This question prompted by discussion regarding this answer to a question about vegetarianism.
I recently came across a U.N. review of studies seeking to determine the earth's maximum sustainable human population: "One Planet, How Many People? A Review of Earth’s Carrying Capacity".
The review itself is from 2012, when the world's population was 7.1 billion. The population today is around 7.5 billion. The range of estimates reviewed goes from 2 billion to 1 trillion(?!):
Conveniently, most studies put the limit at 8 billion, a number just below the present population.
In the six years since this review, has a more robust, consensus-driven method been developed to determine the limit? What limit has been determined?
I'm interested both in the estimate itself, and a discussion of how the methodology used to make the estimate has improved over time.