the dried-up channel is covered with snow, which is gradually compacted, and the natural dam is restored. In the next summer season, the lake begins to fill with melt water again. It takes several years until the lake is filled and its waters again break into the sea.

Nature of Antarctica:

As a result of global warming, tundra began to actively form on the Antarctic Peninsula. According to scientists, in 100 years the first trees may appear in Antarctica.

An oasis on the Antarctic Peninsula covers an area of 400 km2, the total area of oases is 10,000 km2, and the area of ice-free regions (including snowless rocks) is 30,000–40,000 km2.

The biosphere in Antarctica is represented in four “arenas of life”: coastal islands and ice, coastal oases on the mainland (for example, the “Banger oasis”), the nunatak arena (Mount Amundsen near Mirny, Mount Nansen on Victoria Land, etc.) and the arena of the ice sheet .

From plants there are flowering, fern (on the Antarctic Peninsula), lichens, fungi, bacteria, algae (in oases). Seals and penguins live on the coast.

Plants and animals are most common in the coastal zone. Ground vegetation in ice-free areas exists mainly in the form of various types of mosses and lichens and does not form a continuous cover (Antarctic moss-lichen deserts).

Antarctic animals are completely dependent on the coastal ecosystem of the Southern Ocean: due to the scarcity of vegetation, all significant food chains of coastal ecosystems begin in the waters surrounding Antarctica. Antarctic waters are particularly rich in zooplankton, primarily krill. Krill directly or indirectly form the basis of the food chain for many species of fish, cetaceans, squid, seals, penguins and other animals; There are no completely land mammals in Antarctica, invertebrates are represented by about 70 species of arthropods (insects and arachnids) and nematodes living in soils.

Terrestrial animals include seals (Weddell, crabeater seals, leopard seals, Ross, elephant seals) and birds (several petrel species (antarctic, snowy), two skuas, Arctic tern, Adélie penguins and emperor penguins).

In freshwater lakes of continental coastal oases - "dry valleys" - there are oligotrophic ecosystems inhabited by blue-green algae, roundworms, copepods (cyclops) and daphnia, while birds (petrels and skuas) fly here occasionally.

Nunataks are characterized only by bacteria, algae, lichens and heavily oppressed mosses; only skuas following people occasionally fly onto the ice sheet.

There is an assumption about the presence in the subglacial lakes of Antarctica, such as Lake Vostok, of extremely oligotrophic ecosystems, practically isolated from the outside world.

In 1994, scientists reported a rapid increase in the number of plants in the Antarctic, which seems to confirm the hypothesis of global warming on the planet.

The Antarctic Peninsula with adjacent islands has the most favorable climatic conditions on the mainland. It is here that two species of flowering plants found in the region grow - antarctic meadow grass and kito colobanthus.

Population of Antarctica:

In the 19th century, several whaling bases existed on the Antarctic Peninsula and adjacent islands. Subsequently, they were all abandoned.

The harsh climate of Antarctica prevents its settlement. Currently, there is no permanent population in Antarctica; there are several dozen scientific stations here, where, depending on the season, from 4,000 people (150 Russian citizens) live in summer and about 1,000 in winter (about 100 Russian citizens).

In 1978, the first man of Antarctica, Emilio Marcos Palma, was born at the Esperanza station in Argentina.

Antarctica has been assigned the Internet top-level domain .aq and the telephone prefix +672.

Legal status of Antarctica:

In accordance with the Antarctic Convention, signed on December 1, 1959 and entered into force on June 23, 1961, Antarctica does not belong to any state. Only scientific activities are allowed.

The deployment of military installations, as well as the entry of warships and armed vessels south of 60 degrees south latitude, are prohibited.

In the 1980s, Antarctica was also declared a nuclear-free zone, which excluded the appearance of nuclear-powered ships in its waters, and nuclear power units on the mainland.

Now the parties to the treaty are 28 states (with the right to vote) and dozens of observer countries.

Orthodox Church in Antarctica:

The first Orthodox Church in Antarctica was built on the island of Waterloo (South Shetland Islands) near the Russian Bellingshausen station with the blessing of His Holiness Patriarch Alexy II. They collected it in Altai, and then transported it to the icy mainland on the scientific vessel Akademik Vavilov. The fifteen-meter temple was cut down from cedar and larch. It accommodates up to 30 people.

The temple was consecrated in the name of the Holy Trinity on February 15, 2004 by the vicar of the Holy Trinity Sergius Lavra, Bishop Feognost of Sergiev Posad, in the presence of numerous clergy, pilgrims and sponsors, who arrived on a special flight from the nearest city, Chilean Punta Arenas. Now the temple is the Patriarchal Compound of the Trinity-Sergius Lavra.

The Church of the Holy Trinity is considered the southernmost Orthodox church in the world. To the south, there is only the chapel of St. John of Rylsky at the Bulgarian station St. Kliment Ohridsky and the chapel of St. Vladimir Equal-to-the-Apostles at the Ukrainian station Academician Vernadsky.

On January 29, 2007, the first wedding in Antarctica took place in this temple (daughter of a polar explorer, Russian woman Angelina Zhuldybina and Chilean Eduardo Aliaga Ilabac, who works at the Chilean Antarctic base).