Climate and Ice Ages

Modulation of ice ages via precessionand dust-albedo feedbacks

Dust, albedo, and the pace of the ice ages

Ralph Ellis and Michael PalmerNovember 2016

Geoscience Frontiers, volume 7, issue 6, pages 891–909. DOI 10.1016/j.gsf.2016.04.004.

A 2016 paper with Michael Palmer. Late-Pleistocene ice ages, they argue, are paced by precession and regulated by dusty ice sheets. Carbon dioxide is not, in their account, the main feedback.

Chart comparing ice volume, Epica temperature, carbon dioxide, dust, Milankovitch insolation at the north pole, and the eccentricity of Earth’s orbit, across 800,000 years. — The comparison in the 2016 paper: ice volume, temperature, carbon dioxide, dust, northern summer insolation, and orbital eccentricity. Ellis and Palmer.

The question

The standard Milankovitch account uses precession to pace the ice ages. The paper says this does not explain the long intervals between interglacials. It asks what holds a glaciation in place, and what finally ends it.

What the paper states

The published abstract says that the high albedo of the northern ice sheets keeps global temperature and carbon dioxide down through a glacial, even when a later precession maximum would otherwise warm the north. It says atmospheric carbon dioxide falls to about 200 parts per million, forests and grasslands die back, and the eroded soil becomes dust. That dust lands on the ice. At the next rise in northern sunlight, the darker ice melts.

The journal’s own highlights name precession as the forcing and albedo as the feedback. They say the dust is produced because carbon dioxide is low. Those are the authors’ claims in a reviewed paper. They are not a consensus finding.

His reading of it

Ellis has put the same point in plainer words: that carbon dioxide is only a small player in the temperature, and that the main ice-age feedback is dusty ice sheets. He has also said that he has not seen the argument refuted. Both sentences are his summary. They are not a finding added by the journal.

Read the paper

Ellis, R., & Palmer, M. (2016). Modulation of ice ages via precession and dust-albedo feedbacks. Geoscience Frontiers, 7(6), 891–909. DOI: 10.1016/j.gsf.2016.04.004. This page summarises the paper. It does not reproduce it.

Evidence library

Modulation of ice ages via precession and dust-albedo feedbacks

Sources

Ellis, R., & Palmer, M. (2016). Modulation of ice ages via precession and dust-albedo feedbacks. Geoscience Frontiers, 7(6), 891–909. DOI: 10.1016/j.gsf.2016.04.004.