Today, China consumes only a third as much oil as the United States, which burns a quarter of the world’s oil each day. By 2030, India and China together will import as much oil as the United States and Japan do today.

While demand is growing fastest abroad, Americans’ appetite for big cars and large houses has pushed up oil demand steadily in this country, too. Europe has managed to rein in oil consumption through a combination of high gasoline taxes, small cars and efficient public transportation, but Americans have not. Oil consumption in the United States, where gasoline is far cheaper than in Europe, has jumped to 21 million barrels a day this year, from about 17 million barrels in the early 1990s.

If the Chinese and Indians consumed as much oil for each person as Americans do, the world’s oil consumption would be more than 200 million barrels a day, instead of the 85 million barrels it is today. No expert regards that level of production as conceivable.

More realistically, global demand is expected to rise to about 115 million barrels a day by 2030, a level that is likely to tax the world’s ability to pump more oil out of the ground. Already, the world is running on a limited cushion of spare capacity; any interruption in supplies, whether from hurricanes or armed conflict, causes prices to spike.

“We don’t have any shock absorbers,” Mr. Goldstein said.

For oil companies, high prices have set off a frenzied search for new sources around the world. After a long lull in investments through most of the 1990s because of low prices, major oil companies have invested billions of dollars to bring in more supplies.

The trouble is that these big new developments take a long time, and companies have been hobbled by higher costs. The cost of drilling rigs, for example, the basic tool of the trade, has doubled in recent years. Analysts say it will take time, but new supplies will eventually work their way to market.

Supplies have also been hampered by political tension in the Persian Gulf, the war in Iraq, devastating hurricanes in the oil-producing Gulf of Mexico, production difficulties in Venezuela and violence in Nigeria’s oil-rich province. Many of these geopolitical factors have contributed to a political risk premium variously estimated at $25 to $50 a barrel. Recently, in just nine weeks, oil jumped from $75 to $95 a barrel for little apparent reason.