Similarities among glacials and interglacials in the LR04 benthic oxygen isotope stack over the last 1.014 million years revealed by cluster analysis and a DTW algorithm

Quantitative algorithmic examination of the LR04 oxygen-isotope record using cluster analysis and dynamic time warping (DTW) reveals significant new understandings of changes in glaciation and sea level during the Quaternary. For example, four relatively recent and major glacial stages, MIS 2 (or 2–4), 6, 12 and 16, emerge as a distinct group and suggest an Early Brunhes Shift to more extreme glacial stages about 660 thousand years ago. Secondly, two nominally interglacial stages, MIS 3 and 23, group with glacial stages. Of these two, recognition of MIS 3 as part of the last glacial phase is not a novel finding. However, recognition of MIS 23 as a glacial stage is significant because viewing MIS 22, 23, and 24 as one glacial phase formalizes a ~100,000-year glacial cycle from 960 to 859 ka. That result pushes the Mid-Pleistocene Transition, when the periodicity of climate cycles changed from 41 thousand to 100 thousand years, back to no later than 970 ka, counter to previous views that the Mid-Pleistocene Transition could have been as recent as 700 thousand years ago.