WASHINGTON, D.C. — In the space of a couple of hours last week, crude oil prices hit a record $56 a barrel, President Bush fretted publicly over world oil shortages and the Senate voted to open an Alaskan wildlife refuge to drilling.

The converging events drew attention to what administration officials call a temporary global energy crunch. Bigger worries also are bubbling to the surface — fears of a day of reckoning over world oil reserves.

Even as China and India are joining the grab for oil, most experts agree that world production will peak sometime in the next several decades — more likely in the next couple of years, say a gaggle of academics.

If the falling supply loses out to rising demand before new energy sources are ready, government officials say, a world that runs on oil could face consequences ranging from recessions to famine and even war.

The global oil supply

When oil production stops rising to meet growing demand, it “will result in dramatically higher oil prices, which will cause protracted economic hardship in the United States and the world,” a team of Energy Department consultants warned in a report last month.

“The challenge of oil peaking deserves immediate, serious attention if risks are to be fully understood and mitigation begun on a timely basis.”

The most obvious step is to transform into a fuel efficient fleet the 200 million cars, sport-utility vehicles and trucks that guzzle two-thirds of America’s 21-million-barrel-a-day oil consumption, consultant Robert Hirsch and colleagues wrote. They said it would take 10 to 15 years and cost consumers $1.3 trillion to replace half the fleet with vehicles that run on alternative fuels. Hydrogen, diesel oil or ethanol made from corn are among leading options.

How much time the United States and the rest of the world have to change their ways has been the grist for a sharp debate between government energy experts and critics.

Yet-to-be-found oil

Government geologists say the Earth still contains plenty of oil — as much as 2 trillion barrels of recoverable oil and liquid natural gas and another 939 billion barrels in yet-to-be-discovered reservoirs. The Energy Department’s scenarios call for a production peak somewhere between 2021 and the start of the next century, with 2037 the most likely date.

After the peak, said David Morehouse, a senior petroleum geologist with the department’s Energy Information Administration (EIA), the rate of production drop-off from declining oil fields would likely be “pretty quick.”

“We don’t want the world oil peak to sneak up on us,” said John Wood, who heads a Dallas-based unit that projects oil supply and demand for the EIA.

Kenneth Deffeyes, a Princeton University geology professor, says it may be too late to plan. Deffeyes worked previously in Shell Oil’s research laboratory alongside M. King Hubbert, who gained fame when he accurately predicted in 1956 that oil production in the continental United States would peak between 1965 and 1970.

Using a similar formula, Deffeyes predicts that the global peak will occur by Thanksgiving. But like a number of scientists making similarly dire forecasts, he has had to push back his date a couple of times.

“I’m not the least bit embarrassed,” he said in a phone interview. “There’s a year-to-year jitter — a strike in Venezuela or a warmer-than-average winter in the Northeast. But any year between 2003 and 2007 may end up in the Guinness Book of World Records.”

If Deffeyes is right, Morehouse said, “our goose is cooked.”

“If things get bad enough, and somebody gets desperate enough,” he said, an oil peak scenario could lead to war.

Amos Nur, a Stanford University geophysicist, all but predicts a war with China over oil. He notes that each American consumes an average of 25 barrels of oil each year, while the Chinese average 1.3 barrels and the people of India use less than a barrel. If Chinese and Indian consumption reached a quarter or a third of that of Americans’, he writes, it would require 50 percent more oil, and tensions could “slide into a military conflict.”

Bush told a news conference that new oil demand “from countries like China” is “outracing supply” and driving up prices.

Ed Porter, a research manager for the American Petroleum Institute, also blamed U.S. policies that have barred drilling in offshore sites and the Arctic National Wildlife Refuge. Environmentalists say that even if the Arctic refuge holds the hoped-for 15 billion barrels, it would meet just 2 percent of U.S. crude oil needs.

Alternative fuels

The recent oil price surge could have a positive side: making alternatives such as ethanol more cost competitive, said Ralph Groschen, a marketing specialist with the Minnesota Department of Agriculture.

Bush urged Congress to pass an energy bill that funds continued Energy Department research into other fuels — research that has focused on converting coal to hydrogen or liquid fuels.

“All of the research is underway,” Morehouse said, “but the question is, is it going fast enough?”

That depends partly on the accuracy of peak oil forecasts. The EIA’s varying scenarios are based on a 2000 U.S. Geological Survey assessment in which 40 scientists raised the estimate of global oil reserves and undiscovered reservoirs by hundreds of billion barrels — enough to meet current demand for two decades or more.

Retired USGS senior scientist Warren Hamilton said he looked over the study’s methodology and found it “erred seriously in the overestimation direction.” It relied heavily on guesses to calculate new oil discoveries, he said, and doubled the usual 30 percent recovery rate from reserves “with no technology in mind capable of doing that.”

The EIA’s Wood defended the USGS assessment as “somewhat conservative.” He said enhanced recovery techniques are raising yields at Alaska’s Prudhoe Bay and elsewhere. And, he said, the USGS report intentionally left out 1.6 trillion barrels of heavy oils found in Canadian tar sands and another 1.6 trillion in Venezuela’s Oronoco “tar belt.”

While those resources could significantly delay an oil peak, Wood said, if China’s economic boom pushes world demand to a 3 percent growth rate instead of the usual 2, the oil peak would move a decade nearer.

The U.S. government’s projections also hinge on continued strong Middle East output, especially from Saudi Arabia, which boasts more than 250 billion barrels of recoverable reserves, or nearly half what man has used over the last century.

Matthew Simmons, chairman of a Houston-based, oil-industry investment bank, contends in a forthcoming book that the Saudis damaged their oil fields by overproducing in the early 1970s and again after Iraq invaded Kuwait in 1990. That changed the sub-surface pressure, creating huge water problems that will make it harder to recover oil, he said.

Department officials concede that they have only the kingdom’s assurances that it can ramp up output from about eight million barrels to 10 million or even 12 million barrels a day. Wood said he would “feel more comfortable” if the Saudis shared their data.

If it turns out Saudi Aramco, the state-owned oil company, cannot boost its production, Wood said, “that has significant implications.”

Greg Gordon is at [email protected].