Across
- 7. chain A sequence in which each living thing eats the one below it
- 9. A problem or topic that needs to be discussed or solved
- 11. Describes something that cannot be undone or changed back
- 13. A sudden, terrible event causing great damage or suffering
- 14. Causing damage, danger, or a negative effect
- 15. change A long-term shift in temperatures and weather patterns
Down
- 1. layer A protective part of the atmosphere that blocks dangerous UV rays
- 2. The gradual reduction or use-up of a natural resource
- 3. The outer or top layer of an object or the Earth
- 4. cancer A serious illness caused by too much exposure to sunlight
- 5. A person who conducts experiments to understand how things work
- 6. A substance that makes air, water, or land dirty or dangerous
- 8. rain Precipitation that contains harmful chemicals from air pollution
- 10. A goal or something a person tries to achieve
- 12. The act of releasing gases, especially harmful ones, into the air