Regarding climate transitions, different scenario emerges from another recent work (Shackleton et al., 2020) that describes the change from glacial to interglacial period as follows:
"Mean ocean temperature reached its maximum value of 1.1 ± 0.3 °C warmer-than-modern values at the end of the penultimate deglaciation at 129 ka, which resulted in 0.7 ± 0.3 m of thermosteric sea-level rise relative to the present level. However, this maximum in ocean heat content was a transient feature; mean ocean temperature decreased in the first several thousand years of the interglacial and achieved a stable, comparable-to-modern value by ~127 ka."
Thus, the Earth system's net "heat content" is critical in climate transitions. In comparison, the transition from the interglacial to glacial period is also a transient process (Ramadhin and Yi, 2020). They state that "The termination of a glacial period occurs rapidly while the changeover to a glacial period takes tens of thousands of years to be completed, resulting in an interesting asymmetrical shape for which there is yet no consensus on the mechanism(s) (Tziperman and Gildor, 2003)".
Transient processes are non-linear and chaotic. However, an order exists within that chaos in the realm of the "Universality Principle." I suppose that at the state of criticality during climate transitions, the energy condenses within a specific domain when the "tipping point" is reached. Then, "thermalization" - the tendency for energy to spread throughout a system - takes the lead, and that slows down the rapid change in the climate. The intensity of the negative-feedback mechanisms, namely the "sea-ice precipitation feedback" and "sea ice-insulation feedback", limits the rate of thermalization. And that results in asymmetrical transitions between icehouse and greenhouse states.
The large-scale involvement of ice probably reduces the transient time required for glacial to interglacial transition. The extension of ice diminishes during interglacials. Thus, the change from interglacial to glacial periods might occur slowly due to active negative feedback.
For further background on the "Universality Principle" and "Thermalization", please read:
1) The Universal Law That Aims Time's Arrow
2) In Mysterious Pattern, Math and Nature Converge
References:
Ramadhin, C., Yi, C., 2020. ESD Ideas: Why are glaciations slower than deglaciations? Earth Syst. Dynam. 11, 13–16. https://doi.org/10.5194/esd-11-13-2020
Shackleton, S., Baggenstos, D., Menking, J.A., Dyonisius, M.N., Bereiter, B., Bauska, T.K., Rhodes, R.H., Brook, E.J., Petrenko, V.V., McConnell, J.R., Kellerhals, T., Häberli, M., Schmitt, J., Fischer, H., Severinghaus, J.P., 2020. Global ocean heat content in the Last Interglacial. Nat. Geosci. 13, 77–81. https://doi.org/10.1038/s41561-019-0498-0
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