1. True or false? A single year of record-breaking heat is a definite sign of climate change.

2. True or false? Modern human emissions of CO₂ are about equal to natural emissions from volcanoes.

3. True or false? Most of Earth’s carbon is stored in the lithosphere.

4. True or false? To stabilize CO₂ concentrations in the atmosphere, human carbon emissions must be cut by about 80% in the next few decades.

5. True or false? Worldwide, most mountain glaciers are receding upslope in response to anthropogenic climate change.

6. Multiple choice: During the last 800,000 years, natural atmospheric CO₂ concentrations did not rise above

7. Multiple choice: Today’s atmospheric CO₂ concentration is about

8. Multiple choice: Why are the oceans becoming more acidic?

9. Fill in the blank: The ___________________ is a graph of measurements that show increasing CO₂ concentrations in the atmosphere.

10. Fill in the blank: The study of ancient climate is called _________________________________.