What is the single largest source of carbon dioxide being added to the atmosphere every year?

What compound is now used as the primary replacement for CFCs?

Livestock, the production of fossil fuels, and the decomposition of wastes in landfills are common sources of what greenhouse gas?

If everyone on Earth lived like Americans do, hypothetically, we would need 5 Earths to support everyone.

Estimates from different sources vary, but it is generally thought that, globally, about how many people die from starvation and/or complications related to malnutrition every year?

With respect to vehicles, what does the abbreviation “CAFE” stand for?

Which is an example of a conditionally renewable energy resource?

The U.S. currently makes up approximately what percent of the world’s total population?

Globally (at the current rate of deforestation) approximately what percent of tropical rainforest will be destroyed by 2050?

What Law of Physics states that when energy is converted from one form to another, some of it is always transformed to less usable or unusable energy?