δ18O and SST signal decomposition and dynamic of the Pliocene-Pleistocene climate system: new insights on orbital nonlinear behavior vs. long-term trend

• Published in: Progress in earth and planetary science Vol. 5; no. 1; pp. 1 - 37
• Main Author: Viaggi, Paolo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 07.12.2018; Springer Nature B.V; SpringerOpen
• Subjects: 1. Space and planetary sciences; Atmospheric Sciences; Biogeosciences; Carbon cycle; Carbon dioxide; Chaotic; Climate system; Damping; Decomposition; Earth and Environmental Science; Earth Sciences; Erosion; Feedback; Geophysics/Geodesy; Global temperatures; Hydrogeology; Ice sheets; Milankovitch; Nonlinear; Obliquity; Oceans; Orography; Paleoclimate; Paleogeography; Paper with Full Data Attached; Planetology; Pleistocene; Pliocene; Positive feedback; Precession; Sea surface temperature; Singular spectrum analysis; Spectrum analysis; Surface temperature; Time series; Singular spectrum analysis; Damping; Nonlinear; Paleoclimate; Milankovitch; Greenhouse; Pliocene-Pleistocene; Chaotic
• ISSN: 2197-4284; 2197-4284
• DOI: 10.1186/s40645-018-0236-z

The global LR04 δ 18 O, the tropical ODP Site 846 sea surface temperature (SST), and the global ΔSST stack records were investigated using the advanced method for time-series decomposition singular spectrum analysis to outline the quantitative role of orbital forcings and to investigate the nonlinear dynamics of the Pliocene and Pleistocene climate system. For the first time, a detailed quantitative evaluation is provided of the δ 18 O and SST variance paced by long-period orbital modulation, short eccentricity, obliquity, precession, and half-precession cycles. New insights into the nonlinear dynamic of the orbital components suggest considering astronomical signals as composite feedback lagged responses paced by orbitals and damped (Early Pliocene) or amplified (Mid-Late Pleistocene) in a range of − 100 to + 400% the forcing. The Early Pliocene asymptotic decay of the δ 18 O and SST response sensitivity up to − 100% observed for the first time in all orbital responses is interpreted as damping effect of a wide global forest cover along with a possible high ocean primary productivity, through the CO 2 -related negative feedbacks during time of global greenhouse. An anomalous post-Mid-Pleistocene Transition (MPT) sharply declines to near-zero in obliquity response sensitivity observed in both global δ 18 O and tropical SST, suggesting an attenuation mechanism of the obliquity driving force and a reduction of the related feedback amplification processes. It is hypothesized the post-MPT obliquity damping has contributed to the strengthening of the short eccentricity response by mitigating the obliquity “ice killing”, favoring a long-life ice sheet sensitive to a synergistic ~ 100-kyr amplification of positive feedback processes during the time of a global icy state. The global δ 18 O, the tropical SST, and the global ΔSST trend components, all explaining ~ 76% of the Plio-Pleistocene variance and significantly modifying the mean climate state, appear to be related to the long-term pCO 2 proxies, supposedly controlled by plate tectonics through the global carbon cycle (CO 2 outgassing, explosive volcanism, orography and erosion, paleogeography, oceanic paleocirculation, and ocean fertilization). Finally, singular spectrum analysis provides a valuable tool in cyclostratigraphy with the remarkable advantage of separating full-resolution time series by variance strength.