Your article (Big BP discovery refuels debate over 'peak oil', 3 September) gets it wrong. The peak oil debate is complex and mainly revolves around how much oil Opec really have and how much oil can be recovered from fields that have already been discovered. In the two years and hundreds of interviews I carried out for my 2008 film PetroApocalypseNow?, nobody claimed that new discoveries could avert the peak of global oil production. In fact for 50 years, the amount of oil discovered has been steadily dropping and for 30 it has been less than we consume. A 5bn barrel discovery, though extremely lucrative, is only two months' global consumption. The difficulty of BP's remarkable discovery is evidence that as far as oil exploration is concerned we are now scraping the bottom of the barrel.

Andrew Evans

Carnevale Films

www.guardian.co.uk