If the cost of energy skyrockets, are the suburbs doomed? Would Long Island, already paying among the highest fuel and electricity rates in the country, become an unsustainably expensive place to live?

A way of thinking that says “yes” is circulating, and has assumed tangible form in a video called “The End of Suburbia: Oil Depletion and the Collapse of the American Dream.” Made in Toronto by the independent producers Gregory Greene and Barry Silverthorn, it explores the idea that the world is running out of cheap petrofuels and predicts the utter ruin of North America’s suburbs – and not in the distant future, but somewhere between 5 and 25 years from now.

The video was screened last month at Molloy College in Rockville Centre, under the sponsorship of Long Island Neighborhood Network, an environmental advocacy group, and Vision Long Island, an organization that promotes the “new urbanism” or “smart growth” philosophy, which favors high-density, mixed-use, work-where-you-live downtowns over the classic low-density, home-with-a-yard model of suburbia.

The video opens with nostalgic clips of the early days of suburbia – excited young couples holding boxy little home models, families piling up their shopping carts, neat little back yards – and asserts that the new sprawl pattern, totally dependent on the automobile, became synonymous with the American dream. It also represents, in the words of a featured commentator, James Howard Kunstler, “the greatest misallocation of resources in the history of the world. America took all its postwar wealth and invested it in a living arrangement that has no future.”

In this view the 21st-century poison is peak oil theory, the idea that the world has reached its maximum oil production or soon will, and that we are entering a period when escalating energy costs will make the suburban lifestyle untenable. The case is made by assorted geologists, professors, writers and oil industry pundits, but most notably Mr. Kunstler, a new urbanist whose book “Geography of Nowhere” is a strident criticism of suburbia.

As envisioned by Messrs. Greene and Silverthorn, the consequences go way beyond violence at the gas pump to include: unending economic depression, with radical downsizing of everything from manufacturing to education; a slump in food production because of soil degradation, lack of oil-based fertilizers and skyrocketing shipping costs; political upheavals; the election of demagogues; and global conflict as the United States tries by military means to maintain its disproportionate consumption of the world’s oil. The filmmakers see the American suburbs as the slums of the future where people are desperately relearning how to grow their own food.

“I do see a lot of potential for darkness,” Mr. Kunstler comments. “There’ll be a great scramble to get out of the suburbs, a sort of fight over the table scraps of the 20th century.”

The video’s original footage was shot near Toronto and various areas of the United States, and in fact the suburbs all do look remarkably alike. Mr. Greene said in a telephone interview that no shooting was done on Long Island, but that he had heard of Levittown.

Mr. Kunstler, whose ideas form the backbone of “End of Suburbia,” lived in Roslyn for three years as a child beginning in 1954 and visited regularly thereafter. “Certainly my impressions were shaped there,” he said. “That part of the Island was only beginning to be destroyed and I actually watched the process vividly as the estate that ran behind my back yard was turned into a cul de sac subdivision. The experience stayed with me.”

Following the screening was a discussion period. “Is this where we get out the purple Kool-Aid?” asked Eric Alexander, executive director of Vision Long Island.

The audience of about 50 in the auditorium in Rockville Centre, in the heart of what is often described as the first suburb, was enthusiastic, in a shell-shocked sort of way. Since most in attendance had gotten wind of the screening via environmentalist networking channels, they tended to find reinforcement for their own beliefs rather than reason to question the basic premises. There were comments about the need to grow our own food, create new lifestyle models on the Island, fight nimbyism and conserve energy in both large-scale and personal ways.

In the bleak future projected by the film, the only glimpse of hope is new urbanism. This is the philosophy that drives Vision Long Island.

“We were laughed at when we started in 1997,” Mr. Alexander said. His group is engaged in half a dozen projects around the Island advancing a smart-growth agenda. But one of the barriers he sees is that too few people are “aware of or thinking about alternatives in every form,” so the film’s value is in mobilizing people.

“It’s a little jolt to the system,” he said, “important because we can’t get complacent intellectually or practically.”

For some, a post-carbon age can’t come soon enough. Gordian Raacke, executive director of Renewable Energy Long Island, said: “It doesn’t matter which comes first, running out of oil and other cheap fossil fuel sources, or out of places to dump our pollution. We have problems caused by our consuming patterns and addiction to polluting fossil fuels and have to immediately change our course, realizing we’re affecting our own quality of life and changing the climate of the whole planet.”

Mr. Raacke said that moving rapidly toward clean energy such as wind and solar is crucial. “I think we are at a tipping point,” he said. “Renewable energy is moving into the spotlight as the obvious solution. It’s a matter of political will.”

Richard M. Kessel, chairman of the Long Island Power Authority, essentially agreed. “Long Island and this region are clearly too dependent on oil not just to produce electricity but all types of activities,” he said. “Over 90 percent of our electricity is produced with oil and natural gas, and both are finite resources. I’m not sure I subscribe to the notion that we’ll run out in two decades, but if we don’t figure out a way – not just Long Island but the whole country – to reduce our dependence on oil, we will have long-term devastating consequences.”

LIPA’s investment in windmill energy and fuel cell technology reflects this viewpoint, Mr. Kessel said.

But “The End of Suburbia” is dismissive of alternative energy source development. “No combination of alternative energy systems will allow us to run what we are running,” Mr. Kunstler said in a telephone interview. “If by some miracle we developed an energy system as potent as our fossil fuels, at the very least it would not come about before we went through a punishing and prolonged period of economic hardship, and personally I think the losses would be so great we might not even be able to gear up a system like this again.”

Not everyone agrees, of course, that we are actually in near danger of running out of relatively cheap petrofuels. “The theory that suburbia will collapse because the era of inexpensive gas is over is a very premature and dark prediction,” said Richard Guardino, the former Hempstead town supervisor who is now dean of the Center for Suburban Studies at Hofstra University. “I think people will be very creative and are already finding new alternatives, but you can debate whether things are happening at the urgency they must.”

Matthew C. Cordaro, director of the C. W. Post/Long Island University Center for Management Analysis and a former Lilco executive, said that even projecting factors like the growth of China, there’s still enough oil for 60 to 80 years, perhaps 100. We have almost unlimited amounts of energy around the earth, he said, when resources like coal (which can be converted to natural gas), hydrogen and uranium are taken into account. “It’s very difficult for me to conceive of skyrocketing unaffordability given this trend,” he said, “because you can produce electricity from a lot of sources of fuel and easily distribute it.”

“Prices will increase – that you can count on, like death and taxes – but not disproportionately,” Dr. Cordaro said. “Competitive forces will hold them in check.”

David Manning, senior vice president for corporate affairs at Keyspan and formerly Canada’s deputy energy minister, also said economic forces will protect us from disaster. “What we’re seeing is that the economy is continuing to run and grow even at $50 per barrel for oil,” he said. “At that price we’re bringing along new resources that would have been unaffordable, such as the oil sands of western Canada.”

But Mr. Manning had a warning. “Knowing there’s still an abundant supply of energy doesn’t mean we’re using it wisely,” he said. “So how can Long Island leadership make the right decisions about efficiency, invest dollars in the infrastructure?”

That’s a central question for Ernest Fazio, chairman of Long Island Mid-Suffolk Business Action, which involves itself in economic and transportation issues. He said the first responses to the oil shock of the early 1970’s, including the switch to smaller cars, evolved into “better methods in every area, because we became attuned to energy being a more costly product.” That we have backslid to larger cars and bigger houses he finds “an aggravating fact.”

Significant efficiency could be achieved on Long Island, according to Dr. Cordaro’s Center for Policy Analysis, by re-engineering the three largest of Long Island’s aging generators – Northport, Port Jefferson and Island Park. This could triple their electricity output while radically reducing harmful emissions, according to the center’s analysis.

Governor Pataki’s energy guidelines require the state to get almost 25 percent of its electric needs from renewable, environmentally friendly sources by 2013. Just last week, Nassau legislators passed a resolution that commits the county to meeting a similar 25 percent goal by 2010.

A developer has been selected for the Offshore Wind Project, a wind generator farm to be located southwest of Robert Moses State Park, with the hope of generating 140 megawatts of electricity, enough to power about 44,000 homes. “This will be the first offshore wind project in North America,” Mr. Kessel said, “and there are real challenges with costs, with permitting. But we have to do it.”

Also, a request for proposals has been issued for a 10-megawatt fuel cell plant. Fuel cells are devices that use the chemical energy of hydrogen to produce electricity, and may prove a superior way to power vehicles electrically, as well as for heating, cooling, and general electrical supply.

“We have to aggressively pursue renewable technology,” Mr. Kessel said. “Looked at in isolation, these projects are not economical. Powering homes through wind costs more now, but over the long term, if you subscribe to the notion that oil and gas won’t be here forever, and will continue to jump in price, investing in renewables is critically important so we have enough energy to keep the economy humming and provide a cleaner environment too.”

Mr. Manning said that even without a spike in energy costs, “there is a conservation imperative coming, though the most immediate concerns are congestion and time and affordable housing. If we can make affordable housing in proximity to train stations, there’ll be a huge demand. Energy costs will contribute to this realization down the line.”

Does the Long Island Rail Road provide some insulation against the havoc that astronomical fuel prices could wreak? Opinions vary here too.

“We have a huge, efficient commuting system relative to other North American cities,” Mr. Manning said, “so New York and Long Island are probably better set up to withstand price increases. But the transportation doesn’t always take you where you want to go.”

Mr. Guardino elaborated. “The issue is the railroad runs east to west,” he said. “What’s happening is that suburban communities are becoming separate economic entities while their infrastructure was developed to provide transportation for commuters. So with the roads more and more crowded with people driving here and there and not going to the city, the whole system has to be creatively rethought.”

Some think government mandates, incentives and subsidies are essential to move us in the right direction, others that natural response to a shifting landscape of costs will prod us to change.

“We don’t leave the lights on, we put in more insulation,” Dr. Cordaro said. “But energy costs are not so high as to change trends. We still buy bigger houses and cars, more appliances.”

Mr. Guardino agreed. “The sense of urgency is not out there yet,” he said. “It will take a combination of government leadership, private-sector leadership and a sense of urgency from the general population to make it clear to government that these things are priorities.

“I just have a positive outlook about the Island and its ability to adapt,” he added. “When you combine that with the positives – a very vibrant economy, extraordinary education system, increasing property values, the emerging biotech industry – I think even if we’re faced with some extraordinary increases in oil prices, we’re capable of adapting.”

Mr. Kunstler doesn’t agree. “I am certainly pessimistic about the great megalopolis smudge from north of Boston to south of Washington,” he said, “and would certainly include Long Island in that assessment. It has the added geographic problem of being a dead end, a kind of cul de sac cut off from the rest of America.”

He said the public has been “stupendously resistant” to thinking seriously about the issues raised in the video because it is so heavily invested in the status quo. “The dirty secret of the American economy for the last decade or so,” Mr. Kunstler said, “is that it is largely based on the creation of suburban sprawl – the furnishing and accessorizing it and servicing of it. If you challenge or stop that activity, you will be in effect questioning the whole American economy.”

Mr. Fazio takes a middle ground.

“The predictions that we’re running out of oil never come true,” he remarked, “but still, if we don’t change, it’s doomsday! As dumb as we are, when pushed up against the wall with a two by four, we say ‘Oh, I get it.’ We’re slow but we’re trainable.”

He has seen “The End of Suburbia” and hopes more people will. “It’s absolutely essential that people know what could happen and that things don’t have to be that way,” he said.

More than 10,000 DVD’s of “The End of Suburbia” have been sold. Meanwhile, the filmmakers are working on a sequel called “Escape From Suburbia” which, Mr. Greene said, “will tell the stories of interesting initiatives that are being fought for around the world, to find scalable, affordable energy alternatives in time for the crisis.”

Mr. Greene said he is an optimist, but reckoned that we have 10 years, and said that he’s moving soon from Toronto to France because he’s convinced that “the European dream will speak to how things play out in the 21st century, more than the American, which was a 20th-century dream.” His collaborator, Mr. Silverthorn, is moving to rural Ontario to learn his ancestors’ farming skills.