Since 2005, the global production of oil has remained relatively flat, peaking in 2008 and declining since, even as demand for petroleum has continued to increase. The result has been wild fluctuations in the price of oil as small changes in demand set off large shocks in the system.
In today's issue of Nature, two authors (the University of Washington's James Murray and Oxford's David King) argue that this sort of volatility will be all we can expect from here on out—and we're likely to face it with other fossil fuels, as well.
The Nature article is behind a paywall, but I found a nice summary on Ars Technica.
The concern is not only with oil:
US coal production peaked in 2002, and the global peak has been predicted to hit as soon as 2025. The last time global coal reserves were evaluated, in 2005, the total was cut by more than half compared to previous estimates. Fracking has boosted the production of natural gas dramatically, but even here the authors find some reasons for concern. Recent reports suggest that shale gas reserves have been overestimated, and many fields that have been in production for a while have experienced large declines in production.
Now is the time to wean ourselves off of our addiction to fossil fuel. We need alternatives, ASAP.