Today’s energy predicament is a strange situation that most modelers have never really considered. Let me explain some of the issues I see, using some charts.
 It is probably not possible to reduce current energy consumption by 80% or more without dramatically reducing population.
A glance at energy consumption per capita for a few countries suggests that cold countries tend to use a lot more energy per person than warm, wet countries.
This shouldn’t be a big surprise: Our predecessors in Africa didn’t need much energy. But as humans moved to colder areas, they needed extra warmth, and this required extra energy. The extra energy today is used to build sturdier homes and vehicles, to heat and operate those homes and vehicles, and to build the factories, roads and other structures needed to keep the whole operation going.
Saudi Arabia (not shown on Figure 1) is an example of a hot, dry country that uses a lot of energy. Its energy consumption per capita in 2019 (322 GJ per capita) was very close to that of Norway. It needs to keep its population cool, besides running its large oil operation.
If the entire world population could adopt the lifestyle of Bangladesh or India, we could indeed get our energy consumption down to a very low level. But this is difficult to do when the climate doesn’t cooperate. This means that if energy usage needs to fall dramatically, population will probably need to fall in areas where heating or air conditioning are essential for living.
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