The global LR04 δ¹⁸O, 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 δ¹⁸O 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 δ¹⁸O 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 CO₂-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 δ¹⁸O 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 δ¹⁸O, 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 pCO₂ proxies, supposedly controlled by plate tectonics through the global carbon cycle (CO₂ 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.

中文翻译：

---

上新世-更新世气候系统的δ18 O和SST信号分解与动态：轨道非线性行为与长期趋势的新见解

全球LR04δ ¹⁸ O，热带ODP站点846海面温度（SST）和全球ΔSST堆栈记录使用时间序列分解奇异谱分析的先进方法勾勒轨道强迫的定量作用，并探讨进行了调查上新世和更新世气候系统的非线性动力学。首次，详细定量评价提供了δ的¹⁸O和SST的变化取决于长期的轨道调制，短的离心率，倾角，进动和半进动周期。对轨道分量的非线性动力学的新见解建议考虑将天文学信号视为由轨道定速的复合反馈滞后响应，并在强迫的−100至+ 400％范围内进行阻尼（早期上新世）或放大（中晚期更新世）。的δ的上新世早期渐近衰变¹⁸ O和SST响应灵敏度高达-在所有轨道响应首次观察到100％的被解释为具有尽可能高的海洋初级生产力阻尼宽全球森林覆盖的效果，通过一氧化碳₂全球温室气体相关的负面反馈。异常后中更新世过渡（MPT）急剧下降到接近零的在两个全球δ观察倾角响应灵敏度¹⁸ O和热带SST，暗示倾角驱动力的衰减机构和还原相关的反馈扩增过程的。据推测，MPT后的倾角阻尼通过减轻倾角的“杀冰”而有助于增强短时的偏心率响应，有利于长寿命的冰盖，对冰激凌过程中正反馈过程的协同〜100 ky放大敏感。全球冰冷状态的时间。全球δ ¹⁸O，热带SST和全球ΔSST趋势成分都解释了〜76％的上新世-更新世变化并显着改变了平均气候状态，似乎与长期的pCO ₂代理有关，据推测是由板块构造控制的全球碳循环（CO ₂放气，火山爆发，地形和侵蚀，古地理，海洋古环流和海洋施肥）。最后，奇异频谱分析提供了一种重要的手段，在旋回地层学中具有重要的优势，可以通过方差强度将全分辨率时间序列分开。