It only lasted a moment, but it was enough to make history: for the first time ever, the price of crude oil traded on futures exchanges jumped to $100 a barrel yesterday afternoon.

Oil had traded above $90 a barrel for the greater part of three months, capping a year of almost vertical price movement propelled by rising global demand, supply constraints, political uncertainty and pure speculation. Yesterday, traders responded to a trifecta of bad news events: a fresh outbreak of violence in Nigeria on Tuesday; the closure of several Mexican oil export ports due to rough weather; and a discouraging report on future production from the Organization of the Petroleum Exporting Countries.

In Nigeria, Africa's largest oil producer, bands of armed men attacked two police stations and raided the lobby of a major hotel in Port Harcourt, the center of the nation's oil industry.

Meanwhile, OPEC announced that by 2024, it may not be able to meet its share of global oil demand.

While $100 may be a significant psychological benchmark, the real significance of oil prices lies in the new range over which they roam, said Robert K. Kaufmann, director of the Center for Energy and Environmental Studies at Boston University.

"There's nothing magical about $100," he said. "It's expensive whether it's $85 or $100. Granted, it's $15 more expensive than $85, but $85 is still a lot more than we were paying a year ago."

And it is where Mr. Kaufmann sees the price of oil remaining "for the next couple of months." The likely impact of such sustained prices, he said, is that "maybe we're looking at $4 gasoline."

Global inventories of crude have been dropping for six weeks, and a report due this morning is expected to show a further decline.

The solution to high prices lies in expanding domestic oil and gas production and increasing the nation's refining capacity, Energy Department spokeswoman Megan Barnett said.

Fariborz Ghadar, director of the Center for Global Business Studies at Penn State, said that he does not see that happening.

"We're not doing anything to encourage oil exploration and production," he said, either domestically or abroad. To the contrary, the war in Iraq and sanctions in Iran are helping to constrain even further supplies already tightened by Venezuela's nationalization of its oil, Russia's centralized control of its resources and civil unrest in Nigeria.

"Everything looks terrible," he said. "$100 is now not a plateau, it's a base ... it will continue to go up until we encourage production."

Mr. Kaufmann offered an even more dour assessment.

"All this talk about increasing U.S. domestic production of oil, giving producers big tax breaks, really encouraging them to drill oil, it is nonsense," he said. "We did that in the 1980s. There was a huge burst of drilling effort ... the problem is we didn't find any oil. We took tens of billions of investments and basically flushed them down the toilet drilling dry holes.

"Anybody who thinks we are going to produce our way out of this predicament is seriously misguided."