Ghawar is in Saudi Arabia and is by far the largest oil field ever discovered. Once it (most likely right now) goes into terminal decline its production cannot be made up from other sources and the age oil will be over in short order.
>> Then what happens? <<
Again, oil is not like any other commodity....I mean if mad cow gets out of hand, we all have to eat chicken. But what comes after oil? Right now the answer is alot of hungry people......we need our next source of energy- now.