Northern link dating site
Here we quantify and visualize the changing paleoclimate response to astronomical forcing (i.e., different astronomical rhythms) throughout geologic time. The underlying statistical model is a Gaussian process (see the Data Repository) that renders the dependence of one variable, here δ records were densely tuned to obliquity and precession.The wavelet spectrograms in Figures 1A and 1B show a remarkable transition from a δ response surfaces in a three-dimensional space spanned by obliquity and eccentricity-modulated precession (Figs. To alleviate this issue, we preserved only one tie point between depth and time every ∼100 k.y., so that the phase relationship between astronomical forcing and δ can be evaluated independently.Antarctic ice cover and global climate, represented by δ, mainly depended on Southern Hemisphere summer insolation, with minimum Antarctic ice volume and peak warmth when Southern Hemisphere summer insolation was maximum, i.e., perihelion in January (Fig. At the same time, the influence of the Northern Hemisphere was growing.For example, through ice-albedo feedback mechanisms, which became more important in the cooling Arctic region (Darby, 2008; Krylov et al., 2008; Stein et al., 2016).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.
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.
3C), Oligocene global warmth consistently occurs when Earth reaches perihelion in May or June (Fig. The late Oligocene response is consistent with an amplification of a Northern Hemisphere summer insolation signal through a vigorous feedback mechanism.
This is remarkable, considering that during the Oligocene, continental ice in the Arctic was probably limited to no more than a few isolated glaciers (Eldrett et al., 2007; Pekar et al., 2006).
Arctic sea ice, however, may have played a central role in positive feedback mechanisms, through its albedo as well as through its effect on deep-water formation and ocean conveyor circulation.
At the same time in the Southern Hemisphere, the Antarctic continent was still heavily glaciated.