Across
- 3. - Essential natural resource for all life forms
- 4. - Variety of plant and animal species in an ecosystem
- 5. - Sustainable energy sources
- 10. - Increase in acidity of oceans due to carbon dioxide absorption
- 12. - Pertaining to the entire world
- 13. - Gradual wearing away of land by natural forces
- 15. - Reusing materials to reduce waste
- 17. - Protection and preservation of natural resources
- 19. - Animals in their natural habitat
- 20. - Contamination of the environment
Down
- 1. - Excessive number of people in a given area
- 2. - Clearing of forests for agriculture or development
- 6. - Natural home or environment of a plant or animal
- 7. - Community of organisms and their environment
- 8. - Element found in greenhouse gases
- 9. - Unwanted or discarded materials
- 11. - Disappearance of a species from the Earth
- 14. - Synthetic material that contributes to pollution
- 16. - Long-term weather patterns
- 18. - Protective layer in the Earth's atmosphere