Across
- 4. the season when Carbon dioxide levels are highest.
- 7. ice that is in the sea.
- 8. CO2
- 9. water expands in volumes as it warms.
- 12. ice cores.
- 14. one of the greenhouse gasses.
- 15. when the hemisphere is facing the sun.
Down
- 1. the thin layer of gases that surrounds the earth.
- 2. the glaciers retreat back to the poles.
- 3. ice that is on land.
- 5. used to measure the past atmosphere of the earth.
- 6. when the glaciers are expanding.
- 10. the season when Carbon dioxide levels are the lowest.
- 11. the letter O on the periodic table.
- 13. rising because water is flowing in form melting ice sheets.