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Abstract Paleoclimate records can be considered low‐dimensional projections of the climate system that generated them. Understanding what these projections tell us about past climates, and changes in their dynamics, is a main goal of time series analysis on such records. Laplacian eigenmaps of recurrence matrices (LERM) is a novel technique using univariate paleoclimate time series data to indicate when notable shifts in dynamics have occurred. LERM leverages time delay embedding to construct a manifold that is mappable to the attractor of the climate system; this manifold can then be analyzed for significant dynamical transitions. Through numerical experiments with observed and synthetic data, LERM is applied to detect both gradual and abrupt regime transitions. Our paragon for gradual transitions is the Mid‐Pleistocene Transition (MPT). We show that LERM can robustly detect gradual MPT‐like transitions for sufficiently high signal‐to‐noise (S/N) ratios, though with a time lag related to the embedding process. Our paragon of abrupt transitions is the “8.2 ka” event; we find that LERM is generally robust at detecting 8.2 ka‐like transitions for sufficiently high S/N ratios, though edge effects become more influential. We conclude that LERM can usefully detect dynamical transitions in paleogeoscientific time series, with the caveat that false positive rates are high when dynamical transitions are not present, suggesting the importance of using multiple records to confirm the robustness of transitions. We share an open‐source Python package to facilitate the use of LERM in paleoclimatology and paleoceanography. 

Abstract Speleothem oxygen isotope records offer unique insights into Asian Monsoon evolution, with their precise chronologies used to identify abrupt climatic events. However, individual records are sometimes used to draw broad conclusions about global climate, without considering the dynamical context in which they exist. We present a robust framework for assessing the regional significance, and hence the potential global significance, of paleoclimate events, using the proposed Meghalayan age onset (associated with the “4.2 ka event”) as a case study. Analyzing 14 well‐dated speleothem oxygen isotope records from the SISAL v3 database and recent literature, we investigate the regional coherency of rapid shifts in Asian paleohydrology, which is the regional center of action for the proposed event, over the Holocene. Three robust methods fail to detect spatially coherent variability consistent with a 4.2 ka event across Asia, either because none exists or because it is of insufficient magnitude. In contrast, the 8.2 ka event is expressed in most records that resolve it. The absence of a clear isotopic excursion across this data set suggests that the “4.2 ka megadrought” was not global, with important implications for archeology and geochronology. This casts doubt on the proposal that the 4.2 ka event marks the onset of a new geologic age. We do, however, observe support for a gradual isotopic enrichment between 3.9 and 3.6 ka, followed by partial recovery—consistent with the “Double Drying” hypothesis and possibly related to changes in El Niño‐Southern Oscillation variability.