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Example: Snowball Earth

Example: Snowball Earth. Several putative episodes between 750 Myr and 580 Myr ago. Evidence controversial, but puzzling (e.g., glaciers at sea level at the equator Freeze-fry cycles (global mean temperature -40C to 40C !). Hoffman and Schragg, Sci. Am. 2000. .

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Example: Snowball Earth

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  1. Example: Snowball Earth • Several putative episodes between 750 Myr and 580 Myr ago. • Evidence controversial, but puzzling (e.g., glaciers at sea level at the equator • Freeze-fry cycles (global mean temperature -40C to 40C !) Hoffman and Schragg, Sci. Am. 2000

  2. . 50 Myr ago, Eocene warm period Crocodiles on Ellesmere Island (80N) • How do you get crocodiles (cold-blooded) to survive • through the polar night on Ellesmere Island? • Or palm trees in Wyoming (interior of continents)?

  3. The last 70 Million years (Zachos et al.,Science 2001)

  4. The Ice Ages • Long term cooling and cyclic ice ages over the last 4 Myr Time (Myr) d18O in ocean sediment (Proxy for global ice volume)

  5. The Ice Ages

  6. A wobbly planet (Milankovitch) Time (kyr)

  7. The ice ages • Reconstruction of land and sea ice 21,000 years ago February July CLIMAP reconstruction

  8. Different wildlife!

  9. Ice sheet margin (northern Greenland)

  10. mid Holocene 5000 to 6000 yrs ago - Hippos in the Sahara Lamb: Climate, history, and the modern world

  11. The little ice age ~1600 to ~1850 A Frost Fair on the Thames at Temple Stairs (1684) Abraham Hondius, 1684 Extensive advance of glaciers in Europe Long, severe winters Was it global?

  12. oC Warm phase Cool phase

  13. Example of PDO impacts Mantua et al., 1997

  14. El-Nino Southern Oscillation Nino 3 index of Pacific sea surface temperatures

  15. Climate impacts of ENSO are global

  16. North American temperatures

  17. Sea surface temperatures

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