Illegal drug trade
The illegal drug trade or drug trafficking is a global black market dedicated to the cultivation, manufacture and sale of drugs that are subject to drug prohibition laws. Most jurisdictions prohibit trade, except under license, of many types of drugs through the use of drug prohibition laws; the United Nations Office on Drugs and Crime's World Drug Report 2005 estimates the size of the global illicit drug market at US$321.6 billion in 2003 alone. With a world GDP of US$36 trillion in the same year, the illegal drug trade may be estimated as nearly 1% of total global trade. Consumption of illegal drugs is widespread globally and remains difficult for local authorities to thwart its popularity. Chinese authorities issued edicts against opium smoking in 1729, 1796 and 1800; the West prohibited addictive drugs throughout the late early 20th centuries. In the early 19th century, an illegal drug trade in China emerged; as a result, by 1838 the number of Chinese opium-addicts had grown to between four and twelve million.
The Chinese government responded by enforcing a ban on the import of opium. The United Kingdom forced China to allow British merchants to sell Indian-grown opium. Trading in opium was lucrative, smoking opium had become common in the 19th century, so British merchants increased trade with the Chinese; the Second Opium War broke out in 1856. After the two Opium Wars, the British Crown, via the treaties of Nanking, Tianjin, obligated the Chinese government to pay large sums of money for opium they had seized and destroyed, which were referred to as "reparations". In 1868, as a result of the increased use of opium, the UK restricted the sale of opium in Britain by implementing the 1868 Pharmacy Act. In the United States, control of opium remained under the control of individual US states until the introduction of the Harrison Act in 1914, after 12 international powers signed the International Opium Convention in 1912. Between 1920 and 1933 the Eighteenth Amendment to the United States Constitution banned alcohol in the United States.
Prohibition proved impossible to enforce and resulted in the rise of organized crime, including the modern American Mafia, which identified enormous business opportunities in the manufacturing and sale of illicit liquor. The beginning of the 21st century saw drug use increase in North America and Europe, with a increased demand for marijuana and cocaine; as a result, international organized crime syndicates such as the Sinaloa Cartel and'Ndrangheta have increased cooperation among each other in order to facilitate trans-Atlantic drug-trafficking. Use of another illicit drug, has increased in Europe. Drug trafficking is regarded by lawmakers as a serious offense around the world. Penalties depend on the type of drug, the quantity trafficked, where the drugs are sold and how they are distributed. If the drugs are sold to underage people the penalties for trafficking may be harsher than in other circumstances. Drug smuggling carries severe penalties in many countries. Sentencing may include lengthy periods of incarceration and the death penalty.
In December 2005, Van Tuong Nguyen, a 25-year-old Australian drug smuggler, was hanged in Singapore after being convicted in March 2004. In 2010, two people were sentenced to death in Malaysia for trafficking 1 kilogram of cannabis into the country. Execution is used as a deterrent, many have called upon much more effective measures to be taken by countries to tackle drug trafficking; the countries of drug production and transit are some of the most affected by the drug trade, though countries receiving the illegally imported substances are adversely affected. For example, Ecuador has absorbed up to 300,000 refugees from Colombia who are running from guerrillas and drug lords. While some applied for asylum, others are still illegal immigrants; the drugs that pass from Colombia through Ecuador to other parts of South America create economic and social problems. Honduras, through which an estimated 79% of cocaine passes on its way to the United States, has the highest murder rate in the world. According to the International Crisis Group, the most violent regions in Central America along the Guatemala–Honduras border, are correlated with an abundance of drug trafficking activity.
In many countries worldwide, the illegal drug trade is thought to be directly linked to violent crimes such as murder. This is true in all developing countries, such as Honduras, but is an issue for many developed countries worldwide. In the late 1990s in the United States the Federal Bureau of Investigation estimated that 5% of murders were drug-related. In Colombia, Drug violence can be caused by factors such as, the economy, poor governments, no authority within the law enforcement. After a crackdown by US and Mexican authorities in the first decade of the 21st century as part of tightened border security in the wake of the September 11 attacks, border violence inside Mexico surged; the Mexican government estimates. A report by the UK government's Drug Strategy Unit, leaked to the press, stated that due to the expensive price of addictive drugs heroin and coc
Search and rescue
Search and rescue is the search for and provision of aid to people who are in distress or imminent danger. The general field of search and rescue includes many specialty sub-fields determined by the type of terrain the search is conducted over; these include mountain rescue. International Search and Rescue Advisory Group is a UN organization that promotes the exchange of information between national urban search and rescue organizations; the duty to render assistance is covered by Article 98 of the UNCLOS. There are many different definitions of search and rescue, depending on the agency involved and country in question. Canadian Forces: "Search and Rescue comprises the search for, provision of aid to, ships or other craft which are, or are feared to be, in distress or imminent danger." United States Coast Guard: "The use of available resources to assist persons or property in potential or actual distress." United States Defense Department: A search is "an operation coordinated by a Rescue Coordination Center or rescue sub-center, using available personnel and facilities to locate persons in distress" and rescue is "an operation to retrieve persons in distress, provide for their initial medical or other needs, deliver them to a place of safety".
One of the world's earliest well-documented SAR efforts ensued following the 1656 wreck of the Dutch merchant ship Vergulde Draeck off the west coast of Australia. Survivors sought help, in response three separate SAR missions were conducted, without success. On 29 November 1945, a Sikorsky R-5 performed the first civilian helicopter rescue operation in history, with Sikorsky's chief pilot Dmitry "Jimmy" Viner in the cockpit, using an experimental hoist developed jointly by Sikorsky and Breeze. All 5 crew members of an oil barge, which had run aground on Penfield Reef, were saved before the barge sank. In 1983, Korean Air Lines Flight 007 with 269 occupants was shot down by a Soviet aircraft near Sakhalin; the Soviets sent SAR helicopters and boats to Soviet waters, while a search and rescue operation was initiated by U. S. South Korean, Japanese ships and aircraft in international waters, but no survivors were found. In July 2009, Air France Flight 447 was lost in the middle of the Atlantic Ocean.
An international SAR effort was launched, to no avail. A third effort nearly two years discovered the crash site and recovered the flight recorders. In early 2014, Malaysia Airlines Flight 370 crashed under mysterious circumstances. Many nations contributed to the initial SAR effort, fruitless. In June 2014, the Australian Transport Safety Bureau commissioned the MV Fugro Equator to lead a three-month survey of the ocean bed, for which it had budgeted $60mn; the search for Flight 370 has become the largest SAR so far with the largest budget. Ground search and rescue is the search for persons who are lost or in distress on land or inland waterways. People may go missing for a variety of reasons; some may disappear voluntarily, due to issues like domestic abuse. Others disappear for involuntary reasons such as mental illness, getting lost, an accident, death in a location where they cannot be found or, less due to abduction. Ground search and rescue missions that occur in urban areas should not be confused with "urban search and rescue", which in many jurisdictions refers to the location and extraction of people from collapsed buildings or other entrapments.
In most countries, the police are the primary agency for carrying out searches for a missing person on land. Some places have voluntary search and rescue teams that can be called out to assist these searches. Mountain rescue relates to search and rescue operations in rugged and mountainous terrain. Cave rescue is a specialized form of rescue for rescuing injured, trapped or lost cave explorers. Urban search and rescue referred to as Heavy Urban Search and Rescue, is the location and rescue of persons from collapsed buildings or other urban and industrial entrapments. Due to the specialized nature of the work, most teams are multi-disciplinary and include personnel from police and emergency medical services. Unlike traditional ground search and rescue workers, most US&R responders have basic training in structural collapse and the dangers associated with live electrical wires, broken natural gas lines and other hazards. While earthquakes have traditionally been the cause of US&R operations, terrorist attacks and extreme weather such as tornadoes and hurricanes have resulted in the deployment of these resources.
Combat search and rescue is search and rescue operations that are carried out during war that are within or near combat zones. Maritime search and rescue is carried out at sea to save sailors and passengers in distress, or the survivors of downed aircraft; the type of agency which carries out maritime search and rescue varies by country. When a distressed or missing vessel is located, these organizations deploy lifeboats to return them to land. In some cases, the agencies may carry out an air-sea rescue; this refers to the combined use of aircraft and surface vessels. NationalThe Australian search and rescue service is provided by AusSAR, part of the Australian Maritime Safety Authority. AusSAR operates a 24-hour Rescue Coordination Centre in Canbe
Non-lethal weapons called less-lethal weapons, less-than-lethal weapons, non-deadly weapons, compliance weapons, or pain-inducing weapons are weapons intended to be less to kill a living target than conventional weapons such as knives and firearms. It is understood that unintended or incidental casualties are risked wherever force is applied, but non-lethal weapons try to minimise the risk as much as possible. Non-lethal weapons are used in policing and combat situations to limit the escalation of conflict where employment of lethal force is prohibited or undesirable, where rules of engagement require minimum casualties, or where policy restricts the use of conventional force. Non-lethal weapons may be used by conventional military in a range of missions across the force continuum, they may be used by military police, by United Nations forces, by occupation forces for peacekeeping and stability operations. Non-lethal weapons may be used to channelize a battlefield, control the movement of civilian populations, or to limit civilian access to restricted areas.
When used by police forces domestically, similar weapons, tactics and procedures are called "less lethal" or "less than lethal" and are employed in riot control, prisoner control, crowd control, refugee control, self-defense. In the past and police faced with undesirable escalation of conflict had few acceptable options. Military personnel guarding embassies found themselves restricted to carrying unloaded weapons. National guards or policing forces charged with quelling riots were able to use only batons or similar club-like weapons, or bayonet or saber charges, or fire live ammunition at crowds. In the late 1980s and early 1990s, the Non-lethality Policy Review Group at U. S. Global Strategy Council in Washington and other independent think tanks around the world called for a concerted effort to develop weapons that were more life-conserving, environmentally friendly, fiscally responsible than weapons available at that time; the U. S. Congress and other governments agreed and began an organized development of non-lethal weapons to provide a range of options between talking and shooting.
Recognizing the need to limit the escalation of force and development of a range of non-lethal weapons has since been undertaken internationally by governments and weapons manufacturers to fill the need for such weapons. Some non-lethal weapons may provide more effective riot control than firearms, truncheons or bayonets with less risk of loss of life or serious injury. Before the general availability of early military non-lethal weapons in the mid 1990s, war-fighters had few or no casualty-limiting options for the employment of scalable force and were continually at risk whenever lethal force was prohibited during sensitive missions. In 2001 the United States Marine Corps revealed its development of a less-than-lethal energy weapon called the Active Denial System, a focused high frequency microwave device said to be capable of heating all living matter in the target area and continuously for the duration of the beam, causing transient intolerable pain but no lasting damage; the skin temperature of a person subjected to this weapon can jump to 130 °F in as little as 2 seconds depending on the skin's starting temperature.
The system is nonlethal. In 2004, author Jon Ronson cited an unclassified military report titled "Non-Lethal Weapons: Terms and References" 21 acoustic weapons were listed, in various stages of development, including the Infrasound", however no such effects had been achieved as of 2002. In 2011, the Joint Non-Lethal Weapons Directorate Non-Lethal Weapons Reference Book was created; the weapons in this book are in development. Until the development of non-lethal weapons, police officers around the world had few if any non-lethal options for riot control. Common tactics used by police that were intended to be non-lethal or less lethal included a advancing wall of men with batons, officers on horses trained to deal with policing situations, or a charge into a riot using the flats of sabers. Other reasonably successful approaches included shotguns with lower-powered cartridges, "salt shells", using bean-bag rounds and ricocheting the shot off of the ground. In the mid-20th century, with the integration of fire-control systems into major cities, police found that high-pressure fire hoses could be effective in dispersing a crowd.
Trained police dogs were commonly used to scare and disperse rioters and apprehend individuals. In the 1980s the development of the high-tensile plastics Kevlar and Lexan revolutionized personal armor and shields, led to new tactics for riot squads and other special-purpose teams. Officers could now stand up against violent rioters throwing dangerous projectiles without having to resort to lethal methods to disperse the danger. Coupled with the introduction of effective non-lethal chemical agents such as tear gas and offensive odor canisters, non-lethal impact rounds such as rubber bullets and "bean bag" flexible baton rounds, riot tactics were modified to rely less on violent response to attacking rioters than on a return to the advancing wall, with supporting officers firing non-lethal ordnance into the cro
Los Angeles the City of Los Angeles and known by its initials L. A. is the most populous city in California, the second most populous city in the United States, after New York City, the third most populous city in North America. With an estimated population of four million, Los Angeles is the cultural and commercial center of Southern California; the city is known for its Mediterranean climate, ethnic diversity and the entertainment industry, its sprawling metropolis. Los Angeles is the largest city on the West Coast of North America. Los Angeles is in a large basin bounded by the Pacific Ocean on one side and by mountains as high as 10,000 feet on the other; the city proper, which covers about 469 square miles, is the seat of Los Angeles County, the most populated county in the country. Los Angeles is the principal city of the Los Angeles metropolitan area, the second largest in the United States after that of New York City, with a population of 13.1 million. It is part of the Los Angeles-Long Beach combined statistical area the nation's second most populous area with a 2015 estimated population of 18.7 million.
Los Angeles is one of the most substantial economic engines within the United States, with a diverse economy in a broad range of professional and cultural fields. Los Angeles is famous as the home of Hollywood, a major center of the world entertainment industry. A global city, it has been ranked 6th in the Global Cities Index and 9th in the Global Economic Power Index; the Los Angeles metropolitan area has a gross metropolitan product of $1.044 trillion, making it the third-largest in the world, after the Tokyo and New York metropolitan areas. Los Angeles hosted the 1932 and 1984 Summer Olympics and will host the event for a third time in 2028; the city hosted the Miss Universe pageant twice, in 1990 and 2006, was one of 9 American cities to host the 1994 FIFA men's soccer World Cup and one of 8 to host the 1999 FIFA women's soccer World Cup, hosting the final match for both tournaments. Home to the Chumash and Tongva, Los Angeles was claimed by Juan Rodríguez Cabrillo for Spain in 1542 along with the rest of what would become Alta California.
The city was founded on September 4, 1781, by Spanish governor Felipe de Neve. It became a part of Mexico in 1821 following the Mexican War of Independence. In 1848, at the end of the Mexican–American War, Los Angeles and the rest of California were purchased as part of the Treaty of Guadalupe Hidalgo, becoming part of the United States. Los Angeles was incorporated as a municipality on April 4, 1850, five months before California achieved statehood; the discovery of oil in the 1890s brought rapid growth to the city. The completion of the Los Angeles Aqueduct in 1913, delivering water from Eastern California assured the city's continued rapid growth; the Los Angeles coastal area was settled by the Chumash tribes. A Gabrieleño settlement in the area was called iyáangẚ, meaning "poison oak place". Maritime explorer Juan Rodríguez Cabrillo claimed the area of southern California for the Spanish Empire in 1542 while on an official military exploring expedition moving north along the Pacific coast from earlier colonizing bases of New Spain in Central and South America.
Gaspar de Portolà and Franciscan missionary Juan Crespí, reached the present site of Los Angeles on August 2, 1769. In 1771, Franciscan friar Junípero Serra directed the building of the Mission San Gabriel Arcángel, the first mission in the area. On September 4, 1781, a group of forty-four settlers known as "Los Pobladores" founded the pueblo they called El Pueblo de Nuestra Señora la Reina de los Ángeles,'The Town of Our Lady the Queen of the Angels'; the present-day city has the largest Roman Catholic Archdiocese in the United States. Two-thirds of the Mexican or settlers were mestizo or mulatto, a mixture of African and European ancestry; the settlement remained a small ranch town for decades, but by 1820, the population had increased to about 650 residents. Today, the pueblo is commemorated in the historic district of Los Angeles Pueblo Plaza and Olvera Street, the oldest part of Los Angeles. New Spain achieved its independence from the Spanish Empire in 1821, the pueblo continued as a part of Mexico.
During Mexican rule, Governor Pío Pico made Los Angeles Alta California's regional capital. Mexican rule ended during the Mexican–American War: Americans took control from the Californios after a series of battles, culminating with the signing of the Treaty of Cahuenga on January 13, 1847. Railroads arrived with the completion of the transcontinental Southern Pacific line to Los Angeles in 1876 and the Santa Fe Railroad in 1885. Petroleum was discovered in the city and surrounding area in 1892, by 1923, the discoveries had helped California become the country's largest oil producer, accounting for about one-quarter of the world's petroleum output. By 1900, the population had grown to more than 102,000; the completion of the Los Angeles Aqueduct in 1913, under the supervision of William Mulholland, assured the continued growth of the city. Due to clauses in the city's charter that prevented the City of Los Angeles from selling or providing water from the aqueduct to any area outside its borders, many adjacent city and communities became compelled to annex themselves into Los Angeles.
Los Angeles created the first municipal zoning ordinance in the United States. On September 14, 1908, the Los Angeles City Council promulgated residential and industrial land use zones; the new ordinance established three residential zones of a single type, where industrial uses were
San Diego is a city in the U. S. state of California. It is in San Diego County, on the coast of the Pacific Ocean in Southern California 120 miles south of Los Angeles and adjacent to the border with Mexico. With an estimated population of 1,419,516 as of July 1, 2017, San Diego is the eighth-largest city in the United States and second-largest in California, it is part of the San Diego–Tijuana conurbation, the second-largest transborder agglomeration between the U. S. and a bordering country after Detroit–Windsor, with a population of 4,922,723 people. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches, long association with the United States Navy, recent emergence as a healthcare and biotechnology development center. San Diego has been called "the birthplace of California". Home to the Kumeyaay people, it was the first site visited by Europeans on what is now the West Coast of the United States. Upon landing in San Diego Bay in 1542, Juan Rodríguez Cabrillo claimed the area for Spain, forming the basis for the settlement of Alta California 200 years later.
The Presidio and Mission San Diego de Alcalá, founded in 1769, formed the first European settlement in what is now California. In 1821, San Diego became part of the newly independent Mexico, which reformed as the First Mexican Republic two years later. California became part of the United States in 1848 following the Mexican–American War and was admitted to the union as a state in 1850; the city is the seat of San Diego County and is the economic center of the region as well as the San Diego–Tijuana metropolitan area. San Diego's main economic engines are military and defense-related activities, international trade, manufacturing; the presence of the University of California, San Diego, with the affiliated UCSD Medical Center, has helped make the area a center of research in biotechnology. The original inhabitants of the region are now known as the San La Jolla people; the area of San Diego has been inhabited by the Kumeyaay people. The first European to visit the region was explorer Juan Rodríguez Cabrillo, sailing under the flag of Castile but born in Portugal.
Sailing his flagship San Salvador from Navidad, New Spain, Cabrillo claimed the bay for the Spanish Empire in 1542, named the site "San Miguel". In November 1602, Sebastián Vizcaíno was sent to map the California coast. Arriving on his flagship San Diego, Vizcaíno surveyed the harbor and what are now Mission Bay and Point Loma and named the area for the Catholic Saint Didacus, a Spaniard more known as San Diego de Alcalá. On November 12, 1602, the first Christian religious service of record in Alta California was conducted by Friar Antonio de la Ascensión, a member of Vizcaíno's expedition, to celebrate the feast day of San Diego. Permanent colonization of California and of San Diego began in 1769 with the arrival of four contingents of Spaniards from New Spain and the Baja California peninsula. Two seaborne parties reached San Diego Bay: the San Carlos, under Vicente Vila and including as notable members the engineer and cartographer Miguel Costansó and the soldier and future governor Pedro Fages, the San Antonio, under Juan Pérez.
An initial overland expedition to San Diego from the south was led by the soldier Fernando Rivera and included the Franciscan missionary and chronicler Juan Crespí, followed by a second party led by the designated governor Gaspar de Portolà and including the mission president Junípero Serra. In May 1769, Portolà established the Fort Presidio of San Diego on a hill near the San Diego River, it was the first settlement by Europeans in. In July of the same year, Mission San Diego de Alcalá was founded by Franciscan friars under Serra. By 1797, the mission boasted the largest native population in Alta California, with over 1,400 neophytes living in and around the mission proper. Mission San Diego was the southern anchor in Alta California of the historic mission trail El Camino Real. Both the Presidio and the Mission are National Historic Landmarks. In 1821, Mexico won its independence from Spain, San Diego became part of the Mexican territory of Alta California. In 1822, Mexico began its attempt to extend its authority over the coastal territory of Alta California.
The fort on Presidio Hill was abandoned, while the town of San Diego grew up on the level land below Presidio Hill. The Mission was secularized by the Mexican government in 1834, most of the Mission lands were granted to former soldiers; the 432 residents of the town petitioned the governor to form a pueblo, Juan María Osuna was elected the first alcalde, defeating Pío Pico in the vote. However, San Diego had been losing population throughout the 1830s and in 1838 the town lost its pueblo status because its size dropped to an estimated 100 to 150 residents. Beyond town Mexican land grants expanded the number of California ranchos that modestly added to the local economy. Americans gained increased awareness of California, its commercial possibilities, from the writings of two countrymen involved in the officially forbidden, to foreigners, but economically significant hide and tallow trade, where San Diego was a major port and the only one with an adequate harbor: William Shaler's "Journal of a Voyage Between China and the North-Western Coast of America, Made in 1804" and Richard Henry Dana's more substantial and convincing account, of his 1834–36 voyage, the classic Two Years Before the Mast.
In 1846, the United States went to war against Mexico and sent a naval and land expedition to conquer Alta California. At firs
Immigration is the international movement of people into a destination country of which they are not natives or where they do not possess citizenship in order to settle or reside there as permanent residents or naturalized citizens, or to take up employment as a migrant worker or temporarily as a foreign worker. As for economic effects, research suggests that migration is beneficial both to the receiving and sending countries. Research, with few exceptions, finds that immigration on average has positive economic effects on the native population, but is mixed as to whether low-skilled immigration adversely affects low-skilled natives. Studies show that the elimination of barriers to migration would have profound effects on world GDP, with estimates of gains ranging between 67 and 147 percent. Development economists argue that reducing barriers to labor mobility between developing countries and developed countries would be one of the most efficient tools of poverty reduction; the academic literature provides mixed findings for the relationship between immigration and crime worldwide, but finds for the United States that immigration either has no impact on the crime rate or that it reduces the crime rate.
Research shows that country of origin matters for speed and depth of immigrant assimilation, but that there is considerable assimilation overall for both first- and second-generation immigrants. Research has found extensive evidence of discrimination against foreign born and minority populations in criminal justice, the economy, health care and politics in the United States and Europe; the term immigration was coined in the 17th century, referring to non-warlike population movements between the emerging nation states. When people cross national borders during their migration, they are called migrants or immigrants from the perspective of the country which they enter. From the perspective of the country which they leave, they are called outmigrant. Sociology designates immigration as migration; as of 2015, the number of international migrants has reached 244 million worldwide, which reflects a 41% increase since 2000. One third of the world's international migrants are living in just 20 countries.
The largest number of international migrants live in the United States, with 19% of the world's total. Germany and Russia host 12 million migrants each, taking the second and third place in countries with the most migrants worldwide. Saudi Arabia hosts 10 million migrants, followed by the United Arab Emirates. Between 2000 and 2015, Asia added more international migrants than any other major area in the world, gaining 26 million. Europe added the second largest with about 20 million. In most parts of the world, migration occurs between countries that are located within the same major area. In 2015, the number of international migrants below the age of 20 reached 37 million, while 177 million are between the ages of 20 and 64. International migrants living in Africa were the youngest, with a median age of 29, followed by Asia, Latin America/Caribbean, while migrants were older in Northern America and Oceania. Nearly half of all international migrants originate in Asia, Europe was the birthplace of the second largest number of migrants, followed by Latin America.
India has the largest diaspora in the world, followed by Russia. A 2012 survey by Gallup found that given the opportunity, 640 million adults would migrate to another country, with 23% of these would-be immigrant choosing the United States as their desired future residence, while 7% of respondents, representing 45 million people, would choose the United Kingdom; the other top desired destination countries were Canada, Saudi Arabia, Australia and Spain. One theory of immigration distinguishes between pull factors. Push factors refer to the motive for immigration from the country of origin. In the case of economic migration, differentials in wage rates are common. If the value of wages in the new country surpasses the value of wages in one's native country, he or she may choose to migrate, as long as the costs are not too high. In the 19th century, economic expansion of the US increased immigrant flow, nearly 15% of the population was foreign born, thus making up a significant amount of the labor force.
As transportation technology improved, travel time and costs decreased between the 18th and early 20th century. Travel across the Atlantic used to take up to 5 weeks in the 18th century, but around the time of the 20th century it took a mere 8 days; when the opportunity cost is lower, the immigration rates tend to be higher. Escape from poverty is a traditional push factor, the availability of jobs is the related pull factor. Natural disasters can amplify poverty-driven migration flows. Research shows that for middle-income countries, higher temperatures increase emigration rates to urban areas and to other countries. For low-income countries, higher temperatures reduce emigration. Emigration and immigration are sometimes mandatory in a contract of employment: religious missionaries and employees of transnational corporations, international non-governmental organizations, the diplomatic service expect, by definition, to work "overseas", they are referred to as "expatriates", their conditions of employment are equal to or better than those applying in the host country.
An ocean is a body of water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean; these are, in descending order by area, the Pacific, Indian and Arctic Oceans. The word "ocean" is used interchangeably with "sea" in American English. Speaking, a sea is a body of water or enclosed by land, though "the sea" refers to the oceans. Saline water covers 361,000,000 km2 and is customarily divided into several principal oceans and smaller seas, with the ocean covering 71% of Earth's surface and 90% of the Earth's biosphere; the ocean contains 97% of Earth's water, oceanographers have stated that less than 5% of the World Ocean has been explored. The total volume is 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the principal component of Earth's hydrosphere, it is integral to life, forms part of the carbon cycle, influences climate and weather patterns; the World Ocean is the habitat of 230,000 known species, but because much of it is unexplored, the number of species that exist in the ocean is much larger over two million.
The origin of Earth's oceans is unknown. Extraterrestrial oceans may be composed of water or other compounds; the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories and Venus are theorized to have had large water oceans; the Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, a runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of natural satellites; the Solar System's giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone.
Ocean planets are a hypothetical type of planet with a surface covered with liquid. The word ocean comes from the figure in classical antiquity, the elder of the Titans in classical Greek mythology, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world; the concept of Ōkeanós has an Indo-European connection. Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases. Though described as several separate oceans, the global, interconnected body of salt water is sometimes referred to as the World Ocean or global ocean; the concept of a continuous body of water with free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, other criteria.
Oceans are fringed by smaller, adjoining bodies of water such as seas, bays and straits. The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system, part of every ocean and the longest mountain range in the world; the continuous mountain range is 65,000 km long. The total mass of the hydrosphere is about 1.4 quintillion metric tons, about 0.023% of Earth's total mass. Less than 3% is freshwater; the area of the World Ocean is about 361.9 million square kilometers, which covers about 70.9% of Earth's surface, its volume is 1.335 billion cubic kilometers. This can be thought of as a cube of water with an edge length of 1,101 kilometers, its average depth is about 3,688 meters, its maximum depth is 10,994 meters at the Mariana Trench. Nearly half of the world's marine waters are over 3,000 meters deep; the vast expanses of deep ocean cover about 66% of Earth's surface. This does not include seas not connected to the World Ocean, such as the Caspian Sea; the bluish ocean color is a composite of several contributing agents.
Prominent contributors include dissolved organic chlorophyll. Mariners and other seafarers have reported that the ocean emits a visible glow which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow, it is most caused by bioluminescence. Oceanographers divide the ocean into different vertical zones defined by physical and biological conditions; the pelagic zone includes all open ocean regions, can be divided into further regions categorized by depth and light abundance. The photic zone includes the oceans from the surface to a depth of