And other factors. There are “instant”, tidal, average daily, average monthly, average annual and average long-term sea levels.

Under the influence of wind waves, tides, heating and cooling of the sea surface, fluctuations in atmospheric pressure, precipitation and evaporation, river and glacial runoff, sea level continuously changes. The long-term average sea level is independent of these sea surface fluctuations. The position of the average long-term sea level is determined by the distribution of gravity and the spatial unevenness of hydrometeorological characteristics (water density, atmospheric pressure, etc.).

The average long-term sea level constant at each point is taken to be baseline, from which heights on land are measured. To measure the depths of seas with low tides, this level is taken as zero depth - the water level mark from which depths are measured in accordance with shipping requirements. In Russia and most other countries of the former USSR, as well as in Poland, the absolute heights of points on the earth's surface are measured from the average long-term level of the Baltic Sea, determined from the zero gauge in Kronstadt.

Notes

Wikimedia Foundation. 2010.

See what “World Ocean Level” is in other dictionaries:

    GOST 31170-2004: Vibration and noise of machines. List of vibration, noise and force characteristics that are subject to declaration and control when testing machines, mechanisms, equipment and power plants of civil ships and means of exploration of the world's oceans at the stands of supplier factories- Terminology GOST 31170 2004: Vibration and noise of machines. List of vibration, noise and power characteristics subject to declaration and control when testing machines, mechanisms, equipment and power plants civil courts and means... ... Dictionary-reference book of terms of normative and technical documentation

    Sea level is the position of the free surface of the World Ocean, measured along a plumb line relative to some conventional reference point. This position is determined by the law of gravity, the moment of rotation of the Earth, temperature, tides and others... ... Wikipedia

    LEVEL, vnya, husband. 1. A horizontal plane, a surface as a boundary, from which the height is measured. U. water in the river. 2. The degree of size, development, significance of something. Cultural u. U. life (the degree of satisfaction of the population with material and... Dictionary Ozhegova

    A graph showing fluctuations in the level of the World Ocean over the past 550 million years Sea level the position of the free surface of the World Ocean, measured by ... Wikipedia

    The position of the free surface of the World Ocean, tending to be perpendicular to the resultant of all forces applied to the mass of water. Changes in the position of surface levels are manifested in sea level fluctuations. * * * SEA LEVEL… … Encyclopedic Dictionary

    SEA LEVEL- the position of the undisturbed surface of the World Ocean, tending to be perpendicular to the direction of the resultant of all forces (mainly gravity) applied to the mass of water. Sea level is subject to fluctuations relative to the conventional beginning... ... Marine encyclopedic reference book

    In rivers and lakes a x, the position of the free surface of water in rivers and lakes relative to any horizontal surface that is constant in height; such a surface is taken to be some plane of arbitrary height,... ...

    One of the main elements of the relief and geological structure of the bottom of the World Ocean. Covers its abyssal part (see Abyssal) minus the mid-ocean ridges. Characterized by the development of a typical oceanic earth's crust.… … Great Soviet Encyclopedia

    The level at which the entire solid surface of the earth would be if it were perfectly flat. Currently it corresponds to a depth of about 2.4 km below the modern one. average level of the World Ocean. Geological Dictionary: in 2 volumes. M.: Subsoil.... ... Geological encyclopedia

    The level of the basin into which the water stream flows. General (or main) B. e. the level of the World Ocean. Local (or temporary) B. e. flowing lakes, places where a tributary flows into the main river, as well as outcrops of strong rocks that slow down the deep... Great Soviet Encyclopedia

Books

  • War of Sea and Land, Kovalevskaya Alexandra Vikentievna. The distant future... On the eve of the Third World War, the best scientists of the planet founded Underwater Colonies in the depths of the World Ocean. The nuclear nightmare of a global apocalypse has thrown back the inhabitants...

The level of the World Ocean is a common reference point for all, with which you can measure the height of land areas, as well as the depth of water basins around the globe. This became possible due to the peculiarity of our planet, where the continents are only islands in the vast expanses of water of the World Ocean.

Changes in sea level

The level of the World Ocean is constantly changing due to many factors. Among them, the most important are human activities and volcanic activity.

Fluctuations in ocean waters can be of two types:

  • Periodic- fluctuations occur as a result of ebb and flow.
  • Non-periodic- arise as a result of tsunamis, typhoons, cyclones, hurricanes.

Oscillations are also distinguished by duration:

  • Short- are regulated by the ebb and flow of the tides and last exactly 6 hours 12.5 minutes.
  • Long-term- occur over many hundreds of years, and are associated with global change volume of water in the ocean.

Rice. 1. Fluctuations in the level of the World Ocean over the past 200 thousand years.

The first long-term or secular changes in the fluctuations of ocean waters occurred during the historical glaciation of the planet - during this period, the ocean level decreased by 200 m. With the gradual melting of glaciers, it began to rise. In the near future, it is predicted to rise by another 30 cm, which could entail a serious environmental threat to all life on the planet.

A map of the areas on Earth at greatest risk of being flooded by rising sea levels. Areas that will go under water if the sea rises six meters are marked in red.

American climatologists have found that the rise in the average level of the world's seas on Earth due to global warming slowly accelerating. According to data obtained using satellite measurements over the past 25 years, the rate of sea level rise every year is increasing by an average of 0.084 millimeters per year, scientists write in Proceedings of the National Academy of Sciences.

One of the direct consequences of global warming on Earth is an increase in the average level of the world's seas, which has been observed since the mid-19th century. It occurs due to the thermal expansion of ocean water, as well as the melting of polar ice sheets in Antarctica and Greenland and mountain glaciers. Only for the 20th century intermediate level The sea has risen by 17 centimeters and continues to rise. According to some forecasts, some countries located at low altitude, in particular, island states in Pacific Ocean, may be completely flooded in the middle of the 21st century. To more accurately assess the possible dynamics of average sea level in the near future, scientists offer a variety of computer and mathematical models, however, so far their results are quite divergent and cannot be considered sufficiently accurate.

To create a more accurate model describing the dynamics of sea level on the planet, American climatologists led by Robert S. Nerem from the University of Colorado at Boulder analyzed the latest satellite data on the dynamics of the average global sea level and found that sea level change over the past 25 years can be described by considering that its growth occurs with a constant average acceleration. Our work used all available data from altimeters installed on the satellites of four oceanographic missions of NASA and the US National Oceanic and Atmospheric Administration: from TOPEX / Poseidon launched in 1992 to the Jason-3 satellite, which was launched into orbit by a Falcon 9 launch vehicle in January 2016. From these data, scientists determined the average rate and average acceleration of mean sea level rise on Earth from 1993 to 2017. At the same time, in their study, the authors did not consider the available data obtained using tide gauges (either for previous years or carried out simultaneously with satellite measurements), which are somewhat inferior in accuracy and may differ slightly from the results of satellite measurements.

At the same time, in order to determine the impact on sea level only of global climate changes and to avoid the contribution of local single events (which lead to noticeable fluctuations, but do not reflect general quantitative trends), scientists tried to estimate and subtract from the overall dependence the contribution of the two most noticeable events that occurred during this period. period. The first of these was a series of powerful eruptions of the Philippine volcano Pinatubo, which occurred in the early 90s of the 20th century. Due to the release of huge amounts of aerosol particles into the atmosphere, these eruptions had a significant impact on the Earth's climate - in particular, they led to an increase in average temperature and an increase in area ozone hole over Antarctica. A second important factor that also led to a local acceleration of sea level rise was El Niño, an active phase of cyclical Pacific surface currents that leads to a significant increase in temperature on Earth; the last such phase was observed in 2015-2016. According to scientists, both of these factors lead to significant local deviations from the general trend associated with climate change on the planet, and for quantitative analysis the associated fluctuations were subtracted from the overall dependence.


Dynamics of changes in the global mean sea level (GMSL) from 1993 to 2017. Blue indicates the original data, red - minus the influence of the Pinatubo eruptions, green - minus the contributions of the Pinatubo and El Niño eruptions

R. S. Nerem et al./ PNAS, 2018

As a result of analyzing the data obtained, adjusted for the influence of El Niño and the Pinatubo eruptions, climatologists determined the average rate of rise in average sea level on the planet, which amounted to 2.9 millimeters per year, as well as its acceleration. It turned out that data on changes in average sea level over the past 25 years are very well described by the constant acceleration model, and on average the rate of sea level rise increases by 0.084 millimeters per year each year (the measurement error was about 30 percent).

Based on the average rate of sea level rise, scientists proposed to consider the process uniformly accelerated and, based on this model, made an estimate of sea level in 2100, which should increase by 65 centimeters compared to 2005. According to the scientists, these results are qualitatively consistent with the data of the most accurate predictions to date obtained using computer modeling, but in the future the accuracy of estimates should improve by analyzing data over longer periods of time.

Note that New Zealand climatologists recently asked whether sea level rise is really so dangerous for the Pacific Islands. It turned out that even the islands of Tuvalu, for which the risk of being flooded is considered to be maximum, over the past 30 years not only have not decreased in area, but have even grown slightly. The area's growth has occurred even as sea levels there are rising about twice as fast as the global average.

Alexander Dubov

It is always interesting to imagine very unlikely, but in principle real things. What would happen if all the ice on Earth, which is more than 20 million cubic kilometers, melted?

National Geographic has created a series interactive maps, which demonstrate what catastrophic consequences would happen on our planet. The melted ice that would fall into the oceans and seas would lead to a rise in sea levels of 65 meters. It would consume cities and countries, changing general view continents and coastlines, wiping out entire populations.

Scientists believe it will take about 5,000 years for temperatures to rise enough to melt all the ice on Earth. However, a start has already been made.

For last century, the temperature on Earth increased by about 0.5 degrees Celsius, and this led to a rise in sea levels of 17 cm.

If we continue to burn our coal, oil and gas reserves, the average temperature on our planet will reach 26.6 degrees Celsius instead of today's 14.4 degrees Celsius.

So let's see what happens to the continents...

In Europe, cities such as London and Venice will be under water. The Netherlands and most of Denmark will also be flooded. The Mediterranean Sea will expand and increase the size of the Black and Caspian Seas.

In Asia, China and Bangladesh will be flooded, and more than 760 million people will be underwater. Cities destroyed will include: Karachi, Baghdad, Dubai, Kolkata, Bangkok, Ho Chi Minh City, Singapore, Hong Kong, Shanghai, Tokyo and Beijing. The Indian coastline will also shrink significantly.

IN North America the entire Atlantic coastline in the US will disappear along with Florida and the Gulf Coast. In California, the hills of San Francisco will turn into islands, and the California Valley will become a huge bay.

IN South America The Amazonian lowland and the Paraguay River basin will become straits Atlantic Ocean, wiping out Buenos Aires, coastal Uruguay and parts of Paraguay.

Compared to other continents, Africa will lose less land mass due to rising sea levels. However, rising temperatures will cause most of it to become uninhabitable. In Egypt, Alexandria and Cairo will be flooded by the Mediterranean Sea.

Australia will gain a continental sea, but will lose most of its narrow coastal strip, where 4 out of 5 Australians live.

In Antarctica, what was once continental ice will no longer be ice or continent. This will happen because under the ice there is continental relief, which is below sea level.

What does Antarctica look like without ice?

Antarctica may be the largest ice sheet in the world, but what lies underneath it?

Scientists from NASA have shown the surface of Antarctica, which has been hidden under a thick layer of ice for more than 30 million years. In a project called BedMap2, researchers calculated the total volume of ice in Antarctica to predict future sea level rise. To do this, they needed to know the underlying topography, including wide valleys and hidden mountain ranges.

Some of the most impressive discoveries in Antarctica were the deepest point of all continents, the valley below the Bird Glacier, which lies 2,780 meters below sea level. Scientists also obtained the first detailed images of the Gamburtsev Mountains, which are located under a 1.6-kilometer layer of ice.

The new map is based on surface elevation, ice thickness and base topography, which were made using ground, air and satellite surveys. Scientists also used radar, sound waves and electromagnetic instruments to create the map.


Piazza and Basilica of San Marco. A decent slope of the bell tower, which unexpectedly collapsed in 1902. After 10 years, the bell tower was rebuilt again “in the same form and in the same place where it had always been...”
And how many of these remakes are there?

The water rose at least 3 steps. The BRIDGE seems to be the same, but only its thickness is different, the HOUSE on the right had new bricks in the masonry, was without windows, now has windows, along the way there was also a “reconstruction” in this place.

"Farmacia alle due Sereni" in the Canareggio area

Ca'd'Oro Palace

Canale di S. Trovaso

Traghetto S.M.Giglio

It’s strange that in the photo of the Ca’d’Oro Palace the water level is the same as it is today. And on the rest, at least 50 cm lower. They say that the photos are from about the same period about 100 years ago. Either someone is making the photos look old, or there was something there that was dramatically increased.

Let's move to Kronstadt, port channel:

4 blocks and 5 blocks, probably about the same 50 cm as in Venice.

Peter and Paul Fortress:

It is clearly visible that the entire floor was “licked off by a cow with its tongue.”

At the end of the 19th century, new loopholes were made above the old ones?

The same Venice and only the lazy did not walk along the 1st floor of St. Petersburg.

What does official science say?

From 26 years of observations in Kronstadt, it was possible to notice regular level changes that are tidal in nature, the amplitude of which, however, does not reach five centimeters. When there are calms, the water level, according to observations in Kronstadt, is usually 8–9 centimeters below the average, which depends on the predominance of westerly winds over eastern winds in the bay, as a result of which the average level is higher than the level during calm.

Those. seasonal fluctuations in water levels Gulf of Finland cannot be half a meter.
Let's move on...

Rising sea levels.

Over the past 150 years, there has been a rise in sea levels. Reconstructions of the position of this level in late XIX- the beginning of the 20th century, and then coastal measurements and, finally, global satellite altimetry indicate an increase in sea level by 1.7 mm per year in the 20th century, but in recent decades the rise in sea level has intensified and is now 3 mm per year. The reasons for this rise in level are obviously related to an increase in temperature, which, on the one hand, leads to the expansion of the warming surface thickness of the ocean, and on the other, is caused by the melting of glaciers and thereby an increase in the increase in water in the ocean.

This is associated with ongoing warming. It has a very serious impact on the condition of the perennial ice cover in the Arctic Ocean. More recently heavy ice seriously complicated navigation along the Northern sea ​​route, and the Northwest Passage in the Canadian Arctic Archipelago was virtually impassable. Nowadays, ice with a concentration of more than 7 points persists only in the polar region and in the north of the Canadian archipelago. A total area ice cover has been steadily decreasing over the past 20 years. In general, over the past 10 years, the area of ​​multi-year ice in the Arctic has decreased by approximately 40%. At the same time, the average thickness sea ​​ice in October, according to satellite laser altimetry data, since 2004 it has decreased from 2 to 1.4 m, their area has decreased by 26%, and their volume has decreased by 50%.

Informer from another source. The increase in level over 150 years is about 100mm. For some reason, it is more than 3 times lower than in the previous source. But the fact of growth is obvious.

We backtracked a bit, let’s continue...

Of course, rising sea levels are associated with an increase in the amount of greenhouse gases in the atmosphere:

Changes in temperature and greenhouse gas content based on ice core data from deep well at the Vostok station in Antarctica for two (left) and four (right) climate cycles.

One of the ways to determine the dating of these indicators is dating by the “annual rings” of continental ice. As stated, this was done at Vostok station.
Regarding the fundamental error of scientists in the method of dating ice using “annual rings,” I wrote here:
I will conclude that because of this error, the age of the ice is approximately 700 times less than it is attributed to.

Pay attention to the right graph, which shows CO2 levels, temperature and water levels of the world's oceans. Am I the only one seeing this or is someone else? Every approximately 120 thousand years there is a rapid increase in CO2, temperature and sea level, and a sharp decrease with fluctuations in indicators. And synchronous! What is this? Pole shift? Development and death of civilizations? Fluctuations, I think, are climate restoration: warming and cooling. But why is there a rapid increase in indicators again towards the end of the period? Or is all this connected with the life of the planet? Does she have such periods? The graph of the greenhouse gas CH4 (methane) also coincides synchronously with the others. And it is mainly released from swamps, coal basins, and faults in the earth’s crust. As they say, gaseous breathing of the earth, during powerful degassing processes it is released many times more.
And if we take into account that modern scientists make mistakes in dating by 700 times, we get that something like this happens every ~170 years! This is very close to Kungurov’s version about the nuclear cleansing 200 years ago. And these indicators are not so far from the figures of periodic shifts, shifts geographic poles. I will say that the scientists’ error is 700 times approximate, obtained by dividing the number of layers of ice by ~50 years of aircraft being in this place, under the ice where they were discovered (link above). But the order of the figure turns out to be, I think, 200 (±50) years.
And the worst thing this graph says is that we are at the peak of the rise in indicators. In the coming years, there should be a sharp decline: a drop in the level of the world's oceans, a decrease in temperature and the content of greenhouse gases in the atmosphere. It’s scary to think what it will be. Pole shift?

Next question. Where did so much water come from to raise the world's oceans? Here is information from scientists:

It is possible that under certain conditions (asteroid impact, pole shift) a rapid release of water to the surface occurs. Well, before that it accumulates in the depths. Let me remind you that according to the hypothesis of a hydride Earth, when hydrogen is released, not all of it reaches the surface, but burns almost completely (water is formed in the mantle). According to another hypothesis, this hydrogen is an element of the synthesis of matter when absorbed by the ether nucleus. But this is a separate topic... I had a post about broadcasting.
In any case, even according to official data, there is more water in the depths than on the surface and it can, apparently, come to the surface.