Combined production of crude oil, gas and condensates in the United States is on course to a hit a record this year, passing the previous peak set in 1972. The rise in output has confounded the famous forecast made by Shell geologist M King Hubbert who predicted that U.S. oil and gas production would peak in the 1970s and then decline. Hubbert's prediction was contained in a paper entitled "Nuclear Energy and the Fossil Fuels," published in 1956, in which he argued the coming decline of oil and gas output would make the development of nuclear energy essential. Hubbert's prediction of peaking oil and gas production came to be known as "Hubbert's peak" and spawned the popular and influential theory known as "peak oil".