Decoding Cenozoic climate variability: dominant timescales beyond critical transitions

Abstract

While previous climate transitions are easily identifiable, a comprehensive understanding of their underlying mechanisms and timescales remains elusive. In this investigation, we employ dimensional analysis of benthic stable isotope records to unveil the associations between climatic fluctuations in the Cenozoic era and changes in the number of effective degrees of freedom across various timescales. The Hothouse and Warmhouse states are predominantly influenced by precession timescales, whereas the Icehouse climate is primarily shaped by obliquity and eccentricity timescales. Remarkably, the Coolhouse state lacks distinct dominant timescales. Our analytical approach effectively identifies abrupt climate shifts and extremes objectively, as evidenced by high-resolution data from the last glacial cycle, which reveals sudden climate shifts within a single climate state. These findings have profound implications for our comprehension of the inherent stability of each climate state and the assessment of (paleo-)climate models' ability to accurately replicate crucial features of past and future climate states and transitions.