A pandemic is an apocalyptic solution but it is the most democratic as people throughout the world would be killed. We also have a pandemic about every 20 years.
A world war sounds a bit bloody and compulsory sterilization is a bit fascist!
A big push towards upscaling CO2 capture and storage technology along nuclear power and more renewables would be my first preference.
And the big hope in a couple of decades is unlimited fusion energy--then we can create a paradise for 10 billion people.
