When will it end, this crushing rise in the price of gasoline, now averaging $4.10 a gallon at the pump? The question is uppermost in the minds of American motorists as they plan vacations or simply review their daily journeys. The short answer is simple as well: "Not soon."

    As yet there is no sign of a reversal in oil's upward price thrust, which has more than doubled in a year, cresting recently above $146 a barrel. The current oil shock, the fourth of its kind in the past three-and-a-half decades, and the deadliest so far, shows every sign of continuing for a long, long stretch.

    The previous oil shocks - in 1973-74, 1980, and 1990-91 - stemmed from specific interruptions of energy supplies from the Middle East due, respectively, to an Arab-Israeli war, the Iranian revolution, and Iraq's invasion of Kuwait. Once peace was restored, a post-revolutionary order established, or the invader expelled, vital Middle Eastern energy supplies returned to normal. The fourth oil shock, however, belongs in a different category altogether.

    Nothing Like It Before

    Unlike in the past, the present price spurt has been caused mainly by global demand for energy outstripping available supply. Alarmingly, there is no short-term prospect that supply will match demand. For a commodity like petroleum that underwrites and permeates every aspect of modern life - from fuel to fertilizers, paints to plastics, resins to rubber - "balance" requires a 5% safety factor on the supply side.

    At present, however, spare capacity in the oil industry is less than 2%, down from more than 6% in 2002. As a result, the price of oil responds instantly to negative news of any sort: a threat against Iran by an Israeli cabinet minister, a fire on a Norwegian offshore drilling rig, or an attack on an oil facility by armed rebels in Nigeria.

    Aomori, Japan - Faced with record-high oil prices, the world's leading economies and oil consumers have pledged greater investment in energy efficiency and green technologies to control their spiraling thirst for petroleum.

    In a joint statement, energy ministers from the Group of Eight countries - joined by China, India and South Korea - also urged oil producers to boost output, which has stalled at about 85 million barrels a day since 2005, and called for cooperation between buyers and producers.

    But with little prospect for a production surge soon, the focus of Sunday's meeting in Japan was on what wealthy nations should do to rein in consumption, while reducing carbon emissions blamed for global warming.

    "We also have to address too the demand side of the equation," said John Hutton, Britain's business secretary. "We will do that through new measures to improve energy efficiency (and) accelerate our moves to a new, low-carbon form of energy generation."

    The 11 nations account for 65 percent of the world's energy consumption and face record-high oil costs. Prices gained 8 percent Friday to US$138.54 on the New York Mercantile Exchange.

    Energy experts say most producers have little ability to expand output. The exception is Saudi Arabia, which could increase output by about 2 million barrels a day.

    Worries that world oil demand will outstrip global supplies intensified on Thursday, sending ripples through the global economy as oil prices leaped above $135, a new record high.

    The price spike occurred overnight, and by Thursday morning oil had fallen back slightly to $132.87, down 30 cents from its close on Wednesday.

    But the leap capped a rally that has seen oil rise nearly $5 a barrel in two days, underscoring the dire implications of the current price run-up for businesses across the globe.

    Ford Motor Company, the American auto manufacturer, said on Thursday it would cut vehicle production for the rest of this year and fall short of reaching profitability in 2009, a long-held company goal. In a statement, a top Ford executive said rising gasoline prices "are having a tremendous impact on our sales, our manufacturing operations and our profitability."

    Meanwhile, Europe's biggest airline, Air France-KLM, warned of a profound reshaping of the world airline industry caused by what it called the "explosion" in the price of oil. And American Airlines said on Wednesday that it would slash flights and begin charging passengers to check bags, part of a company effort to cut costs in the face of skyrocketing fuel prices.