Across
- 1. living things and their environment in one area
- 4. ground that stays frozen all year
- 7. blanket of air that surrounds Earth
- 9. rotting of dead plants and animals that releases carbon
- 11. long term change in Earths temperature and weather
- 13. process plants use to turn sunlight and carbon dioxide into food
- 14. system of who eats whom in an ecosystem
- 18. gas we breathe out and plants use
- 19. large body of salt water that takes in carbon dioxide from the air
- 20. animal that eats plants or other animals
Down
- 2. element found in all living things
- 3. gas made in swamps and in animal guts
- 5. process where living things use oxygen and give off carbon dioxide
- 6. cutting down trees in a forest
- 8. burning of fuels that puts carbon dioxide into the air
- 10. partly rotted plant material in wet ground
- 12. plant that makes its own food
- 15. warming of Earth when gases trap heat
- 16. coal oil and gas made from ancient plants and animals
- 17. total amount of living matter in an area