Human beings are everywhere. With settlements on every continent, we can be found in the most isolated corners of Earth’s jungles, oceans and tundras. Our impact is so profound, most scientists believe humanity has left a permanent mark on Earth’s geological record. So what would happen if suddenly, every human on Earth disappeared? Dan Kwartler investigates.

Here are some questions related to the video:

1. How long would the underground rail systems flood when the drainage bumps are abandoned?

2. Which place would decay more slowly, rural or urban?

3. Would the reduced light pollution save or destroy birds?

4.How many years would it take for CO2 to return pre-human levels?

5. What would survive for 7.2 million years?

Blanken the space below to check your answers:

1. 3 days

2. Rural

3. It would save a billion birds each year.

4. 65000 years

5. Carved in unyielding granite, America's Mt. Rushmore