Mean sea level is an average level of the surface of one or more of Earths oceans from which heights such as elevations may be measured. A common and relatively straightforward mean sea-level standard is the midpoint between a low and mean high tide at a particular location. Sea levels can be affected by factors and are known to have varied greatly over geological time scales. The careful measurement of variations in MSL can offer insights into ongoing climate change, the term above sea level generally refers to above mean sea level. Precise determination of a sea level is a difficult problem because of the many factors that affect sea level. Sea level varies quite a lot on several scales of time and this is because the sea is in constant motion, affected by the tides, atmospheric pressure, local gravitational differences, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point, for example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point.
One measures the values of MSL in respect to the land, hence a change in MSL can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates. In the UK, the Ordnance Datum is the sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the datum was MSL at the Victoria Dock, in Hong Kong, mPD is a surveying term meaning metres above Principal Datum and refers to height of 1. 230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and it is used for a part of continental Europe and main part of Africa as official sea level. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001, height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum.
It is used in aviation, where some heights are recorded and reported with respect to sea level, and in the atmospheric sciences. An alternative is to base height measurements on an ellipsoid of the entire Earth, in aviation, the ellipsoid known as World Geodetic System 84 is increasingly used to define heights, differences up to 100 metres exist between this ellipsoid height and mean tidal height. The alternative is to use a vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, the elevation of a mountain denotes the highest point or summit and is typically illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, for one such case, see Amsterdam Airport Schiphol
Northern fur seal
The northern fur seal is an eared seal found along the north Pacific Ocean, the Bering Sea, and the Sea of Okhotsk. It is the largest member of the fur seal subfamily and the living species in the genus Callorhinus. A single fossil species, Callorhinus gilmorei, is known from the Pliocene of Japan, Northern fur seals have extreme sexual dimorphism, with males being 30–40% longer and more than 4.5 times heavier than adult females. The head is foreshortened in both sexes because of the short, down-curved muzzle, and small nose, which extends slightly beyond the mouth in females. The pelage is thick and luxuriant, with a dense underfur in a creamy color, the underfur is obscured by the longer guard hairs, although it is partially visible when the animals are wet. Features of both fore and hind flippers are unique and diagnostic of the species, Fur is absent on the top of the fore flippers and an abrupt clean line is seen across the wrist where the fur ends. The hind flippers are proportionately the longest in any otariid because of extremely long, small claws are on digits 2–4, well back from the flap-like end of each digit.
The ear pinnae are long and conspicuous, and naked of dark fur at the tips in older animals, the mystacial vibrissae can be very long, and regularly extend beyond the ears. The eyes are large and conspicuous, especially on females, subadults. Adult males are stocky in build, and have enlarged necks, a mane of coarse, longer guard hairs extends from the lower neck to the shoulders. And covers the nape, neck and upper back, adult males have abrupt foreheads formed by the elevation of the crown from development of the sagittal crests, and thicker fur of the mane on the top of their heads. Canine teeth are longer and have a greater diameter in adult males than those found on adult females. Adult females and juveniles are moderate in build, distinguishing the sexes is difficult until about age five. The body is modest in size and the neck, adult females and subadults have more complex and variable coloration than adult males. They are dark silver-gray to charcoal above, the flanks, chest and underside of the neck, often forming a chevron pattern in this area, are cream to tan with rusty tones.
Variable cream to rust-colored areas are on the sides and top of the muzzle, chin, in contrast, adult males are medium gray to black, or reddish to dark brown all over. Their manes can have variable amounts of silver-gray or yellowish tinting on the guard hairs, pups are blackish at birth, with variable oval areas of buff on the sides, in the axillary area, and on the chin and sides of the muzzle. After three to four months, pups molt to the color of females and subadults
California is the most populous state in the United States and the third most extensive by area. Located on the western coast of the U. S, California is bordered by the other U. S. states of Oregon and Arizona and shares an international border with the Mexican state of Baja California. Los Angeles is Californias most populous city, and the second largest after New York City. The Los Angeles Area and the San Francisco Bay Area are the nations second- and fifth-most populous urban regions, California has the nations most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The Central Valley, an agricultural area, dominates the states center. What is now California was first settled by various Native American tribes before being explored by a number of European expeditions during the 16th and 17th centuries, the Spanish Empire claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its war for independence.
The western portion of Alta California was organized as the State of California, the California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom. If it were a country, California would be the 6th largest economy in the world, fifty-eight percent of the states economy is centered on finance, real estate services and professional, scientific and technical business services. Although it accounts for only 1.5 percent of the states economy, the story of Calafia is recorded in a 1510 work The Adventures of Esplandián, written as a sequel to Amadis de Gaula by Spanish adventure writer Garci Rodríguez de Montalvo. The kingdom of Queen Calafia, according to Montalvo, was said to be a land inhabited by griffins and other strange beasts. This conventional wisdom that California was an island, with maps drawn to reflect this belief, shortened forms of the states name include CA, Cal. Calif. and US-CA.
Settled by successive waves of arrivals during the last 10,000 years, various estimates of the native population range from 100,000 to 300,000. The Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups were diverse in their organization with bands, villages. Trade and military alliances fostered many social and economic relationships among the diverse groups, the first European effort to explore the coast as far north as the Russian River was a Spanish sailing expedition, led by Portuguese captain Juan Rodríguez Cabrillo, in 1542. Some 37 years English explorer Francis Drake explored and claimed a portion of the California coast in 1579. Spanish traders made unintended visits with the Manila galleons on their trips from the Philippines beginning in 1565
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are shoaling, and if the group is swimming in the same direction in a coordinated manner, they are schooling. In common usage, the terms are used rather loosely. About one quarter of fish species shoal all their lives, Fish derive many benefits from shoaling behaviour including defence against predators, enhanced foraging success, and higher success in finding a mate. It is likely that fish benefit from shoal membership through increased hydrodynamic efficiency, Fish use many traits to choose shoalmates. Generally they prefer larger shoals, shoalmates of their own species, shoalmates similar in size and appearance to themselves, healthy fish, the oddity effect posits that any shoal member that stands out in appearance will be preferentially targeted by predators. This may explain why fish prefer to shoal with individuals that resemble themselves, the oddity effect would thus tend to homogenize shoals. An aggregation of fish is the term for any collection of fish that have gathered together in some locality.
Fish aggregations can be structured or unstructured, an unstructured aggregation might be a group of mixed species and sizes that have gathered randomly near some local resource, such as food or nesting sites. If, in addition, the aggregation comes together in an interactive, social way, shoaling groups can include fish of disparate sizes and can including mixed-species subgroups. If the shoal becomes more organised, with the fish synchronising their swimming so they all move at the same speed and in the same direction. Schooling fish are usually of the species and the same age/size. Fish schools move with the individual members precisely spaced from each other, the schools undertake complicated manoeuvres, as though the schools have minds of their own. The intricacies of schooling are far from understood, especially the swimming and feeding energetics. Many hypotheses to explain the function of schooling have been suggested, such as orientation, synchronized hunting, predator confusion. Schooling has disadvantages, such as excretion buildup in the media and oxygen.
The way the array in the school probably gives energy saving advantages. Fish can be obligate or facultative shoalers, obligate shoalers, such as tunas and anchovy, spend all of their time shoaling or schooling, and become agitated if separated from the group. Facultative shoalers, such as Atlantic cod and some carangids, shoal only some of the time, shoaling fish can shift into a disciplined and coordinated school, shift back to an amorphous shoal within seconds
Leatherback sea turtle
The leatherback sea turtle, sometimes called the lute turtle or leathery turtle, is the largest of all living turtles and is the fourth-heaviest modern reptile behind three crocodilians. It is the living species in the genus Dermochelys and family Dermochelyidae. It can easily be differentiated from other sea turtles by its lack of a bony shell. Instead, its carapace is covered by skin and oily flesh, Dermochelys is the only extant genus of the family Dermochelyidae. D. coriacea is the species in genus Dermochelys. The genus, in turn, contains the only extant member of the family Dermochelyidae, domenico Agostino Vandelli named the species first in 1761 as Testudo coriacea after an animal captured at Ostia and donated to the University of Padua by Pope Clement XIII. In 1816, French zoologist Henri Blainville coined the term Dermochelys, the leatherback was reclassified as Dermochelys coriacea. In 1843, the zoologist Leopold Fitzinger put the genus in its own family, in 1884, the American naturalist Samuel Garman described the species as Sphargis coriacea schlegelii.
The two were united in D. coriacea, with each given subspecies status as D. c. coriacea. The subspecies were labeled invalid synonyms of D. coriacea, the turtles common name comes from the leathery texture and appearance of its carapace. Older names include leathery turtle and trunk turtle, relatives of modern leatherback turtles have existed in some form since the first true sea turtles evolved over 110 million years ago during the Cretaceous period. The dermochelyids are relatives of the family Cheloniidae, which contains the six extant sea turtle species. However, their sister taxon is the extinct family Protostegidae that included species that did not have a hard carapace. Leatherback turtles have the most hydrodynamic body design of any sea turtle, with a large, a large pair of front flippers powers the turtles through the water. Like other sea turtles, the leatherback has flattened fore limbs adapted for swimming in the open ocean, claws are absent from both pairs of flippers. The leatherbacks flippers are the largest in proportion to its body among extant sea turtles, Leatherbacks front flippers can grow up to 2.7 m in large specimens, the largest flippers of any sea turtle.
The leatherback has several characteristics that distinguish it from sea turtles. Its most notable feature is the lack of a bony carapace, instead of scutes, it has thick, leathery skin with embedded minuscule osteoderms
Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. They are a grouping within the infraorder Cetacea, usually excluding dolphins. Whales and porpoises belong to the order Cetartiodactyla with even-toed ungulates and their closest living relatives are the hippopotamuses, the two parvorders of whales, baleen whales and toothed whales, are thought to have split apart around 34 million years ago. The whales comprise eight extant families, Balaenidae, Eschrichtiidae, Physeteridae, Whales are creatures of the open ocean, they feed, give birth and raise their young at sea. So extreme is their adaptation to life underwater that they are unable to survive on land. Whales range in size from the 2.6 metres and 135 kilograms dwarf sperm whale to the 29.9 metres and 190 metric tons blue whale, the sperm whale is the largest toothed predator on earth. Several species exhibit sexual dimorphism, in that the females are larger than males, baleen whales have no teeth, instead they have plates of baleen, a fringe-like structure used to expel water while retaining the krill and plankton which they feed on.
They use their throat pleats to expand the mouth to take in huge gulps of water, balaenids have heads that can make up 40% of their body mass to take in water. Toothed whales, on the hand, have conical teeth designed for catching fish or squid. Some species, such as whales, are well adapted for diving to great depths to catch squid. Whales have evolved from land-living mammals, as such they must breathe air regularly, though they can remain submerged for long periods. They have blowholes located on top of their heads, through air is taken in. They are warm-blooded, and have a layer of fat, or blubber, under the skin, with streamlined fusiform bodies and two limbs that are modified into flippers, whales can travel at up to 20 knots, though they are not as flexible or agile as seals. Whales produce a variety of vocalizations, notably the extended songs of the humpback whale. Although whales are widespread, most species prefer the waters of the Northern and Southern Hemispheres. Species such as humpbacks and blue whales are capable of travelling thousands of miles without feeding, males typically mate with multiple females every year, but females only mate every two to three years.
Calves are typically born in the spring and summer months and females bear all the responsibility for raising them, mothers of some species fast and nurse their young for one to two years. Once relentlessly hunted for their products, whales are now protected by international law, the North Atlantic right whales nearly became extinct in the twentieth century, with a population low of 450, and the North Pacific gray whale population is ranked Critically Endangered by the IUCN
Juvenile fish go through various stages between birth and adulthood. They start as eggs which hatch into larvae, the larvae are not able to feed themselves, and carry a yolk-sac which provides their nutrition. Before the yolk-sac completely disappears, the fish must become capable of feeding themselves. When they have developed to the point where they are capable of feeding themselves, when, in addition, they have developed scales and working fins, the transition to a juvenile fish is complete and it is called a fingerling. Fingerlings are typically about the size of fingers, the juvenile stage lasts until the fish is fully grown, sexually mature and interacting with other adult fish. Ichthyoplankton are the eggs and larvae of fish and they are usually found in the sunlit zone of the water column, less than 200 metres deep, sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, Fish eggs cannot swim at all, and are unambiguously planktonic.
Early stage larvae swim poorly, but stage larvae swim better, Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are eaten by larger animals. According to Kendall et al.1984 there are three main stages of fish, Egg stage, Spawning to hatching. This stage is used instead of using a stage because there are aspects, such as those to do with the egg envelope. Larval stage, From hatching till all fin rays are present, a key event is when the notochord associated with the tail fin on the ventral side of the spinal cord develops and becomes flexible. A transitional stage, the larval stage, lasts from hatching to the absorption of the yolk-sac. Juvenile stage, Starts when the transformation or metamorphosis from larva to juvenile is complete, that is and these features are that all the fin rays are present and that scale growth is under way. The stage completes when the juvenile becomes adult, that is and this article is about the juvenile stage.
Fingerling – refers to a fish that has reached the stage where the fins can be extended, in this stage, the fish is typically about the size of a finger. Fry and fingerling are terms that can be applied to fish of most species. But some groups of fishes have juvenile development stages particular to the group and this section details the stages and the particular names used for juvenile salmon
The humpback whale is a species of baleen whale. One of the larger species, adults range in length from 12–16 m. The humpback has a body shape, with long pectoral fins. It is known for breaching and other distinctive surface behaviors, making it popular with whale watchers, males produce a complex song lasting 10 to 20 minutes, which they repeat for hours at a time. Its purpose is not clear, though it may have a role in mating, found in oceans and seas around the world, humpback whales typically migrate up to 25,000 km each year. Humpbacks feed in polar waters, and migrate to tropical or subtropical waters to breed and give birth when they fast and their diet consists mostly of krill and small fish. Humpbacks have a repertoire of feeding methods, including the bubble net technique. Like other large whales, the humpback was a target for the whaling industry, once hunted to the brink of extinction, its population fell by an estimated 90% before a 1966 moratorium. While stocks have partially recovered, entanglement in fishing gear, collisions with ships, the rorquals are believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Miocene.
However, it is not known when the members of these families diverged from each other, though clearly related to the giant whales of the genus Balaenoptera, the humpback is the sole member of its genus. The humpback was first identified as de la Nouvelle Angleterre by Mathurin Jacques Brisson in his Regnum Animale of 1756. In 1781, Georg Heinrich Borowski described the species, converting Brissons name to its Latin equivalent, in 1804, Lacépède shifted the humpback from the family Balaenidae, renaming it B. jubartes. In 1846, John Edward Gray created the genus Megaptera, classifying the humpback as Megaptera longipinna, the common name is derived from the curving of their backs when diving. The generic name Megaptera from the Greek mega-/μεγα- giant and ptera/πτερα wing, the specific name means New Englander and was probably given by Brisson due to regular sightings of humpbacks off the coast of New England. Some biologists believe that these should be regarded as separate subspecies, humpbacks can easily be identified by their stocky body, obvious hump, black dorsal coloring and elongated pectoral fins.
The head and lower jaw are covered with knobs called tubercles, the fluked tail, which typically rises above the surface when diving, has wavy trailing edges. Humpbacks have 270 to 400 darkly colored baleen plates on each side of their mouths, the plates measure from 18 in in the front to about 3 ft in the back, behind the hinge. Ventral grooves run from the jaw to the umbilicus, about halfway along the underside of the body
It has been widely introduced into inland recreational fisheries across the United States. Striped bass found in the Gulf of Mexico are a separate strain referred to as Gulf Coast striped bass. The striped bass is the fish of Maryland, Rhode Island, and South Carolina, and the state saltwater fish of New York, New Jersey, Virginia. The history of the striped bass fishery in North America dates back to the Colonial period, many written accounts by some of the first European settlers describe the immense abundance of striped bass, along with alewives and spawning up most rivers in the coastal Northeast. The striped bass is a member of the Moronidae family in shape, having a streamlined. Common mature size is 8 to 40 pounds, the largest specimen recorded was 124 pounds, netted in 1896. Striped bass are believed to live for up to 30 years, the maximum length is 1.8 m. The average size is about 67–100 cm and 4. 5–14.5 kg, striped bass are native to the Atlantic coastline of North America from the St.
Lawrence River into the Gulf of Mexico to approximately Louisiana. They are anadromous fish migrate between fresh and salt water. Spawning takes place in fresh water, striped bass have been introduced into waters in Ecuador, Latvia, Russia, South Africa, and Turkey, primarily for sport fishing and aquaculture. The spawning success of striped bass has been studied in the San Francisco Bay-Delta water system, at levels as low as 200 mg/l TDS, an observable diminution of spawning productivity occurs. They can be found in lakes, ponds and this pressure on their food source was putting their own population at risk due to the population of prey naturally not coming back to the same spawning areas. In Canada, the province of Quebec designated the striped bass population of the Saint Lawrence as extirpated in 1996, analysis of available data implicated overfishing and dredging in the disappearance. In 2002, a program was successful. Striped bass spawn in water, and although they have been successfully adapted to freshwater habitat.
Four important bodies of water with breeding stocks of striped bass are, Chesapeake Bay, Massachusetts Bay/Cape Cod, Hudson River, many of the rivers and tributaries that emptied into the Atlantic, had at one time, bred stock of striped bass. One of the largest breeding areas is the Chesapeake Bay, where populations from Chesapeake, stocking of striped bass was discontinued at Lake Mead in 1973 once natural reproduction was verified. Striped bass have been hybridized with white bass to produce hybrid striped bass known as wiper, whiterock bass, sunshine bass, palmetto bass and these hybrids have been stocked in many freshwater areas across the US
San Francisco, officially the City and County of San Francisco, is the cultural and financial center of Northern California. It is the birthplace of the United Nations, the California Gold Rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. San Francisco became a consolidated city-county in 1856, after three-quarters of the city was destroyed by the 1906 earthquake and fire, San Francisco was quickly rebuilt, hosting the Panama-Pacific International Exposition nine years later. In World War II, San Francisco was a port of embarkation for service members shipping out to the Pacific Theater. Politically, the city votes strongly along liberal Democratic Party lines, San Francisco is the headquarters of five major banking institutions and various other companies such as Levi Strauss & Co. Dolby, Weebly, Pacific Gas and Electric Company, Pinterest, Uber, Mozilla, Wikimedia Foundation, as of 2016, San Francisco is ranked high on world liveability rankings.
The earliest archaeological evidence of habitation of the territory of the city of San Francisco dates to 3000 BC. Upon independence from Spain in 1821, the became part of Mexico. Under Mexican rule, the system gradually ended, and its lands became privatized. In 1835, Englishman William Richardson erected the first independent homestead, together with Alcalde Francisco de Haro, he laid out a street plan for the expanded settlement, and the town, named Yerba Buena, began to attract American settlers. Commodore John D. Sloat claimed California for the United States on July 7,1846, during the Mexican–American War, montgomery arrived to claim Yerba Buena two days later. Yerba Buena was renamed San Francisco on January 30 of the next year, despite its attractive location as a port and naval base, San Francisco was still a small settlement with inhospitable geography. The California Gold Rush brought a flood of treasure seekers, with their sourdough bread in tow, prospectors accumulated in San Francisco over rival Benicia, raising the population from 1,000 in 1848 to 25,000 by December 1849.
The promise of fabulous riches was so strong that crews on arriving vessels deserted and rushed off to the gold fields, leaving behind a forest of masts in San Francisco harbor. Some of these approximately 500 abandoned ships were used at times as storeships and hotels, many were left to rot, by 1851 the harbor was extended out into the bay by wharves while buildings were erected on piles among the ships. By 1870 Yerba Buena Cove had been filled to create new land, buried ships are occasionally exposed when foundations are dug for new buildings. California was quickly granted statehood in 1850 and the U. S. military built Fort Point at the Golden Gate, silver discoveries, including the Comstock Lode in Nevada in 1859, further drove rapid population growth. With hordes of fortune seekers streaming through the city, lawlessness was common, and the Barbary Coast section of town gained notoriety as a haven for criminals, entrepreneurs sought to capitalize on the wealth generated by the Gold Rush
Northern elephant seal
The northern elephant seal is one of two species of elephant seal. It is a member of the family Phocidae, Elephant seals derive their name from their great size and from the males large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating competition. The huge male northern elephant seal typically weighs 1, 500–2,300 kg and measures 4–5 m, although some males can weigh up to 3,700 kg. Females are much smaller and can range from 400 to 900 kg in weight, or roughly a third of the males bulk, both adult and juvenile elephant seals are bar-skinned and black before molting. After molting, they generally have a silver to gray coat that fades to brownish-yellow. Adult males have hairless necks and chests speckled with pink, pups are mostly black at birth and molt to a silver gray after weaning. The eyes are large and black, the width of the eyes and a high concentration of low light pigments suggest sight plays an important role in the capture of prey.
Like all seals, elephant seals have atrophied hind limbs whose underdeveloped ends form the tail and tail fin, each of the feet can deploy five long, webbed fingers. This agile, dual palm is used to propel water, the pectoral fins are used little while swimming. While their hind limbs are unfit for locomotion on land, elephant seals use their fins as support to propel their bodies and they are able to propel themselves quickly in this way for short-distance travel, to return to water, catch up with a female or chase an intruder. Like other seals, elephant seals bloodstreams are adapted to the cold in which a mixture of small veins surrounds arteries capturing heat from them and this structure is present in extremities such as the hind legs. A unique characteristic of the elephant seal is that it has developed the ability to store oxygenated red blood cells within its spleen. In a 2004 study researchers used MRI to observe physiological changes of the spleen of 5 seal pups during simulated dives, by 3 minutes, the spleens on average contracted to a fifth of their original size, indicating a dive-related sympathetic contraction of the spleen.
Also, a delay was observed between contraction of the spleen and increased hematocrit within the blood, and attributed to the hepatic sinus. This ability to slowly introduce RBC into the stream is likely to prevent any harmful effects caused by a rapid increase in hematocrit. The northern elephant seal lives in the eastern Pacific Ocean and they spend most of their time at sea, and usually only come to land to give birth and molt. These activities occur at rookeries that are located on islands or remote mainland beaches. The majority of these rookeries are in California and northern Baja California, ranging from Point Reyes National Seashore, California to Isla Natividad, in recent decades the breeding range has extended northwards
World War II
World War II, known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the worlds countries—including all of the great powers—eventually forming two opposing alliances, the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people from over 30 countries. Marked by mass deaths of civilians, including the Holocaust and the bombing of industrial and population centres. These made World War II the deadliest conflict in human history, from late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, and formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Finland and the Baltic states. In December 1941, Japan attacked the United States and European colonies in the Pacific Ocean, and quickly conquered much of the Western Pacific.
The Axis advance halted in 1942 when Japan lost the critical Battle of Midway, near Hawaii, in 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained all of its territorial losses and invaded Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in South Central China and Burma, while the Allies crippled the Japanese Navy, thus ended the war in Asia, cementing the total victory of the Allies. World War II altered the political alignment and social structure of the world, the United Nations was established to foster international co-operation and prevent future conflicts. The victorious great powers—the United States, the Soviet Union, the United Kingdom, the Soviet Union and the United States emerged as rival superpowers, setting the stage for the Cold War, which lasted for the next 46 years. Meanwhile, the influence of European great powers waned, while the decolonisation of Asia, most countries whose industries had been damaged moved towards economic recovery.
Political integration, especially in Europe, emerged as an effort to end pre-war enmities, the start of the war in Europe is generally held to be 1 September 1939, beginning with the German invasion of Poland and France declared war on Germany two days later. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or even the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred simultaneously and this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935. The British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the forces of Mongolia and the Soviet Union from May to September 1939, the exact date of the wars end is not universally agreed upon.
It was generally accepted at the time that the war ended with the armistice of 14 August 1945, rather than the formal surrender of Japan