What are signs we have/haven't reached peak oil?

In reality, we won't know whether we have hit peak until several years of declines. But a combination of very high prices and little incremental production in response is a sign that something is afoot. At present, global production rates have been flat to slightly increasing since about 2005. It is possible that we may squeeze a small bit more out before peaking.

But the actual peak date is somewhat irrelevant. We are already experiencing symptoms of peak oil, whether the event has actually taken place or not. The huge run-up in prices over the past decade provides a strong indication that the supply/demand situation is worsening. When the actual peak occurs and production rates are declining year after year, the price spikes of recent years are likely to look mild in hindsight.

Determining whether we have reached world peak oil production depends partly on how one defines oil. In the past oil has been defined as crude oil plus lease condensate (very light hydrocarbons captured and separated at the wellhead or field). Both of these are easily refined into petroleum products such gasoline, diesel, and kerosene by conventional refineries.

Using this definition oil production appears to be on a plateau which began in 2005 bouncing between 70 and 75 million barrels per day with production not responding to record prices of recent years. This would indicate an impending peak. Geology is now trumping technology and limiting our access to this conventional crude.

The fact that most energy agencies and private consultancies now use a broader definition of oil called total liquids tells us that the world must now rely increasingly on liquid fuels which have not heretofore been lumped in with oil. This category includes fuels such as ethanol, biodiesel, natural gas liquids, bitumen from the tar sands, extra-heavy oil, coal-to-liquids, gas-to-liquids, and shale oil (not to be confused with oil shale which has never been produced commercially).

Government energy agencies admit that growing supplies of liquid fuels now depend on these fuels which are beyond the category of conventional oil. As such they are typically much more energy intensive to extract and process (yielding less net energy than conventional oil), much more expensive to produce (per unit of energy), have longer lead times before known sources can be exploited, have very high capital costs, and typically flow at slower rates. All of this means that if conventional oil production begins to decline in earnest, it will be very difficult for these unconventional sources to make up that gap, let alone provide growth in supplies.

Therefore, I conclude that even peak liquids production is nearby, certainly no more than a decade away and probably less. Naturally, technological developments, unexpected new large discoveries, events in the world economy which hamper or help the oil and gas industry in its exploration and production efforts could move this date forward or backward. But I don't think that movement will amount to more than a few years.

(Please note that peak production is really about the rate of extraction, not the size of reserves. There are indeed large reserves remaining of both conventional and unconventional sources of liquid fuels. The key question is at what RATE we can extract them. Here is an analogy: If you inherit a million dollars with the stipulation that you can only draw out $500 a month, you may be a millionaire, but you will never live like one. That increasingly is our situation with regard to the rate of production of liquid fuels.)

Prices are high but not that high. The US alone has enough oil to last for hundreds of years but politics and political (environmental) correctness won't allow us to tap most of it. Imagine the jobs that would be created and the economic boon.

The hundreds of years prediction might be very conservative. The abiotic theory suggests that oil is not a fossil fuel but is constantly being created in the Earth's crust and mantle.

Whether the powers in business and world governments know this is unknown. However, if it was known or proven to be true, oil prices would be 5 bucks a barrel and profits would cease for oil companies as well as for OPEC and dictators like Chavez.