Warm El Niño current emerging. El Niño - what is it? Where the current is formed, its direction. The phenomenon and phenomenon of El Niño. Extensive influence of El Niño conditions
The natural phenomenon of El Niño, which broke out in 1997-1998, had no equal in scale in the entire history of observations. What is this mysterious phenomenon that has made so much noise and attracted close attention of the media?
In scientific terms, El Niño is a complex of interdependent changes in the thermobaric and chemical parameters of the ocean and atmosphere, which take on the character of natural disasters. According to reference literature, it is a warm current that sometimes occurs for unknown reasons off the coast of Ecuador, Peru and Chile. In Spanish, "El Niño" means "baby". This name was given to it by Peruvian fishermen, because the warming of the water and the mass fish kills associated with it usually occur at the end of December and coincide with Christmas. Our journal already wrote about this phenomenon in N 1 for 1993, but since that time researchers have accumulated a lot of new information.
NORMAL SITUATION
To understand the anomalous nature of the phenomenon, let us first consider the usual (standard) climatic situation near the South American Pacific coast. It is rather peculiar and is determined by the Peruvian current, which carries cold waters from Antarctica along the western coast of South America to the Galapagos Islands lying on the equator. Usually the trade winds blowing here from the Atlantic, crossing the high barrier of the Andes, leave moisture on their eastern slopes. And because the western coast of South America is a dry rocky desert, where rain is extremely rare - sometimes it does not fall for years. When the trade winds pick up so much moisture that they carry it to the western shores of the Pacific Ocean, they form the prevailing westerly direction of surface currents here, causing a surge of water off the coast. It is unloaded by the counter-trade current of Cromwell in the equatorial zone of the Pacific Ocean, which captures a 400-kilometer strip here and, at depths of 50-300 m, carries huge masses of water back to the east.
The attention of specialists is attracted by the colossal biological productivity of the Peruan-Chilean coastal waters. Here, in a small space, constituting some fractions of a percent of the entire water area of the World Ocean, the annual fish production (mainly anchovy) exceeds 20% of the world's. Its abundance attracts here huge flocks of fish-eating birds - cormorants, boobies, pelicans. And in the areas of their accumulation, colossal masses of guano (bird droppings) are concentrated - a valuable nitrogen-phosphorus fertilizer; its deposits with a thickness of 50 to 100 m became the object of industrial development and export.
CATASTROPHE
During the El Niño years, the situation changes dramatically. First, the water temperature rises by several degrees and the mass death or departure of fish from this area begins, and as a result, birds disappear. Then atmospheric pressure drops in the eastern Pacific Ocean, clouds appear above it, the trade winds subside, and air currents over the entire equatorial zone of the ocean change direction. Now they go from west to east, carrying moisture from the Pacific region and bringing it down on the Peruvian-Chilean coast.
Events are developing especially catastrophically at the foot of the Andes, which now block the path of the western winds and take all their moisture onto their slopes. As a result, floods, mudflows, floods rage in a narrow strip of rocky coastal deserts of the western coast (at the same time, the territories of the Western Pacific region suffer from a terrible drought: tropical forests burn out in Indonesia, New Guinea, crop yields in Australia drop sharply). To top it off, so-called "red tides" are developing from the Chilean coast to California, caused by the rapid growth of microscopic algae.
So, the chain of catastrophic events begins with a noticeable warming of surface waters in the eastern part of the Pacific Ocean, which has recently been successfully used to predict El Niño. A network of buoy stations has been installed in this water area; with their help, the temperature of ocean water is constantly measured, and the data obtained through satellites are promptly transmitted to research centers. As a result, it was possible to warn in advance about the onset of the most powerful El Niño known so far - in 1997-98.
At the same time, the reason for the heating of ocean water, and therefore the emergence of El Niño itself, is still not completely clear. The appearance of warm water south of the equator is explained by oceanographers as a change in the direction of the prevailing winds, while meteorologists consider the change in winds to be a consequence of the heating of the water. Thus, a kind of vicious circle is created.
To get closer to understanding the genesis of El Niño, let's pay attention to a number of circumstances that are usually overlooked by climate scientists.
EL NIÑO DEGASSING SCENARIO
For geologists, the following fact is quite obvious: El Niño develops over one of the most geologically active parts of the world rift system - the East Pacific Rise, where the maximum spreading rate (the expansion of the ocean floor) reaches 12-15 cm/year. In the axial zone of this underwater ridge, a very high heat flow from the earth's interior was noted, manifestations of modern basalt volcanism are known here, thermal water outcrops and traces of an intensive process of modern ore formation in the form of numerous black and white "smokers" were found.
In the water area between 20 and 35 s. sh. nine hydrogen jets were recorded at the bottom - the outlets of this gas from the earth's interior. In 1994, an international expedition discovered here the most powerful hydrothermal system in the world. In its gaseous emanations, the isotope ratios 3He/4He turned out to be anomalously high, which means that the source of degassing is located at a great depth.
A similar situation is typical for other "hot spots" of the planet - Iceland, the Hawaiian Islands, the Red Sea. There, at the bottom, there are powerful centers of hydrogen-methane degassing and above them, most often in the Northern Hemisphere, the ozone layer is destroyed.
, which gives grounds to apply my model of the destruction of the ozone layer by hydrogen and methane flows to El Niño.
Here is how this process begins and develops. Hydrogen, released from the ocean floor from the rift valley of the East Pacific Rise (its sources were found there instrumentally) and reaching the surface, reacts with oxygen. As a result, heat is generated, which begins to heat the water. The conditions here are very favorable for oxidative reactions: the surface layer of water is enriched with oxygen during wave interaction with the atmosphere.
However, the question arises: can hydrogen coming from the bottom reach the ocean surface in appreciable quantities? A positive answer was given by the results of American researchers who found in the air over the Gulf of California twice the content of this gas compared to the background. But here at the bottom there are hydrogen-methane sources with a total debit of 1.6 x 10 8 m 3 / year.
Hydrogen, rising from the water depths into the stratosphere, forms an ozone hole into which ultraviolet and infrared solar radiation "falls". Falling on the surface of the ocean, it intensifies the heating of its upper layer that has begun (due to the oxidation of hydrogen). Most likely, it is the additional energy of the Sun that is the main and determining factor in this process. The role of oxidative reactions in heating is more problematic. One could not talk about this if it were not for the significant (from 36 to 32.7%o) desalination of ocean water going synchronously with it. The latter is probably carried out by the very addition of water that is formed during the oxidation of hydrogen.
Due to the heating of the surface layer of the ocean, the solubility of CO 2 in it decreases, and it is released into the atmosphere. For example, during the El Niño of 1982-83. an additional 6 billion tons of carbon dioxide got into the air. Evaporation of water also intensifies, and clouds appear over the eastern Pacific Ocean. Both water vapor and CO 2 are greenhouse gases; they absorb thermal radiation and become an excellent accumulator of additional energy that came through the ozone hole.
Gradually, the process is gaining momentum. The anomalous heating of the air leads to a decrease in pressure, and a cyclonic region is formed over the eastern part of the Pacific Ocean. It is she who breaks the standard trade wind scheme of atmospheric dynamics in the area and "sucks in" air from the western part of the Pacific Ocean. Following the subsiding of the trade winds, the water surge near the Peruvian-Chilean coast decreases and the Cromwell equatorial countercurrent ceases to operate. A strong heating of the water leads to the emergence of typhoons, which is very rare in normal years (due to the cooling effect of the Peruvian current). From 1980 to 1989, ten typhoons appeared here, seven of them in 1982-83, when El Niño raged.
BIOLOGICAL PRODUCTIVITY
Why is there a very high biological productivity off the western coast of South America? According to experts, it is the same as in the abundantly "fertilized" fish ponds of Asia, and 50 thousand times higher (!) than in other parts of the Pacific Ocean, if we count on the number of fish caught. Traditionally, this phenomenon is explained by upwelling - a wind driven warm water from the coast, forcing cold water enriched with nutrients, mainly nitrogen and phosphorus, to rise from the depths. During El Niño years, when the wind changes direction, the upwelling is interrupted and, consequently, the feed water stops flowing. As a result, fish and birds die or migrate due to starvation.
All this resembles a perpetual motion machine: the abundance of life in surface waters is explained by the supply of nutrients from below, and their excess below is due to the abundance of life above, because dying organic matter settles to the bottom. However, what is primary here, what gives impetus to such a cycle? Why does it not dry out, although, judging by the thickness of the guano deposits, it has been operating for millennia?
The mechanism of wind upwelling itself is not very clear either. The rise of deep water associated with it is usually determined by measuring its temperature on profiles of different levels oriented perpendicular to the coastline. Then they build isotherms that show the same low temperatures near the coast and at great depths away from it. And in the end, they conclude that the rise of cold waters. But it is known that near the coast the low temperature is due to the Peruvian current, so the described method for determining the rise of deep waters is hardly correct. And finally, one more ambiguity: the mentioned profiles are built across the coastline, and the prevailing winds here blow along it.
I am by no means going to overthrow the concept of wind upwelling - it is based on an understandable physical phenomenon and has the right to life. However, with a closer acquaintance with it in a given region of the ocean, all of the above problems inevitably arise. Therefore, I propose a different explanation for the anomalous biological productivity off the western coast of South America: it is again determined by the degassing of the earth's interior.
In fact, not the entire strip of the Peruvian-Chilean coast is equally productive, as it should be under the action of climatic upwelling. Two "spots" are isolated here - northern and southern, and their position is controlled by tectonic factors. The first is located above a powerful fault leaving the ocean to the continent to the south of the Mendana fault (6-8 o S) and parallel to it. The second spot, somewhat smaller, is located just north of the Nazca Ridge (13-14 S). All of these oblique (diagonal) geological structures running from the East Pacific Rise towards South America are, in essence, zones of degassing; through them, a huge amount of various chemical compounds comes from the bowels of the earth to the bottom and into the water column. Among them there are, of course, vital elements - nitrogen, phosphorus, manganese, and enough trace elements. In the thickness of the coastal Peruvian-Ecuadorian waters, the oxygen content is the lowest in the entire World Ocean, since the main volume here is made up of reduced gases - methane, hydrogen sulfide, hydrogen, ammonia. But a thin surface layer (20-30 m) is abnormally rich in oxygen due to the low temperature of the water brought here from Antarctica by the Peruvian current. In this layer above the fault zones - sources of nutrients of endogenous nature - unique conditions are created for the development of life.
However, there is an area in the World Ocean that is not inferior in bioproductivity to Peruvian, and possibly even surpasses it - off the western coast of South Africa. It is also considered a wind upwelling zone. But the position of the most productive area here (Walvis Bay) is again controlled by tectonic factors: it is located above a powerful fault zone that runs from the Atlantic Ocean to the African continent somewhat north of the Southern Tropic. And along the coast from the Antarctic runs the cold, oxygen-rich Benguela Current.
The region of the South Kuril Islands is also distinguished by its colossal fish productivity, where a cold current passes over the submeridional marginal-oceanic fault of Iona. In the midst of saury fishing season, literally the entire Far Eastern fishing fleet of Russia gathers in the small water area of the South Kuril Strait. It is appropriate here to recall Kuril Lake in South Kamchatka, where one of the largest spawning grounds for sockeye salmon (a type of Far Eastern salmon) is located in our country. The reason for the very high biological productivity of the lake, according to experts, is the natural "fertilization" of its water with volcanic emanations (it is located between two volcanoes - Ilyinsky and Kambalny).
But back to El Niño. During the period when degassing intensifies off the coast of South America, a thin surface layer of water saturated with oxygen and teeming with life is blown through with methane and hydrogen, oxygen disappears, and the mass death of all life begins: a huge number of bones of large fish are lifted from the bottom of the sea by trawls, on Seals are dying in the Galapagos Islands. However, it is unlikely that the fauna is dying due to a decrease in the bioproductivity of the ocean, as the traditional version says. She is most likely poisoned by poisonous gases rising from the bottom. After all, death comes suddenly and overtakes the entire marine community - from phytoplankton to vertebrates. Only birds die of starvation, and even then mostly chicks - adults simply leave the danger zone.
"RED TIDES"
However, after the mass disappearance of biota, the amazing riot of life off the western coast of South America does not stop. In oxygen-deprived waters purged with poisonous gases, unicellular algae, dinoflagellates, begin to flourish. This phenomenon is known as the "red tide" and is so named because only intensely colored algae thrive in such conditions. Their coloration is a kind of protection from solar ultraviolet, acquired back in the Proterozoic (over 2 billion years ago), when there was no ozone layer and the surface of water bodies was subjected to intense ultraviolet radiation. So during the "red tides" the ocean, as it were, returns to its "pre-oxygen" past. Due to the abundance of microscopic algae, some marine organisms, usually acting as water filterers, such as oysters, become poisonous at this time and their consumption threatens with severe poisoning.
Within the framework of the gas-geochemical model developed by me of the anomalous bioproductivity of local areas of the ocean and the periodically rapid death of biota in it, other phenomena are also explained: the massive accumulation of fossil fauna in the ancient shales of Germany or phosphorites of the Moscow region, overflowing with remains of fish bones and cephalopod shells.
MODEL CONFIRMED
I will give some facts testifying to the reality of the El Niño degassing scenario.
During the years of its manifestation, the seismic activity of the East Pacific Rise sharply increases - such a conclusion was made by the American researcher D. Walker, after analyzing the relevant observations from 1964 to 1992 in the section of this underwater ridge between 20 and 40s. sh. But, as it has long been established, seismic events are often accompanied by increased degassing of the earth's interior. In favor of the model I have developed is also the fact that the waters off the western coast of South America during El Niño years are literally seething from the release of gases. The hulls of the ships are covered with black spots (the phenomenon was called "El Pintor", translated from Spanish - "painter"), and the fetid smell of hydrogen sulfide spreads over large areas.
In the African Gulf of Walvis Bay (mentioned above as an area of anomalous bioproductivity), ecological crises also occur periodically, proceeding according to the same scenario as off the coast of South America. Gas emissions begin in this bay, which leads to the mass death of fish, then "red tides" develop here, and the smell of hydrogen sulfide on land is felt even 40 miles from the coast. All this is traditionally associated with the abundant release of hydrogen sulfide, but its formation is explained by the decomposition of organic residues on the seabed. Although it is much more logical to consider hydrogen sulfide as an ordinary component of deep emanations - after all, it comes out here only above the fault zone. The penetration of gas far on land is also easier to explain by its flow from the same fault, tracing from the ocean into the depths of the mainland.
It is important to note the following: when deep gases enter the ocean water, they are separated due to a sharply different (by several orders of magnitude) solubility. For hydrogen and helium, it is 0.0181 and 0.0138 cm 3 in 1 cm 3 of water (at temperatures up to 20 C and a pressure of 0.1 MPa), and for hydrogen sulfide and ammonia it is incomparably more: 2.6 and 700 cm, respectively 3 in 1 cm3. That is why the water above the degassing zones is greatly enriched with these gases.
A strong argument in favor of the El Niño degassing scenario is a map of the average monthly ozone deficit over the planet's equatorial region, compiled at the Central Aerological Observatory of the Hydrometeorological Center of Russia using satellite data. It clearly shows a powerful ozone anomaly over the axial part of the East Pacific Rise a little south of the equator. I note that by the time the map was published, I had published a qualitative model explaining the possibility of the destruction of the ozone layer just above this zone. By the way, this is not the first time that my predictions of the place where ozone anomalies might appear are confirmed by field observations.
LA NINA
This is the name of the final phase of El Niño - a sharp cooling of the water in the eastern part of the Pacific Ocean, when its temperature drops several degrees below normal for a long period. The natural explanation for this is the simultaneous destruction of the ozone layer both over the equator and over Antarctica. But if in the first case it causes the water to warm up (El Niño), then in the second case it causes a strong melting of ice in Antarctica. The latter increases the inflow of cold water into the Antarctic area. As a result, the temperature gradient between the equatorial and southern parts of the Pacific Ocean increases sharply, and this leads to an increase in the cold Peruvian current, which cools the equatorial waters after degassing weakens and the ozone layer recovers.
THE ROOT CAUSE IS IN SPACE
First, I would like to say a few "justifying" words about El Niño. The media is, to put it mildly, not quite right when they accuse him of causing such disasters as floods in South Korea or unprecedented frosts in Europe. After all, deep degassing can simultaneously intensify in many regions of the planet, which leads to the destruction of the ozonosphere there and the appearance of anomalous natural phenomena, which have already been mentioned. For example, the heating of water preceding the occurrence of El Niño occurs under ozone anomalies not only in the Pacific, but also in other oceans.
As for the intensification of deep degassing, it is determined, in my opinion, by cosmic factors, mainly by the gravitational effect on the liquid core of the Earth, which contains the main planetary reserves of hydrogen. An important role in this is probably played by the relative position of the planets and, first of all, interactions in the Earth-Moon-Sun system. G.I. Voitov and his colleagues from the Joint Institute of Physics of the Earth named after V.I. O. Yu. Schmidt of the Russian Academy of Sciences established a long time ago: the degassing of the bowels noticeably increases in periods close to the full moon and new moon. It is also influenced by the position of the Earth in the near-solar orbit, and the change in the speed of its rotation. A complex combination of all these external factors with processes in the depths of the planet (for example, the crystallization of its inner core) determines the momentum of increasing planetary degassing, and hence the El Niño phenomenon. Its 2-7-year quasi-periodicity was revealed by the domestic researcher N. S. Sidorenko (Hydrometeorological Center of Russia), by analyzing a continuous series of atmospheric pressure drops between the stations of Tahiti (on the island of the same name in the Pacific Ocean) and Darwin (the northern coast of Australia) over a long period - from 1866 to the present.
Candidate of Geological and Mineralogical Sciences V. L. SYVOROTKIN, Lomonosov Moscow State University M. V. Lomonosov
The first time I heard the word "El Niño" in the US was in 1998. At that time, this natural phenomenon was well known to Americans, but almost unknown in our country. And not surprising, because. El Niño originates in the Pacific Ocean off the coast of South America and greatly affects the weather in the southern states of the United States. El Niño(translated from Spanish El Nino- baby, boy) in the terminology of climatologists - one of the phases of the so-called Southern Oscillation, i.e. fluctuations in the temperature of the surface layer of water in the equatorial part of the Pacific Ocean, during which the area of heated surface waters shifts to the east. (For reference: the opposite phase of the oscillation - the displacement of surface waters to the west - is called La Niña (La Nina- baby, girl)). Periodically occurring in the ocean, the El Niño phenomenon strongly affects the climate of the entire planet. One of the largest El Niño occurred just in 1997-1998. It was so strong that it attracted the attention of the world community and the press. At the same time, theories about the connection of the Southern Oscillation with global climate changes spread. According to experts, the El Niño warming event is one of the main drivers of our natural climate variability.
In 2015 The World Meteorological Organization (WMO) has said that the early El Niño, dubbed "Bruce Lee," could become one of the most powerful since 1950. Its appearance was expected last year, based on data on the increase in air temperature, but these models did not justify themselves, and El Niño did not appear.
In early November, the American agency NOAA (National Oceanic and Atmospheric Administration) released a detailed report on the state of the Southern Oscillation and analyzed the possible development of El Niño in 2015-2016. The report is published on the NOAA website. The conclusions of this paper state that the conditions for the formation of El Niño are currently in place, the average surface temperature of the equatorial Pacific Ocean (SST) is elevated and continues to rise. The probability that El Niño will develop during the winter of 2015-2016 is 95% . A gradual decline in El Niño is predicted in the spring of 2016. The report has an interesting graph showing the evolution of the SST since 1951. The blue areas represent low temperatures (La Niña), and the orange areas show high temperatures (El Niño). The previous strong increase in SST by 2 °C was observed in 1998.
Data obtained in October 2015 suggest that the SST anomaly at the epicenter is already reaching 3°C.
Although the causes of El Niño are not yet fully understood, it is known that it begins with the trade winds weakening over several months. A series of waves move along the Pacific Ocean along the equator and create a warm water mass near South America, where the ocean usually has low temperatures due to the rise of deep ocean waters to the surface. The weakening of the trade winds, with strong westerly winds counteracting them, could also create a twin cyclone (to the south and north of the equator), which is another sign of the future of El Niño.
Studying the causes of El Niño, geologists drew attention to the fact that the phenomenon occurs in the eastern part of the Pacific Ocean, where a powerful rift system has developed. The American researcher D. Walker found a clear connection between the increase in seismicity in the East Pacific Rise and El Niño. The Russian scientist G. Kochemasov saw another curious detail: the relief fields of oceanic warming almost one to one repeat the structure of the earth's core.
One of the interesting versions belongs to the Russian scientist - Doctor of Geological and Mineralogical Sciences Vladimir Syvorotkin. It was first mentioned back in 1998. According to the scientist, the most powerful centers of hydrogen-methane degassing are located in the hot spots of the ocean. And easier - sources of constant emission of gases from the bottom. Their visible signs are the outlets of thermal waters, black and white smokers. In the area of the coasts of Peru and Chile, during the years of El Niño, there is a massive release of hydrogen sulfide. Water boils, there is a terrible smell. At the same time, an amazing force is pumped into the atmosphere: approximately 450 million megawatts.
The El Niño phenomenon is now being studied and discussed more and more intensively. A team of researchers from the German National Center for Geosciences has concluded that the mysterious disappearance of the Maya civilization in Central America could be caused by strong climate changes caused by El Niño. At the turn of the 9th and 10th centuries AD, at opposite ends of the earth, the two largest civilizations of that time almost simultaneously ceased to exist. We are talking about the Maya Indians and the fall of the Chinese Tang dynasty, followed by a period of internecine strife. Both civilizations were located in monsoonal regions, the moistening of which depends on the seasonal precipitation. However, there came a time when the rainy season was not able to provide enough moisture for the development of agriculture. The drought and subsequent famine led to the decline of these civilizations, the researchers believe. Scientists came to these conclusions by studying the nature of sedimentary deposits in China and Mesoamerica related to the specified period. The last emperor of the Tang Dynasty died in 907 AD, and the last known Mayan calendar dates back to 903.
Climatologists and meteorologists say that El Niño2015, which will peak between November 2015 and January 2016, will be one of the strongest. El Niño will lead to large-scale disturbances in atmospheric circulation, which can cause droughts in traditionally wet regions and floods in dry ones.
A phenomenal phenomenon, which is considered one of the manifestations of the developing El Niño, is now observed in South America. The Atacama Desert, which is located in Chile and is one of the driest places on Earth, is covered with flowers.
This desert is rich in deposits of saltpeter, iodine, common salt and copper; no significant precipitation has been observed here for four centuries. The reason is that the Peruvian current cools the lower atmosphere and creates a temperature inversion that prevents precipitation. Rain falls here once every few decades. However, in 2015, the Atacama was hit by unusually heavy rainfall. As a result, dormant bulbs and rhizomes (horizontally growing underground roots) sprouted. The pale plains of the Atacama were covered with yellow, red, purple and white flowers - nolans, bomareys, rhodophials, fuchsias and mallows. The desert bloomed for the first time in March, after unexpectedly intense rains caused floods in the Atacama and killed about 40 people. Now the plants have bloomed for the second time in a year, before the beginning of the southern summer.
What will El Niño 2015 bring? A powerful El Niño is expected to bring long-awaited downpours to the arid regions of the United States. In other countries, the effect may be the opposite. In the western Pacific, El Niño creates high atmospheric pressure, bringing dry and sunny weather to vast areas of Australia, Indonesia, and sometimes even India. El Niño's impact on Russia has so far been limited. It is believed that under the influence of El Niño in October 1997 in Western Siberia, the temperature was set above 20 degrees, and then they started talking about the retreat of the permafrost to the north. In August 2000, experts from the Ministry of Emergency Situations attributed the series of hurricanes and downpours that swept across the country to the influence of the El Niño phenomenon.
At all times, the yellow press has raised its ratings due to various news that have a mystical, catastrophic, provocative or revealing character. Recently, however, more and more people are beginning to be frightened by various natural disasters, the end of the world, etc. In this article, we will talk about one natural phenomenon that sometimes borders on mysticism - the warm El Niño current. What's this? This question is often asked by people on various Internet forums. Let's try to answer it.
The natural phenomenon of El Niño
In 1997-1998 one of the largest natural disasters in the history of observations associated with this phenomenon broke out on our planet. This mysterious phenomenon has made a lot of noise and attracted close attention of the world media, and its name is for the phenomenon, the encyclopedia will tell. In scientific terms, El Niño is a complex of changes in the chemical and thermobaric parameters of the atmosphere and ocean, which take on the character of a natural disaster. As you can see, the definition is very difficult to perceive, so let's try to consider it through the eyes of an ordinary person. The reference literature says that the El Niño phenomenon is just a warm current that sometimes occurs off the coast of Peru, Ecuador and Chile. Scientists cannot explain the nature of the appearance of this current. The very name of the phenomenon comes from the Spanish language and means "baby". El Niño got its name from the fact that it appears only at the end of December and coincides with Catholic Christmas.
Normal situation
In order to understand the whole anomalous nature of this phenomenon, we first consider the usual climatic situation in this region of the planet. Everyone knows that mild weather in Western Europe is determined by the warm Gulf Stream, while in the Pacific Ocean of the Southern Hemisphere, the tone is set by the cold Antarctic. The prevailing Atlantic winds here are the trade winds that blow on the western South American coast, crossing the high Andes, leaving all the moisture on the eastern slopes. As a result, the western part of the mainland is a rocky desert, where rainfall is extremely rare. However, when the trade winds take in so much moisture that they can carry it across the Andes, they form a powerful surface current here, which causes a surge of water off the coast. The attention of specialists was attracted by the colossal biological activity of this region. Here, in a relatively small area, the annual fish production exceeds the global one by 20%. This leads to an increase in fish-eating birds in the region. And in places of their accumulation, a colossal mass of guano (litter) is concentrated - a valuable fertilizer. In some places, the thickness of its layers reaches 100 meters. These deposits have become the object of industrial production and export.
Catastrophe
Now consider what happens when a warm El Niño occurs. In this case, the situation changes dramatically. An increase in temperature leads to the mass death or departure of fish and, as a result, birds. Further, there is a drop in atmospheric pressure in the eastern part of the Pacific Ocean, clouds appear, the trade winds subside, and the winds change their direction to the opposite. As a result, streams of water fall on the western slopes of the Andes, floods, floods, and mudflows rage here. And on the opposite side of the Pacific Ocean - in Indonesia, Australia, New Guinea - a terrible drought begins, which leads to forest fires and the destruction of agricultural plantations. However, the El Niño phenomenon is not limited to this: from the Chilean coast to California, "red tides" begin to develop, which are caused by the growth of microscopic algae. It would seem that everything is clear, but the nature of the phenomenon is not completely clear. Thus, oceanographers consider the appearance of warm waters to be the result of a change in winds, while meteorologists explain the change in winds by heating the waters. Is this a vicious circle? However, let's look at some of the circumstances that climatologists missed.
El Niño Degassing Scenario
What is this phenomenon, geologists helped to understand. For ease of perception, we will try to move away from specific scientific terms and tell everything in a generally accessible language. It turns out that El Niño is formed in the ocean over one of the most active geological sections of the rift system (a break in the earth's crust). Hydrogen is actively released from the bowels of the planet, which, reaching the surface, forms a reaction with oxygen. As a result, heat is generated, which heats the water. In addition, this leads to the formation over the region, which also contributes to more intense heating of the ocean by solar radiation. Most likely, the role of the Sun is decisive in this process. All this leads to an increase in evaporation, a decrease in pressure, as a result of which a cyclone is formed.
biological productivity
Why is there such a high biological activity in this region? According to scientists, it corresponds to abundantly "fertilized" ponds in Asia and more than 50 times higher than that in other parts of the Pacific Ocean. Traditionally, this is usually explained by the wind-driven warm waters from the shore - upwelling. As a result of this process, cold water, enriched with nutrients (nitrogen and phosphorus), rises from the depths. And when El Niño appears, upwelling is interrupted, as a result of which birds and fish die or migrate. It would seem that everything is clear and logical. However, here, too, scientists do not agree on much. For example, the mechanism of raising water from the depths of the ocean slightly. Scientists measure temperatures at various depths, oriented perpendicular to the shore. Then graphs (isotherms) are built, comparing the level of coastal and deep waters, and on this the above-mentioned conclusions are made. However, the temperature measurement in coastal waters is incorrect, because it is known that their coldness is determined by the Peruvian Current. And the process of drawing isotherms across the coastline is wrong, because the prevailing winds blow along it.
But the geological version easily fits into this scheme. It has long been known that the water column of this region has a very low oxygen content (caused by a geological gap) - lower than anywhere else on the planet. And the upper layers (30 m), on the contrary, are anomalously rich in it because of the Peruvian Current. It is in this layer (above the rift zones) that unique conditions are created for the development of life. When the El Niño current appears, degassing intensifies in the region, and a thin surface layer is saturated with methane and hydrogen. This leads to the death of living beings, and not the lack of food supply.
red tides
However, with the onset of an ecological catastrophe, life here does not stop. In the water, unicellular algae - dinoflagellates - begin to actively multiply. Their red color is protection from solar ultraviolet (we already mentioned that an ozone hole is forming over the region). Thus, due to the abundance of microscopic algae, many marine organisms that act as ocean filters (oysters, etc.) become poisonous, and eating them leads to severe poisoning.
The model is confirmed
Let's consider an interesting fact confirming the reality of the degassing version. The American researcher D. Walker carried out work on the analysis of sections of this underwater ridge, as a result of which he came to the conclusion that during the years of the appearance of El Niño, seismic activity sharply increased. But it has long been known that it is often accompanied by increased degassing of the bowels. So, most likely, scientists simply confused cause and effect. It turns out that the changed direction of the flow of El Niño is a consequence, and not the cause of subsequent events. This model is also supported by the fact that in these years the water literally seethes from the release of gases.
La Niña
This is the name of the final phase of El Niño, which results in a sharp cooling of the water. The natural explanation for this phenomenon is the destruction of the ozone layer over Antarctica and the Equator, which causes and leads to an influx of cold water in the Peru Current, which cools El Niño.
Cause in space
The media blame El Niño for floods in South Korea, unprecedented frosts in Europe, droughts and fires in Indonesia, the destruction of the ozone layer, etc. However, if we recall the fact that the mentioned current is just a consequence of geological processes occurring in bowels of the Earth, then you should think about the root cause. And it is hidden in the impact on the core of the planet of the Moon, the Sun, the planets of our system, as well as other celestial bodies. So it's useless to scold El Nino ...
07.12.2007 14:23
Fires and floods, droughts and hurricanes all hit our Earth together in 1997. The fires turned the forests of Indonesia to ashes, then raged across the expanses of Australia. Downpours are frequent over the Chilean Atacama Desert, which is particularly dry. Heavy rains and floods did not spare South America either. The total damage from the willfulness of the elements amounted to about 50 billion dollars. The cause of all these disasters, meteorologists believe the phenomenon of El Niño.
El Niño means "baby" in Spanish. This is the name given to the anomalous warming of the surface waters of the Pacific Ocean off the coast of Ecuador and Peru, which occurs every few years. This affectionate name reflects only the fact that El Niño most often begins around the Christmas holidays, and the fishermen of the west coast of South America associated it with the name of Jesus in infancy.
In normal years, along the entire Pacific coast of South America, due to the coastal rise of cold deep waters caused by the surface cold Peruvian Current, the ocean surface temperature fluctuates in a narrow seasonal range - from 15°C to 19°C. During the El Niño period, the ocean surface temperature in the coastal zone rises by 6-10°C. As evidenced by geological and paleoclimatic studies, the mentioned phenomenon exists for at least 100 thousand years. Fluctuations in the temperature of the surface layer of the ocean from extremely warm to neutral or cold occur with periods of 2 to 10 years. Currently, the term "El Niño" is used in relation to situations where abnormally warm surface waters occupy not only the coastal region near South America, but also most of the tropical Pacific Ocean up to the 180th meridian.
There is a constant warm current, originating from the coast of Peru and stretching to the archipelago lying southeast of the Asian continent. It is an elongated tongue of heated water, equal in area to the territory of the United States. The heated water evaporates intensively and "pumps" the atmosphere with energy. Clouds form over the warm ocean. Usually trade winds (constantly blowing easterly winds in the tropical zone) drive a layer of this warm water from the American coast towards Asia. Approximately in the region of Indonesia, the current stops, and monsoon rains pour over southern Asia.
During El Niño near the equator, this current warms up more than usual, so the trade winds weaken or do not blow at all. The heated water spreads to the sides, goes back to the American coast. An anomalous convection zone appears. Rains and hurricanes hit Central and South America. Over the past 20 years, there have been five active El Niño cycles: 1982-83, 1986-87, 1991-1993, 1994-95 and 1997-98.
The La Niño phenomenon, the opposite of El Niño, manifests itself as a drop in surface water temperature below the climatic norm in the eastern tropical Pacific. Such cycles were observed in 1984-85, 1988-89 and 1995-96. Unusually cold weather sets in the East Pacific during this period. During the formation of La Niño, the trade winds (east) winds from the west coast of both Americas increase significantly. The winds shift the zone of warm water and the "language" of cold waters stretches for 5000 km, exactly in the place (Ecuador - Samoa Islands), where during El Niño there should be a belt of warm waters. During this period, powerful monsoon rains are observed in Indochina, India and Australia. The Caribbean and the United States suffer from droughts and tornadoes. La Niño, like El Niño, most often occurs from December to March. The difference is that El Niño occurs on average once every three to four years, while La Niño occurs once every six to seven years. Both phenomena bring with them an increased number of hurricanes, but during La Niño there are three to four times more than during El Niño.
According to recent observations, the reliability of the onset of El Niño or La Niño can be determined if:
1. At the equator, in the eastern Pacific Ocean, a patch of warmer water than usual (El Niño), colder (La Niño) is formed.
2. The atmospheric pressure trend between the port of Darwin (Australia) and the island of Tahiti is compared. With El Niño, pressure will be high in Tahiti and low in Darwin. With La Niño, the opposite is true.
Research over the past 50 years has established that El Niño means more than just the coordinated fluctuations in surface pressure and ocean water temperature. El Niño and La Niño are the most pronounced manifestations of interannual climate variability on a global scale. These phenomena are large-scale changes in ocean temperatures, precipitation, atmospheric circulation, and vertical air movements over the tropical Pacific.
Abnormal weather conditions on the globe during El Niño years
In the tropics, there is an increase in precipitation over areas east of the central Pacific and a decrease from the norm over northern Australia, Indonesia and the Philippines. In December-February, more than normal precipitation is observed along the coast of Ecuador, in northwestern Peru, over southern Brazil, central Argentina and over equatorial, eastern Africa, during June-August in the western United States and over central Chile.
El Niño events are also responsible for large-scale air temperature anomalies around the world. During these years, there are outstanding temperature rises. Warmer than normal conditions in December-February were over southeast Asia, over Primorye, Japan, the Sea of Japan, over southeast Africa and Brazil, southeast Australia. Warmer than normal temperatures occur in June-August along the west coast of South America and over southeastern Brazil. Colder winters (December-February) occur along the southwest coast of the United States.
Abnormal weather conditions on the globe during the La Niño years
During La Niño periods, precipitation increases over the western equatorial Pacific, Indonesia and the Philippines and is almost completely absent in the eastern part. More precipitation falls in December-February over northern South America and over South Africa, and in June-August over southeastern Australia. Dryer-than-normal conditions occur over the coast of Ecuador, over northwest Peru and equatorial east Africa during December-February, and over southern Brazil and central Argentina in June-August. There are large-scale abnormalities around the world with the largest number of areas experiencing abnormally cool conditions. Cold winters in Japan and the Primorye, over South Alaska and western, central Canada. Cool summer seasons over southeast Africa, over India and southeast Asia. Warmer winters over the US Southwest.
Some aspects of telecommunication
Despite the fact that the main events associated with El Niño occur in the tropical zone, they are closely related to processes occurring in other regions of the globe. This can be traced on long-distance communications over the territory and in time - teleconnections. During El Niño years, energy transfer to the troposphere of tropical and temperate latitudes increases. This is manifested in an increase in thermal contrasts between tropical and polar latitudes, and intensification of cyclonic and anticyclonic activity in temperate latitudes. The frequency of occurrence of cyclones and anticyclones in the northern part of the Pacific Ocean from 120°E was calculated at the Far Eastern Research Institute of Geological Research. up to 120°W It turned out that the cyclones in the band 40°-60° N.L. and anticyclones in the band 25°-40° N.L. formed in subsequent winters after El Niño more than in previous ones; processes in the winter months after El Niño are characterized by greater activity than before this period.
During the El Niño years:
1. weakened Honolulu and Asian anticyclones;
2. the summer depression over southern Eurasia is filled, which is the main reason for the weakening of the monsoon over India;
3. the summer depression over the Amur basin, as well as the winter Aleutian and Icelandic depressions, are more developed than usual.
On the territory of Russia during the El Niño years, areas of significant air temperature anomalies are distinguished. In spring, the temperature field is characterized by negative anomalies, that is, spring during El Niño years is usually cold in most of Russia. In summer, the focus of below zero anomalies over the Far East and Eastern Siberia remains, and over Western Siberia and the European part of Russia, centers of above zero air temperature anomalies appear. In the autumn months, significant air temperature anomalies over the territory of Russia were not identified. It should only be noted that in the European part of the country the temperature background is slightly lower than usual. El Niño years experience warm winters over most of the area. The center of negative anomalies can be traced only over the northeast of Eurasia.
We are currently in a weakening El Niño cycle - a period of average distribution of ocean surface temperatures. (The El Niño and La Niño events represent opposite extremes of ocean pressure and temperature cycles.)
Over the past few years, great progress has been made in the comprehensive study of the El Niño phenomenon. Scientists believe that the key issues of this problem are fluctuations in the system atmosphere - ocean - Earth. In this case, atmospheric oscillations are the so-called Southern Oscillation (coordinated surface pressure oscillations in a subtropical anticyclone in the southeast Pacific Ocean and in a trough stretching from northern Australia to Indonesia), ocean oscillations - El Niño and La Niño phenomena and Earth oscillations - movement of geographic poles. Also of great importance in the study of the El Niño phenomenon is the study of the impact of external cosmic factors on the Earth's atmosphere.
Especially for Primpogoda, the leading weather forecasters of the Department of Meteorological Forecasts of the Primorsky UGMS T. D. Mikhailenko and E. Yu. Leonova
The Southern Oscillation and El Niño are a global ocean-atmospheric phenomenon. As a feature of the Pacific Ocean, El Niño and La Niña are temperature fluctuations in surface waters in the tropics of the Eastern Pacific. The names of these phenomena, borrowed from the Spanish language of the locals and first introduced into scientific circulation in 1923 by Gilbert Thomas Walker, mean "baby" and "baby", respectively. Their influence on the climate of the southern hemisphere is difficult to overestimate. The Southern Oscillation (atmospheric component of the phenomenon) reflects monthly or seasonal fluctuations in the difference in air pressure between the island of Tahiti and the city of Darwin in Australia.Named after Volcker, the circulation is an essential aspect of the Pacific ENSO (El Nino Southern Oscillation) phenomenon. ENSO is a set of interacting parts of one global system of ocean-atmospheric climate fluctuations that occur as a sequence of oceanic and atmospheric circulations. ENSO is the world's best known source of interannual weather and climate variability (3 to 8 years). ENSO has signatures in the Pacific, Atlantic and Indian Oceans.
In the Pacific, during significant El Niño warm events, as it warms up, it expands over much of the Pacific tropics and becomes in direct relation to the intensity of the SOI (Southern Oscillation Index). While ENSO events are mostly between the Pacific and Indian Oceans, ENSO events in the Atlantic Ocean lag behind the first by 12-18 months. Most of the countries that are subject to ENSO events are developing countries, with economies heavily dependent on the agricultural and fishing sectors. New opportunities to predict the onset of ENSO events in three oceans could have global socio-economic implications. Since ENSO is a global and natural part of the Earth's climate, it is important to find out if the change in intensity and frequency could be the result of global warming. Low frequency changes have already been detected. Inter-decadal ENSO modulations may also exist.
El Niño and La Niña
Common pacific pattern. Equatorial winds collect a warm water basin towards the west. Cold waters rise to the surface along the South American coast.And La Niña officially defined as long-term marine surface temperature anomalies greater than 0.5 °C across the Pacific Ocean in its central tropical region. When a +0.5 °C (-0.5 °C) condition is observed for up to five months, it is classified as an El Niño (La Niña) condition. If the anomaly persists for five months or longer, then it is classified as an El Niño (La Niña) episode. The latter occurs at irregular intervals of 2-7 years and usually lasts one or two years.
Rising air pressure over the Indian Ocean, Indonesia and Australia.
Drop in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean.
The trade winds in the South Pacific are weakening or heading east.
Warm air appears next to Peru, causing rain in the deserts.
Warm water spreads from the western part of the Pacific Ocean to the east. She brings rain with her, causing it in areas where it is usually dry.
Warm El Niño Current, consisting of plankton-poor tropical water and heated by its easterly channel in the Equatorial Current, replaces the cold, plankton-rich waters of the Humboldt Current, also known as the Peruvian Current, which contains large populations of game fish. Most years, warming lasts only a few weeks or months, after which weather patterns return to normal and fish catches increase. However, when El Niño conditions last several months, more extensive ocean warming occurs and its economic impact on local fisheries for the export market can be severe.
The Volcker circulation is visible on the surface as easterly trade winds, which move westward water and air heated by the sun. It also creates oceanic upwelling off the coast of Peru and Ecuador and cold waters rich in plankton flow to the surface, increasing fish stocks. The western equatorial part of the Pacific Ocean is characterized by warm, humid weather and low atmospheric pressure. The accumulated moisture falls out in the form of typhoons and storms. As a result, in this place the ocean is 60 cm higher than in its eastern part.
In the Pacific, La Niña is characterized by unusually cold temperatures in the eastern equatorial region compared to El Niño, which, in turn, is characterized by unusually high temperatures in the same region. Atlantic tropical cyclone activity generally increases during La Niña. The La Niña condition often occurs after El Niño, especially when the latter is very strong.
Southern Oscillation Index (SOI)
The Southern Oscillation Index is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.Long-term negative SOI values often signal El Niño episodes. These negative values are usually associated with prolonged warming in the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific trade winds and a decrease in precipitation in the east and north of Australia.
Positive SOI values are associated with strong Pacific trade winds and warming water temperatures in northern Australia, well known as the La Niña episode. The waters of the central and eastern tropical Pacific become colder during this time. Together, all of this increases the likelihood of more rainfall in eastern and northern Australia than usual.
El Niño influence
As El Niño's warm waters feed the storms, it creates an increase in rainfall in the east-central and eastern Pacific Oceans.In South America, the El Niño effect is more pronounced than in North America. El Niño is associated with warm and very wet summers (December-February) along the coasts of northern Peru and Ecuador, causing severe flooding whenever the event is strong. Effects during February, March, April can become critical. Southern Brazil and northern Argentina also experience wetter than normal conditions, but mostly during the spring and early summer. The central region of Chile gets a mild winter with plenty of rain, and the Peruvian-Bolivian Plateau experiences occasional winter snowfalls that are unusual for this region. Dryer and warmer weather is observed in the Amazon Basin, Colombia and Central America.
Direct effects of El Niño lead to a decrease in humidity in Indonesia, increasing the likelihood of wildfires in the Philippines and northern Australia. Also in June-August, dry weather is observed in the regions of Australia: Queensland, Victoria, New South Wales and eastern Tasmania.
The west of the Antarctic Peninsula, Ross Land, the Bellingshausen and Amundsen seas are covered with large amounts of snow and ice during El Niño. The latter two and the Wedell Sea are getting warmer and under higher atmospheric pressure.
In North America, winters tend to be warmer than usual in the Midwest and Canada, while it is getting wetter in central and southern California, northwestern Mexico, and the southeastern United States. The Pacific Northwest states, in other words, are drained during El Niño. Conversely, during La Niña, the US Midwest dries up. El Niño is also associated with a decrease in Atlantic hurricane activity.
Eastern Africa, including Kenya, Tanzania and the White Nile Basin, experience prolonged rains from March to May. Droughts haunt the southern and central regions of Africa from December to February, mainly Zambia, Zimbabwe, Mozambique and Botswana.
Warm Basin of the Western Hemisphere. A study of climate data has shown that there is an unusual warming of the Western Hemisphere Warm Basin in about half of the post-El Niño summers. This affects the weather in the region and seems to be related to the North Atlantic Oscillation.
Atlantic effect. An El Niño-like effect is sometimes observed in the Atlantic Ocean, where the water along the African equatorial coast becomes warmer, while off the coast of Brazil it becomes colder. This can be attributed to the Walker circulations over South America.
Non-climatic effects of El Niño
Along the east coast of South America, El Niño reduces the upwelling of cold, plankton-rich water that supports large populations of fish, which in turn support an abundance of seabirds whose droppings support the fertilizer industry.The local fishing industry along the coastline may be short of fish during long El Niño events. The largest global fish collapse due to overfishing, which occurred in 1972 during El Niño, led to a decrease in the population of Peruvian anchovies. During the events of 1982-83, populations of southern horse mackerel and anchovies decreased. Although the number of shells in warm water increased, but the hake went deeper into the cold water, and the shrimp and sardines went south. But the catch of some other fish species has been increased, for example, the common horse mackerel increased its population during warm events.
Changes in location and types of fish due to changing conditions have provided challenges for the fishing industry. The Peruvian sardine left due to El Nino to the Chilean coast. Other conditions have only led to further complications, such as the government of Chile in 1991 created restrictions on fishing.
It is postulated that El Niño led to the disappearance of the Mochico Indian tribe and other tribes of the pre-Columbian Peruvian culture.
Causes of El Niño
The mechanisms that can trigger El Niño events are still under investigation. It is difficult to find patterns that can show causes or allow predictions to be made.Bjerknes in 1969 suggested that the anomalous warming in the eastern Pacific could be attenuated by east-west temperature differences, causing weakenings in the Volcker circulation and trade winds that push warm water westward. The result is an increase in warm water towards the east.
Wirtky in 1975 suggested that the trade winds could create a westerly bulge of warm waters, and any weakening of the winds could allow warm waters to move east. Nevertheless, no bulges were noticed on the eve of the events of 1982-83.
Rechargeable Oscillator: Some mechanisms have been proposed that when warm regions are created in the equatorial region they are dispersed to higher latitudes via El Niño events. The cooled areas are then recharged with heat for several years before the next event occurs.
Western Pacific Oscillator: In the Western Pacific, several weather conditions may have caused easterly wind anomalies. For example, a cyclone in the north and an anticyclone in the south create an east wind between them. Such patterns can interact with the westerly current across the Pacific Ocean and create a continued eastward trend. The weakening of the westerly current at this time may be the final trigger.
The Equatorial Pacific can lead to El Niño-like conditions with a few random variations in behavior. Weather patterns from outside or volcanic activity can be such factors.
The Madden-Julian Oscillation (MJO) is a major source of variability that can contribute to a more abrupt evolution leading to El Niño conditions through fluctuations in low-level winds and precipitation over the western and central parts Pacific Ocean. The eastward propagation of oceanic Kelvin waves may be caused by MJO activity.
History of El Niño
The first mention of the term "El Niño" dates back to 1892, when Captain Camilo Carrilo reported at the Congress of the Geographical Society in Lima that Peruvian sailors called the warm north current "El Niño" because it is most noticeable in the Christmas area. However, even then, the phenomenon was only interesting because of its biological impact on the efficiency of the fertilizer industry.Normal conditions along the western Peruvian coast are a cold south current (Peruvian current) with upwelling water; upwelling of plankton leads to active ocean productivity; cold currents lead to a very dry climate on earth. Similar conditions exist everywhere (California Current, Bengal Current). So replacing it with a warm northern current leads to a decrease in biological activity in the ocean and to heavy rains, leading to flooding, on earth. The association with flooding was reported in 1895 by Pezet and Eguiguren.
Towards the end of the nineteenth century, interest arose in predicting climate anomalies (for food production) in India and Australia. Charles Todd in 1893 suggested that droughts in India and Australia occur at the same time. Norman Lockyer pointed out the same thing in 1904. In 1924, Gilbert Walker first coined the term "Southern Oscillation".
For most of the twentieth century, El Niño was considered a large local phenomenon.
The big El Niño in 1982-83 led to the fact that the interest of the scientific community in this phenomenon jumped sharply.
The history of the phenomenon
ENSO conditions have happened every 2-7 years for at least the last 300 years, but most have been mild.
Big ENSO events occurred in 1790-93, 1828, 1876-78, 1891, 1925-26, 1982-83 and 1997-98.
The most recent El Niño events occurred in 1986-1987, 1991-1992, 1993, 1994, 1997-1998 and 2002-2003.
The 1997-1998 El Niño in particular was strong and brought international attention to the phenomenon, while it was unusual for the 1990-1994 period that El Niño was very frequent (but mostly weak).
El Niño in the history of civilization
The mysterious disappearance of the Mayan civilization in Central America could be caused by strong climatic changes. This conclusion was reached by a group of researchers from the German National Center for Geosciences, writes the British newspaper The Times.Scientists tried to establish why at the turn of the 9th and 10th centuries AD, on opposite ends of the earth, the two largest civilizations of that time almost simultaneously ceased to exist. We are talking about the Maya Indians and the fall of the Chinese Tang dynasty, followed by a period of internecine strife.
Both civilizations were located in monsoonal regions, the moistening of which depends on the seasonal precipitation. However, at the indicated time, apparently, the rainy season was not able to provide the amount of moisture sufficient for the development of agriculture.
The ensuing drought and subsequent famine led to the decline of these civilizations, the researchers believe. They attribute climate change to the natural phenomenon "El Niño", which refers to temperature fluctuations in the surface waters of the eastern Pacific Ocean in tropical latitudes. This leads to large-scale disturbances in atmospheric circulation, which causes droughts in traditionally wet regions and floods in dry ones.
Scientists came to these conclusions by studying the nature of sedimentary deposits in China and Mesoamerica related to the specified period. The last emperor of the Tang Dynasty died in 907 AD, and the last known Mayan calendar dates back to 903.