Caption: The end of oil?

The values used in the figure are out-of-date since they come from 2003 and may NOT have been too accurate even then. But the R/P ratio is of order decades in any case.

The R/P Ratio for Oil:

For a non-astronomical example---a real R/P ratio example---the proven reserves of oil (AKA petroleum) (which is that part of oil resources thought to be economically extractable: Wikipedia: Mineral Resources) is circa 2020 of order 1800 Gbl (i.e., 1800 billion barrels or gigabarrels: see Wikipedia: List of Countries by Proven Oil Reserves) and the world circa 2020 uses about 30 Gbl/year (see Wikipedia: List of Countries by Proven Oil Reserves). So R/P ratio is given by

t = R/P ≅ 1800 Gbl/(30 Gbl/year) = 60 years .

If used numbers are treated as hard, then there are ∼ 60 years before all the oil in the world is gone. But the numbers are NOT hard.

Of course, things are NOT as simple as the calculated R/P ratio value suggests:

1. The rate of use may change. It may go up with increasing demand from rapidly developing countries---most obviously China---but it must fall eventually.

2. The proven reserves may change with new calculation methods.

3. Much more oil may be found---but this is unlikely since the discovery of giant oil fields peaked in the 1960s or 1970s (see Wikipedia: Giant oil and gas fields: Recent and future giants).

4. On the other hand, improved extraction techniques can increase proven reserves. They often do improve.

5. Then there is currently, economically unrecoverable oil-like fluids: e.g., shale oil (which is NOT the "shale oil" produced by fracking). These are currently too expensive to utilize: "There are no economically viable ways yet known to extract and process shale oil for commercial purposes." (Wikipedia: shale oil: Reserves and production). However, potentially such fluids could keep us burning "oil" for all of the 21st century.

6. But we might NOT want to burn all oil and oil-like fluids if we want want to stop the rising carbon dioxide (CO2) abundance in the Earth's atmosphere that is causing global warming.

   Maybe we will NOT burn the last drop of oil and oil-like fluids, but move to a renewable-energy economy sooner.

7. In any case, oil and oil-like fluids might become too expensive compared to renewable energy sometime soon.