Literature Review: Ice Ages and Climate

by Carl Strang

Today’s literature focus is on two studies from last year that increased our understanding of ice age dynamics and how our changes to the atmosphere may alter them.

Kokechik Bay, Alaska, late winter

Kokechik Bay, Alaska, late winter

Ballantyne, Ashley P., et al. 2013. The amplification of Arctic terrestrial surface temperatures by reduced sea-ice extent during the Pliocene. Palaeogeography, Palaeoclimatology, Palaeoecology, DOI: 10.1016/j.palaeo.2013.05.002  As described in a ScienceDaily article. Recent measures of carbon dioxide in the atmosphere have brought current levels into the range of the Pliocene, which was 3.5-9 degrees F warmer than today. A modeling study indicates that the difference may have been that the Arctic Ocean then was open year-round, a condition toward which we are trending now.

Kerr, Richard A. 2013. How to make a great ice age, again and again and again. Science 341:599. News article describing a study published in Nature that reports an advance in understanding the continental glacier cycle. That cycle corresponds to the 100,000-year stretching and shrinking of the Earth’s orbit around the sun, but that’s too weak to account for ice building and declining. The group led by Ayako Abe-Ouchi modeled in the 23,000-year wobble in the Earth’s spin axis, plus global climate modeling and data on northern ice sheets, which involve changing carbon dioxide levels and the mass of the ice. Simulated ice sheets expanded and contracted in close to the actual pattern. Ice gradually builds over the 100,000-year cycle, but then the 23,000-year cycle corresponds to the warming phase of the longer one, adding summer warmth. By then, crustal depression by the ice mass means that the ice is at a lower, warmer altitude (1 km of depression), and the glacier rapidly melts.

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