Crude oil prices surged to $147.50 per barrel in July 2008 before tumbling to $35 five months later in the eye of the financial storm. Price are now hovering between $70 and $80 per barrel.
"Volatility has receded compared to the roller-coaster of 2007 and 2008," Nobuo Tanaka told reporters on the sidelines of an energy forum in Tokyo.
"But the market could easily become again more volatile once the world economy grows again and the supply tightens." Among factors that would induce volatility, Tanaka cited the absence of fruitful negotiations over tackling climate change as well as persistent uncertainty over the outlook of many economies.
According to a scenario offered by the Paris-based IEA, which represents the energy interests of 28 developed economies, oil prices may climb to $100 a barrel in 2020 and up to $200 in 2030.
The rise would be less if measures are taken at a global level to improve energy efficiency, according to the agency.
"The cheap energy age is over and we have to prepare for that in the government and private sector," said Tanaka.
He urged governments to open access to energy reserves and said "encouraging investment on the production side could lessen volatility."
The IEA held a two-day forum that ended Friday to examine potential policies and regulatory measures aimed at increasing oil market transparency.
World oil prices jumped close to $80 on Friday as traders welcomed news of stronger-than-expected economic growth in top energy consumer the United States.
New York's main futures contract, light sweet crude for April delivery, rallied $1.47 to $79.64 a barrel, having touched $79.98 after publication of the data.
London's Brent North Sea crude for April delivery soared $1.24 to $76.53 per barrel at about 1550 GMT.
