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How obliquity cycles powered early Pleistocene global ice‐volume variability
Author(s) -
Tabor Clay R.,
Poulsen Christopher J.,
Pollard David
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063322
Subject(s) - milankovitch cycles , geology , climatology , ice sheet , precession , orbital forcing , cryosphere , atmospheric sciences , geophysics , glacial period , sea ice , insolation , paleontology , geomorphology , physics , astronomy
Milankovitch theory proposes that the magnitude of high‐latitude summer insolation dictates the continental ice‐volume response by controlling summer snow melt, thus anticipating a substantial ice‐volume contribution from the strong summer insolation signal of precession. Yet almost all of the early Pleistocene δ 18 O records' signal strength resides at the frequency of obliquity. Here we explore this discrepancy using a climate‐vegetation‐ice sheet model to simulate climate‐ice sheet response to transient orbits of varying obliquity and precession. Spectral analysis of our results shows that despite contributing significantly less to the summer insolation signal, almost 60% of the ice‐volume power exists at the frequency of obliquity due to a combination of albedo feedbacks, seasonal offsets, and orbital cycle duration differences. Including eccentricity modulation of the precession ice‐volume component and assuming a small Antarctic ice response to orbital forcing produce a signal that agrees with the δ 18 O ice‐volume proxy records.