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Past Climates or

Past Climates or. Paleoclimatology. Estimated Phanerozoic Temperatures (14° is Today; 16° is Critical and 18° is Catastrophic for Humans). Generalized Climates for the Past 3 Billion Years. Climate Change During Past 180 Million Years. Cenozoic Era. End of Cretaceous (65 My BP). Present Day.

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Past Climates or

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  1. Past Climatesor Paleoclimatology

  2. Estimated Phanerozoic Temperatures(14° is Today; 16° is Critical and 18° is Catastrophic for Humans)

  3. Generalized Climates for the Past 3 Billion Years

  4. Climate Change During Past 180 Million Years

  5. Cenozoic Era End of Cretaceous (65 My BP) Present Day

  6. The Paleocene-Eocene Thermal Maximum (PETM)

  7. The Pliocene/Pleistocene “Ice House”

  8. Summary: Cenozoic Era 1.Dominant Forcing: Natural Differences in CO2 - Rate ~100 ppm/Million years (0.0001 ppm/year) - Human-made rate today: ~2 ppm/year (20,000 times faster than the natural rate) Humans Overwhelm Slow Geologic Changes 2. Climate Sensitivity High - Antarctic ice forms if CO2 < ~450 ppm - Ice sheet formation reversible Humans Could Produce “A Different Planet”

  9. Change in Sea Level During the Last Glacial and Interglacial Periods

  10. Sea Level in North America if all Ice on Earth Melted

  11. Extent of the Ice Sheet that Covered North America during the Last Ice Age

  12. Temperature Variations During the Past 140,000 Years

  13. Abrupt Climate Change: Our Worst Nightmare

  14. Variations in Temperature During part of the Last Ice Age

  15. The Younger Dryas (YD) and Other Abrupt Climate Changes

  16. Several Abrupt Climate Changes

  17. Nine current tipping elements vulnerable to possible abrupt change. The time frames and threshold temperature increases may be modified with more data.

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