[notmyfriend]

Fossil fuels are only part of the usage. Oil and hydrocarbons are used in a lot industrial production, housing, foams, chemical plants etc. Even if you somehow replaced all fossil fuels with some other energy alternative (nuclear container ships, electric cars, trucks, trains and planes) you would still use a massive amount of hydrocarbons from oil and gas to power the worlds economy.

And before you say use plant based hydrocarbons. It's kind of perverse to use trees and food crops to create fuel and industrial products.