Unit review game

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Across
  1. 3. Rev Farming method that led to high crop yields, but also environmental damage
  2. 5. formation Pollutants trapped near the Earth's surface by heat
  3. 11. acidification The rising acidity of oceans due to CO₂ absorption
  4. 12. Engineered crops with modified DNA
  5. 17. The process by which land becomes desert
  6. 18. A process that removes salt from seawater
  7. 20. The spread of cities and loss of natural land
Down
  1. 1. Fishing practice that leads to species depletion
  2. 2. Wastewater treatment that makes water safe again
  3. 4. The increasing number of people on Earth
  4. 6. Farming practice of growing one crop over large areas
  5. 7. warming The human-caused increase in Earth's temperature
  6. 8. pollution Contamination of land by human activities
  7. 9. Harmful substances entering water bodies
  8. 10. A gas that contributes to smog and acid rain
  9. 13. Extracting minerals from the earth
  10. 14. A gas that contributes to the greenhouse effect
  11. 15. pollution Harmful substances in the air
  12. 16. The process of clearing trees without replanting them
  13. 19. layer The thinning of a protective atmospheric layer