ON THIN ICE

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Across
  1. 2. the action of making the air dirty
  2. 4. make less
  3. 6. to cover a place with water
  4. 7. switch off the lights
  5. 8. to look for sth
  6. 12. an increase in the world's temperature due to pollution
  7. 14. a flat part of land usually below sea level
  8. 17. to no longer exist or be seen
  9. 19. to make or become larger;add to
Down
  1. 1. a long period without rain
  2. 3. the plants we grow to eat don't grow properly
  3. 5. the large areas of ice at the polar regions
  4. 9. to not waste electricity
  5. 10. to die under the water because you cannot breathe
  6. 11. to become part of sth
  7. 13. a repeating change in weather conditions
  8. 15. in place of
  9. 16. height, position
  10. 18. to become liquid because of heating