In:
Climate of the Past, Copernicus GmbH, Vol. 15, No. 6 ( 2019-11-22), p. 1959-1983
Abstract:
Abstract. The increasingly nonlinear response of the climate–cryosphere
system to insolation forcing during the Pliocene and Pleistocene, as
recorded in benthic foraminiferal stable oxygen isotope ratios (δ18O), is marked by a distinct evolution in ice-age cycle frequency,
amplitude, phase, and geometry. To date, very few studies have thoroughly
investigated the non-sinusoidal shape of these climate cycles, leaving
precious information unused to further unravel the complex dynamics of the
Earth's system. Here, we present higher-order spectral analyses of the LR04
δ18O stack that describe coupling and energy exchanges among
astronomically paced climate cycles. These advanced bispectral computations
show how energy is passed from precession-paced to obliquity-paced climate
cycles during the Early Pleistocene (from ∼2500 to ∼750 ka) and ultimately to eccentricity-paced climate cycles during the
Middle and Late Pleistocene (from ∼750 ka onward). They also
show how energy is transferred among many periodicities that have no primary
astronomical origin. We hypothesise that the change of obliquity-paced
climate cycles during the mid-Pleistocene transition (from ∼1200 to ∼600 ka), from being a net sink into a net source of
energy, is indicative of the passing of a land-ice mass loading threshold in
the Northern Hemisphere (NH), after which cycles of crustal depression and
rebound started to resonate with the ∼110 kyr eccentricity
modulation of precession. However, precession-paced climate cycles remain
persistent energy providers throughout the Late Pliocene and Pleistocene,
which is supportive of a dominant and continuous fuelling of the NH ice ages
by insolation in the (sub)tropical zones, and the control it exerts on
meridional heat and moisture transport through atmospheric and oceanic
circulation.
Type of Medium:
Online Resource
ISSN:
1814-9332
DOI:
10.5194/cp-15-1959-2019
DOI:
10.5194/cp-15-1959-2019-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2019
detail.hit.zdb_id:
2217985-9
