QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Glacial-Interglacial VariabilityRecords of the Pleistocene Ice Ages

740 kyr - Present

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

European Project for Ice Coring in Antarctica (EPICA)Vostok

Antarctic and Greenland Ice Cores

Ice Coring

Temperature and Greenhouse Gases from Ice Core Records

• Oxygen isotopes from benthic forams are a proxy for ice volume

• Variations of Deuterium (heavy isotope of Hydrogen) used as a proxy for temperature change

• Greenhouse Gases trapped in air bubbles:

Carbon Dioxide (CO2), Methane (CH4), Nitrous

Oxide (N2O)

• 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 tomodern levels:CO2 (370 ppm) CH4

(1750 ppb) N2O (315 ppb)

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

Gray barsshow rangeof natural variability

CO2

CH4

N2O

Homework #9

1. Introduction (justification, background?)

2. Description of Experiments

3. Description of GCM you are using

4. Attach print outs of Simulation Summary and Rundeck for all runs you set up

Probably about 3 pages single-spaced Use images and references

Glacial/Interglacial Cycles

Orbital Variations and the Ice Ages(Sea Level Change)

Glacial/Interglacial Cycles

Orbital Variations and the Ice Ages(Sea Level Change)

Solar Irradiance Across Latitude and TimeSolar Irradiance Across Latitude and Time

DJF

Ann.

JJA

Orbital VariationsOrbital Variations

• Eccentricity

• Obliquity

• Precession of theEquinoxes(OmegaT in EdGCM)

Milankovitch Cycles

Can GCMs simulate the onset of Ice Ages?Can GCMs simulate the onset of Ice Ages?

• No

• Sort ofGallimore and Kutzbach (1996) suggested that tundra increase and boreal forest decrease may have helped trigger ice ages.

• But, not reallyOther models don’t get this result and the distribution of snow accumulation was not correct in G&K Gallimore and Kutzbach, Nature, 1996

A. 115,000 solar insolation based on orbital parameter changes.

B. + reduced CO2C. + ground albedo

increase (tundra expansion)

D. + more albedo increase

E. (boreal forest reduction)

Sea Level Rise: Last Glacial Maximum to PresentSea Level Rise: Last Glacial Maximum to Present

Sea Level Rise:1880 - 2000Sea Level Rise:1880 - 2000Sea Level Rise1880 - 2100Sea Level Rise1880 - 2100

Onset of melting during last interglacial periodOnset of melting during last interglacial period

Overpeck et al., Science, 2006

A. Last interglacial melting begins (135kyr BP)

B. Max N.H. summer insolation last interglacial(135kyr BP)

C. Most recent interglacial melting begins(15kyr BP)

D. Max N.H. summer insolation current interglacial(15kyr BP)

Source of sea level rise during last interglacialSource of sea level rise during last interglacial

1. 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

ModernLast Interglacial

AnomalyAD2100Anomaly

AD2130Anomaly(~4xCO2)

GCM Simulations of Climate Change in Greenland and Antarctica:Last Interglacial & Future Global WarmingsGCM Simulations of Climate Change in Greenland and Antarctica:Last Interglacial & Future Global Warmings

∆ 2000-04 minus 1958-62

GCM Simulations of Climate Change in Greenland:Current Global Warming (EdGCM, GISS Model II)GCM Simulations of Climate Change in Greenland:Current Global Warming (EdGCM, GISS Model II)

∆ 2000-04 minus 1958-62

GCM Simulations of Climate Change in Greenland:Current Global Warming (EdGCM, GISS Model II)GCM Simulations of Climate Change in Greenland:Current Global Warming (EdGCM, GISS Model II)

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