The price of oil fell below $100 a barrel on Tuesday for the first time in two weeks as investors dumped commodities for safer assets amid worries that the widening disaster in Japan could lead to a global economic slowdown.

But the slide in the price of energy may be short-lived. A variety of factors could increase fuel costs in the next few months, even as supplies remain tight because of the continuing unrest in the Middle East.

“Uncertainty and volatility remain key features of the oil market in the short term,” J. P. Morgan’s commodity analysts wrote on Tuesday. The benchmark American crude spot oil price fell nearly 4 percent, to $97.18 a barrel, in New York after spending the previous nine trading sessions above $100. If the lower price persists, it will probably slow the increase in gas prices at the pump, which averaged $3.56 a gallon nationwide on Tuesday, according to AAA.

Countervailing forces are at work in the energy markets. The combination of earthquake, tsunami and nuclear accidents in Japan could reduce energy demand by Japanese consumers and industries in coming months. Some investors worry that the toll could drive the global economy back into a recession.