> That’s for the world population on relatively short time frames (20 to 30 years in the future)
That's one generation. Population models are generally pretty good for two, so out to ~2075 from today. World models are easier because you don't have to model immigration.
“Many of the UN’s historical projections – even as far back as the 1960s – have been remarkably close to the truth.”
That’s for the world population on relatively short time frames (20 to 30 years in the future), though.
Things get harder if you take smaller groups of people or look further ahead.
That’s why, if you look at the UN reports, you’ll see a huge spread in predictions for 2100.
https://www.un.org/development/desa/pd/sites/www.un.org.deve... for example predicts a world population of between (eyeballing the chart) 9 and 12 billion in 2100, and why this article says could and not will.