Across
- 4. A treaty to reduce greenhouse gases in 1997
- 5. the warming of Earth's atmosphere caused by increased concentrations of greenhouse gases from human activities, which trap more heat than the natural greenhouse effect
- 7. a large geographical region characterized by its climate
- 8. site for the disposal of waste materials
- 12. the complete disappearance of species
- 15. measure of the Earth's global average surface temperature increase that results from a doubling of atmospheric carbon dioxide
- 16. outermost rocky shell of a terrestrial planet or natural satellite
- 17. it is composed of roughly 78% nitrogen, 21% oxygen and 1% other
- 19. gases in Earth's atmosphere that trap heat
- 20. the dehydration of fertile land
Down
- 1. the gradual increase in the temp of the earth
- 2. acts as a protective shield by absorbing most of the sun's harmful ultraviolet radiation
- 3. the removal of forests
- 6. the sum of all ecosystems on earth
- 9. the sum of all water on and under earth surface
- 10. was a peace agreement
- 11. the total collection of all genes
- 13. long, cylindrical samples of ice drilled
- 14. the variety of all life on earth
- 18. a natural process that warms the earth