A common concern about life extension is that we would rapidly overrun the planet, and without management, this could happen. However, there a few factors in our favour.
In many countries, fertility rates are already dropping below that required to maintain a population, and without immigration the number of people living there would be falling.
Even with biological immortality, if people were limited to one child each, then there would be a finite maximum population to deal with. And biological immortality does not mean fictional immortality - people will still die in accidents, conflict or by choice, meaning the global population would eventually start falling again.
We will have a lot of time to come up with a solution - the population won't double overnight, it might take a 100 years or so, and it's impossible to imagine what technologies may have been developed by then to help.
According to David Wood of London Futurists if death stopped tomorrow it
would take a hundred years to double the planet's
See also: Space Colonization
ResourcesMore Overpopulation resources
Overpopulation Blog Posts
Ghost towns getting recolonized by flourishing wildlife
Guardian - 24-Jan-2021
Falling birth rate is a global concern; nature reserves reclaimed abandoned townsRead more...
South Korea's falling birth rate is worrisome
BBC - 04-Jan-2021
A declining population is detrimental to the country's economyRead more...
Researchers estimate world population could crash by 2100
BBC - 14-Jul-2020
Decline in fertility rate may shrink the global population drasticallyRead more...