Abstract
Changes in Earth’s orbit set the pace of glacial cycles, but the role of spatial variability in the insolation forcing of global ice volume remains unknown. Here, we leverage the intrinsic dynamical information in empirical records to show that ice volume responded to summer energy at high northern latitudes, as predicted by Milankovitch theory. However, the external forcing of ice volume encompasses insolation signals with a wide range of orbital frequency content, and cannot be fully accounted for by a unique time series. Southern mid-latitude insolation forcing coincides with the position of the subtropical front and the westerlies, which have been implicated in Quaternary climate changes. Dominant forcing modes at northern mid-latitudes are anti-phased with the canonical Milankovitch forcing, consistent with ice volume sensitivity to latitudinal insolation gradients.
Highlights
Earth’s climate and global ice volume oscillated in tune with changes in orbital geometry during the Quaternary period
If latitudinally varying insolation was a dynamical influence on changes in ice volume, information about this insolation forcing should be recoverable from the global sea level (GSL) record of ice volume variations
Each summer energy time series corresponds to spatially separate physical forcing scenarios that span different portions of the year, and we seek to detect the dynamical influence of these local processes on global ice volume
Summary
Earth’s climate and global ice volume oscillated in tune with changes in orbital geometry during the Quaternary period. Milankovitch theory predicts that if insolation controls continental ice sheet dynamics, northern latitude summer insolation plays a central role[13] We test this prediction by quantifying the dynamical response of global ice volume to latitudinal insolation forcing. If latitudinally varying insolation was a dynamical influence on changes in ice volume, information about this insolation forcing should be recoverable from the GSL record of ice volume variations. To test this assertion, we use a model-free time series analysis method, convergent cross mapping (CCM)[18,19]. Latitude, there is empirical support for local insolation at that latitude contributing to the dynamical forcing of ice volume
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