The IEA (2009) esteems that the era of cheap oil has passed and that prices will soon revert to $100 a barrel leading to a price tag of $200 a barrel by 2030. The main reason for this being that oil and gas companies will find it increasingly difficult to extract enough oil to make up for the decrease productivity of mature oil fields. The oil industry will have to invest $350 billion dollars each year until 2030 in order to overcome the sharp decrease in productivity of the existing oil wells and to discover new fields. The IEA believes that output from the world’s oil fields is declining at 9%. This problem is magnified as the oil giants are pulling out of projects in places like Kazakhstan and Canada as the low price means costly excavations are no longer viable. The IEA estimates that firms like Shell and BP need to invest $350bn a year to replace older wells as well as meet demand from fast growing economies like China.