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Paleoclimate

Paleoclimate. Primary Source: IPCC WG-I Chapter 6 - Paleoclimate. How do we know past temperature?. Changes in growth (e.g., tree rings) Changes in organism/plant distributions (e.g. via pollen) Changes in isotope ratios Historical records . Need cross verification!.

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Paleoclimate

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  1. Paleoclimate Primary Source: IPCC WG-I Chapter 6 - Paleoclimate

  2. How do we know past temperature? Changes in growth (e.g., tree rings) Changes in organism/plant distributions (e.g. via pollen) Changes in isotope ratios Historical records Need cross verification!

  3. How do we know past CO2? • Gas particles in ice cores [ to ~ 650k yr] • Carbon isotope differences between atmosphere & • soils (palaeosols) • seawater (phytoplankton) • Boron isotopes • Stomatal openings versus CO2 concentrations Need cross verification!

  4. Dating Methods

  5. Climate in the Distant Past - 1 Extent of ice sheets Reference CO2 Levels Current: ~ 370 ppm Pre-industrial: ~ 275 ppm

  6. Climate in the Distant Past - 2 Reference CO2 Levels Current: ~ 370 ppm Pre-ind: ~ 275 ppm Ice Volume Temperature

  7. Climate from Ice Cores Year 2000 Marine Record

  8. Locations of Proxy Records • Sources • Tree Rings • Boreholes • Ice cores • Documentary data • “Other” • Thermometers

  9. Northern Hemisphere Temperature Reconstructions

  10. Simulations with “Models of Intermediate Complexity” All Forcings Natural Only

  11. END Paleoclimate

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