Dynamics between order and chaos in conceptual models of glacial cycles

TL;DR

This paper investigates the complex dynamics of glacial cycles using conceptual models, revealing that strange nonchaotic attractors may explain the intermediate behaviors observed in climate variations.

Contribution

It demonstrates that most models of glacial cycles exhibit strange nonchaotic attractors, suggesting a new perspective on climate dynamics beyond traditional quasiperiodic or chaotic regimes.

Findings

Four models exhibit strange nonchaotic attractors

Climate state dependence on astronomical forcing is geometrically complex

SNA may be a key dynamic in glacial cycle behavior

Abstract

The dynamics of glacial cycles is studied in terms of the dynamical systems theory. We explore the dependence of the climate state on the phase of astronomical forcing by examining five conceptual models of glacial cycles proposed in the literature. The models can be expressed as quasiperiodically forced dynamical systems. It is shown that four of them exhibit a strange nonchaotic attractor (SNA), which is an intermediate regime between quasiperiodicity and chaos. Then, the dependence of the climate state on the phase of astronomical forcing is not given by smooth relations, but constitutes a geometrically strange set. Our result suggests that the dynamics of SNA is a candidate for the dynamics of glacial cycles, in addition to the well-known dynamics of quasiperiodicity and chaos.