Final answer:
The calculation is a simple division of the known oil reserves by the annual oil consumption rate, indicating approximately 40 years of oil left. The factors affecting the lifespan of reserves include new discoveries, geopolitical aspects, and technological advances in extraction.
Step-by-step explanation:
The calculation mentioned in the student's question is an example of estimating the remaining time we have before the world's oil reserves are exhausted. Given that there are 1.2 trillion barrels of oil reserves and a consumption rate of 30 billion barrels a year, dividing the total reserves by the annual consumption rate gives us approximately 40 years of oil left. This calculation assumes that no new reserves are found, and that annual consumption rates remain constant.
However, as noted in the provided information, estimates such as peak oil production and remaining years of oil supply can be quite complex and are not just a simple matter of division.
Factors such as additional discoveries, geopolitical concerns, technological advancements in extraction, and varying consumption rates all influence the lifespan of the world's oil reserves.
Even though proven reserves suggest a certain amount of years remaining, continual exploration could potentially add more to these reserves. Nevertheless, these resources are finite, and global economies must consider future strategies for energy production.