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Glacial-Interglacial Variability Records of the Pleistocene Ice Ages

Antarctic and Greenland Ice Cores. Glacial-Interglacial Variability Records of the Pleistocene Ice Ages. 740 kyr - Present. Vostok. European Project for Ice Coring in Antarctica (EPICA). Ice Coring. Temperature and Greenhouse Gases from Ice Core Records.

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Glacial-Interglacial Variability Records of the Pleistocene Ice Ages

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  1. Antarctic and Greenland Ice Cores Glacial-Interglacial VariabilityRecords of the Pleistocene Ice Ages • 740 kyr - Present Vostok European Project for Ice Coring in Antarctica (EPICA)

  2. Ice Coring

  3. Temperature and Greenhouse Gases from Ice Core Records Oxygen isotopes from benthic forams are a proxy for ice volume • Greenhouse Gases trapped in air bubbles: Carbon Dioxide (CO2),Methane (CH4),Nitrous Oxide (N2O) • Variations of Deuterium (heavy isotope of Hydrogen) used as a proxy for temperature change

  4. Glacial-Interglacial cycles during past ~450 kyr are of large amplitude and last approximately 100 kyr • Interglacial warm periods constitute only about 20% of the time and were similar in length to the Holocene • Earlier interglacials were generally colder on average Compare to modern levels: CO2 (370 ppm)CH4(1750 ppb) N2O(315 ppb)

  5. How do the Glacial-Interglacial variations in greenhouse gases (GHGs) compare with the Industrial Era GHG increase?

  6. Gray bars show range of natural variability N2O CO2 CH4

  7. Homework #9 Introduction (justification, background?) Description of Experiments Description of GCM you are using Attach print outs of Simulation Summary and Rundeck for all runs you set up • Probably about 3 pages single-spaced • Use images and references

  8. Glacial/Interglacial Cycles Orbital Variations and the Ice Ages (Sea Level Change)

  9. Solar Irradiance Across Latitude and Time DJF Ann. JJA

  10. Orbital Variations • Eccentricity • Obliquity • Precession of the Equinoxes (OmegaT in EdGCM) Milankovitch Cycles

  11. Can GCMs simulate the onset of Ice Ages? • No • Sort of Gallimore and Kutzbach (1996) suggested that tundra increase and boreal forest decrease may have helped trigger ice ages. • But, not really Other models don’t get this result and the distribution of snow accumulation was not correct in G&K 115,000 solar insolation based on orbital parameter changes. + reduced CO2 + ground albedo increase (tundra expansion) + more albedo increase (boreal forest reduction) Gallimore and Kutzbach, Nature, 1996

  12. Sea Level Rise: Last Glacial Maximum to Present

  13. Sea Level Rise: 1880 - 2000 Sea Level Rise 1880 - 2100

  14. Onset of melting during last interglacial period • Last interglacial melting begins (135kyr BP) • Max N.H. summer insolation last interglacial (135kyr BP) • Most recent interglacial melting begins (15kyr BP) • Max N.H. summer insolation current interglacial (15kyr BP) Overpeck et al., Science, 2006

  15. Source of sea level rise during last interglacial Evidence that West Antarctic Ice Sheet (WAIS) contributed to sea level rise during last interglacial includes ice core temperature data showing a substantial warming over East Antarctica despite the lack of a significant insolation signal at that latitude. A

  16. GCM Simulations of Climate Change in Greenland and Antarctica: Last Interglacial & Future Global Warmings AD2130 Anomaly (~4xCO2) Last Interglacial Anomaly AD2100 Anomaly Modern

  17. GCM Simulations of Climate Change in Greenland: Current Global Warming (EdGCM, GISS Model II) ∆ 2000-04 minus 1958-62

  18. GCM Simulations of Climate Change in Greenland: Current Global Warming (EdGCM, GISS Model II) ∆ 2000-04 minus 1958-62

  19. GCM Simulations of Climate Change in Greenland: Current Global Warming (Observations)

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