Final answer:
The geographic extent of the petroleum system at a critical moment is influenced by extraction rates, geology, geopolitical factors, and the availability of easier resources. Hubbert's Peak Oil theory and geopolitical distribution of reserves also contribute to the definition of this extent.
Step-by-step explanation:
The geographic extent of the petroleum system at the critical moment is defined by various factors such as the rate of extraction, geological considerations, and geopolitical influences. Hubbert's Peak Oil theory suggests that production rates tend to peak when about half of the resource is depleted. With diminishing reserves, nations like the United States cannot meet their oil demands domestically, leading them to extract oil from more challenging environments, which can cause environmental risks and geopolitical tension. As easier resources are consumed, countries are compelled to turn to more difficult and less energy-efficient sources like bitumen and oil shale, which have significant environmental consequences.
Additionally, the available extraction machinery and the depth at which oil is found can limit the rate at which oil can be extracted. Geopolitical aspects also play a pivotal role as proven oil reserves are often found in countries that may not have the best relations with those with the highest consumption. Recognition of this dynamic is essential, especially in the case of fossil fuel-dependent economies that are on a collision course with resource limitations and environmental concerns.