Early Pleistocene British-Irish ice rafting: Was the onset of Northern Hemisphere glaciation more widespread than previously assumed?

The Earth has undergone enormous changes in its snow and ice cover during geological time. There have been at least six major Ice Ages, as well as periods when there has probably been no ice, like the Cretaceous. Ice ages are periods when significant portions of the Earth’s surface are covered by glaciers and extensive sheets of ice; there is no strict quantitative definition. The major ice ages were the Huronian/Makganyene glaciations in the Neoarchean–Paleoproterozoc (~2,700 to 2,200 million years ago, Ma), the Sturtian, Marinoan, and Ediacaran glaciations of the Neoproterozoic (~730–700 Ma, 665–635 Ma, and 635–542 Ma), the late Ordovician glaciation (460 Ma), the late Devonian glaciation (360 Ma), the Permo-Carboniferous glaciation (320–250 Ma) and the late Cenozoic glaciation (beginning ~40 Ma). Glaciations appear to account for ~28 percent of Paleozoic time.

Ice age

Devonian

10.1017/cbo9780511977947.011

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Antarctic Peninsula Ice Sheet evolution during the Cenozoic Era

Quaternary Science Reviews (2011)

Bethan J. Davies Michael J. Hambrey John L. Smellie Jonathan L. Carrivick Neil F. Glasser

Antarctic ice sheet

Peninsula

Wisconsin glaciation

Ice-sheet model

10.1016/j.quascirev.2011.10.012

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Citations (106)

SHALDRIL II: Record of Climate, Cryosphere and Ecological Changes in the Antarctic Peninsula Region During the Late Paleogene and Neogene

AGU Fall Meeting Abstracts (2006)

John J. Anderson Julia S. Wellner T.N. Smith S.W. Jr. Wise Denise K. Kulhanek

Paleogene

Neogene

Peninsula

Fossil Record

Source

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Evidence for ephemeral middle Eocene to early Oligocene Greenland glacial ice and pan-Arctic sea ice

Nature Communications (2018)

Aradhna Tripati Dennis A. Darby

Abstract Earth’s modern climate is defined by the presence of ice at both poles, but that ice is now disappearing. Therefore understanding the origin and causes of polar ice stability is more critical than ever. Here we provide novel geochemical data that constrain past dynamics of glacial ice on Greenland and Arctic sea ice. Based on accurate source determinations of individual ice-rafted Fe-oxide grains, we find evidence for episodic glaciation of distinct source regions on Greenland as far-ranging as ~68°N and ~80°N synchronous with ice-rafting from circum-Arctic sources, beginning in the middle Eocene. Glacial intervals broadly coincide with reduced CO 2 , with a potential threshold for glacial ice stability near ~500 p.p.m.v. The middle Eocene represents the Cenozoic onset of a dynamic cryosphere, with ice in both hemispheres during transient glacials and substantial regional climate heterogeneity. A more stable cryosphere developed at the Eocene-Oligocene transition, and is now threatened by anthropogenic emissions.

Ice core

Ice-sheet model

10.1038/s41467-018-03180-5

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Citations (83)

Evidence for glaciation in the Northern Hemisphere back to 44 Ma from ice-rafted debris in the Greenland Sea

Earth and Planetary Science Letters (2007)

Aradhna Tripati Robert A. Eagle Andrew Morton Julian A. Dowdeswell Katie L. Atkinson

Iceberg

Tidewater

Wisconsin glaciation

10.1016/j.epsl.2007.09.045