Throughout history. Its weight is about a trillion tons, reports MIR 24 TV channel correspondent Marina Razbegaeva.
Its area is approximately equal to Palestine, its weight is a trillion tons. This is one of the largest icebergs that has ever broken off from Antarctica. It carries a mass of frozen water twice the size of Lake Erie, one of the Great Lakes of North America. If it melts, the level of the world's seas is guaranteed to change.
“Antarctica has a lot of ice. If large glaciers melt, the world's sea levels will rise. This is inevitable,” says geophysicist Edward King (UK).
Scientists have been waiting for this event for a long time - for several months they continuously monitored the growing crack on the Larsen Ice Shelf.
“There are a lot of changes on the Antarctic Peninsula. Where the Larsen Glacier is located, temperatures have risen much faster than in the rest of Antarctica. Therefore, this place needs to be monitored, regularly monitored from satellites in order to understand what is happening there,” said Edward King.
Experts are not yet ready to say how it will behave next. Most likely, it will split into several smaller ones. These pieces can remain in place for decades, or they can drift north into warmer waters.
“If you look at all the ice in Antarctica, you can roughly imagine what would happen to the world's oceans if it melted. We are not saying that it will happen tomorrow or next year. This process will take a long time - but it has already begun,” warns the geophysicist.
While scientists are vying with each other about the fate of the planet, for Internet users this is just a new reason for jokes.
An iceberg that broke off from Antarctica will become part of Russia on March 18, 2018. Russian hackers hacked the glacier? And your iceberg has come unstuck. An iceberg the size of your ex has broken off from a glacier in Antarctica.
Meanwhile, another iceberg on the nearby Brunt Glacier is threatening to break off. The giant fault appeared a long time ago, but six months ago it suddenly began to grow at tremendous speed. The British polar station was urgently evacuated from there. According to some scientists, it is no longer possible to stop the process of melting glaciers. This will lead to the most unexpected consequences.
“A huge amount of methane is concentrated in the world’s oceans. Warming releases it. That is, heating masses of water could theoretically lead to the fact that our atmosphere could become composed of methane,” noted ecologist Pavel Sukhonin.
Experts attribute such splits to global warming and climate change. Over the past half century, temperatures in Antarctica have increased by 2.5 degrees Celsius.
What is an iceberg?
Icebergs are pieces of ice that form on land and float in the sea or lake. Icebergs come in all shapes and sizes, from small ice cubes to chunks of ice the size of a small country. The term "iceberg" generally refers to a piece of ice larger than 5 meters (16 feet) across. Small icebergs, iceberg fragments, can be especially dangerous to ships because they are more difficult to detect. The North Atlantic and the waters surrounding Antarctica are the main habitat for most of the icebergs on Earth.
How do icebergs form and move?
Icebergs form from the ice of glaciers, ice shelves, or break off from an even larger iceberg. Icebergs move with ocean currents, sometimes stopping in shallow water or landing on the shore.
When the iceberg reaches warm waters, the temperature affects it. On the surface of an iceberg, warm air melts snow and ice, small lakes can form on it, which can seep through the iceberg, through cracks in it, thereby expanding them and destroying the iceberg itself. At the same time, warm water acts on the iceberg in its underwater part, gradually melting it and reducing its volume. The underwater part melts faster than the surface part.
Why is it important to study icebergs?
Icebergs pose a hazard to ships passing through the North Atlantic and the waters around Antarctica. After the Titanic tragically sank off Newfoundland in 1912, the United States and twelve other countries created the International Ice Watch to warn ships of the presence of icebergs in the North Atlantic.
The International Ice Survey uses aircraft and radar to track icebergs floating in the paths of major shipping lanes. In the US, the National ICE Center uses satellite data to monitor icebergs off the coast of Antarctica. However, it is only capable of tracking icebergs larger than 500 square meters (5,400 sq ft).
Icebergs can also serve as material for scientists to learn more about climate and ocean processes.
By studying the factors that cause icebergs to form, researchers hope to better understand the reasons that lead to the collapse of ice shelves.
Oceanologists also study icebergs because large volumes of cold fresh water can affect ocean currents and the circulation of ocean waters.
Biologists study icebergs to find out how they affect ocean life. How nutrients change in the ocean when an iceberg melts. Recent studies have shown that the waters around icebergs are filled with plankton and there are large concentrations of fish and other marine life.
Photos of icebergs:
An iceberg is a huge floe of ice floating in the world's oceans.
Where do icebergs come from?
Huge pieces of ice break off from the glaciers that cover the continents and float freely. For example, northern icebergs break off from the Greenland ice sheet, and southern ones from Antarctica, and southern icebergs are much larger in size than northern ones. Not only does the duration of existence and the range of its voyage depend on the properties of an iceberg, it also depends on factors such as the direction and speed of the current in the ocean.
The largest in size and frozen down to -60 C, the icebergs of Antarctica “live” for many years, sometimes even more than a decade. Whereas Greenland icebergs are slightly smaller in size and their deep freezing temperature reaches -30C. They live much shorter, and their melting period is 2-3 years.
Ice is much lighter than water, which explains why even the deepest bodies of water do not freeze completely in winter. If it were the other way around, then, in fact, the ice falling to the bottom would displace the lower layers of water to the surface, and gradually all the water in the reservoir would simply freeze.
But when water freezes, the exact opposite happens. When water transforms into ice, its volume increases by about ten percent, and as a result, the density of ice is much less than that of water. This explains why ice floats on the surface.
At considerable depths of the world's oceans, the water temperature is below zero degrees, but the water there does not freeze. This is interpreted by the pressure that the upper layers of water form.
For the first time, Mikhail Lomonosov answered the question why icebergs do not sink. The density of the iceberg is 920 kg/m?. Additionally, an iceberg or block of ice is made of fresh water and is separated from ice shelves.
Due to the fact that sea water is denser than an iceberg and does not sink completely. And then it is important to know that only a tenth of it floats on the surface of the water - the top, everything else - 90% of this block of ice is hidden under water.
Meeting him is very dangerous for ships on the high seas. If the ship does not notice the moving iceberg in time, then in a collision it can receive very serious damage or even die.
11. Ice in the ocean.
© Vladimir Kalanov,
"Knowledge is power".
Ice is the solid phase of water, one of its aggregate states. Pure fresh water freezes at a temperature almost equal to zero (below zero by only 0.01-0.02 ° C). At the same time, water that has been purified in laboratory conditions to the maximum possible extent and is in a calm state can be cooled without forming ice to a temperature of minus 33°C. But the smallest piece of ice or other tiny object placed in such supercooled water will instantly cause rapid ice formation.
Normal ocean water, with a salinity of 35‰, freezes at minus 1.91°C. At a salinity of 25 ‰ (White Sea) water freezes at a temperature of minus 1.42°C, at a salinity of 20 ‰ (Black Sea) - at minus 1.07°C, and in the Sea of Azov (salinity 10 ‰) surface water freezes at a temperature minus 0.53°C.
Freezing fresh water does not change its composition. The situation is different when sea water freezes. Freezing begins with the formation of thin, elongated ice crystals, which contain absolutely no salt. Gradually, when the lumps of these crystals begin to freeze, salt gets into the ice.
The salinity of sea ice, i.e. The salinity of the water formed when it melts is on average about 10% of the salinity of ocean water. Over time, this figure decreases, and multi-year ice can be almost fresh.
The volume of ice is 9 percent greater than the volume of water from which it was formed, because... In the crystal lattice of ice, the packing of water molecules is ordered and becomes less dense. Therefore, the density of sea ice is less than the density of sea water and ranges from 0.85-0.94 g/cm 3 . That is why floating ice rises above the surface of the water by 1/7 - 1/10 of its thickness.
The strength of sea ice is noticeably lower than that of freshwater ice, but it increases with decreasing temperature and salinity of the ice. Multi-year ice has the greatest strength.
Ice 60 cm thick, which forms on freshwater bodies in the depths of winter, can withstand a load of up to 15-18 tons, if, of course, this load is not applied concentratedly, but in the form of, say, a cargo platform on a caterpillar track, the supporting surface of which is approximately 2 .5 m2.
At this point we will make a small digression, but not at all lyrical. Lake Ladoga, as is known, has only a weak connection with the oceans and ocean ice. But we want to remind you that in 1941-1942 the ice “Road of Life” was laid along this lake, which saved the lives of many tens of thousands of people. Our young readers should definitely familiarize themselves with the heroic and dramatic history of the construction and operation of this legendary road of life.
In the oceans, ice forms in high and temperate latitudes. In the polar regions, ice remains for several years. This perennial, so-called pack ice reaches its greatest thickness in the central regions of the Arctic Ocean - up to 5 meters. Sea ice begins to melt when its temperature exceeds minus 23°C. In the Arctic in summer, the thickness of ice due to the melting of its upper layers can decrease by 0.5-1.0 meters, but over the winter up to 3 meters of ice can freeze below. This multi-year ice is gradually carried by currents to temperate latitudes, where it melts relatively quickly. It is believed that the lifespan of Arctic ice that forms off the coast of Russia ranges from 2 to 9 years, and Antarctic ice lasts even longer. The ice cover in the oceans reaches its greatest extent at the end of winter: in the Arctic it covers an area of about 11 million km 2 by April, and about 20 million km 2 in the Antarctic by September. If speak about permanent ice cover , then it makes up 3-4 percent of the total area of the World Ocean.
Ice cover may consist not only of fast ice, i.e. motionless ice frozen to the shore, but also moving drifting ice With a strong wind coinciding in direction with the sea current, drifting ice can travel a distance of up to 100 km per day.
Falling snow often creates large drifts on the ice. The snow gradually freezes, increasing the thickness of the ice cover. Sometimes hurricane-force winds break the ice, creating high hummocks. If we talk about the Arctic, only a polar bear can move on such ice, and even then with great difficulty.
But the ocean also contains ice that formed on land. These are so-called icebergs - huge blocks of fresh ice.(German Eisberg - ice mountain). Icebergs are delivered to the ocean by continental glaciers at polar latitudes. The largest ice sheet on Earth is located in Antarctica. Its area is 13.98 million km 2, i.e. 1.5 times the area of Australia. At the same time, the area of the continent of Antarctica itself is estimated at 12.09 million km 2. the rest is accounted for by the ice that covers almost the entire shelf of Antarctica. The average thickness of Antarctic ice is 2.2 km, and the greatest thickness is 4.7 km. The volume of ice is estimated at 26 million cubic kilometers. The enormous weight of ice pressed this continent into the earth's crust. As a result, much of Antarctica's surface lies below sea level. The Antarctic glacier annually receives 2000-2200 km 3 of ice from snow and loses about the same amount to icebergs. Of course, this balance cannot be accurately calculated. Therefore, the scientific world does not yet have a clear answer to the question of whether the Antarctic glacier is increasing or decreasing.
Icebergs in the form of huge blocks, similar to mountains, slowly slide from the mainland into the sea, and then crash into the water with a roar. In Antarctica, the largest volume of ice in the form of icebergs is provided by two giant ice shelves advancing into the Ross and Weddell seas. For example, the Ross Ice Shelf has an area exceeding 500 thousand km 2, and the ice thickness here reaches 700 meters. In the Ross Sea, this glacier approaches in the form of a huge ice barrier almost 900 km long and up to 50 meters high.
There are about 100 thousand icebergs constantly floating around Antarctica. Comprehensive monitoring, including iceberg monitoring, is carried out by 35 scientific stations operating here from different countries. Russia has 8 scientific stations here, the USA - 3, Great Britain - 2. Ukraine, Poland, Argentina and other countries also have Antarctic scientific stations.
The international legal regime of Antarctica and other territories located south of 60° S is regulated by the Antarctic Treaty of December 1, 1959.
In the Northern Hemisphere, the main supplier of icebergs to the ocean is Greenland. It is believed that up to 15 thousand huge pieces of ice break off from the glaciers of this island every year. From here they sail into one of the busiest areas of the Atlantic Ocean.
Icebergs also break off from the glaciers of the islands of the Arctic Ocean - Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, Spitsbergen and the Canadian Arctic Archipelago.
In general, glaciers occupy 16.1 million km 2 of land, of which 14.4 million km 2 are covered by ice sheets (85.3% in Antarctica, 12.1% in Greenland). In terms of area and volume of water, glaciers occupy the second place on Earth after the World Ocean, and in terms of fresh water content they exceed all rivers, lakes and groundwater combined.
Icebergs are table-shaped and pyramidal in shape. The table-shaped shape is characteristic of Antarctic icebergs, which are formed when they are separated from a huge mass of ice of a homogeneous structure. When glaciers move relatively quickly, the shape of the broken pieces often resembles a pyramid. As the underwater and surface parts melt unevenly, icebergs take on various, most bizarre shapes, and with loss of stability they can capsize.
Icebergs can reach enormous sizes. Especially large icebergs form from the ice shelves of Antarctica. In 1987, with the help of Earth satellites, an iceberg 153 km long and 36 km wide was discovered in the Ross Sea area.
An iceberg called B-15 broke off from the same glacier in 2000. This giant had an area of more than 11,000 km 2. If an ice floe of such an area ended up on Lake Ladoga, it would cover 63% of the surface of this large (17.7 thousand km 2) lake.
The mass of such giants can amount to hundreds of millions and even billions of tons. But this is clean fresh water, the shortage of which has long been felt by many countries.
The heat capacity of ice melting is very high. It takes 80 calories to melt 1 gram of ice, not including the heat it takes to warm the ice to zero degrees. It is no coincidence that projects for towing icebergs to the shores of such coastal states as Japan, Saudi Arabia, Kuwait, and the United Arab Emirates have long arisen. Calculations show that an iceberg of “medium” size: 1 km long, 600 m wide and a total height of 300 m during the towing journey, for example, from Antarctica to Saudi Arabia, will lose no more than 20% of its volume. The initial weight of such an iceberg would be about 180 million tons (in water it is much less). If towing an iceberg of this size remains a technically difficult task, then the delivery of relatively small ice fragments with a volume of 200-300 thousand cubic meters is quite doable and is already carried out from time to time by the countries mentioned above.
Having broken off from glaciers, icebergs, picked up by currents and driven by winds, sometimes float far beyond the polar regions. Antarctic icebergs reach the southern coasts of Australia, South America and even Africa. Icebergs from Greenland penetrate into the North Atlantic up to forty degrees north latitude, i.e. latitudes of New York, and sometimes further south, reaching the Azores and even Bermuda.
The cruising range of icebergs and the time of their existence in the ocean depend not only on the direction and speed of sea currents, but also on the physical properties of the icebergs themselves. Very large and deeply frozen (down to minus 60 degrees) Antarctic icebergs exist for several years, and in some cases even decades.
Greenland icebergs melt much faster, in just 2-3 years, because... they are not so large in size and their freezing temperature is no more than minus 30 degrees.
It is unnecessary to explain what danger floating ice mountains pose for shipping. More than once collisions with icebergs have led to disasters at sea. But none of these disasters can compare with the tragedy that took place at the beginning of the 20th century in the North Atlantic.
Nowadays, the danger of colliding with icebergs has decreased significantly compared to the times of the Titanic. Quite reliable radar and other equipment for tracking, alerting and warning about the danger of encountering icebergs is installed on sea vessels, in ports, and on artificial earth satellites. In the North Atlantic, where there are busy shipping routes, a special ice patrol . It warns ship captains about the locations of large icebergs. The International Ice Patrol includes 16 countries. His ships detect icebergs, warn about the location of icebergs and the direction of their movement. The functions of the ice patrol also include the fight against icebergs, which is carried out with the help of explosions, the use of incendiary bombs, dark coloring of ice blocks, for example, by applying a layer of soot to the surface of the iceberg to speed up the melting process, etc.
However, the measures taken cannot be exhaustive. Icebergs appear in the ocean according to the laws of nature. No one can completely guarantee sea vessels against ice hazards. The ocean is large and often fraught with dangers, for which it is always necessary to prepare in advance.
© Vladimir Kalanov,
"Knowledge is power"