The cause of the 100,000-year geomagnetic and climate cycles

Abstract. Paleotemperature and paleogeomagnetic data commonly exhibit a dominant 100,000-year cyclicity. Spectral and statistical analyses demonstrate that paleogeomagnetic intensity variations are strongly and significantly correlated to orbital inclination, obliquity and eccentricity oscillations. These orbital fluctuations vary the Earth-incident solar wind power, which is here shown to be the primary cause of geomagnetic fluctuations. The 100,000-year glacial-interglacial climate cyclicity is very likely controlled by similar orbital inclination forcings. The switch from 41,000-year glacial-interglacial cyclicity to 100,000-year cyclicity that occurred around the mid-Pleistocene Transition demonstrates that long-term climate cyclicity very likely varies due to orbital eccentricity modulating the relative strengths of orbital inclination and obliquity forcings.