ESTIMATED TIMES FOR THE DISAPPEARANCES OF TRACES OF MAN [it's so typically egocentric for humans to think the world will end when we do...]

Immediately:
Most endangered species start recovering.

24 – 48 hours:
Light pollution ended.

3 Months:
Air pollution(nitrogen and sulfur oxides) lessens.

Within 10 Years:
Rural roads and villages overgrown.
GM crops disappear.

Within 50 Years:
Fish stocks recover.
Nitrates and phosphates in fresh water gone.

50 to 100 Years:
Urban streets and buildings overgrown.

100 Years:
Wooden buildings decay.

100 to 200 Years:
Bridges collapse.

Within 200 Years:
Metal and glass buildings collapse.
US grain belt returns to prairie.

Within 250 Years:
Dams collapse.

Within 500 Years:
Corals regenerate.

500 to 1,000 Years:
Organic landfill wastes mostly decayed.

1,000 Years:
Most brick, stone, and concrete buildings gone.
Carbon dioxide in atmosphere back to pre-industrial levels.

50,000 Years:
Mankind’s tenure is mostly marked by a few archaeological remains.

But some man-made chemicals only disappear after 200,000 years, and nuclear waste can remain deadly for up to two million years.