In this work address a fundamental enigma in the field of paleoclimatology called the mid-Pleistocene transition (MPT). There are two phenomena of the Pleistocene glacial-interglacial cycles that have been deemed ‘paradoxes’. The first is that during the last million years, a 100-kyr periodicity exists in climate records despite a lack in spectral power of the 100-kyr (eccentricity) frequency. The second is concerning why this 100-kyr cyclicity appears at 1.2-0.7 Ma when there is no change in orbital forcing.
These are commonly referred to jointly as the 100-kyr problem. The transition from the obliquity (41-kyr) to the eccentricity (100-kyr) paced world is referred to as the MPT. The motivating question I seek to understand is whether climate records spanning the last 2 Ma record MPT-type behavior and do they all show it with the same or differenttimings and magnitudes?
This project addresses the question of why there existsa shift in cyclicity from 41-kyr to 100-kyr periods with no insolation forcing at that frequency. There are several reasonable hypotheses to explain this shift, but consensus has not yet been reached. This project illuminates the MPT further by providing a synthesis of the current state of the literature on all relevant climate time-series records that span the last 2 Myr to characterize the climate evolution across the MPT.
I employed multiple time-series statistical approaches to characterize the variance, regional mean states, global means, spectra of periodicity, time-evaluative spectra, relative timing and cross-spectral analyses. Many of these datasets had been previously investigated independently or in smallgroups, but this research represents a novel and more comprehensive view of ourcurrent understanding of the MPT. This work will provide a summary of our current best understanding of the evolution and periodicity of climate records spanning the MPT.