Peak Oil is a hypothetical event that asserts that there is a point at which global oil production will reach a peak or maximum, from which it then begins an irreversible decline. The theory has been floated by some geologists and promoted by fossil fuels opponents, but suffers from a lack of supporting evidence.
Additional oil resources
Michael Lynch, president of Strategic Energy & Economic Research, an energy consultancy firm that works for oil companies, says "Not much can be said about additional oil resources because we haven't really started looking for them yet."  There is likely to be a lot of oil in as-yet undiscovered smaller fields.
New technologies could help solve extraction problems according to Sam Kazman of the Competitive Enterprise Institute, a non-profit public policy think tank in Washington, D.C. New technologies have already turned fields that once seemed to be dormant into steady supplies of oil.
Popular and fringe theories
James Howard Kunstler's 2005 book The Long Emergency is a popular book claiming that civilization is doomed during the next couple of decades due to peak oil. Similar doomsday scenarios are promoted by Richard Heinberg in a series of books with names like The Party's Over, Powerdown, Peak Everything, and Blackout. On the Internet, a blog called "The Oil Drum" and the website "Dieoff.org" are the most prominent popularizers of "peak oil" doomsday scenarios, including the notion that mass starvation will occur in the next few decades.
Global oil production will peak sometime between 2008 and 2018 and then decline, according to a controversial new model developed Swedish University of Uppsalla physicist Fredrik Robelius. According to a recent U.S. Government GAO report, world oil production will peak between now and 2040
Rejection of theory
Exxon's Australia chief, Mark Nolan, told an industry conference in Adelaide, Australia, that "the end of oil is nowhere in sight." Mr. Nolan cited a U.S. Geological Survey estimate of more than three trillion barrels of conventional recoverable oil resources, of which one trillion barrels has been produced. Conservative estimates of heavy-oil and shale-oil resources push the total to four trillion barrels, while a 10% increase in recoverability will deliver an extra 800 billion barrels according to Nolan.
It should also be noted that this is not a new concept, but has been around in different forms for many years. During the early 1970's in the United States, it was claimed that world oil would run out in 35 years, a claim that never came to pass.
Lindsey Williams, a Baptist chaplain to the 1970s Trans-Alaska Pipeline project, asserts in his 1980 book The Energy Non-Crisis that oil finds have been deliberately suppressed including a large find at Gull Island, Alaska. Williams has resurfaced recently giving public speeches on the same topic in response to recent "peak oil" and "energy crisis" scares.
The Myth of the Oil Crisis by Robin M. Mills is a 2008 book extensively documenting how "peak oil" theories are based on flawed assumptions and discredited science. Mills asserts that unconventional oil resources are much larger than conventional oil sources and have barely been developed at this point, leaving hundreds of years of oil yet to extract.
Peter Huber and Mark Mills' 2005 book The Bottomless Well: The Twilight of Fuel, the Virtue of Waste, and Why We Will Never Run Out of Energy documents why energy is not scarce, new energy sources and transmission and storage are always being developed, and rapidly improving energy effeciency correlates with both increased usage and new sources leading to ever-cheaper, less polluting energy and more prosperity; in sum, no "energy crisis" is on the horizon for the foreseeable future and we may even see an energy glut, making any concerns over diminishing oil supplies a non-issue.
Maybe not "Fossil Fuel"
An alternative hypothesis to that of the common "fossil fuel" hypothesis of oil formation is the "abiotic" or "abiogenic" hypothesis. Thomas Gold of Cornell University has been the most prominent advocate of this theory in the West during his lifetime. Gold died in 2004.
Thomas Gold asserts that the sources of oil may not be “fossil fuels” in limited supply, but instead abiotic in nature (meaning not produced by a life process). According to Professor Gold, oil is produced by an abiogenic process, deep within the earth. The scientific community has not been eager to affirm this thesis. In fact, they tend to resist it. In 1992 Gold published a paper titled “The Deep Hot Biosphere”, later expanded into a 1999 book of the same name. In this paper he suggested that oil is non-biologically produced, deep within the earth. In other words, oil is not a fossil fuel. The Department of Energy refused to fund his research although both outcomes would have been good - If the research uncovered sources of oil that did not take millions of years to produce, it would be a bonanza for oil companies. If abiogenic petroleum sources are found to be abundant, it would mean Earth contains vast reserves of untapped petroleum. On the other hand, if his research failed, this research proposal will contribute strongly to fundamental science in petroleum engineering. So far, the DOE has refused to fund any of his research because it is counter to the mainstream effort.
- Peak Oil Debunked blog - Debunking peak oil hype with facts and figures, and exposing the agendas behind peak oil.
- Experts: Global Oil Production May Peak Soon April 28, 2006 Fox News
- With Gas so Cheap and Well Drilling Down, Why is Gas Production so High? Jan 19, 2012 Post Carbon Institute
- "It’s the theory that geological scarcity will at some point make it impossible for global petroleum production to avoid falling, heralding the end of the oil age and, potentially, economic catastrophe." 
- Melinda Wenner Study: 'Peak Oil' Will Be Reached by 2018 April 18, 2007 Fox News
- Coverage of the GAO peak oil report Energy Bulletin, Mar 29, 2007
- Bhushan Bahree and Jeffrey Ball Some insiders reject 'peak-oil theory' September 14, 2006 Mail Tribune
- J. R. Nyquist Debunking Peak Oil May 8, 2006 Geopolitical.