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Glacial-Interglacial Variability Records of the Pleistocene Ice Ages

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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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Presentation Transcript
slide1

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)

temperature and greenhouse gases from ice core records

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
slide4

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)

slide5

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

slide6

Gray bars

show range

of natural

variability

N2O

CO2

CH4

slide7

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
slide8

Glacial/Interglacial Cycles

Orbital Variations and the Ice Ages

(Sea Level Change)

slide10

Orbital Variations

  • Eccentricity
  • Obliquity
  • Precession of the

Equinoxes

(OmegaT in EdGCM)

Milankovitch Cycles

slide11

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

slide13

Sea Level Rise:

1880 - 2000

Sea Level Rise

1880 - 2100

slide14

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

slide15

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

slide16

GCM Simulations of Climate Change in Greenland and Antarctica:

Last Interglacial & Future Global Warmings

AD2130

Anomaly

(~4xCO2)

Last Interglacial

Anomaly

AD2100

Anomaly

Modern

slide17

GCM Simulations of Climate Change in Greenland:

Current Global Warming (EdGCM, GISS Model II)

∆ 2000-04 minus 1958-62

slide18

GCM Simulations of Climate Change in Greenland:

Current Global Warming (EdGCM, GISS Model II)

∆ 2000-04 minus 1958-62

slide19

GCM Simulations of Climate Change in Greenland:

Current Global Warming (Observations)

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