The Tonight Show
The Tonight Show is an American late-night talk show broadcast from the NBC Studios in Rockefeller Center in New York City, the show's original location and airing on NBC since 1954. The series has been hosted by six comedians: Steve Allen, Jack Paar, Johnny Carson, Jay Leno, Conan O'Brien, Jimmy Fallon, had several recurring guest hosts including Ernie Kovacs during the Steve Allen era and Joan Rivers, Garry Shandling and Jay Leno during Johnny Carson's stewardship, although the practice has been abandoned since Carson's departure, with hosts preferring reruns to showcasing potential rivals; the Tonight Show is the world's longest-running talk show, the longest-running scheduled entertainment program in the United States. It Meet the Press. Over the course of more than 60 years, The Tonight Show has undergone only minor title changes, it aired under the name Tonight for several of its early years, as well as Tonight Starring Jack Paar and The Jack Paar Show due to the runaway popularity of its host settling permanently on The Tonight Show after Carson began his tenure in 1962 albeit with the host's name always included in the title.
Beginning with Carson's debut episode, network programmers and the show's announcers would refer to the show by including the name of the host. In 1957, the show tried a more news-style format, it has otherwise adhered to the talk show format honed further by Paar. Carson is the longest-serving host to date although not the host with the most episodes; the Tonight Show Starring Johnny Carson aired for 30 seasons between October 1962 and May 1992. Leno, has the record of having hosted the greatest number of total televised episodes. Leno's record accounts for the fact that unlike Carson, Leno never used guest hosts on The Tonight Show with Jay Leno and produced new shows five days a week. Leaving out Leno's five years as permanent guest host, Leno hosted 119 more episodes as full-time host than Carson. During Carson's first four years, the show ran for 105 minutes was reduced to ninety minutes in early 1967 when Carson stopped appearing for the first 15 minutes because most affiliates were carrying their local news during that time slot as they expanded to half an hour.
During Carson's 1980 contract negotiations, the show was shortened to sixty minutes. NBC broadcast The Best of Carson which were repeats of some of Carson's popular older albeit recent shows. Prior to the debut of Saturday Night Live in October 1975, NBC aired The Best of Carson on Saturday nights at 11:30 pm. Outside of its brief run as a news show in 1957, Conan O'Brien is the shortest-serving host. O'Brien hosted 146 episodes over the course of less than eight months before, with ratings continuously plummeting, Leno was brought back as host, where he served for four additional years. Current host Fallon took the helm on February 17, 2014. Fallon had hosted Late Night with Jimmy Fallon, before Late Night he was a popular member of the cast of Saturday Night Live, co-hosting the "Weekend Update" with Tina Fey as well as performing sketches. From 1950 to 1951 NBC aired Broadway Open House, a nightly variety show hosted by comic Jerry Lester, it was not a success. A spinoff, Dagmar's Canteen, aired the following season on Saturday nights.
The format of The Tonight Show can be traced to a nightly 40-minute local program in New York, hosted by Allen and titled The Knickerbocker Beer Show. It was retitled The Steve Allen Show; this premiered in 1953 on the local station affiliate in New York City. Beginning in September 1954, it was renamed Tonight! and began its historic run on the full NBC network. Notes for hosting history The first Tonight announcer was Gene Rayburn. Allen's version of the show originated talk show staples such as an opening monologue, celebrity interviews, audience participation, comedy bits in which cameras were taken outside the studio, as well as music including guest performers and a house band under Lyle "Skitch" Henderson; when the show became a success, Allen got a primetime Sunday comedy/variety show in June 1956, leading him to share Tonight hosting duties with Ernie Kovacs during the 1956–57 season. To give Allen time to work on his Sunday evening show, Kovacs hosted Tonight on Monday and Tuesday nights with his own announcer and bandleader.
During the Steve Allen years, regular audience member Lillian Miller became such an integral part that she was forced to join American Federation of Television and Radio Artists, the television/radio performers union. She would continue to perform the same service for most of the major talk shows for decades, including those hosted by Paar, Merv Griffin, Mike Douglas, a
Columbia University is a private Ivy League research university in Upper Manhattan, New York City. Established in 1754, Columbia is the oldest institution of higher education in New York and the fifth-oldest institution of higher learning in the United States, it is one of nine colonial colleges founded prior to the Declaration of Independence, seven of which belong to the Ivy League. It has been ranked by numerous major education publications as among the top ten universities in the world. Columbia was established as King's College by royal charter of George II of Great Britain in reaction to the founding of Princeton University in New Jersey, it was renamed Columbia College in 1784 following the Revolutionary War and in 1787 was placed under a private board of trustees headed by former students Alexander Hamilton and John Jay. In 1896, the campus was moved from Madison Avenue to its current location in Morningside Heights and renamed Columbia University. Columbia scientists and scholars have played an important role in the development of notable scientific fields and breakthroughs including: brain-computer interface.
The Columbia University Physics Department has been affiliated with 33 Nobel Prize winners as alumni, faculty or research staff, the third most of any American institution behind MIT and Harvard. In addition, 22 Nobel Prize winners in Physiology and Medicine have been affiliated with Columbia, the third most of any American institution; the university's research efforts include the Lamont-Doherty Earth Observatory, Goddard Institute for Space Studies and accelerator laboratories with major technology firms such as IBM. Columbia is one of the fourteen founding members of the Association of American Universities and was the first school in the United States to grant the M. D. degree. The university administers the Pulitzer Prize annually. Columbia is organized into twenty schools, including three undergraduate schools and numerous graduate schools, it maintains research centers outside of the United States known as Columbia Global Centers. In 2018, Columbia's undergraduate acceptance rate was 5.1%, making it one of the most selective colleges in the United States, the second most selective in the Ivy League after Harvard.
Columbia is ranked as the 3rd best university in the United States by U. S. News & World Report behind Princeton and Harvard. In athletics, the Lions field varsity teams in 29 sports as a member of the NCAA Division I Ivy League conference; the university's endowment stood at $10.9 billion in 2018, among the largest of any academic institution. As of 2018, Columbia's alumni and affiliates include: five Founding Fathers of the United States — among them an author of the United States Constitution and co-author of the Declaration of Independence. S. presidents. Discussions regarding the founding of a college in the Province of New York began as early as 1704, at which time Colonel Lewis Morris wrote to the Society for the Propagation of the Gospel in Foreign Parts, the missionary arm of the Church of England, persuading the society that New York City was an ideal community in which to establish a college. However, it was not until the founding of the College of New Jersey across the Hudson River in New Jersey that the City of New York considered founding a college.
In 1746, an act was passed by the general assembly of New York to raise funds for the foundation of a new college. In 1751, the assembly appointed a commission of ten New York residents, seven of whom were members of the Church of England, to direct the funds accrued by the state lottery towards the foundation of a college. Classes were held in July 1754 and were presided over by the college's first president, Dr. Samuel Johnson. Dr. Johnson was the only instructor of the college's first class, which consisted of a mere eight students. Instruction was held in a new schoolhouse adjoining Trinity Church, located on what is now lower Broadway in Manhattan; the college was founded on October 31, 1754, as King's College by royal charter of King George II, making it the oldest institution of higher learning in the state of New York and the fifth oldest in the United States. In 1763, Dr. Johnson was succeeded in the presidency by Myles Cooper, a graduate of The Queen's College, an ardent Tory. In the charged political climate of the American Revolution, his chief opponent in discussions at the college was an undergraduate of the class of 1777, Alexander Hamilton.
The American Revolutionary War broke out in 1776, was catastrophic for the operation of King's College, which suspended instruction for eight years beginning in 1776 with the arrival of the Continental Army. The suspension continued through the military occupation of New York City by British troops until their departure in 1783; the college's library was looted and its sole building requisitioned for use as a military hospital first by American and British forces. Loyalists were forced to abandon their King's College in New York, seized by the rebels and renamed Columbia College; the Loyalists, led by Bishop Charles Inglis fled to Windsor, Nova Scotia, where the
George H. W. Bush
George Herbert Walker Bush was an American politician who served as the 41st president of the United States from 1989 to 1993 and the 43rd vice president of the United States from 1981 to 1989. A member of the Republican Party, he held posts that included those of congressman, CIA director; until his son George W. Bush became the 43rd president in 2001, he was known as George Bush. Bush postponed his university studies after the attack on Pearl Harbor on December 7, 1941, enlisted in the Navy on his 18th birthday, became one of its youngest aviators, he served until September 1945, attended Yale University, graduating in 1948. He moved his family to West Texas where he entered the oil business and became a millionaire by the age of 40 in 1964. After founding his own oil company, Bush was defeated in his first run for the United States Senate in 1964, but won election to the House of Representatives from Texas's 7th congressional district in 1966, he was reelected in 1968 but was defeated for election to the Senate in 1970.
In 1971, President Richard Nixon appointed Bush as Ambassador to the United Nations, he became Chairman of the Republican National Committee in 1973. The following year, President Gerald Ford appointed him Chief of the Liaison Office in China and made him the director of Central Intelligence. Bush ran for president in 1980, was defeated in the Republican primary by Ronald Reagan, as Reagan's running mate Bush became vice-president after the ticket's election. During his eight-year tenure as vice president, Bush headed task forces on deregulation and the war on drugs. Bush in 1988 defeated Democratic opponent Michael Dukakis, becoming the first incumbent vice president to be elected president in 152 years. Foreign policy drove the Bush presidency. Bush signed the North American Free Trade Agreement, which created a trade bloc consisting of the United States and Mexico. Domestically, Bush signed a bill to increase taxes, he lost the 1992 presidential election to Democrat Bill Clinton following an economic recession and the decreased importance of foreign policy in a post–Cold War political climate.
After leaving office in 1993, Bush was active in humanitarian activities alongside Clinton, his former opponent. With George W. Bush's victory in the 2000 presidential election and his son became the second father–son pair to serve as President, following John Adams and John Quincy Adams. At the time of his death, he was the longest-lived president in U. S. history, a record surpassed by Jimmy Carter on March 22, 2019. George Herbert Walker Bush was born at 173 Adams Street in Milton, Massachusetts on June 12, 1924 to Prescott Sheldon Bush and Dorothy Bush; the Bush family moved from Milton to Connecticut shortly after his birth. Bush was named after his maternal grandfather George Herbert Walker, known as "Pop", young Bush was called "Poppy" as a tribute to his namesake. Bush began his formal education at the Greenwich Country Day School attended Phillips Academy in Andover, Massachusetts beginning in 1938, where he held a number of leadership positions which included president of the senior class, secretary of the student council, president of the community fund-raising group, a member of the editorial board of the school newspaper, captain of the varsity baseball and soccer teams.
Six months after the United States entered World War II following Japan's attack on Pearl Harbor, Bush enlisted in the U. S. Navy after he graduated from Phillips Academy on his 18th birthday, he became a naval aviator. After completing the 10-month course, he was commissioned as an ensign in the Naval Reserve at Naval Air Station Corpus Christi on June 9, 1943, just three days before his 19th birthday, which made him one of the youngest aviators in the Navy. In September 1943, he was assigned to Torpedo Squadron 51 as the photographic officer; the following year, his squadron was based in USS San Jacinto as a member of Air Group 51, where his lanky physique earned him the nickname "Skin". During this time, the task force was victorious at the Battle of the Philippine Sea, one of the largest air battles of World War II. Bush was promoted to lieutenant on August 1, 1944, San Jacinto commenced operations against the Japanese in the Bonin Islands, he piloted one of the four Grumman TBM Avengers of VT-51 that attacked the Japanese installations on Chichijima on September 2, 1944.
His crew included Lt. William White, his aircraft was hit by flak during the attack, but Bush released bombs and scored several hits. With his engine ablaze, he flew several miles from the island, where he and one other crew member bailed out. Bush spent four hours in his inflated liferaft, protected by fighter aircraft circling above, until the submarine USS Finback came to his rescue, he participated in the rescue of other aviators. Several of those shot down during the attack were executed, their livers were eaten by their captors; this experience shaped Bush profoundly, leading him to ask, "Why had I been spared and what did God have for me?"In November 1944, Bush returned to San Jacinto and participated in operations in the Philippines until his squadron was replaced and sent home to the United States. By 1944 he had flown 58 combat missions for which he received the Distinguished Flying Cross, three Air Medals, the Presiden
England is a country, part of the United Kingdom. It shares land borders with Wales to Scotland to the north-northwest; the Irish Sea lies west of England and the Celtic Sea lies to the southwest. England is separated from continental Europe by the North Sea to the east and the English Channel to the south; the country covers five-eighths of the island of Great Britain, which lies in the North Atlantic, includes over 100 smaller islands, such as the Isles of Scilly and the Isle of Wight. The area now called England was first inhabited by modern humans during the Upper Palaeolithic period, but takes its name from the Angles, a Germanic tribe deriving its name from the Anglia peninsula, who settled during the 5th and 6th centuries. England became a unified state in the 10th century, since the Age of Discovery, which began during the 15th century, has had a significant cultural and legal impact on the wider world; the English language, the Anglican Church, English law – the basis for the common law legal systems of many other countries around the world – developed in England, the country's parliamentary system of government has been adopted by other nations.
The Industrial Revolution began in 18th-century England, transforming its society into the world's first industrialised nation. England's terrain is chiefly low hills and plains in central and southern England. However, there is upland and mountainous terrain in the west; the capital is London, which has the largest metropolitan area in both the United Kingdom and the European Union. England's population of over 55 million comprises 84% of the population of the United Kingdom concentrated around London, the South East, conurbations in the Midlands, the North West, the North East, Yorkshire, which each developed as major industrial regions during the 19th century; the Kingdom of England – which after 1535 included Wales – ceased being a separate sovereign state on 1 May 1707, when the Acts of Union put into effect the terms agreed in the Treaty of Union the previous year, resulting in a political union with the Kingdom of Scotland to create the Kingdom of Great Britain. In 1801, Great Britain was united with the Kingdom of Ireland to become the United Kingdom of Great Britain and Ireland.
In 1922 the Irish Free State seceded from the United Kingdom, leading to the latter being renamed the United Kingdom of Great Britain and Northern Ireland. The name "England" is derived from the Old English name Englaland, which means "land of the Angles"; the Angles were one of the Germanic tribes that settled in Great Britain during the Early Middle Ages. The Angles came from the Anglia peninsula in the Bay of Kiel area of the Baltic Sea; the earliest recorded use of the term, as "Engla londe", is in the late-ninth-century translation into Old English of Bede's Ecclesiastical History of the English People. The term was used in a different sense to the modern one, meaning "the land inhabited by the English", it included English people in what is now south-east Scotland but was part of the English kingdom of Northumbria; the Anglo-Saxon Chronicle recorded that the Domesday Book of 1086 covered the whole of England, meaning the English kingdom, but a few years the Chronicle stated that King Malcolm III went "out of Scotlande into Lothian in Englaland", thus using it in the more ancient sense.
According to the Oxford English Dictionary, its modern spelling was first used in 1538. The earliest attested reference to the Angles occurs in the 1st-century work by Tacitus, Germania, in which the Latin word Anglii is used; the etymology of the tribal name itself is disputed by scholars. How and why a term derived from the name of a tribe, less significant than others, such as the Saxons, came to be used for the entire country and its people is not known, but it seems this is related to the custom of calling the Germanic people in Britain Angli Saxones or English Saxons to distinguish them from continental Saxons of Old Saxony between the Weser and Eider rivers in Northern Germany. In Scottish Gaelic, another language which developed on the island of Great Britain, the Saxon tribe gave their name to the word for England. An alternative name for England is Albion; the name Albion referred to the entire island of Great Britain. The nominally earliest record of the name appears in the Aristotelian Corpus the 4th-century BC De Mundo: "Beyond the Pillars of Hercules is the ocean that flows round the earth.
In it are two large islands called Britannia. But modern scholarly consensus ascribes De Mundo not to Aristotle but to Pseudo-Aristotle, i.e. it was written in the Graeco-Roman period or afterwards. The word Albion or insula Albionum has two possible origins, it either derives from a cognate of the Latin albus meaning white, a reference to the white cliffs of Dover or from the phrase the "island of the Albiones" in the now lost Massaliote Periplus, attested through Avienus' Ora Maritima to which the former served as a source. Albion is now applied to England in a more poetic capacity. Another romantic name for England is Loegria, related to the Welsh word for England and made popular by its use in Arthurian legend; the earliest known evidence of human presence in the area now known as England was that of Homo antecessor, dating to approximate
Nobel Peace Prize
The Nobel Peace Prize is one of the five Nobel Prizes established by the will of Swedish industrialist and armaments manufacturer Alfred Nobel, along with the prizes in Chemistry, Physiology or Medicine, Literature. Since March 1901, it has been awarded annually to those who have "done the most or the best work for fraternity between nations, for the abolition or reduction of standing armies and for the holding and promotion of peace congresses". Per Alfred Nobel's will, the recipient is selected by the Norwegian Nobel Committee, a five-member committee appointed by the Parliament of Norway. Since 1990, the prize is awarded on 10 December in Oslo City Hall each year; the prize was awarded in the Atrium of the University of Oslo Faculty of Law, the Norwegian Nobel Institute, the Parliament. Due to its political nature, the Nobel Peace Prize has, for most of its history, been the subject of numerous controversies. According to Nobel's will, the Peace Prize shall be awarded to the person who in the preceding year "shall have done the most or the best work for fraternity between nations, for the abolition or reduction of standing armies and for the holding and promotion of peace congresses".
Alfred Nobel's will further specified that the prize be awarded by a committee of five people chosen by the Norwegian Parliament. Nobel died in 1896 and he did not leave an explanation for choosing peace as a prize category; as he was a trained chemical engineer, the categories for chemistry and physics were obvious choices. The reasoning behind the peace prize is less clear. According to the Norwegian Nobel Committee, his friendship with Bertha von Suttner, a peace activist and recipient of the prize, profoundly influenced his decision to include peace as a category; some Nobel scholars suggest. His inventions included dynamite and ballistite, both of which were used violently during his lifetime. Ballistite was used in war and the Irish Republican Brotherhood, an Irish nationalist organization, carried out dynamite attacks in the 1880s. Nobel was instrumental in turning Bofors from an iron and steel producer into an armaments company, it is unclear why Nobel wished the Peace Prize to be administered in Norway, ruled in union with Sweden at the time of Nobel's death.
The Norwegian Nobel Committee speculates that Nobel may have considered Norway better suited to awarding the prize, as it did not have the same militaristic traditions as Sweden. It notes that at the end of the 19th century, the Norwegian parliament had become involved in the Inter-Parliamentary Union's efforts to resolve conflicts through mediation and arbitration; the Norwegian Parliament appoints the Norwegian Nobel Committee, which selects the Nobel Peace Prize laureate. Each year, the Norwegian Nobel Committee invites qualified people to submit nominations for the Nobel Peace Prize; the statutes of the Nobel Foundation specify categories of individuals who are eligible to make nominations for the Nobel Peace Prize. These nominators are: Members of national assemblies and governments and members of the Inter-Parliamentary Union Members of the Permanent Court of Arbitration and the International Court of Justice at the Hague Members of Institut de Droit International University professors of history, social sciences, philosophy and theology, university presidents, directors of peace research and international affairs institutes Former recipients, including board members of organizations that have received the prize Present and past members of the Norwegian Nobel Committee Former permanent advisers to the Norwegian Nobel Institute Nominations must be submitted to the Committee by the beginning of February in the award year.
Nominations by committee members can be submitted up to the date of the first Committee meeting after this deadline. In 2009, a record 205 nominations were received, but the record was broken again in 2010 with 237 nominations; the statutes of the Nobel Foundation do not allow information about nominations, considerations, or investigations relating to awarding the prize to be made public for at least 50 years after a prize has been awarded. Over time, many individuals have become known as "Nobel Peace Prize Nominees", but this designation has no official standing, means only that one of the thousands of eligible nominators suggested the person's name for consideration. Indeed, in 1939, Adolf Hitler received a satirical nomination from a member of the Swedish parliament, mocking the nomination of Neville Chamberlain. Nominations from 1901 to 1956, have been released in a database. Nominations are considered by the Nobel Committee at a meeting where a short list of candidates for further review is created.
This short list is considered by permanent advisers to the Nobel institute, which consists of the Institute's Director and the Research Director and a small number of Norwegian academics with expertise in subject areas relating to the prize. Advisers have some months to complete reports, which are considered by the Committee to select the laureate; the Committee seeks to achieve a unanimous decision. The Nobel Committee comes to a conclusion in mid-September, but the final decision has not been made until the last meeting before the official announcement at the beginning of October; the Chairman of the Norwegian Nobel Committee presents the Nobel Peace Prize in the presence of the King of Norway on 10 December each year. The Peace Pri
Good Morning America
Good Morning America is an American morning television show, broadcast on ABC. It debuted on November 3, 1975, first expanded to weekends with the debut of a Sunday edition on January 3, 1993; the Sunday edition was canceled in 1999. The weekday program airs from 7:00 to 9:00 a.m. in all U. S. time zones. The Saturday and Sunday editions are one hour long and are transmitted to ABC's stations live at 7:00 a.m. Eastern Time, although stations in some markets air them at different times. Viewers in the Pacific Time Zone receive an updated feed with a specialized opening and updated live reports. A third hour of the weekday broadcast aired from 2007 to 2008 on ABC News Now; the program features news, weather forecasts, special-interest stories, feature segments such as "Pop News", the "GMA Heat Index" and "Play of the Day". It is produced by ABC News and broadcasts from the Times Square Studios in New York City's Times Square district; the primary anchors are Robin Roberts, George Stephanopoulos, Michael Strahan alongside breaking news anchor Amy Robach, entertainment anchor Lara Spencer and weather anchor Ginger Zee.
Good Morning America has been the most watched morning show in total viewers and key demos each year since Summer 2012. GMA placed second in the ratings, behind NBC's Today from 1995 to 2012, it overtook its rival for a period from the early to mid-1980s with anchors David Hartman and Joan Lunden, from the late 1980s to the mid-1990s with Charles Gibson and Lunden, in April 2012 with Roberts and Stephanopoulos. Good Morning America won the first three Daytime Emmy Awards for "Outstanding Morning Program", sharing the inaugural 2007 award with Today and winning the 2008 and 2009 awards outright. On January 6, 1975, ABC launched AM America in an attempt to compete with NBC's Today; the program was hosted by Bill Beutel and Stephanie Edwards, with Peter Jennings and Robert Kennedy reading the news. Because the show could not find an audience against Today, ABC sought a new approach; the network found that one of its affiliates, WEWS in Cleveland, had been pre-empting AM America in favor of airing a locally produced show called The Morning Exchange.
Unlike AM America and Today, The Morning Exchange featured an easygoing and less dramatic approach by offering news and weather updates only at the top and bottom of every hour and used the rest of the time to discuss general-interest/entertainment topics. The Morning Exchange established a group of regular guests who were experts in certain fields, including health, consumer affairs and travel. Unlike both the NBC and ABC shows, The Morning Exchange was not broadcast from a newsroom set but instead one that resembled a suburban living room. In the process of screening the Cleveland morning program as a creative source, ABC began looking at another local show, Good Morning!, produced by Boston ABC affiliate WCVB-TV. Good Morning! was similar in format to The Morning Exchange, but with a lesser emphasis on news and weather. In fact, once the revamped ABC morning show took to the air late in 1975 under the title Good Morning America, WCVB station manager Bob Bennett accused ABC entertainment president Fred Silverman of deliberately stealing the title of Good Morning!.
The launch of Good Morning America did result in the Boston morning show changing its name—to Good Day!. ABC used it as a pilot episode. After positive reviews for the pilot, the format replaced AM America on Monday, November 3, as Good Morning America; the first host was actor David Hartman, with actress Nancy Dussault as co-host. For the first seven years, weather forecasts were presented by John Coleman, former chief meteorologist for ABC owned-and-operated station WLS-TV in Chicago, who left GMA in 1982 to start The Weather Channel with Landmark Communications CEO Frank Batten. Dave Murray provided the forecasts for both Good Morning America and ABC's early morning news program ABC News This Morning from 1983 to 1986. In August 1986, he was replaced by Spencer Christian, who worked at WABC-TV in New York City and served as fill-in meteorologist for both Coleman and Murray whenever they were away on vacation or assignment; the program's ratings climbed but throughout the 1970s and into the 1980s while Today experienced a slight slump in viewership with Walters' decision to leave NBC for a job at ABC News.
On August 30, 1976, Tom Brokaw began anchoring Today while the program began a search for a female co-host. Within a year, Today managed to beat back the Good Morning America ratings threat with Brokaw and new co-host Jane Pauley, featuring art and entertainment contributor Gene Shalit. Good Morning America continued to threaten Today's ratings dominance into the 1980s after Brokaw left the latter program to become co-anchor of NBC Nightly News with Roger Mudd for 17 months before being named sole anchor of that program. For the first time, Good Morning America became the highest-rated morning news program in the United States as Today fell to second place. At the outset, Good Morning America was a talk program with a main host, joined by a side
A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range. Greenhouse gases cause the greenhouse effect; the primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, nitrous oxide and ozone. Without greenhouse gases, the average temperature of Earth's surface would be about −18 °C, rather than the present average of 15 °C; the atmospheres of Venus and Titan contain greenhouse gases. Human activities since the beginning of the Industrial Revolution have produced a 40% increase in the atmospheric concentration of carbon dioxide, from 280 ppm in 1750 to 406 ppm in early 2017; this increase has occurred despite the uptake of more than half of the emissions by various natural "sinks" involved in the carbon cycle. The vast majority of anthropogenic carbon dioxide emissions come from combustion of fossil fuels, principally coal and natural gas, with additional contributions coming from deforestation, changes in land use, soil erosion and agriculture.
Should greenhouse gas emissions continue at their rate in 2017, Earth's surface temperature could exceed historical values as early as 2047, with harmful effects on ecosystems and human livelihoods. At current emission rates temperatures could increase by 2 °C, which the United Nations' IPCC designated as the upper limit to avoid "dangerous" levels, by 2036; the main gases in Earth's atmosphere are: Nitrogen and Argon. The other gases are: carbon dioxide, nitrous oxides and ozone, they are trace gases that account for a tenth of 1% of Earth's atmosphere. Greenhouse gases are those that absorb and emit infrared radiation in the wavelength range emitted by Earth. In order, the most abundant greenhouse gases in Earth's atmosphere are: Water vapor Carbon dioxide Methane Nitrous oxide Ozone Chlorofluorocarbons Hydrofluorocarbons Atmospheric concentrations are determined by the balance between sources and sinks; the proportion of an emission remaining in the atmosphere after a specified time is the "airborne fraction".
The annual airborne fraction is the ratio of the atmospheric increase in a given year to that year's total emissions. As of 2006 the annual airborne fraction for CO2 was about 0.45. The annual airborne fraction increased at a rate of 0.25 ± 0.21% per year over the period 1959–2006. The major atmospheric constituents, nitrogen and argon, are not greenhouse gases because molecules containing two atoms of the same element such as N2 and O2 have no net change in the distribution of their electrical charges when they vibrate, monatomic gases such as Ar do not have vibrational modes. Hence they are totally unaffected by infrared radiation; some molecules containing just two atoms of different elements, such as carbon monoxide and hydrogen chloride, do absorb infrared radiation, but these molecules are short-lived in the atmosphere owing to their reactivity and solubility. Therefore they do not contribute to the greenhouse effect and are omitted when discussing greenhouse gases; some gases have indirect radiative effects.
This happens in two main ways. One way is. For example and carbon monoxide are oxidized to give carbon dioxide. Oxidation of CO to CO2 directly produces an unambiguous increase in radiative forcing although the reason is subtle; the peak of the thermal IR emission from Earth's surface is close to a strong vibrational absorption band of CO2. On the other hand, the single CO vibrational band only absorbs IR at much shorter wavelengths, where the emission of radiant energy from Earth's surface is at least a factor of ten lower. Oxidation of methane to CO2, which requires reactions with the OH radical, produces an instantaneous reduction in radiative absorption and emission since CO2 is a weaker greenhouse gas than methane. However, the oxidations of CO and CH4 are entwined. In any case, the calculation of the total radiative effect includes both direct and indirect forcing. A second type of indirect effect happens when chemical reactions in the atmosphere involving these gases change the concentrations of greenhouse gases.
For example, the destruction of non-methane volatile organic compounds in the atmosphere can produce ozone. The size of the indirect effect can depend on where and when the gas is emitted. Methane has indirect effects in addition to forming CO2; the main chemical that reacts with methane in the atmosphere is the hydroxyl radical, thus more methane means that the concentration of OH goes down. Methane increases its own atmospheric lifetime and therefore its overall radiative effect; the oxidation of methane can produce both water. CO and NMVOCs produce CO2, they remove OH from the atmosphere, this leads to higher concentrations of methane. The surprising effect of this is that the global warming potential of CO is three times that of CO2; the same process that converts NMVOCs to carbon dioxide can lead to the formation of tropospheric ozone. Halocarbons have an indirect effect because they destroy stratospheric