Persistent orbital influence on millennial climate variability through the Pleistocene

Abundant evidence from marine, ice-core and terrestrial records demonstrates that Earth’s climate has experienced co-evolution of orbital- and millennial-scale variability through the Pleistocene. The varying magnitude of millennial climate variability (MCV) was linked to orbitally paced glacial cycles over the past 800 kyr. Before this interval, global glaciations were less pronounced but more frequent, yet scarcity of a long-term integration of high-resolution continental and marine records hampers our understanding of the evolution and dynamics of MCV before the mid-Pleistocene transition. Here we present a synthesis of four centennial-resolved elemental time series, which we interpret as proxies for MCV, from North Atlantic, Iberian margin, Balkan Peninsula (Lake Ohrid) and Chinese Loess Plateau. The proxy records reveal that MCV was pervasive and persistent over the mid-latitude Northern Hemisphere during the past 1.5 Myr. Our results suggest that the magnitude of MCV is not only strongly modulated by glacial boundary conditions on Earth after the mid-Pleistocene transition, but also persistently influenced by variations in precession and obliquity through the Pleistocene. The combination of these four proxies into a new MCV stack offers a credible reference for further assessing the dynamical interactions between orbital and millennial climate variability. Orbital forcing consistently influenced the magnitude of millennial-scale climate variability through the Pleistocene, according to an analysis of four high-resolution Northern Hemisphere proxy records covering the past 1.5 Myr.