Broadly, there are two schools of thought with regards to the relationship between orbital cycles and Ice Ages: either the orbital cycles directly force the Ice Ages or the Ice Ages are an oscillation within the climate system that is phase-locked to the orbital cycles. Both of these schools of thought implicitly assume that the orbital forcing makes the climate system "forget" its initial state. Here, Verbitsky & Volobuev perform idealized ice-sheet simulations and show that the system doesn't "forget" its initial state. Furthermore, this system exhibits spontaneous periodicity changes. The authors argue that this behaviour depends on the memory duration of the climate system. Therefore, this work opens an important avenue to be addressed by future research, focusing on the length of the memory of the climate system.

This study identifies a potential instability in the global carbon cycle driven by feedbacks between climate, weathering, and ocean chemistry, suggesting abrupt shifts under extreme perturbations. Although the conditions required are severe, the findings reveal that Earth’s carbon system may have multiple stable states, with implications for climate tipping points. The work offers a crucial theoretical framework for understanding past and future carbon cycle disruptions, making it highly relevant to geoscientific and climate research.