Across
- 2. Pesticide criticized in the '60s
- 6. Unwanted byproducts
- 9. Element associated with greenhouse gases
- 11. Study of organisms and their environment
- 14. Type of sustainable energy
- 17. Large body of salt water
- 18. Layer protecting Earth
- 19. Environmental club founded by John Muir
- 20. The natural world
Down
- 1. Group of organisms capable of interbreeding
- 3. Poisonous substance
- 4. Energy from the sun
- 5. Reuse waste materials
- 7. Air pollution problem
- 8. Contaminate the environment
- 10. Knowledge or perception
- 12. Fossil fuel causing spills
- 13. Silent Spring author
- 15. Community of living organisms
- 16. Large area covered chiefly with trees