Why the ice of Antarctica is not melting. Chain reaction of glaciers. How terrible is an iceberg that broke away from Antarctica. About the rivers of Antarctica
If you travel to the very south of South America, then first you get to Cape Froward on the Brunswick Peninsula, and then, having overcome the Strait of Magellan, to the Tierra del Fuego archipelago. Its extreme southern point is the famous Cape Horn on the shores of the Drake Passage, which separates South America and Antarctica.
If you go through this strait along the shortest path to Antarctica, then (of course, subject to a successful voyage) you get to the South Shetland Islands and further to the Antarctic Peninsula - the northernmost part of the continent of Antarctica. It is there that the Antarctic glacier, the most distant from the South Pole, is located - the Larsen Ice Shelf.
For nearly 12,000 years since the last ice age, the Larsen Glacier has held a tight grip on the east coast of the Antarctic Peninsula. However, a study conducted at the beginning of the 21st century showed that this ice formation is undergoing a serious crisis and may soon disappear altogether.
As the New Scientist noted, until the middle of the 20th century. the trend was the opposite: glaciers were advancing on the ocean. But in the 1950s, this process suddenly stopped and rapidly reversed.
Researchers from the British Antarctic Survey concluded that the retreat of glacial masses has accelerated since the 1990s. And if its pace does not slow down, then in the near future the Antarctic Peninsula will resemble the Alps: tourists will see black mountains with white caps of snow and ice.
According to British scientists, such a rapid melting of glaciers is associated with a sharp warming of the air: its average annual temperature near the Antarctic Peninsula has reached 2.5 degrees above zero Celsius. Most likely, warm air is sucked into Antarctica from warmer latitudes due to changes in habitual air currents. In addition, the ongoing warming of ocean water also plays a significant role.
Similar conclusions were reached in 2005 by Canadian climatologist Robert Gilbert, who published the results of his research in the journal Nature. Gilbert warned that the melting of the Antarctic ice shelves could set off a chain reaction. In fact, it has already begun. In January 1995, the northernmost (that is, the most distant from the South Pole, and therefore, located in the warmest place) Larsen A glacier with an area of 1500 square meters completely disintegrated. km. Then, in several stages, the Larsen B glacier collapsed, much more extensive (12 thousand sq. km) and located to the south (ie, in a colder place than Larsen A).
IN final act During this drama, an iceberg broke away from the glacier, with an average thickness of 220 m and an area of 3250 sq. km, which is larger than the area of Rhode Island. It suddenly broke up in just 35 days - from January 31 to March 5, 2002.
According to Gilbert's calculations, during the 25 years before this catastrophe, the temperature of the waters washing Antarctica rose by 10 ° C, while the average temperature of the waters of the World Ocean for the entire time that has elapsed since the end of the last ice age has grown by only 2-3 ° C. Thus, Larsen B was "eaten" by relatively warm water, which undermined its sole for a long time. The melting of the outer shell of the glacier, caused by an increase in air temperature over Antarctica, also contributed.
Having broken up into icebergs and freed up the place on the shelf that it had occupied for ten millennia, Larsen B opened the way to sliding into the warm sea for glaciers lying either on solid ground or in shallow water. The deeper the "land" glaciers slide into the ocean, the faster they will melt - and the higher the level of the world's oceans will be, and the faster the ice will melt ... This chain reaction will last until the last Antarctic glacier, Gilbert predicted.
In 2015, NASA (US National Aerospace Administration) announced the results of a new study that showed that only a 1,600 sq. km, which is rapidly melting and is likely to completely disintegrate by 2020.
And just the other day, an even more grandiose event took place than the destruction of Larsen B. Literally in a couple of days, between July 10 and 12, 2017, from located even to the south (i.e. in an even colder place) and even more extensive (50 thousand sq. Km) of the Larsen C glacier, an iceberg with a mass of about 1 trillion tons and an area of about 5800 sq. km broke off. km, which would freely accommodate two Luxembourg.
The split was discovered back in 2010, the growth of the crack accelerated in 2016, and already in early 2017, the British Antarctic research project MIDAS warned that a huge fragment of the glacier was “hanging by a thread”. At the moment, one giant iceberg has moved away from the glacier, but glaciologists from MIDAS suggest that it may subsequently split into several parts.
According to scientists, in the near future the iceberg will move rather slowly, but it needs to be monitored: sea currents can carry it to where it will pose a danger to ship traffic.
Although the iceberg is huge, its formation did not in itself lead to a rise in the level of the world's oceans. Because Larsen is an ice shelf, its ice is already floating in the ocean rather than resting on land. And when the iceberg melts, the ocean level will not change at all. "It's like an ice cube in your glass of gin and tonic. It is already floating, and if it melts, the level of the drink in the glass does not change," Anna Hogg, a glaciologist from the University of Leeds (UK), explained intelligibly.
In the short term, the destruction of Larsen C is not worrisome, scientists say. Fragments of glaciers break off from Antarctica every year, part of the ice subsequently grows again. However, in the long term, the loss of ice on the periphery of the continent is dangerous because it destabilizes the remaining, much more massive glaciers - their behavior is more important for glaciologists than the size of icebergs.
First of all, the iceberg's breakaway could affect the rest of the Larsen C glacier. "We are confident, although many others disagree, that the remaining glacier will be less stable than it is now," says MIDAS project leader Prof. Alan Lachman. If he's right, then the chain reaction of the collapse of the ice shelves will continue.
With the liberation of the Antarctic Peninsula from glaciers, the prospect of its settlement will become more and more real. Argentina has long considered this territory to be its own, against which Great Britain objects. This dispute is directly related to the fact that the Falkland (Malvinas) Islands are located to the north of the Antarctic Peninsula, which the UK considers its own, and Argentina - its own.
The largest icebergs in history
In 1904, the tallest iceberg in history was discovered and explored off the Falkland Islands. Its height reached 450 m. Due to the imperfection of the then scientific equipment, the iceberg was not thoroughly investigated. Where and how he ended his drift in the ocean is unknown. He did not even have time to assign a code and a proper name. So he went down in history as the tallest iceberg discovered in 1904.
In 1956, the American military icebreaker U.S.S. Glacier has discovered a large iceberg in the Atlantic Ocean that has broken off the coast of Antarctica. The dimensions of this iceberg, which received the name "Santa Maria", were 97 × 335 km, the area was about 32 thousand square meters. km, which is larger than the area of Belgium. Unfortunately, at that time there were no satellites that could confirm this estimate. After making a circle around Antarctica, the iceberg broke and melted.
In the satellite era, the largest iceberg was B-15 with a mass of more than 3 trillion tons and an area of 11 thousand square meters. km. This Jamaica-sized block of ice broke off the Ross Ice Shelf adjacent to Antarctica in March 2000. After drifting quite a bit in open water, the iceberg got stuck in the Ross Sea and then broke up into smaller icebergs. The largest fragment was named iceberg B-15A. Since November 2003, it drifted in the Ross Sea, becoming an obstacle to the supply of resources to three Antarctic stations, and in October 2005 it also got stuck and broke into smaller icebergs. Some of them were seen in November 2006 only 60 km from the coast of New Zealand.
The ice of the Arctic and Antarctic is by no means eternal. In our time, in connection with the impending global warming caused by the ecological 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 various 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 in the process of 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 proved that the ice cover of Antarctica arose relatively recently. Similar conclusions were drawn for the Arctic.
First, the data of 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 just 5,000 years ago than it is now. It is assumed that then it occupied only half of the current territory covered by it. Until now, according to some experts, the slow freezing of this gigantic ice tongue continues.
Drilling wells in the thickness of the continental ice gave unexpected results. The cores clearly showed how the next layers of ice were frozen over during the last 10-15 millennia. Spores of bacteria and plant pollen were found in different layers. Consequently, the ice sheet of the mainland grew and actively developed during the last millennia. This process was influenced by climatic and other factors, since the rate of formation of layers of ice varies.
Some of the bacteria (up to 12 thousand years old) found frozen in the thickness of the Antarctic ice have been revived and studied under a microscope. Along the way, a study of air bubbles walled up in these huge layers of frozen water was organized. Work in this area has not been completed, but it is clear that in the hands of scientists were 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 happened over 2000 million years ago. Then these colossal catastrophes were repeated quite often. The Ordovician glaciation falls on an epoch remote from our time by 440 million years. During this climatic cataclysm, a great number of marine invertebrates died. There were no other animals at that time. They appeared much later, to become victims of the next freeze attacks, covering almost all continents.
The last glaciation, apparently, has not yet ended, but retreated for a while. The great retreat of the ice occurred about 10 thousand years ago. Since then, the powerful ice shells that once covered Europe, a significant part of Asia and North America have remained only in Antarctica, on the Arctic islands and above the waters of the Arctic Ocean. Modern humanity lives in the period of the so-called. interglacial period, which will have to be replaced by a new advance of ice. Unless, of course, before they melt completely.
Geologists have received a lot of interesting facts about Antarctica itself. The great white continent, apparently, was once completely free of ice and was distinguished by an even and warm climate. 2 million years ago, dense forests, like taiga, grew on its coasts. In areas open from ice, it is possible to systematically find fossils of a later, Middle Tertiary time - imprints of leaves and twigs of ancient heat-loving plants.
Then, more than 10 million years ago, despite the cooling that began on the continent, the local expanses were occupied by vast groves of laurels, chestnut oaks, laurel cherries, beeches and other subtropical plants. It can be assumed that these groves were inhabited by animals characteristic of that time - mastodons, saber-toothed, hipparions, etc. But much more striking are the oldest finds in Antarctica.
In the central part of Antarctica, for example, the skeleton of a fossil lizard of Lystrosaurus was found - not far from the South Pole, in rock outcrops. A large reptile of two meters in length was distinguished by an extremely terrible appearance. The age of the find is 230 million years.
Lysrosaurs were, like other animal lizards, typical representatives of the heat-loving fauna. They inhabited hot swampy lowlands, abundantly overgrown with vegetation. Scientists have discovered an entire belt in the geological sediments of South Africa, brimming with the bones of these animals, which is called the Zone of Listrosaurs. Something similar has been found on the South American continent, as well as in India. Obviously, 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, imperceptible in our interglacial era, 10 millennia ago bound a huge part of the land and the oceans under the shell of hardened water? What is causing this dramatic climate change? None of the hypotheses is convincing enough to be generally accepted. Nevertheless, it is worth remembering the most popular ones. Three hypotheses can be distinguished, conditionally called space, 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 the data of geological surveys and astrophysical observations. When establishing the age of moraine and other rocks deposited by ancient glaciers, it turned out that climatic catastrophes happened with strict periodicity. The earth froze in the interval of time, as if specially allotted for this. Each great cooling is separated from the others by a period of 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, powerful ice caps formed. Climatologists turned to the materials accumulated by astrophysicists: what could be the reason for such an incredibly long time between several iterative (regularly occurring) events in the atmosphere and hydrosphere of a space object? Perhaps with space events comparable in scale and time frame?
Calculations of astrophysicists call as such an event - the revolution of the Sun around the galactic nucleus. The dimensions of the Galaxy are extremely large. The diameter of this cosmic disk reaches a size of about 1000 trillion km. The sun is located at a distance of 300 trillion km from the galactic core, so the complete revolution of our star around the center of the system is delayed for such a colossal period of time. Apparently, on its way the Solar system crosses some region 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 the facts on the basis of which it could be proved or at least convincingly confirmed. There are no facts confirming the galactic influence on the million-year fluctuations in the planet's climate, except for a strange coincidence of numbers. Astrophysics has not found a mysterious region in the Galaxy where the Earth begins to freeze. The type of external influence, due to which something similar can happen, has not been found. Someone suggests a decrease in solar activity. It seems that the “cold zone” reduced the intensity of the solar radiation flux, and as a result, the Earth began to receive less heat. But this is just speculation.
Supporters of the original version came up with a name for the imaginary processes taking place in the star system. A complete revolution of the solar system around the galactic core was called a galactic year, and a short interval during which the Earth is in an unfavorable "cold zone" was called a cosmic winter.
Some proponents 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. Milanković. He took into account the tilt of the earth to the plane of the ecliptic and the tilt of the ecliptic proper to the solar axis. According to Milankovitch, the key to the great glaciations should be sought here.
The fact is that depending on these slopes, the amount of radiant energy of the Sun reaching the earth's surface is most directly determined. In particular, different latitudes receive different numbers of rays. The interposition of the axes of the Sun and the Earth, which changes 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 changing the warm and cold phases.
In the 90s. 20th century this hypothesis has been extensively tested using computer models. Numerous external influences on the position of the planet relative to the Sun were taken into account - the Earth's orbit slowly evolved under the influence of the gravitational fields of neighboring planets, the Earth's trajectory was gradually transformed.
The French geophysicist A. Berger compared the obtained figures with geological data, with the results of a radioisotope analysis of marine sediments, showing temperature changes over millions of years. The temperature fluctuations of oceanic waters completely coincided with the dynamics of the process of transformation of the earth's orbit. Consequently, the cosmic factor could well have provoked the beginning of a cooling of the climate and global glaciation.
At present, it cannot be said that the Milankovitch conjecture has been proven. First, it requires additional long-term checks. Secondly, scientists tend to adhere to 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-climatic hypothesis is based precisely on this provision. The planet is a huge climate machine that, with its rotation, directs the movement of air currents, cyclones and typhoons. The inclined position with respect to the plane of the ecliptic causes non-uniform heating of its surface. In a sense, the planet itself is a powerful climate regulator. And her inner strengths are the reasons for his metamorphosis.
These internal forces include mantle currents, or the so-called. convection currents in layers of molten magmatic matter that composes 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, mountain building processes. These same currents cause 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 under the pressure of convection currents. Volcanic activity is extremely high in these zones. Here, mantle matter constantly pours out from the bowels. According to the planetary-climatic hypothesis, it is magma outpourings that play a decisive role in the oscillatory process of the historical transformation of the weather regime.
Rift faults on the ocean floor during periods of greatest activity generate enough heat to cause intense evaporation of seawater. From this, a lot of moisture accumulates in the atmosphere, which then falls to the surface of the Earth as precipitation. In cold latitudes, precipitation falls in the form of snow. But since their precipitation is too intense and the number is large, the snow cover becomes more powerful than is usually the case.
The snow cap melts extremely slowly, for a long time the arrival of precipitation exceeds their consumption - melting. As a result, it begins to grow and transforms into a glacier. The climate on the planet is also gradually changing, as a stable area of non-melting ice is formed. After some time, the glacier begins to expand, because the dynamic system of uneven income-expenditure cannot be in balance, and the ice increases to an incredible size and binds almost the entire planet.
However, the maximum glaciation becomes at the same time the beginning of its degradation. Having reached a critical point, an extremum, the growth of ice stops, having met the stubborn resistance of other natural factors. The dynamics has become reversed, the rise has been replaced by a decline. However, the victory of "summer" over "winter" does not come immediately. Initially, a protracted "spring" begins for several millennia. 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, will end at the end of the 3rd millennium AD, i.e. about 3000. From this moment, another cooling will begin, which will reach its apogee after 8000 of our calendar.
The main argument of the planetary-climatic hypothesis is the fact of periodic change of tectonic activity in rift valleys. Convection currents in the bowels of the Earth excite the earth's crust with different strengths, and this leads to the existence of such epochs. Geologists have materials that convincingly prove that climatic fluctuations are chronologically linked to periods of the greatest tectonic activity of the bowels.
Rock deposits show that the next cooling of the climate is accompanied by significant movements of thick 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 varieties of a single geophysical hypothesis, since it relies on data on the geophysics of the planet, namely, it relies entirely on paleogeography and tectonics in its calculations. Tectonics studies the geology and physics of the movement of crustal blocks, while paleogeography studies the consequences of such movement.
As a result of multi-million-year displacements of colossal masses of solid matter on the earth's surface, the outlines of the continents, as well as the relief, changed significantly. The fact that thick strata of marine sediments or bottom silts are found on land directly indicates the movements of crustal blocks, accompanied by its sagging or uplift in this region. For example, the Moscow region is composed in large quantities of limestone, abounding in the remains of sea lilies 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 at least twice flooded with sea waters - 300 and 180 million years ago.
Each time, as a result of the displacement of huge blocks of the crust, either a lowering or an uplift of a certain section of it occurred. In the case of subsidence, ocean waters invaded the mainland, the seas advanced, and transgression occurred. When the sea rose, they receded (regression), the land surface grew, and often mountain ranges rose in place of the former salt basin.
The ocean is the most 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 currents, air composition, precipitation and temperature patterns over vast areas of land. Naturally, an increase or decrease in its surface area affects the nature of global climatic processes.
Each transgression significantly increased the area of saline waters, while the regression of the seas significantly reduced this area. Accordingly, climate fluctuations occurred. Scientists have found that periodic global cooling roughly coincided in time with periods of regression, while the advance of the seas on land was invariably accompanied by climate warming. It would seem that another mechanism of global glaciation has been found, which, perhaps, is the most important, if not exceptional. However, there is another climate-forming factor accompanying tectonic movements - mountain building.
The advance and retreat of oceanic waters passively accompanied the growth or destruction of mountain ranges. The earth's crust, under the influence of convection currents, wrinkled with chains of the highest peaks here and there. Therefore, an exceptional role in long-term climatic fluctuations should still be given to the process of mountain building (orogeny). Not only the surface area of the ocean depended on it, but also the direction of air currents.
If a mountain range disappeared or a new one arose, then the movement of large air masses changed dramatically. Following this, the long-term weather regime in the area was transformed. So, as a result of mountain building, local climates radically changed throughout the planet, which led to a general rebirth of the Earth's climate. As a result, the emerging trend towards global cooling was only gaining momentum.
The last glaciation is tied to the epoch of the Alpine mountain building, which is ending before our eyes. The Caucasus, the Himalayas, the Pamirs and many other highest mountain systems of the planet became the result of this orogeny. The eruptions of the volcanoes Santorin, Vesuvius, Nameless and others are provoked by this process. We can say that today this hypothesis dominates modern science, although it is not fully proven.
The hypothesis received an unexpected development, moreover, in the application to the climatology of Antarctica. The ice continent acquired its current appearance entirely due to tectonics, only the decisive role was played not by regression and not by a change in air currents (these factors are considered secondary). The main influence factor should be called water cooling. Nature froze Atlantis in exactly the same way that a person cools a nuclear reactor.
The "nuclear" version of the geophysical hypothesis is based on the theory of continental drift and paleontological findings. Modern scientists do not question the existence of the movement of continental plates. Since, due to the convection of the mantle, the blocks of the earth's crust are mobile, this mobility is accompanied by a horizontal displacement of the continents themselves. They slowly, at a rate of 1-2 cm per year, crawl along the molten mantle layer.
What will happen if the glaciers of Antarctica melt?
Antarctica is the least explored continent located in the south of the world. Most of its surface has an ice cover, up to 4.8 km thick. The Antarctic ice sheet contains 90% (!) of all the ice on our planet. It is so heavy that under it the mainland sank almost 500 m. Today, the world is seeing the first signs of global warming in Antarctica: large glaciers are collapsing, new lakes are appearing, and the soil is losing its ice cover. Let's simulate the situation, what will happen if Antarctica loses its ice.
How will Antarctica itself change?
Today the area of Antarctica is 14,107,000 km². If the glaciers melt, these numbers will drop by a third. The mainland will become almost unrecognizable. Under the ice are numerous mountain ranges and massifs. The western part will definitely become an archipelago, and the eastern part will remain the mainland, although, given the rise of ocean waters, it will not hold such a status for a long time.
At the moment, many representatives of the plant world are found on the Antarctic Peninsula, islands and coastal oases: flowers, ferns, lichens, algae, and recently their diversity has been gradually increasing. There are also fungi and some bacteria, and seals and penguins occupy the coast. Already now, on the same Antarctic Peninsula, the appearance of tundra is observed, and scientists are sure that with warming there will be both trees and new representatives of the animal world. By the way, Antarctica holds several records: the lowest recorded temperature on Earth is 89.2 degrees below zero; there is the largest crater on Earth; the strongest and longest winds. Today there is no permanent population in Antarctica. There are only employees of scientific stations, and sometimes tourists visit it. With climate change, the former cold continent may become suitable for permanent human habitation, but now it is difficult to talk about this with certainty - everything will depend on the current climatic situation.
How will the world change due to the melting of glaciers?
Rising water levels in the world's oceans So, scientists have calculated that after the melting of the ice cover, the level of the world's oceans will rise by almost 60 meters. And this is a lot and will be equated with a global catastrophe. The coastline will shift significantly, and today's coastal zone of the continents will be under water.
If we talk about Russia, then its central part will not suffer much. In particular, Moscow is located 130 meters above the current sea level, so the flood will not reach it. Such large cities as Astrakhan, Arkhangelsk, St. Petersburg, Novgorod and Makhachkala will go under water. Crimea will turn into an island - only its mountainous part will rise above the sea. And in the Krasnodar Territory, only Novorossiysk, Anapa and Sochi will be heated. Siberia and the Urals will not be subjected to too much flooding - mostly residents of coastal settlements will have to be relocated.
The Black Sea will grow - in addition to the northern part of the Crimea and Odessa, it will also clean up Istanbul. Signed cities that will be under water The Baltic States, Denmark and Holland will almost completely disappear. In general, European cities such as London, Rome, Venice, Amsterdam and Copenhagen will go under water along with all their cultural heritage, so while there is time, be sure to visit them and take pictures on Instagram, because your grandchildren will most likely already do this they won't be able to. The Americans will also have a hard time, who will definitely be left without Washington, New York, Boston, San Francisco, Los Angeles and many other large coastal cities.
What will happen to North America. Signed cities that will be under water
The climate will already undergo unpleasant changes that will lead to the melting of the ice sheet. According to environmentalists, the ice of Antarctica, Antarctica and those that are on mountain peaks help maintain the temperature balance on the planet, cooling its atmosphere. Without them, this balance will be upset. The flow of a large amount of fresh water into the world's oceans will certainly affect the direction of large ocean currents, which largely determine the climatic conditions in many regions. So it is not yet possible to say with certainty what will become of our weather.
The number of natural disasters will increase significantly. Hurricanes, typhoons and tornadoes will claim thousands of lives. Paradoxically, but due to global warming, some countries will begin to experience a shortage of fresh water. And not only because of the arid climate. The fact is that deposits of snow in the mountains provide vast territories with water, and after it melts, there will be no such benefit anymore.
Economy
All this will greatly affect the economy, even if the process of flooding is gradual. Take the US and China, for example! Whether you like it or not, these countries greatly influence the economic situation around the world. In addition to the problem of displacing tens of millions of people and losing their capital, the states will lose almost a quarter of their manufacturing capacity, which will ultimately hit the global economy. And China will be forced to say goodbye to its huge trading ports, which will reduce the flow of products to the world market at times.
How are things today?
Some scientists reassure us that the observed melting of glaciers is normal, because. somewhere they disappear, and somewhere they are formed, and thus the balance is maintained. Others point out that there are still reasons for concern, and provide convincing evidence.
Not so long ago, British scientists analyzed 50 million satellite images of the Antarctic ice sheets and came to the conclusion that they are melting very rapidly. In particular, the gigantic Totten glacier, comparable in size to the territory of France, causes concern. The researchers noticed that it was washed away by warm salty waters, accelerating its decay. According to forecasts, this glacier can raise the level of the World Ocean by as much as 2 meters. It is assumed that the Larsen B glacier will collapse by 2020. And he, by the way, as much as 12,000 years.
According to the BBC, Antarctica loses as much as 160 billion ice a year. And this number is growing rapidly. Scientists say they did not expect such a rapid melting of the southern ice.
The most unpleasant thing is that the process of melting glaciers has an even greater effect on the increase in the greenhouse effect. The fact is that the ice sheets of our planet reflect part of the sunlight. Without this, heat will linger in the Earth's atmosphere in large volumes, thereby raising the average temperature. And the growing area of the World Ocean, whose waters collect heat, will only aggravate the situation. In addition, a large amount of melt water also adversely affects glaciers. Thus, the ice reserves, not only in Antarctica, but throughout the globe, are melting faster and faster, which ultimately threatens with big problems.
Conclusion
Opinions of scientists about the melting of the Antarctic ice sheet are very different, but what is known for certain is that man, through his activities, greatly affects the climate. If humanity does not solve the problem of global warming in the next 100 years, then the process will be inevitable.
According to a number of foreign researchers, the situation in Antarctica has become so threatening that it is time to ring all the bells: the data received from satellites irrefutably testify to the catastrophic melting of ice in the territory of West Antarctica. If this continues, glaciologists are convinced, in the near future these glaciers will disappear altogether.
Some of them are shrinking their area at a rate of one to two kilometers per year. But in general, according to measurements received from the CryoSat satellite of the European Space Agency, the ice cover of the Sixth Continent is losing weight by two centimeters every year. At the same time, according to the Air Force, Antarctica is losing about 160 billion ice a year - now the rate of ice melting is already twice as high as four years ago. NASA experts called the Amundsen Sea area the most vulnerable point, where in the six largest glaciers the melting process can already slow down.
The influential Western journal Earth and Planetary Science Letters published a study that proved that as a result of the melting of Antarctica, the earth's crust is deformed at a depth of 400 km. “Despite the fact that the Antarctic ice sheet is growing at a rate of 15 mm per year,” they explain, “generally, there is active melting at great depths under the ice shelves, due to global warming and changes in the chemical composition of the earth’s crust in the Antarctic region.” This process entered a critical phase in the late 1990s. And then there's the ozone hole, which also has a bad effect on the Antarctic climate.
How does this threaten us? As a result, the level of the world's oceans can rise by 1.2 meters or even more in a short time. Strong evaporation and a huge amount of water condensation will give rise to powerful typhoons, hurricanes, tornadoes and other natural disasters, many land areas will be flooded. Mankind cannot change the situation. In short, save who can!
"AiF" decided to interview Russian scientists: when exactly will the world be covered by a wave? According to them, it's not so bad. “If a significant rise in the level of the world ocean does occur, then it will not happen tomorrow or even the day after tomorrow,” AiF explained. Alexander Nakhutin, Deputy Director of the Institute for Global Climate and Ecology of Roshydromet and the Russian Academy of Sciences. - The melting of the Antarctic and Greenland glaciers is a very inertial process, slow even by geological standards. Its consequences, at best, will only be seen by our descendants. And then, if the glaciers melt completely. And it will take not a year or two, but a hundred years or more.
There is also a more positive version. The “global” melting of glaciers has nothing to do with the whole of Antarctica, says Nikolai Osokin, Candidate of Geographical Sciences, Deputy Head of the Department of Glaciology at the Institute of Geography of the Russian Academy of Sciences. — Perhaps the melting of six glaciers in the Amundsen Sea is really irreversible, and they will not recover. Well, no big deal! West Antarctica, a smaller part of the mainland, has indeed visibly melted in recent years. However, in general, the process of active melting of glaciers in Antarctica over the past few years, on the contrary, has slowed down. There is a lot of evidence for this. In the same West Antarctica, for example, the Russian station "Bellingshausen" is located. According to our observations, there is an improvement in the nutrition of glaciers in this area - more snow falls than melts.
Turns out it's not time to ring the bells yet. “In the atlas of snow and ice resources of the world, released by the Institute of Geography of the Russian Academy of Sciences, there is a map: what would happen if all the glaciers on Earth melted at once. It is very popular,” Osokin laughs. - Many journalists use it as a horror story: look, they say, what kind of universal flood awaits us when the level of the world ocean rises as much as 64 meters ... But this is a purely hypothetical possibility. In the next century and even the millennium, this does not threaten us.”
By the way, as a result of studying the ice core in Antarctica, Russian glaciologists have established an interesting fact. It turns out that over the past 800 thousand years on Earth, cooling and warming regularly replace each other. “As a result of warming, glaciers are retreating, melting, the level of the world ocean is rising. And then the reverse process occurs - there is a cooling, glaciers are growing, the ocean level is falling. This has happened at least 8 times already. And now we are just at the peak of warming. This means that in the coming centuries, the Earth, and with it, humanity will go to a new ice age. This is normal and is associated with the eternal processes of oscillation of the earth's axis, its inclination, changes in the distance from the Earth to the Sun.
Meanwhile, the situation with ice in the Arctic is much more unambiguous: they are melting an order of magnitude faster and more globally than the Antarctic. “Over the past ten years, there have already been several records for the minimum area of sea ice in the Arctic Ocean,” recalls Osokin. “The general trend is towards a decrease in the area of ice in the entire North.”
Can humanity, if it wants to, slow down the general warming or cooling? To what extent does anthropogenic activity influence the melting of ice? “If it does, then most likely to a very small extent,” Osokin believes. “The main reason that glaciers are melting is natural factors.” So we just have to wait, hope and believe. For the best, of course."
If you travel to the very south of South America, then first you get to Cape Froward on the Brunswick Peninsula, and then, having overcome the Strait of Magellan, to the Tierra del Fuego archipelago. Its extreme southern point is the famous Cape Horn on the shores of the Drake Passage, which separates South America and Antarctica.
If you go through this strait along the shortest path to Antarctica, then (of course, subject to a successful voyage) you get to the South Shetland Islands and further to the Antarctic Peninsula - the northernmost part of the continent of Antarctica. It is there that the Antarctic glacier, the most distant from the South Pole, is located - the Larsen Ice Shelf.
For nearly 12,000 years since the last ice age, the Larsen Glacier has held a tight grip on the east coast of the Antarctic Peninsula. However, a study conducted at the beginning of the 21st century showed that this ice formation is undergoing a serious crisis and may soon disappear altogether.
As the New Scientist noted, until the middle of the 20th century. the trend was the opposite: glaciers were advancing on the ocean. But in the 1950s, this process suddenly stopped and rapidly reversed.
Researchers from the British Antarctic Survey concluded that the retreat of glacial masses has accelerated since the 1990s. And if its pace does not slow down, then in the near future the Antarctic Peninsula will resemble the Alps: tourists will see black mountains with white caps of snow and ice.
According to British scientists, such a rapid melting of glaciers is associated with a sharp warming of the air: its average annual temperature near the Antarctic Peninsula has reached 2.5 degrees above zero Celsius. Most likely, warm air is sucked into Antarctica from warmer latitudes due to changes in habitual air currents. In addition, the ongoing warming of ocean water also plays a significant role.
Similar conclusions were reached in 2005 by Canadian climatologist Robert Gilbert, who published the results of his research in the journal Nature. Gilbert warned that the melting of the Antarctic ice shelves could set off a chain reaction. In fact, it has already begun. In January 1995, the northernmost (that is, the most distant from the South Pole, and therefore, located in the warmest place) Larsen A glacier with an area of 1500 square meters completely disintegrated. km. Then, in several stages, the Larsen B glacier collapsed, much more extensive (12 thousand sq. km) and located to the south (ie, in a colder place than Larsen A).
IN final act During this drama, an iceberg broke away from the glacier, with an average thickness of 220 m and an area of 3250 sq. km, which is larger than the area of Rhode Island. It suddenly broke up in just 35 days - from January 31 to March 5, 2002.
According to Gilbert's calculations, during the 25 years before this catastrophe, the temperature of the waters washing Antarctica rose by 10 ° C, while the average temperature of the waters of the World Ocean for the entire time that has elapsed since the end of the last ice age has grown by only 2-3 ° C. Thus, Larsen B was “eaten” by relatively warm water, which undermined its sole for a long time. The melting of the outer shell of the glacier, caused by an increase in air temperature over Antarctica, also contributed.
Having broken up into icebergs and freed up the place on the shelf that it had occupied for ten millennia, Larsen B opened the way to sliding into the warm sea for glaciers lying either on solid ground or in shallow water. The deeper the “land” glaciers slide into the ocean, the faster they will melt - and the higher the level of the world ocean will be, and the faster the ice will melt ... This chain reaction will last until the last Antarctic glacier, Gilbert predicted.
In 2015, NASA (US National Aerospace Administration) announced the results of a new study that showed that only a 1,600 sq. km, which is rapidly melting and is likely to completely disintegrate by 2020.
And just the other day, an even more grandiose event took place than the destruction of Larsen B. Literally in a couple of days, between July 10 and 12, 2017, from located even to the south (i.e. in an even colder place) and even more extensive (50 thousand sq. Km) of the Larsen C glacier, an iceberg with a mass of about 1 trillion tons and an area of about 5800 sq. km broke off. km, which would freely accommodate two Luxembourg.
The split was discovered back in 2010, the growth of the crack accelerated in 2016, and already at the beginning of 2017, the British Antarctic research project MIDAS warned that a huge fragment of the glacier was “hanging by a thread”. At the moment, one giant iceberg has moved away from the glacier, but glaciologists from MIDAS suggest that it may subsequently split into several parts.
According to scientists, in the near future the iceberg will move rather slowly, but it needs to be monitored: sea currents can carry it to where it will pose a danger to ship traffic.
Although the iceberg is huge, its formation did not in itself lead to a rise in the level of the world's oceans. Because Larsen is an ice shelf, its ice is already floating in the ocean rather than resting on land. And when the iceberg melts, the ocean level will not change at all. “It's like an ice cube in your gin and tonic glass. It is already floating, and if it melts, the level of the drink in the glass does not change from this, ”Anna Hogg, a glaciologist from the University of Leeds (UK), explained intelligibly.
In the short term, the destruction of Larsen C is not worrisome, scientists say. Fragments of glaciers break off from Antarctica every year, part of the ice subsequently grows again. However, in the long term, the loss of ice on the periphery of the continent is dangerous because it destabilizes the remaining, much more massive glaciers - their behavior is more important for glaciologists than the size of icebergs.
First of all, the iceberg breakaway could affect the rest of the Larsen C glacier. “We are confident, although many others disagree, that the remaining glacier will be less stable than it is now,” says MIDAS project leader Prof. Alan Lachman. If he's right, then the chain reaction of the collapse of the ice shelves will continue.
With the liberation of the Antarctic Peninsula from glaciers, the prospect of its settlement will become more and more real. Argentina has long considered this territory to be its own, against which Great Britain objects. This dispute is directly related to the fact that the Falkland (Malvinas) Islands are located to the north of the Antarctic Peninsula, which the UK considers its own, and Argentina - its own.
The largest icebergs in history
In 1904, the tallest iceberg in history was discovered and explored off the Falkland Islands. Its height reached 450 m. Due to the imperfection of the then scientific equipment, the iceberg was not thoroughly investigated. Where and how he ended his drift in the ocean is unknown. He did not even have time to assign a code and a proper name. So he went down in history as the tallest iceberg discovered in 1904.
In 1956, the American military icebreaker U.S.S. Glacier discovered a large iceberg in the Atlantic Ocean, Yury VISHNEVSKY, which broke off the coast of Antarctica. The dimensions of this iceberg, which received the name "Santa Maria", were 97 × 335 km, the area was about 32 thousand square meters. km, which is larger than the area of Belgium. Unfortunately, at that time there were no satellites that could confirm this estimate. After making a circle around Antarctica, the iceberg broke and melted.
In the satellite era, the largest iceberg was B-15 with a mass of more than 3 trillion tons and an area of 11 thousand square meters. km. This Jamaica-sized block of ice broke off the Ross Ice Shelf adjacent to Antarctica in March 2000. After drifting quite a bit in open water, the iceberg got stuck in the Ross Sea and then broke up into smaller icebergs. The largest fragment was named iceberg B-15A. Since November 2003, it drifted in the Ross Sea, becoming an obstacle to the supply of resources to three Antarctic stations, and in October 2005 it also got stuck and broke into smaller icebergs. Some of them were seen in November 2006 only 60 km from the coast of New Zealand.
Yuri VISHNEVSKY
