Well Ill be derned...
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The United States Geological Survey's (USGS) World Energy Resources Program (WERP) produces the federal government's estimates of world oil resources.
The volume of the world's petroleum reserves is important because of the fear that the oil will run out. This fear should be expected, because the estimated 1 trillion barrels of crude oil is only enough to supply the world for about 50 years.
This prediction is based on the present world consumption, however, world consumption is expected to increase. Although the known reserves are only about a trillion barrels (1 barrel equals 159 liters, 42 gallons, or 0.16 m3), the estimated world reserves, according are about 1.5 x 1011 m3.
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The 400 to 500 years figure was just something I recalled from a popular science magazine about twenty years ago. I never would have imagined the change in estimating would be that drastic.
So whats your point here?