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Global Warming

Global Warming. Or Climate Hysteria?. The Long View. The Earth has repeatedly experienced climate change throughout its long history The Phanerozoic Eon is characterized by fluctuations between “Greenhouse” and “Icehouse” climates. Greenhouse World.

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Global Warming

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  1. Global Warming Or Climate Hysteria?

  2. The Long View • The Earth has repeatedly experienced climate change throughout its long history • The Phanerozoic Eon is characterized by fluctuations between “Greenhouse” and “Icehouse” climates.

  3. Greenhouse World • Cretaceous Period was one of significant warmth. • Tropical temperatures not much different. • Much warmer at poles – no ice! • Current models cannot duplicate these conditions.

  4. The Great Cooling • The bottom water of the ocean has cooled gradually – but dramatically over the past 100 million years. The Eocene Climatic Optimum

  5. The Eocene Climatic Optimum • Tropical fossils found at high latitude. • Fossil forest sites on Axel Heiberg Island, NWT, Canada • Turtles, Crocodiles and other fauna excavated from nearby Ellesmere Island

  6. The Eocene Climatic Optimum • Tropical fossils found at high latitude. • Fossil forest sites on Axel Heiberg Island, NWT, Canada • Turtles, Crocodiles and other fauna excavated from nearby Ellesmere Island

  7. The Eocene Climatic Optimum • Birches, laurels, tulip trees, metasequoia, and other deciduous tree species lived happily at 83N, where six months of darkness prevailed!

  8. Ocean Circulation • Some researchers believe that ocean circulation holds key to long-term changes • Continental drift allowed circumpolar flow around Antarctica in the Miocene • Renewed glaciers in Antarctica

  9. Sea Level Changes • Sea level has also been much higher throughout “recent” Earth history Our most recent ice ages

  10. Rapid Changes Can Also Happen! • Paleocene-Eocene Thermal Maximum (PETM)

  11. Ocean responded within 10,000 years. Caused by sudden release of methane(?) from the continental shelf (??) Back to “normal” within 100,000 years Paleocene-Eocene Thermal Maximum

  12. Earth Today: The Ice Ages • We live in an “icehouse” period that has been around for the last ~1 million years. • Typified by short warm interglacials and then long declines into glacial episodes.

  13. What causes these cycles? • Changes in the Earth’s orbital parameters (Milankovitch cycles). • Distance to the sun • Precession of the Earth’s axis • Changing of angle of inclination • These don’t work all that well, but no one has a better idea!

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