A doomer is one who believes that peak oil is causing or will cause both the collapse of industrial civilization, and a gigantic die-off of most of the human population. Many doomers are also survivalists.
Doomers attribute their beliefs to humanity's over reliance on petroleum for agricultural and industrial productivity. By contrast a "peakist" would be one who has a lighter view on the implications of peak oil, although this label has been dismissed from within the movement as vacuous. "Boomsters" takes the opposite, cornucopian position.
Common themes 
A convinced doomer believes that the Green Revolution will collapse at the end of cheap oil. According to doomers, humanity will be in a state of overshoot after oil depletion makes modern farming methods economically non-viable. Various academics have calculated that our numbers would then far exceed the carrying capacity of the earth. For example: they believe our situation is comparable to bacteria in a petri dish with cheap oil as the human growth medium. As the “growth medium” is consumed and runs out the “bacteria” dies off.
Doomers also hold a wide range of theories about the collapse of complex societies and systems. The influences of Paul R. Ehrlich and the Club of Rome are present in the doomer movement, as are some of the more recent works by Joseph Tainter who wrote The Collapse of Complex Societies in 1988, and Richard C. Duncan who presented his Phd The Peak of World Oil Production and the Road to the Olduvai Gorge in 1989 (now known as the Olduvai theory.) The lectures and DVD by Albert Allen Bartlett, Arithmetic, Population and Energy is also highly influential. (See below for online video streaming of the lecture he has been presenting and refining for over 30 years.)
The common concerns are that of overpopulation leading to resource and energy depletion, soil degradation and environmental destruction all culminating in agricultural collapse and famine. Some doomers[who?] estimate that the anarchic collapse will be so catastrophic that population levels may fall below the levels prior to the industrial revolution — possibly below 2 billion. When trying to calculate the extent of the postulated dieoff, the most extreme doomer will also take into account that the existing eco-infrastructure is massively supported by oil based fertilizers and that we will not only hit peak oil but peak phosphate and peak nitrogen simultaneously. When oil production starts to decline the productivity of the soil will drop far below that of pre-industrial times and thus a drop down to 2 billion is optimistic. This kind of doomer will also ignore technology and dismiss it with commonly believed ideas such as "wind farms cost more energy to build than they get out". This common refrain is generally applied to all technology solutions since it is assumed a priori that a population crash is inevitable.
Survivalist mindset 
The typical doomer response to peak oil and the collapse of the industrial system is to “ignore civilization to death” by setting up a permaculture village. This survivalist mindset is what distinguishes the doomer from the peakist. The peakist may spend many hours campaigning for peak oil awareness, societal change and changes in government policy, while doomers would generally see this as a waste of valuable time. The doomer focus is more on preparing the family and local community for the imminent collapse of civilization.
Influence in peak oil 
A purist doomer concentrates on their "lifeboat" survivalist permaculture farm. If the purist doomer raises awareness at all, it is to selectively encourage necessary tradespeople to join their eco-village, sharing their vital skills with their village to add to their security. Some doomers call for making active survivalist preparations to be ready to survive a protracted societal collapse.
This tension between optimism and pessimism is appreciated by author Richard Heinberg in his book, Powerdown, who argues that local communities should immediately learn how to provide for their own power, water, and food security, while also campaigning for awareness on a State, Federal, and International level. Richard Heinberg admits that the ideal situation would be for the United Nations and Federal Governments to step in and institute a massive "war-time economy" shifting the industrial world from oil dependency. However he argues that there is the strong possibility that societal awareness is all too little too late to prevent "dieoff". As the future is so uncertain, Heinberg argues that the wisest course of action for the local community is to prepare for the implosion of modern infrastructure while also campaigning to prevent this disaster.
The more convinced doomer would typically find the movie The End of Suburbia as unrealistic. While the last 15 minutes of The End of Suburbia focuses on the local community solutions of New Urbanism, the doomer would argue that the movie fails to describe the inevitable Malthusian catastrophe. The doomer protests that The End of Suburbia implies suburban sprawl will experience an orderly transition into New Urbanism. The convinced doomer rejects this outright as an impossibility due to civil unrest.
See also 
- Myth of Progress
- What a Way to Go: Life at the End of Empire
- Mickey Foley (June 24, 2011). "The doomer's curse". Retrieved December 17, 2011.
- Kurt Cobb (December 2, 2007). "What should members of the peak oil movement call themselves?". Retrieved December 17, 2011.
- Toby Hemenway (December 6, 2006). "The origins of peak oil doomerism". Retrieved December 17, 2011.
- Zachary Nowak (October 6, 2007). "Of doomers, realists, powerdowners and fantasists". Retrieved December 17, 2011.
- New limits to growth revive Malthusian fears (March 25, 2008). "New limits to growth revive Malthusian fears". Retrieved December 17, 2011.
- Paul Rogers (November 12, 2007). "Wanted: a new global paradigm". Retrieved December 17, 2011.
- "Peakniks, Doomers, and Collapse". Eclipse Now. Retrieved December 17, 2011.
- Discussion of "Doomer" term
- Doomsters(sic) - A journal article discussing peak oil and "Doomsters"
- So Very Doomed - Real doomers caught in the act of dooming.
- Embracing the Doom:What kind of Doomer am I? Defining and differentiating doomer kind