Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years. Fossil fuels contain high percentages of carbon and include coal, petroleum, and natural gas. They range from volatile materials with low carbon:hydrogen ratios like methane, to liquid petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal. Methane can be found in hydrocarbon fields, alone, associated with oil, or in the form of methane clathrates. Fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the Earth's crust over millions of years. This biogenic theory was first introduced by Georg Agricola in 1556 and later by Mikhail Lomonosov in the 18th century.

It was estimated by the Energy Information Administration that in 2007 primary sources of energy consisted of petroleum 36.0%, coal 27.4%, natural gas 23.0%, amounting to an 86.4% share for fossil fuels in primary energy consumption in the world. Non-fossil sources in 2006 included hydroelectric 6.3%, nuclear 8.5%, and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%. World energy consumption was growing about 2.3% per year.

William Sanford "Bill" Nye (born November 27, 1955), popularly known as Bill Nye the Science Guy, is an American science educator, comedian, television host, actor, mechanical engineer, and scientist. He is best known as the host of the Disney/PBS children's science show Bill Nye the Science Guy (1993–1998) and for his many subsequent appearances in popular media as a science educator.

William Sanford Nye was born in Washington, D.C., the son of Jacqueline (née Jenkins; c. 1920–2000), a codebreaker during World War II, and Edwin Darby "Ned" Nye (died 1997), also a World War II veteran whose experience in a Japanese prisoner of war camp led him to become a sundial enthusiast. Nye is a fourth-generation Washington, D.C. resident on his father's side of the family. After attending Lafayette Elementary and Alice Deal Junior High in the city, he was accepted to the private Sidwell Friends School on a partial scholarship, graduating in 1973. He studied mechanical engineering at Cornell University, where one of his professors was Carl Sagan, and graduated with a Bachelor of Science in 1977. He was awarded an honorary doctorate by The Johns Hopkins University in May 2008. In May 2011, Nye was awarded an Honorary Doctor of Science degree from Willamette University where he was the keynote speaker for that year's commencement exercises.

Desmond Mpilo Tutu (born 7 October 1931) is a South African activist and retired Anglican bishop who rose to worldwide fame during the 1980s as an opponent of apartheid. He was the first black South African Archbishop of Cape Town, South Africa, and primate of the Church of the Province of Southern Africa (now the Anglican Church of Southern Africa).

Tutu has been active in the defense of human rights and uses his high profile to campaign for the oppressed. He has campaigned to fight AIDS, tuberculosis, poverty, racism, sexism, homophobia, and transphobia. Tutu received the Nobel Peace Prize in 1984; the Albert Schweitzer Prize for Humanitarianism in 1986; the Pacem in Terris Award in 1987; the Sydney Peace Prize in 1999; the Gandhi Peace Prize in 2005; and the Presidential Medal of Freedom in 2009. Tutu has also compiled several books of his speeches and sayings.

Desmond Mpilo Tutu was born in Klerksdorp, Transvaal, the second of the three children of Zacheriah Zililo Tutu and his wife, Aletta, and the only son. Tutu's family moved to Johannesburg when he was twelve. His father was a teacher and his mother was a cleaner and cook at a school for the blind. Here he met Trevor Huddleston who was a parish priest in the black slum of Sophiatown. "One day," said Tutu, "I was standing in the street with my mother when a white man in a priest's clothing walked past. As he passed us he took off his hat to my mother. I couldn't believe my eyes – a white man who greeted a black working class woman!"

Hans Rosling (born 27 July 1948 in Uppsala, Sweden) is a Swedish medical doctor, academic, statistician and public speaker. He is Professor of International Health at Karolinska Institute and co-founder and chairman of the Gapminder Foundation, which developed the Trendalyzer software system.

From 1967 to 1974 Rosling studied statistics and medicine at Uppsala University, and in 1972 he studied public health at St. John's Medical College, Bangalore. He became a licenced physician in 1976 and from 1979 to 1981 he served as District Medical Officer in Nacala in northern Mozambique.

On 21 August 1981, Rosling discovered an outbreak of konzo, a paralytic disease, and the investigations that followed earned him a Ph.D. degree at Uppsala University in 1986. He spent two decades studying outbreaks of this disease in remote rural areas across Africa and supervised more than ten Ph.D. students^{[citation needed]}. Outbreaks occur among hunger-stricken rural populations in Africa where a diet dominated by insufficiently processed cassava results in simultaneous malnutrition and high dietary cyanide intake.

William Ernest "Bill" McKibben (born 1960) is an American environmentalist, author, and journalist who has written extensively on the impact of global warming. He is the Schumann Distinguished Scholar at Middlebury College. In 2010, the Boston Globe called him "probably the nation's leading environmentalist" and Time magazine described him as "the world's best green journalist."

In 2009, he led the organization of 350.org, which organized what Foreign Policy magazine called "the largest ever global coordinated rally of any kind," with 5,200 simultaneous demonstrations in 181 countries. The magazine named him to its inaugural list of the 100 most important global thinkers, and MSN named him one of the dozen most influential men of 2009. In 2010, McKibben and 350.org conceived the 10/10/10 Global Work Party, which convened more than 7,000 events in 188 countries as he had told a large gathering at Warren Wilson College shortly before the event. In December 2010, 350.org coordinated a planet-scale art project, with many of the 20 works visible from satellites. In 2011 and 2012 he led the massive environmental fight against the proposed Keystone XL pipeline project and spent three days in jail in Washington D.C. as leader of one of the largest civil disobedience actions in America for decades. . Two weeks later he was inducted into the literature section of the American Academy of Arts and Sciences.