Antarctic glaciers are the greatest in the world, as they represent the drainage system of the world's largest ice sheet. Many of the glaciers would be more accurately called ice streams, since they do not have clearly defined boundaries. Where the glacier flows into the bay, reaching the shore, the ice floats and an ice shelf forms. A glacier descending from a flat section of the coast does not form an ice shelf, but, once afloat, continues to flow directly into the sea. This protrusion is called a glacier tongue and is usually very unstable, although the tongue of the Erebus Glacier, which flows into McMurdo Sound, often extends more than 10 km out to sea before breaking off. Antarctica's largest ice shelves, the Ross and Filchner ice shelves, are so large that they are fed by several glaciers and ice streams. The Ratford Glacier, which flows near the Ellsworth Mountains into the southwestern corner of the Ronne Ice Shelf, reaches more than 1.6 km. in thickness in the place where it finds itself afloat, and demonstrates the most powerful floating ice known in the world.

Lambert Glacier - the largest and longest glacier in the world

The Lambert Glacier in East Antarctica flows approximately north along the 90°E meridian through the Prince Charles Mountains into Prydz Bay. Some tourist ships sail close to these places, but to see the glacier, you need to move deeper into the mainland, preferably by helicopter.

The Lambert Glacier in East Antarctica is probably the world's largest glacier. Its width reaches 64 km. where it crosses the Prince Charles Mountains, and its length, including its offshore extension, the Amery Ice Shelf, is about 700 km. It collects ice from about a fifth of the East Antarctic ice sheet; if you do the math, it turns out that approximately 12% of the fresh water on Earth passes through the Lambert Glacier. This astounding figure is as difficult to comprehend as the majesty of the Antarctic glacier. The popular image of an Alpine or Himalayan glacier flowing down a slope like an icy river is, strictly speaking, inapplicable to the Lambert Glacier due to its colossal size. Shooting from space is the best way to see enough of it to know that it really is a glacier.

Glaciers move slowly. The fastest, the Jakobshavn glacier in Greenland, covers 7 km. per year, while the Lambert Glacier slides down the Prince Charles Mountains at a rate of only 0.23 km. per year, gradually accelerating to 1 km. per year at the Amery Ice Barrier. However, although it does not move quickly, it moves powerfully, since about 35 cubic meters passes through it per year. km. ice.

The surface of a glacier like this, when viewed from a great height, such as from an airplane, is marked by streamlines - natural ridges of the ice that indicate the direction of its movement, like the strokes of a giant brush on the oil of a panoramic painting. From the ground, these ribs are invisible, but they can be identified by areas of parallel cracks. They are created by different speeds of ice movement inside the glacier; they can be formed by unevenness of the glacier bed or obstacles in its path. In this case, a zone of random cracks is formed, as, for example, in places of a sharp change in the angle of inclination of the terrain; this phenomenon is called an icefall and is analogous to a waterfall on a river. Some of the cracks below Gillock Island, formed because the glacier is forced to flow around this island, reach more than 400 m in width and 40 km. in length, surpassing in size some Alpine glaciers.

Snow bridges span these huge cracks, or rifts, instilling timidity in the traveler forced to use them. However, despite their enormous size, crossing them is quite safe, since the additional weight of the tractor is infinitesimal compared to the weight of the snow supported by the bridge. Sir Vivian Fuchs' Transantarctic Expedition (1955-1958) encountered similar cracks upon leaving the South Pole, and is said to have descended the slope to a bridge and climbed the slope again on the other side. The main danger was represented by small cracks at the edge of the bridge itself. Elsewhere, traveling across the glacier can be relatively easy, as long as you avoid known areas of crevasses. Like the rivers of Africa to the pioneers of that continent, the glaciers of Antarctica often offer explorers an obvious route into the interior of the continent. Shackleton discovered the Bridmore Glacier, which provided a direct route from the Ross Ice Shelf to the Polar Plate; Scott and four of his companions chose the same route for their fateful journey to the Pole.

An ice shelf typically forms where glaciers and ice streams flowing from a continental ice sheet flow into a gulf. Having descended along the bottom to a certain depth - usually 300 m - the ice becomes floating and various glaciers merge into a single field. This field continues to grow until it fills the bay. Going beyond the bay, no matter how large it is, the front part of the glacier, having lost the restraining influence of the mouth of the bay, loses stability and becomes vulnerable to the forces of the open ocean. The glacier gradually breaks off along a line connecting the extreme points of the bay, and the glacier “calves” occurs. The ice shelf also loses ice, melting from below and forming cold bottom currents that move north over the ocean floor to then rise to the surface, oxygenating tropical waters. Although the glacier, on the other hand, thickens due to the fall of snow on its surface, the overall result is that it becomes thinner towards the open sea. The ice barrier - the edge of the glacier facing the sea - reaches a thickness of approximately 180 m and rises above sea level by 20-30 m. An object left on the surface of the ice shelf will gradually descend as it approaches the ocean.

Ross Glacier is the largest ice shelf in Antarctica

The Ross Ice Shelf can usually be reached by ship or plane from New Zealand during the transfer of personnel and supplies to the US McMurdo Station and New Zealand's Scott Base. Tourist ships also visit these places, but passengers rarely get to see anything other than the cliff of the ice barrier.

Captain James Cook, during his second voyage, in 1772-1775, became the first person to penetrate the high latitudes of Antarctica, but he never managed to see the continent; all attempts he made to sail further south were thwarted by pack ice. It was only in 1840 that Captain James Clark Ross, by then Britain's most experienced Arctic navigator, sailed south and successfully broke through the belt of pack ice into the waters now known as the Ross Sea. He discovered Ross Island, and to the east of it a ridge, which he called the Victoria Barrier and about which he wrote: “... we had the same chance of overcoming this mass as if we were trying to swim through the rocks of Dover.”
Ross was shocked. Ice cliffs ranging from 46 to 61 m high hung over his ships, and to the south nothing was visible except an endless icy plain. Strictly speaking, the Ross Ice Shelf is an approximately triangular slab of ice whose thickness ranges from 183 m at the ice barrier at its leading edge to 1300 m in the landward part. Its area is 542,344 sq. km. - this is larger than the territory of Spain and almost equal to the area of ​​France; and since it is afloat, it rises and falls under the influence of the tides. Large pieces of shelf ice break off and turn into table icebergs; the largest recorded, with an area of ​​31,080 sq. km, was larger than Belgium.

The Ross Ice Shelf is fed by glaciers. Many of them, such as the Beardmore Glacier, come down from the Transantarctic Mountains, but glacial streams coming from Mary Byrd Land bring more ice. A ship sailing through the Ross Sea in 1950 encountered an iceberg with a corner of a building sticking out of its side, identified as a fragment of a house from one of Admiral Byrd's Little America stations, built about 30 years earlier.

The shelf ice is mostly free of cracks and is easy to move around. It is relatively flat, but the progress of the sled depends on the condition of the surface. Snowy areas are difficult to navigate whether the sled is pulled by people, dogs or tractors. Often there are sastrugi - dense, wind-created ridges of snow that, if their height exceeds 30 cm, can make travel difficult. It’s especially disappointing when the depressions between the ridges are filled with soft snow, the surface appears smooth, but people and tractors fall through.

Were there any great catastrophes?
Primitive organisms became more complex until, through a long line of ancestors, man finally arose. Gradually, the gaps in the geological record were filled, and the harmonious picture of the development of the Earth was already close to completion. It seemed that the prediction of the founder of scientific geology, Charles Lyell, made back in 1830, was coming true: “The order in nature, from the earliest periods, was monotonous in the sense in which we consider it monotonous now, and we hope that it will remain so and for the future."
And yet there were disasters!
Signs of dramatic changes were observed simultaneously throughout the entire Earth. Over the past billion years, four great catastrophes have been of greatest importance - 650, 230, 65 and 35 million years ago.
The first of them was associated with the largest glaciation in the history of the Earth. Its traces have been found on all continents except Antarctica, which is now covered with glaciers and THEREFORE poorly studied. There are signs of glaciation in equatorial regions as well. It may be objected that the continents are moving, and those areas that are now on the equator were once near the poles. But now we have learned to determine the latitude of ancient continents. It turned out that Scotland and Belarus, where glacial deposits with an age of about 650 million years were discovered, were at the equator at that time. This means that glaciers then reached the equator. Before this, the Sun provided several percent less heat than it does now. But there was much more carbon dioxide in the atmosphere, and the greenhouse effect warmed the Earth. Plants appeared in the oceans (blue-green, and then “real” algae), they consumed and decomposed carbon dioxide, and “having eaten their own blanket,” brought the Earth to almost complete glaciation. As a result, many algae died out, and the “blanket” gradually recovered.
The second catastrophe occurred 230 million years ago, shortly after another major glaciation. It was not worldwide and covered only the polar and part of the temperate latitudes of the Southern Hemisphere. As has now been proven, climate aridity is associated with glaciations. Ocean water flowed into huge bays surrounded by deserts and evaporated into them. Salts precipitated. One of these bays was located in the east of the East European Plain. The salt left the ocean, but the water, in the course of its great cycle, returned to it. As a result, the salinity of the ocean waters has decreased significantly. Not all marine organisms were able to survive this. According to some data, 97 percent of the organisms that previously lived in the seas and oceans became extinct. The disaster did not affect terrestrial fauna and flora.
Sixty-five million years ago, the most mysterious event in geological history occurred. Dinosaurs and other giant reptiles that had dominated for more than a hundred million years suddenly became extinct. Together with them the inhabitants became extinct ammonites, belemnites and many types of microscopic organisms that formed the seas. Dozens of hypotheses have been proposed to explain the extinction, but among them there is not a single one that would be convincing from the point of view of all or at least the majority of researchers. The theory of dinosaur extinction has yet to be created.
In the Mesozoic, when dinosaurs lived, a warm climate reigned throughout the Earth. The water on the surface of the oceans in the polar regions had a temperature of 15 and sometimes 18 degrees. Approximately the same conditions prevailed at the beginning of the Cenozoic - the “age of mammals” - until 35 million years ago. But then very quickly, almost instantly (on the scale of geological time, this “instant” lasted about one hundred thousand years) the temperature everywhere dropped by several degrees. In the tropics it became colder than now, but in the temperate and polar latitudes after the cold snap the temperature was still much higher than today.

Reasons for the cold snap
Until recently, temperature changes were judged mainly from the remains of animals and plants. The cooling was indicated by the extinction of heat-loving species. But it was always possible to say that in the past organisms lived under different conditions than now, and extinction is not associated with cooling, but with something else. Now “thermometers” have been found that allow us to more objectively judge the conditions of the past. The isotopic composition of oxygen contained in ancient organisms is determined. In addition to the most common isotope with atomic weight 16, there is also an isotope with atomic weight 18 - the so-called heavy oxygen. But in the remains of ancient organisms, the content of heavy oxygen varies depending on the temperature of the water in which they lived. The oxygen thermometer showed that about 35 million years ago there was a cooling, and not any other change in the environment.
What was the cause of the cold snap? There are many hypotheses. The first of them is the hypothesis of a decrease in the luminosity of the Sun. But astrophysicists are against it - neither the Sun nor stars similar to it can dramatically change their luminosity. It does not decrease, but grows very slowly and gradually - by about one percentage over 100 million years. Some botanists have suggested that the tilt of the earth's axis suddenly changed. Experts in celestial mechanics refuse to even discuss such a hypothesis; it seems completely ridiculous to them.
Is it possible to explain the cooling by the fact that the Earth’s “blanket” has become leaky - the greenhouse effect of its atmosphere has decreased? To do this, the carbon dioxide content in it had to decrease. It depends on how quickly plants consume carbon dioxide. The more lush the vegetation, the higher the photosynthesis and the lower the CO content in the atmosphere. But when it gets colder, the vegetation becomes less lush, and the carbon dioxide content in the air increases. The greenhouse effect inhibits cooling caused by other causes.
Maybe the Earth “changed clothes” into different, lighter clothes? After all, we, too, dress in white to escape the heat. White surfaces reflect the sun's rays. For the Earth to become more white, extensive glaciers, sea ice and snow fields must appear. They appear only at low temperatures. An increase in albedo (reflectivity) can support cooling, but cannot be its cause.
Before 35 million years ago, snow and ice probably did not exist anywhere except in the high mountains. But the polar latitudes received as much solar heat as they receive it now. Where did the extra heat come from? In winter, there is ice in the Sea of ​​Azov, but the southwestern part of the Barents Sea never freezes. This is explained by the fact that a warm current approaches the northern shores of Europe. Maybe 40-50 million years ago it was more powerful? Alas, this explanation does not fit either. Once upon a time there was no sea at all between Scandinavia and Greenland. Fifty-five million years ago they began to slowly move away from each other, and only about 30 million years ago deep-sea communication was established between the Norwegian-Greenland and Polar basins. There was no sea through which the ancient Gulf Stream could flow!
The oceans and the Earth's atmosphere form a single climate machine. The location of the continents of the Northern Hemisphere did not create conditions for the warm climate of the Arctic. But the situation was saved by the Southern Hemisphere. Australia was then much further south and formed a single continent with Antarctica. South America was connected to it - there was no Drake Passage. Under such conditions, warm currents caused by easterly winds in subtropical latitudes turned south along the eastern coasts of South America and Australia and reached Antarctica. Within its borders a fairly warm climate prevailed and forests of southern beech grew. It was through Antarctica that marsupials, many representatives of the plant world and even freshwater crustaceans penetrated from America to Australia. Two huge eddies in the Southern Hemisphere - one in the Pacific and the other in the Atlantic and Indian Oceans - warmed the temperate and polar latitudes. There was so much heat that it was enough to heat the Northern Hemisphere.
55 million years ago, Australia began to slowly move north. But there was an isthmus between it and Antarctica for a long time, and then the strait was narrow and shallow. Only 35 million years ago, a powerful ocean current arose south of Australia, driven by westerly winds. This radically changed the climatic conditions of the entire Earth. Two whirlpools of the Southern Hemisphere merged into one. Now, from the southeastern coast of South America (still connected with Antarctica), the waters of the ocean made an almost round-the-world journey near the coast of Antarctica, the southwestern coast of South America and turned north. Further along the equator they were driven by easterly winds. Through a wide and deep strait between Australia (although it had moved away from Antarctica, it was much further south than now) and Southeast Asia, the current penetrated into the Indian Ocean, then turned south and... the cycle repeated.

Glaciers cover Antarctica
In the far and cold south, during the long journey, the waters managed to cool greatly. Then the cooled waters penetrated into tropical latitudes and cooled them as well. The cooling caused the growth of glaciers in East Antarctica. The names East and West Antarctica are arbitrary. In essence, any part of this continent will be north of the South Pole. But European travelers usually went to Antarctica via the Atlantic Ocean. For them, its more rugged part, adjacent to South America, was in the west, and the main, more massive part was in the east. If you mentally remove the modern ice cover, then West Antarctica will turn into an archipelago of islands, while East Antarctica will still remain a continent.
For glaciers to grow, it is necessary that the snow that falls during the winter does not have time to melt in the summer. There is more and more snow, gradually turning into ice under the weight of the overlying layers. Having accumulated in large masses, the ice begins to flow, like lava (but much slower). Streams of ice move in the mountain valleys, while on the plains huge ice sheets and domes with relatively steep edges and a flat middle, similar to loaves, form. This analogy is not accidental - after all, the dough takes the shape of a loaf according to the same hydromechanical laws by which ice takes the shape of a dome. Both dough and ice can be considered very viscous liquids.
In the center of East Antarctica are the Gamburtsev Mountains. Now they are buried under the ice. The mountains were discovered by measuring the thickness of the glacier.
On the tops of the Gamburtsev Mountains, glaciers could have appeared even before the cold snap began. When the temperature dropped, glaciers occupied the entire mountain range. A cold air mass formed above it, which cooled the surrounding area. The larger the glaciers became, the better the conditions were for their further growth. Very quickly (of course, in a geological sense), in just a few tens of thousands of years, glaciers occupied the entire East Antarctica and reached its shores. But they almost never descended into the sea and almost never gave birth to icebergs.
The emergence of an ice sheet covering an area of ​​10 million square kilometers had a huge impact on the climate and greatly intensified the initial cooling. Ice covered seven percent of the entire land surface. Snow began to fall and sea ice appeared. Huge white surfaces reflected the sun's rays. As a result, the entire Earth has become colder - not only in the Southern, but also in the Northern Hemisphere. The cooling was accompanied by increased aridity - it was at this time that the Sahara Desert was formed.
The growth of glaciers also caused a decrease in sea levels. Water constantly evaporates from its surface, but just as constantly it returns back - the moisture that is transferred by air currents to land, then flows down rivers again into the ocean. But when glaciers grow, the snow that falls on them does not return to the ocean, but is used to build glaciers: the volume of water bound in the glaciers is, as it were, subtracted from the volume of the ocean. 35 million years ago, sea levels dropped by about sixty meters. As a result, vast shallow waters turned into dry land. The sea has left most of the East European Plain and Western Siberia.
The vegetation has changed dramatically. Before the cold snap began, palm trees grew all the way to the coast of the Kara and Okhotsk seas. When it became colder, they survived only in the southern part of the East European Plain, in Central Asia and in the Vladivostok region.
But the animal world has undergone the most important changes. Until 35 million years ago, polytuberculates were widespread - small animals similar to rodents, but with a completely different internal structure. They became extinct and were replaced by rodents. Ancient predators and ancient ungulates became extinct, and in their place the development of modern predators and ungulates began. Changes in the order of primates are of great importance. Until 35 million years ago, only lemurs and tarsiers, the lower primates, were common. Now lemurs are found in Madagascar, but in the rest of the tropical zone, most of them died out with the onset of cooling. Lemurs were replaced by monkeys.
So, the main features of the nature around us were formed 35 million years ago as a result of the beginning of glaciation in East Antarctica. Glaciation was a cause, but it was not the root cause. Everything, as we already know, began with the separation of Australia and Antarctica and the movement of Australia to the north.

The Long Journey of Earth's Nature
35 million years ago, only the basic features of modern nature arose, but it was still not very similar to what we see today. The earth had a long and difficult journey ahead of it. Australia's northward movement continued; about 20 million years ago, the deep-water strait that separated it from Southeast Asia closed (shallow-water straits still exist there). The equatorial current of the Pacific Ocean, which had previously penetrated into the Indian Ocean, turned south along the coast of Australia and began to warm the temperate latitudes of the Southern Hemisphere. In the north, deep-sea communication was finally established between the Norwegian-Greenland and Polar basins, and warm waters penetrated into it. Warming occurred in both the north and the extreme south.
Alas, it was short-lived. 25 million years ago, South America began to move away from Antarctica. 12-14 million years ago the strait between them became quite wide and deep. The Southern Circular Current began to pass through the Drake Passage, encircling Antarctica. Water exchange between tropical and temperate latitudes of the Southern Hemisphere has again sharply decreased. It got colder in the polar latitudes, but it became warmer in the tropics - cold waters from the south no longer reached there. It was then that modern climatic contrasts arose, when some places suffer from heat, while others suffer from cold. The glaciers of Antarctica have increased - they also occupied West Antarctica.
Cooling in temperate latitudes caused increased aridity. It was then, about 12 million years ago, that the steppes arose in the south of the East European Plain. Herds of hipparions roamed the steppes of Eurasia and the savannas of Africa - three-toed relatives of horses that moved from America along the land “bridge” that existed on the site of the modern Bering Strait. Ramapithecus, which can be considered our direct ancestors, spread to southern Asia and Africa. Their height was small - about a meter, but they already walked on two legs.
About three million years ago, ice sheets appeared in the Northern Hemisphere. They covered Greenland, Iceland and the land that was in place of the Barents Sea. The emergence of new genera of animals - elephants, bulls and horses - is associated with new cooling and increased aridity. In East Africa, Australopithecus (descendants of Ramapithecus) began to hunt using the first stone tools - they turned into people.
About a million years ago, glaciation swept across the temperate latitudes of the Northern Hemisphere. At the edge of the glacier, very cold and dry steppes dominated, mammoths and hairy rhinoceroses grazed in them. The glaciers advanced and then retreated again. Our time falls on one of the periods of least development of glaciers.
Will acknowledging drastic changes lead to some incorrect conclusions? Indeed, at the beginning of the 19th century, some believed that after each catastrophe there follows a new “act of divine creation.” The author of the “catastrophe theory” himself, Georges Cuvier, did not write anything like this. In his opinion, the deserted continent was inhabited by animals that came from other places. Cuvier did not specify how they appeared there. Some of Cuvier’s students wrote about “divine creation”, trying to reconcile his views with religious ideology.
What is the situation today, when no one doubts the validity of evolutionary theory? It has now been proven that many organisms that suddenly appeared after the disaster actually existed before it, but were very rare or found only in certain limited areas. When the “masters of the Earth” perished, the former pariahs came to the forefront of geological history. They quickly multiplied, spread widely and became the new masters of the Earth. At first, there were no organisms that could master all the conditions suitable for life. This gave impetus to rapid evolution.
Monkeys, for example, existed before the latest disaster, but were much less common than lemurs. It is possible that if the warm and humid climate had remained, lemurs would still dominate. At one of the reports I gave in Moscow, the question was asked: “If the glaciation of Antarctica had not begun, would we have lived among subtropical forests?” I had to give the following answer: “There would indeed be subtropical forests here, but it would not be us who would live in them, but lemurs with huge eyes.” Cooling increased the rate of evolution many times over. Great catastrophes are, in essence, revolutions in the development of the organic world. Without them, it would have developed much more slowly.
In this regard, we recall the words of the great English naturalist of the 17th century, William Harvey: “Do not praise, do not blame - everyone worked well.” Once upon a time, supporters of Georges Cuvier and Charles Lyell argued fiercely among themselves. Now it is clear that both were right. Both slow and gradual development and disasters are explained by natural causes.
The last great “catastrophe” is associated with the beginning of glaciation in Antarctica. Will another catastrophe occur if human-caused warming causes glaciers to melt and sea levels to rise by 70 meters? A look into the past shows that there will not be a “global flood”. After all, 20-30 million years ago the volume of glaciers was already close to what it is today. At that time, a rather warm climate prevailed in temperate and polar latitudes. The ice sheet of East Antarctica was melting at the edges, but did not decrease in size - much more snow fell on its surface than now.
In my opinion, the upcoming warming will also lead to heavy snowfalls. The largest ice sheets may even increase their thickness as a result. They will produce fewer icebergs and melt a little at the edges, but will not decrease in volume until the volume of melting exceeds the volume of snow water received by the glaciers each year. For this to happen, a warming of 10-12 degrees is needed. Only after this will Antarctica's glaciers begin to disintegrate and sea levels to rise. But there is no talk of such warming in the foreseeable future. With less warming, sea levels could even drop slightly as Antarctic glaciers become thicker.
Homo sapiens, Homo sapiens, evolved from apes that spread widely 35 million years ago. If humanity lives up to this high title and acts wisely, the last great “catastrophe” will not truly turn into a catastrophe.

D. Kvasov, Doctor of Geographical Sciences

The ice of the Arctic and Antarctic is not at all eternal. Nowadays, due to the impending global warming caused by the environmental crisis of thermal and chemical pollution of the atmosphere, the mighty shields of frost-bound water are melting. This threatens a great disaster for a vast territory, which includes low-lying coastal lands of different countries, primarily European ones (for example, Holland).

But since the ice sheet of the poles is capable of disappearing, it means that it once arose during the development of the planet. "White caps" appeared - a very long time ago - within some limited interval of the geological history of the Earth. Glaciers cannot be considered an integral property of our planet as a cosmic body.

Comprehensive (geophysical, climatological, glaciological and geological) studies of the southern continent and many other areas of the planet have convincingly proven that the ice cover of Antarctica arose relatively recently. Similar conclusions were drawn regarding the Arctic.

Firstly, data from glaciology (the science of glaciers) indicate a gradual increase in ice cover over the past millennia. For example, the glacier covering the Ross Sea was much smaller in area just 5,000 years ago than it is now. It is assumed that at that time it occupied only half of the current territory it covers. Until now, according to some experts, the slow freezing of this gigantic tongue of ice continues.

Drilling wells in the thickness of continental ice has yielded unexpected results. The cores clearly showed how successive layers of ice froze over the last 10-15 thousand years. Spores of bacteria and plant pollen were found in different layers. Consequently, the ice sheet of the continent grew and actively developed during the last millennia. This process was influenced by climatic and other factors, since the rate of formation of ice layers varies.

Some of the bacteria found frozen in the Antarctic ice (up to 12 thousand years old) were revived and studied under a microscope. At the same time, a study of air bubbles immured in these huge layers of frozen water was organized. Work in this area has not been completed, but it is clear that scientists have evidence of the composition of the atmosphere in the distant past.

Geological studies have confirmed that glaciation is a short-term natural phenomenon. The oldest global glaciation discovered by scientists occurred over 2000 million years ago. Then these colossal catastrophes were repeated quite often. The Ordovician glaciation occurs in an era 440 million years removed from our time. During this climate cataclysm, a great many marine invertebrates died. There were no other animals at that time. They appeared much later to become victims of the next freezing attacks that covered almost all continents.

The last glaciation, apparently, has not yet ended, but has retreated for a while. The great retreat of the ice occurred about 10 thousand years ago. Since then, powerful ice shells that once covered Europe, large parts of Asia and North America have remained only in Antarctica, on the Arctic islands and on top of the waters of the Arctic Ocean. Modern humanity lives in the so-called period. interglacial period, which should be replaced by a new advance of ice. Unless, of course, they melt completely first.

Geologists have received a lot of interesting facts about Antarctica itself. The Great White Continent apparently was once completely ice-free and had an even and warm climate. 2 million years ago, dense forests, like taiga, grew on its coasts. In ice-free spaces, it is possible to systematically find fossils of a later, Middle Tertiary time - imprints of leaves and twigs of ancient heat-loving plants.

Then, over 10 million years ago, despite the cooling that began on the continent, the local expanses were occupied by vast groves of laurels, chestnut oaks, cherry laurel trees, beech trees and other subtropical plants. It can be assumed that these groves were inhabited by animals characteristic of that time - mastodons, saber-tooths, hipparions, etc. But much more striking are the ancient finds in Antarctica.

In the central part of Antarctica, for example, the skeleton of the fossil lizard Lystrosaurus was found - not far from the South Pole, in rock outcrops. The large reptile, two meters long, had an unusually terrible appearance. The age of the find is 230 million years.

Lystrosaurs were, like other animal lizards, typical representatives of heat-loving fauna. They inhabited hot, swampy lowlands, abundantly overgrown with vegetation. Scientists have discovered an entire belt in the geological deposits of South Africa, overflowing with the bones of these animals, which is called the Lystrosaurus Zone. Something similar was found on the South American continent, as well as in India. It is obvious that in the early Triassic period, 230 million years ago, the climate of Antarctica, Hindustan, South Africa and South America was similar, since the same animals could live there.

Scientists are looking for an answer to the riddle of the birth of glaciers - what global processes, invisible in our interglacial era, 10 thousand years ago bound a huge part of the land and the World Ocean under a shell of solidified water? What causes such drastic climate change. None of the hypotheses are convincing enough to become generally accepted. Nevertheless, it is worth remembering the most popular ones. Among the hypotheses, three can be distinguished, conventionally called cosmic, planetary-climatic and geophysical. Each of them gives preference to a certain group of factors or one decisive factor that served as the root cause for the cataclysm.

The space hypothesis is based on data from geological surveys and astrophysical observations. When establishing the age of moraine and other rocks deposited by ancient glaciers, it turned out that climatic catastrophes occurred with strict frequency. The ground froze in a time interval that seemed specially designated for this. Each great cold snap is separated from the others by approximately 200 million years. This means that after every 200 million years of the dominance of a warm climate, a long winter reigned on the planet, and powerful ice caps formed. Climatologists turned to materials accumulated by astrophysicists: what could be responsible for such an incredibly long time between several iterative (regularly occurring) events in the atmosphere and hydrosphere of a space object? Perhaps with cosmic events comparable in scale and time frame?

Calculations by astrophysicists call such an event the revolution of the Sun around the galactic core. The dimensions of the Galaxy are extremely large. The diameter of this cosmic disk reaches a size of approximately 1000 trillion km. The Sun is located at a distance of 300 trillion km from the galactic core, so the full revolution of our star around the center of the system takes such a colossal period of time. Apparently, on its way, the Solar System crosses some area in the Galaxy, under the influence of which another glaciation occurs on Earth.

This hypothesis is not accepted in the scientific world, although it seems convincing to many. However, scientists do not have facts on the basis of which it could be proven or at least convincingly confirmed. There are no facts confirming the galactic influence on the million-year fluctuations in the planet’s climate; there is nothing except a strange coincidence of numbers. Astrophysicists have not found a mysterious region in the Galaxy where the Earth begins to freeze. The type of external influence that could cause something like this to happen has not been found. Some suggest a decrease in solar activity. It seems that the “cold zone” reduced the intensity of the flow of solar radiation, and as a result, the Earth began to receive less heat. But these are just assumptions.

Supporters of the original version came up with a name for the imaginary processes occurring in the stellar system. The complete revolution of the Solar System around the galactic core was called the galactic year, and the short interval during which the Earth remains in the unfavorable “cold zone” was called the cosmic winter.

Some supporters of the extraterrestrial origin of glaciers are looking for climate change factors not in the distant Galaxy, but inside the Solar System. For the first time such an assumption was made in 1920, its author was the Yugoslav scientist M. Milankovic. He took into account the inclination of the earth to the plane of the ecliptic and the inclination of the ecliptic itself to the solar axis. According to Milankovitch, the answer to the great glaciations should be sought here.

The fact is that depending on these inclinations the amount of radiant energy from the Sun reaching the earth's surface is most directly determined. In particular, different latitudes receive different numbers of rays. The relative position of the axes of the Sun and the Earth, changing over time, causes fluctuations in the amount of solar radiation in different regions of the planet and, under certain circumstances, leads the fluctuations to the stage of alternating warm and cold phases.

In the 90s XX century this hypothesis has been thoroughly tested using computer models. Numerous external influences on the planet's position relative to the Sun were taken into account - the Earth's orbit slowly evolved under the influence of the gravitational fields of neighboring planets, and the Earth's trajectory was gradually transformed.

French geophysicist A. Berger compared the obtained figures with geological data, with the results of radioisotope analysis of marine sediments, showing temperature changes over millions of years. Temperature fluctuations in ocean waters completely coincided with the dynamics of the process of transforming the earth's orbit. Consequently, the cosmic factor could well have provoked the onset of climate cooling and global glaciation.

At the moment, it cannot be said that the Milankovitch conjecture has been proven. First, it requires additional long-term checks. Secondly, scientists tend to be of the opinion that global processes could not be caused by the action of only one factor, especially if it is external. Most likely, there was a synchronization of the action of various natural phenomena, and the decisive role in this sum belonged to the Earth’s own elements.

The planetary-climate hypothesis is based precisely on this position. The planet is a huge climatic machine, which with its rotation directs the movement of air currents, cyclones and typhoons. The inclined position relative to the plane of the ecliptic causes non-uniform heating of its surface. In a sense, the planet itself is a powerful climate control device. And her internal forces are the reasons for his metamorphosis.

These internal forces include mantle currents, or so-called. convection currents in layers of molten magmatic matter that compose the mantle layer underlying the earth's crust. The movements of these currents from the core of the planet to the surface give rise to earthquakes and volcanic eruptions, and mountain-building processes. These same currents cause the appearance of deep splits in the earth's crust, called rift zones (valleys), or rifts.

Rift valleys are numerous on the ocean floor, where the crust is very thin and easily breaks through the pressure of convection currents. Volcanic activity is extremely high in these areas. Here, mantle material is constantly pouring out from the depths. According to the planetary-climate hypothesis, it is magma outpourings that play a decisive role in the oscillatory process of historical transformation of the weather regime.

Rift faults on the ocean floor, during periods of greatest activity, release enough heat to cause intense evaporation of seawater. This causes a lot of moisture to accumulate in the atmosphere, which then falls as precipitation onto the Earth’s surface. In cold latitudes, precipitation falls in the form of snow. But since their fall is too intense and the quantity is large, the snow cover becomes more powerful than usual.

The snow cap melts extremely slowly; for a long time, the influx of precipitation exceeds its outflow - melting. As a result, it begins to grow and transforms into a glacier. The planet's climate is also gradually changing as a stable area of ​​non-melting ice forms. After some time, the glacier begins to expand, since the dynamic system of uneven inflow and outflow cannot remain in balance, and the ice increases to incredible sizes and binds almost the entire planet.

However, the maximum of glaciation simultaneously becomes the beginning of its degradation. Having reached a critical point, an extremum, ice growth stops, encountering stubborn resistance from other natural factors. The dynamics became reversed; the rise gave way to a decline. However, the victory of “summer” over “winter” does not come immediately. Initially, a protracted “spring” begins for several thousand years. This is a change of short bouts of glaciation with warm interglacials.

Earth civilization was formed in the era of the so-called. Holocene interglacial. It began about 10,000 years ago, and, according to mathematical models, it will end at the end of the 3rd millennium AD, i.e. around 3000. From this moment the next cold snap will begin, which will reach its apogee after 8000 of our calendar.

The main argument of the planetary-climate hypothesis is the fact of periodic changes in tectonic activity in rift valleys. Convection currents in the bowels of the Earth excite the earth's crust with varying strengths, and this leads to the existence of such eras. Geologists have materials that convincingly prove that climate fluctuations are chronologically linked to periods of greatest tectonic activity of the subsoil.

Rock deposits show that the next climate cooling was accompanied by significant movements of powerful blocks of the earth's crust, which were accompanied by the appearance of new faults and the rapid release of hot magma from both new and old rifts. However, the same argument is used by supporters of other hypotheses to confirm their correctness.

These hypotheses can be considered as variations of a single geophysical hypothesis, since it is based on data about the geophysics of the planet, namely, it relies entirely on paleogeography and tectonics in its calculations. Tectonics studies the geology and physics of the process of movement of crustal blocks, and paleogeography studies the consequences of such movement.

As a result of multimillion-year displacements of colossal masses of solid matter on the earth's surface, the outlines of the continents, as well as the topography, changed significantly. The fact that thick layers of marine sediments or bottom silts are found on land directly indicates movements of crustal blocks, accompanied by its subsidence or uplift in this region. For example, the Moscow region is composed of large quantities of limestone, abounding in the remains of crinoids and corals, as well as clayey rocks containing mother-of-pearl ammonite shells. It follows from this that the territory of Moscow and its environs was flooded with sea water at least twice - 300 and 180 million years ago.

Each time, as a result of the displacement of huge blocks of the crust, either a lowering or raising of a certain section of it occurred. In the case of subsidence, ocean waters invaded the continent, an advance of seas and transgression occurred. As the seas rose, they retreated (regression), the land surface grew, and often mountain ranges rose in place of the former salt basin.

The ocean is a powerful regulator and even generator of the Earth's climate due to its colossal heat capacity and other unique physical and chemical properties. This water reservoir controls the most important air flows, air composition, precipitation and temperature patterns over vast land areas. Naturally, an increase or decrease in its surface area affects the nature of global climate processes.

Each transgression significantly increased the area of ​​salt waters, while regression of the seas significantly reduced this area. Accordingly, climate fluctuations occurred. Scientists have found that periodic planetary cooling approximately coincided in time with periods of regression, while the advance of seas onto land was invariably accompanied by climate warming. It would seem that another mechanism of global glaciations has been found, which is perhaps the most important, if not exclusive. However, there is another climate-forming factor that accompanies tectonic movements - mountain building.

The advance and retreat of ocean waters passively accompanied the growth or destruction of mountain ranges. The earth's crust, under the influence of convection currents, wrinkled into chains of the highest peaks here and there. Therefore, an exclusive role in long-period climatic fluctuations should still be given to the process of mountain building (orogenesis). Not only the surface area of ​​the ocean, but also the direction of air flows depended on it.

If a mountain range disappeared or a new one appeared, then the movement of large air masses changed dramatically. Following this, the long-term weather regime in the area was transformed. Thus, as a result of mountain building throughout the planet, local climates radically changed, which led to a general degeneration of the Earth’s climate. As a result, the emerging trend towards global cooling only gained momentum.

The last glaciation is tied to the era of the Alpine mountain building that is ending before our eyes. The result of this orogeny was the Caucasus, the Himalayas, the Pamirs and many other highest mountain systems on the planet. The eruptions of volcanoes Santorini, Vesuvius, Bezymianny and others were provoked by this very process. We can say that today this hypothesis dominates modern science, although it is not fully proven.

The hypothesis received an unexpected development, and in application to the climatology of Antarctica. The ice continent acquired its current appearance entirely due to tectonics, but the decisive role was played neither by regression nor by changes in air currents (these factors are considered secondary). The main influencing factor should be called water cooling. Nature froze Atlantis in exactly the same way as a person cools a nuclear reactor.

The “nuclear” version of the geophysical hypothesis is based on the theory of continental drift and paleontological finds. Modern scientists do not doubt the existence of movement of continental plates. Since the blocks of the earth's crust are mobile due to mantle convection, this mobility is accompanied by a horizontal displacement of the continents themselves. They crawl slowly, at a speed of 1-2 cm per year, along the molten mantle layer.

The relative position of the continents changed over time, which affected the Earth's climate, since air and ocean currents depended on it. Fossilized bones of Lystrosaurus in Antarctica and extremely numerous similar finds in Africa, South America and India confirm the assumption of scientists that once all these southern lands, including Australia, were united into one supercontinent.

The single southern continent of Gondwana existed for over 200 million years: from 240 to 35 million years ago. About 35 million years ago, tectonic movements of the crust finally split it into the current “pieces,” one of which was Antarctica. The split had a negative impact on her climate as she found herself isolated.

Previously, the Antarctic coast was washed by only two cold currents, the effect of which was fully compensated by warm ocean currents coming from Australia, docked with Antarctica. After all the pieces of the supercontinent spread out in different directions and left Antarctica alone in the middle of the ocean, it began to be actively washed by many currents, which over time formed a continuous stream - the so-called. circumpolar current.

It surrounded Antarctica and gained strength as the “fifth ocean” - the southern waters of the Antarctic region - grew and deepened. Every second, the current carries more water than all the rivers on the planet, which is not surprising given the average depth of the “southern ocean” of 3 km. The current covers all layers of water to the very bottom, being the greatest climatic barrier in nature. This fantastic barrier absorbs all the heat that is supplied to the white continent from the outside.

It turned out that a drop in air temperature in the Antarctic region of just 3 °C was sufficient for the barrier to begin to act like a refrigerator. Now the increase in snow and ice cover was inevitable even if the relatively warm regime remained on the continent. The glacier gradually, in the process of growth, displaced heat to the outskirts, where it was absorbed by the circumpolar current.

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Modern environmental problems are becoming more serious with each new year. One of them is associated with the sensational global warming, which was caused by sharply increased volumes of greenhouse gases in the atmosphere. They formed a kind of dome over the planet, trapping heat reflected from the surface; The temperature on Earth is rising, as if in a greenhouse, slowly bringing us closer to the most unpleasant consequences. Thus, the process of melting glaciers begins, the climate and the condition of the entire planet change.

Scientists are already making assumptions about what the melting of glaciers will lead to, and these forecasts, alas, cannot be called favorable.

Frightening statistics

90% of the Earth's entire ice sheet is concentrated in Antarctica, the least explored continent. This massif is so huge that the continent is constantly sagging under its weight. Today, the area of ​​the continent's glaciers is slightly more than 14 million square kilometers.

Over the past decades, scientists have observed serious changes in the landscape: large glaciers are melting and collapsing, ice areas are shrinking, and real lakes are forming on the continent. Within a few years, with the further development of this situation, the area will be reduced by as much as a third.

All scientists unanimously attribute universal human disdain for nature to the reasons for the melting of glaciers. Deforestation, colossal volumes of emissions, soil, water and air pollution - everything that ultimately led to the development of the greenhouse effect. Experts make the most dire forecasts based on statistics obtained during research and observations of glaciers:

• By 2040, that is, in a little more than 20 years, while maintaining the same rate of glacier melting, Antarctica will be completely ice-free.
• Under the influence of the greenhouse effect, the state of glaciers is changing not only in the Arctic and Antarctica, but also in the Himalayas. The area of ​​glaciers in Switzerland has decreased by 12% in just the last 10 years.
• According to NASA, the region is losing about hundreds of billions of tons of continental ice every year as a result of the melting of Greenland's glaciers.
• An increase in the average temperature on the planet by 2.5 degrees, observed in the last 50 years, and with it the destruction of glaciers, lead to an increase in the level of the World Ocean. This increase is estimated at 0.4 millimeters per year.
• The ice sheet is melting, and thereby increasing the volume of water vapor in the atmosphere, one of the components of greenhouse gases. This leads to an increase in the greenhouse effect, which, in turn, affects the destruction of glaciers - a real vicious circle.

And these are just the main figures related to the current situation on the planet. The melting of glacial areas continues, and scientists are making more and more new assumptions and forecasts about what the further development of the process may lead to and what are the possibilities for eliminating the consequences of melting glaciers. We will talk about them further.

Possible consequences

Since the problem of melting glaciers is global in nature, its consequences affect the state of the entire planet and its regions. The predictions made by the researchers are related to all aspects of life on the planet.

Modern ecology, already in an unstable state, will change even more. These changes relate to geological transformations, changes in flora and fauna, rising sea levels and its consequences, as well as a number of medical and human health factors.

1. Melting ice will lead to an increase in the water level of the World Ocean by almost 60 meters. The coastlines will shift, and the current coastal zone of all continents will be under water. Thus, cities such as Arkhangelsk, Astrakhan, St. Petersburg in Russia, Tallinn in Estonia, Riga in Latvia, as well as a number of European capitals - Rome, London, Dublin, Amsterdam and Stockholm will be completely flooded. In North America, dozens of cities in the east and west of the continent will disappear, including New York, Washington and Los Angeles.
2. The destruction of glaciers will have a significant effect on the planet's climate. The strengthening of the greenhouse effect associated with an increase in the concentration of water vapor has already been discussed above. Another problem is the increased flow of fresh water into the World Ocean, which will affect the movement and direction of the main ocean currents. It is these currents that provide the current climatic conditions in most regions. It’s hard to even imagine how exactly their change will affect the climate!
3. The World Health Organization notes that global climate change caused by melting glaciers will lead to numerous epidemics. Already today, more than 150 thousand people die every year because of them. A number of diseases common in Africa and Central Asia will soon spread to other continents.
4. The most dangerous forecasts include a sharp increase in the number of natural disasters. Hurricanes, tsunamis and floods will hit all areas of the planet. These disasters also include a severe shortage of fresh water. By 2030, almost 50% of the population will face a shortage. The same goes for food: severe climate change will lead to droughts and floods, wiping out a lot of agricultural land from the face of the Earth.

In other words, the consequences of the process of glacier destruction that has already begun today seem truly catastrophic. Therefore, the problem of melting ice sheets is increasingly worrying scientists and forcing them to look for ways to solve it. Unfortunately, implementing the proposed options turns out to be much more difficult than it seems.

Solution

It is possible to prevent the irreversible consequences of melting glaciers in the Arctic, Antarctic and other regions of the planet only if the necessary measures are taken everywhere and at all levels, from the global level to the actions of each person.

Already today, scientists are developing ways to protect melting glaciers from the destructive effects of temperatures: projects are being proposed to install protective mirrors in the orbit of the planet and shutters in the territories of glaciers. Plants bred through complex selection that are able to absorb carbon dioxide more efficiently are being studied.

A very important aspect of solving the problem is to find alternative energy sources that eliminate the burning of carbon raw materials.

1. Solar panels, wind turbines and tidal power plants are being installed.
2. The most unconventional methods of obtaining energy are being developed, for example, using human thermal energy to heat rooms.
3. The technical characteristics of cars are being improved and hybrid models are being produced.
4. At the state level, strict control is exercised over enterprises, which does not allow them to exceed the level of hazardous and toxic emissions.

Every person can contribute to the preservation of glaciers and the prosperous state of their native planet in their daily activities. Thus, scientists recommend abandoning the excessive use of all kinds of aerosols, which contain chlorofluorocarbons that destroy the ozone layer. Avoiding frequent driving and using bicycles or public transport for short distances can help reduce emissions. If possible, it is recommended to plant areas near the house with green spaces.

One of the most pressing environmental problems of our time is the ever-accelerating process of melting of the planet’s ice sheets. These giant ice masses contain the main reserves of fresh water, and in addition, their prosperity allows them to maintain appropriate climatic conditions. The destruction of glaciers negatively affects the planet's climate, the state of flora and fauna, and human health. To solve the problem, serious measures must be taken at all levels of society. At the global level, the preservation of glaciers depends on scientists and government officials; at the individual level, it depends on each of us.

​Specialists from the US National Aeronautics and Space Administration (NASA) have found the cause of the melting of Antarctic ice, writes The Independent. Researchers believe that the source of heat that melts the ice shell at the South Pole of the Earth may be a mantle plume hiding under the ice (a hot lava flow that can break through the earth's crust and burst to the surface, forming a volcano - editor's note). The temperature of the earth's crust above it rises, which leads to melting, cracking and destruction of glaciers.

About 30 years ago, a scientist from the University of Colorado put forward a hypothesis about the existence of such a plume under the Mary Byrd Land region in West Antarctica. But only recently was it possible to find confirmation of his assumption. NASA specialists were able to verify the veracity of this theory.

For this, experts have developed a special mathematical model. Calculations have shown how much geothermal energy is required for the processes occurring in Mary Baird Land, including the appearance of the underground rivers and lakes that exist there. Having compared the theoretical model with data obtained during Antarctic expeditions, scientists came to the conclusion that beneath the surface there really is a mantle plume that formed 50-110 million years ago - long before the formation of the ice sheet on the continent.

As New Day wrote, the cause of the melting of glaciers in Greenland is also a mantle plume. The study was carried out by an international group of scientists, with the direct participation of employees of the Novosibirsk State University (NSU) and the Institute of Petroleum Geology and Geophysics () SB RAS. Scientists have linked the current decrease in the volume of ice cover with events 80-35 million years ago, when land, which later became known as Greenland, began to rise above the ocean. It was then that the so-called ancient mantle plume originated.

Scientists have discovered meltwater under the glaciers of Greenland. Previously, it was believed that glaciers melt only in the coastal part of the island, but in 2001, in its depths, between rock and ice, they found a layer of liquid water. Due to the fact that the thickness of the glaciers here reaches 3 thousand meters, and there are no above-zero temperatures at all, there should be no melt water that forms subglacial rivers and lakes.

Researchers are confident that the melting of ice is facilitated by a plume, the main part of which is now located under Iceland, and it is called “Icelandic”. It is well known to geologists and, as it turned out, tens of millions of years ago Greenland actually “floated” over it. After calculating the theoretical heat flow that a plume could cause, it turned out that it was quite enough to melt the lower part of the glacier.

“This work provided geophysical evidence that the Icelandic plume left a mark on the island's lithosphere. Thus, the decrease in the mass of Greenland glaciers is influenced not only by rapid climate variations on Earth, but also by echoes of large-scale events that occurred tens of millions of years ago,” said one of the study participants, head of the NSU laboratories and professor Ivana Kulakova. The results of the study were published in the prestigious journal Nature Geoscience.

As Lenta.ru reminds, in October, a massif with an area four times larger than Manhattan Island broke away from one of the two largest glaciers in Antarctica, Pine Island. According to a forecast made on the basis of satellite images of glaciers, in the future the process of melting ice will accelerate two to three times, increasing the level of the World Ocean. In July, one of the largest icebergs on record broke off from the Larsen Ice Shelf in Antarctica. Its area was 5800 square kilometers.

Washington, Ivan Gridin