Past Climate Changes

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Across
  1. 2. Earth got so warm during the Eocene Period that water in places that were normally very cold or even frozen, such as places near the Arctic Circle, became ____________.
  2. 5. Climate changes on Earth have to do with the amount of __________ that enters Earth’s system compared to the amount of energy that exits.
  3. 9. During the__________ Period, the average global temperature may have fallen as low as -12°C (10°F).
  4. 10. Whatever caused Snowball Earth during the Cryogenian Period, __________ energy must have entered Earth’s system than exited.
  5. 12. The only living things on Earth during the Cryogenian Period were simple sponges, worms, and microscopic creatures such as __________ and algae.
  6. 13. Scientists study past climate changes to find out what might happen as Earth’s climate changes, both ___________ and in the future.
  7. 14. ____________ and other dinosaurs may have gone extinct because of a change in climate.
  8. 15. The Cryogenian Period was much colder than any ordinary _____________.
  9. 19. The increase in _____________ in the atmosphere made the climate even warmer during the Eocene Period.
Down
  1. 1. When the energy entering and exiting are in ____________, global average temperatures will stay the same.
  2. 3. Gases that affect the Earth system in a way that stops some outgoing energy from leaving the Earth system, such as carbon dioxide, are called ________________ gases.
  3. 4. During the Cryogenian Period, the equator, which today is warm and tropical, experienced ___________ temperatures back then.
  4. 6. During the Cryogenian Period, nothing lived on land at that time— all life was in the ____________.
  5. 7. The balance of energy entering and exiting the Earth system changed in such a way that ___________ energy entered the system than exited during the Eocene Period.
  6. 8. Whatever caused the extreme warming in the early Eocene Period, the increased temperature tells us that more energy was ___________ by Earth’s surface during that time.
  7. 11. During the Cryogenian Period, Earth’s surface was an icy wasteland that scientists have nicknamed “_____________ Earth.”
  8. 16. Alligators, which are warm-water organisms, lived in the ____________ during the Eocene Period.
  9. 17. The increase in carbon dioxide in the atmosphere made Earth a very warm place in the ___________ Period.
  10. 18. During some periods in Earth’s history, Earth has been ______________ than it is now.