Atmosphere 2

12345678910
Across
  1. 3. Algae evolved 2._____ billion years ago
  2. 4. The 2nd most abundant gas in our atmosphere
  3. 6. Causes global dimming
  4. 9. The name of combustion in limited oxygen
  5. 10. A planet that has a carbon dioxide atmosphere
Down
  1. 1. A gas in the Earth's early atmosphere
  2. 2. Farming produces this greenhouse gas
  3. 5. The most abundant gas in our atmosphere
  4. 7. Acid rain is caused by ______ dioxide
  5. 8. Carbon monoxide has this effect on humans