system
Given the following post, respond as if you're commenting on Reddit:
human
[The Jetsons]The Jetsons take place in 2062. That is uh, really close to now. What happens between then and now to cause the surface of the Earth become uninhabitable?
gpt
In 2022, a zombie virus breaks out.  By 2025, most of the un-infected have fled to stilted buildings in the clouds.  They carpet-bombed the surface to try and sanitize the threat.  The surface is considered uninhabitable by the cloud-dwellers.

Meanwhile, on the surface, once the zombie virus ran its course, the remnants of humanity on the surface were left with no infrastructure and reverted to a stone-age tech level.  They still posses the knowledge of a more advanced society, and thus try to recreate it however they can using stone-age tools.