Humanity lived off th surface of the earth for thousands of years to maybe a billion people. The breaking of the crust say in about 1500 to dig out coal and pump out oil made it possible, with the fossil sources, to increase to 8 billion now . The future projections ot 9, 10 or 11 assume everything else remain in place or augments, We are living off the new resources and by using them polluting, both at the same time suggesting the end of the dependence on fossil sources.
Those who suggest a process over say fifty years to be able to mid course correct, drawing directly from the sun without pollution and without energy companies acting as intermediaries, are not taking into account important details.
Who will do what and when will they do it? The social reaction to anticipated events may be worse earlier than the events themselves. As people sense the looming difficulties childbirth is already down. Our society needs people managing critical infrastructure. What if the people managing say nuclear power plants, elevators, communications networks, begin to leave their jobs which they see as likely to end anyway?
If energy use is really cut many activities would become useless. Office buildings dependent on air conditioning. As a shift is made from fossil to solar everyone would have to rethink what appliances they are using. More than fifty percent of the homes in the US are heated with gas. Same more or less with cooking and hot water. Who pays for the new electrical appliances? How could so many be manufactured without the process itself being a polluter, since new electrical heaters require metals that need to be mined? And the cost of the substitution? And siposal?
So it looks like the logistics of change are going to swamp the process. If curtailing fossil use means less transportation, what do people imagine about food delivery ? And lets face it, travel for fun will either stop or be more costly, and same for business travel, such as conferences. The social reaction across a wide spectrum of activities is likely to be confusing, frustrating and angry.