After two days: With no one to run the pumps, New York subways flood.
Seven days: Generators that cool nuclear reactor cores run out of fuel.
One year: Human head and body lice grow extinct. Wildlife returns to sites of melted-down nuclear reactors.
Three years: In colder climes, walls and roofs start to separate, pipes burst, roaches die.
20years: Panama Canal closes up. Garden vegetables revert to wild strains.
100 years: Feral housecats devastate populations of small predators. Elephant population grows 20-fold as ivory trade ceases.
300 years: New York bridges fall, dams fail worldwide, cities built in river deltas, such as Houston, wash away.
500 years: Forests overtake suburbs in temperate climes, but plastic and metal debris remain.
Thousands of years: Underground structures such as the Chunnel across the English Channel are the last intact human-made structures.
35,000 years: Lead deposited by smokestacks finally is cleansed from the soil.
100,000 years: Carbon dioxide returns to prehuman levels — maybe.
Hundreds of thousands of years: Microbes evolve to eat plastic.
7.2 million years: Traces of Mount Rushmore images remain. PCBs and other toxins remain but are buried.
10.2 million years: Bronze sculptures are still recognizable.
3 billion years: Life still thrives on Earth, in new forms.
4.5 billion years: Depleted Uranium-238 reaches its half-life. Earth begins to warm as sun expands.
5-plus billion years: Earth burns as dying sun swells to envelop inner planets.
