Ice ages and Global Warming. David Damm Greg McCormick. EAS 4610. Outline. Earth Temperature History Climate System Forcing and Response Ice sheet response Other feedbacks and responses Future climate. 3 Million yrs. Past 400k yrs. Past 10k yrs - Interglacial. Present Temperatures.
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insolation – solar energy trapped by earth
Ice sheets advance:Obliquity (41k) and precession (23k) combine for minimum insolation
Ice sheets retreat: maximum insolation during summer months
Current research efforts focus on better understanding of the interaction between external forcing (insolation) and internal forcing/feedbacks such as: GHG’s, albedo, vegetation, ocean/atmosphere circulation, dust, etc.
 Paillard, D. (2006) “What drives the ice age cycle”, Science, 313, 455-456
Ruddiman (2006):Insolation forcing with GHG forcing at 22k signal, and GHG/albedo feedback at 41k. 100k signal is due to uniquely coincident forcing and feedback.
Zeng (2007):Central process is burial and preservation of organic carbon by icesheets; after prolonged glaciation, subglacial transport becomes sufficient to release buried carbon to atmosphere; CO2 is dominant factor in 5°C cooler glacial climate with contributions from insolation and albedo
Huybers (2007):Obliquity at 40k period dominates glacial cycles; deglaciations skip one or two beats for 80k or 120k cycles resulting in “apparent 100k variability”; integrated insolation modeling parameter predicts 33 of 36 deglaciations
Johnston, et al., (2006):Role of dust and other northern forcing of CO2 changes
Courtillot, et al., (2007):Earth’s magnetic field effects on climate
What does the past tell us about the future?
References and resources used
 Ruddiman, W.F. (2001) Earth’s Climate Past and Future, http://www.whfreeman.com/ruddiman/ (figures used here)
 Paillard, D. (2006) “What drives the ice age cycle”, Science, 313 455-456
 Ruddiman, W.F. (2006) “Orbital changes and climate”, Quaternary Science Reviews, 25 3092-3112
 Zeng, N. (2007) “Quasi-100ky glacial-interglacial cycles triggered by subglacial burial carbon release”, Climate of the Past, 3 135-153
 Huybers, P. (2007) “Glacial variability over the last two million years…”, Quaternary Science Reviews, 26 37-55
 Johnston, T.C., Alley, R.B., (2006) “Possible role for dust or other northern forcing …”, Quaternary Science Reviews, 25 3198-3206
 Courtillot, V., et al., (2007) “Are there connections between the Earth’s magnetic…”, Earth and Planetary Science Letters 253 328-339
 Petit, J.R., et al., (1999) “Climate and atmospheric history of the past 420,000 years…”, Nature 399 429-436
 Muller, R.A., MacDonald, G.J., (2000) Ice Ages and Astronomical Causes, Praxis Publishing Ltd.