Today, there are more than six billion people across the _____.

At the city landfill, the smell of _____ garbage was everywhere.

Plants _____ the sugars they need to use for growth.

At the museum, we saw hair and feathers that had been _____.

Carbon is _____ underground by both slow and fast process in nature.

Industrialized countries are _____ the highest amounts of CO2 today.

The habits and actions of modern society are _____ the global environment.

Carbon is _____ by various processes as it flows through the carbon cycle.

We are _____ the levels of CO2 in the environment through the burning of fossil fuel.