seanpm2001 πΊπ¦οΈπ¬π±Population estimate and critical mass
Time it took/takes to go up 1 billion
100,000,000+ years (1 billion)
? years (2 billion)
? years (3 billion) (1960)
14 years (4 billion) (1974)
13 years (5 billion) (1987)
12 years (6 billion) (1999)
12 years (7 billion) (2011)
11 years (8 billion) (2022)
PREDICTION, DATA PATTERN ONLY: 10 years (9 billion) (2032)
PREDICTION, DATA PATTERN ONLY: 9 years (10 billion) (2041) [CRITICAL MASS]
PREDICTION, DATA PATTERN ONLY: 8 years (11 billion) (2049) [TOO OVERPOPULATED TO SURVIVE, 2042-2044+]
These predictions are based on the data pattern only. There are other factors that can have an affect this as well (environment, resources, famine, fertility rate, sex education, war, genocide, extinction, economy) they are much harder to predict in the big picture.
Again, everything regarding doomsday seems to point towards 2050 CE (the date in which most endgame scenarios will happen by) that hasn't changed in over a decade.