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In the MMCT time slice (13.6–12.8 Ma), the isotopic response to precession is bimodal, with lighter δ values when perihelion is reached in either July or January (Fig. These significantly different responses to precession portray the effect of a highly dynamic continental ice sheet.
During the MMCO, the Northern Hemisphere was free of continental ice sheets, while the Antarctic ice sheet was smaller but more dynamic than it is today. 13.8 Ma, this ice sheet grew too big to pulse on the beat of precession, and thereby lost its overwhelming influence on the global climate state.
In contrast to existing compilations and stacks that respectively mix and average time-equivalent data across sites, the megasplice comprises data from a single site at any point in time, allowing analyses that require a high-resolution record at astronomical resolution.
The megasplice provides a novel stratigraphic tool that is suitable as a global framework for orbital-scale correlation of paleoclimate records.
later, relatively warm global climate states occurred during maxima in both Southern Hemisphere and Northern Hemisphere summer insolation.
At that point, the Antarctic ice sheet grew too big to pulse on the beat of precession, and the Southern Hemisphere lost its overwhelming influence on the global climate state. Despite the similarity in δ values and variability, we find different responses to precession forcing.
This pattern is in accordance with previously published paleoclimate modeling results, and suggests an amplifying role for Northern Hemisphere sea ice. Astronomical-scale climatic changes are recorded in δO of benthic foraminifer tests reflects a combination of temperature state and size of Earth’s cryosphere at the time of their formation.The four time windows discussed herein all utilize data from the equatorial Pacific (Ocean Drilling Program Sites 1137, 1138, and 1218), thus avoiding complications when comparing astronomical imprints across oceans or latitudes.The δ values as a function of the astronomical configuration.Figure 2F thus represents a climate that is warmest when the Earth is in perihelion at January, under high eccentricity.We provide a well-known example in Figure DR3 in the Data Repository, in which we compare the astronomical rhythms of the 100 k.y.
Blue to red colors designate cooler to warmer global climates as well as higher to lower global ice volume.