I wonder if there is a paradox here where the more heat is in the system the more STABLE the system is as it resolves the surplus heat relative to the base state?
I.E. imagine two polar cells sitting over North America and Eurasia, exchanging heat energy through massive bomb cyclones. The middle is snow. The periphery is snowing/melting. The tropics are probably still warm. The Arctic is actually probably still warming at this point as it begins to accumulate insolation in spring and summer. But a substantial portion of the extra heat and melting ice from Greenland and the Antarctic is snowing out atop the Rockies and the Himalayas.
And, surprisingly, the new state becomes MORE effective at evacuating heat from the Earth's surface than the old once the snow anomalies begin to spread to lower elevations. Continental albedo at low latitudes is MUCH more effective at deflecting net solar insolation on an annual basis than sea ice at high latitudes.
Why would the Earth spiral to hothouse when we still have Greenland and Antarctica? Why would the cryosphere not redistribute to where it is most effective at evacuating heat? What if the three-cell system we had was "subcritical" and we have now tipped the Earth into "criticality" ?
In a system geared to equalizing residual heat, the more heat that enters the system, THE MORE EFFECTIVE THE SYSTEM BECOMES AT EVACUATING HEAT. Science has ignored this fact.
Why does Greenland have these huge temperature drops, btw? I wonder if it is because it initially is prone to huge melt. But as the North American vortex grows in scope (more regions become inter-annually covered), perhaps Greenland abruptly goes from rapid melt to rapid regrowth? At some point, the continental cells would get so large that the Arctic ultimately WOULD turn back to sea ice, but by that point a huge portion of the continents would be, erm, uninhabitable.
Perhaps we have been overthinking things, then.
What if our climate is really just in a 0-(heat is resolved)->1-(heat accumulates)->0-(heat is resolved)->1-(heat accumulates)->0 pattern here? I suppose 0 would be snow-covered continents, 1 would be ice-covered Arctic Ocean. The transition from 0 to 1 evidently takes 5,000 years but the transition from 1 to 0 can take decades or less as the Younger Dryas indicates.
Thusly it would seem plausible that the Earth-climate system takes a very long time to resolve the accumulation of heat, but the actual event that LEADS to the resolution of surplus heat (snow-covered continents) occurs in a matter of years or a decade?
Is it so inconceivable we are in such a transition right now, or approaching it? History does not repeat but it does rhyme and humans are not exceptional despite all our consternations to the contrary.
Scientists have always been conflating correlation with causation of ice ages (i.e. Milankovitch Cycles)... does it matter if it is Milankovitch Cycles, orbital impact, or GHG release? The net result is the SAME which is why all of the theories have blinded science in general to the real truth here which is IMO illuminated in this thread (or is at least finally STARTING to come to light even though we could definitely and most likely still have a lot wrong).
Earth's ice ages aren't caused by one thing, or another. Earth's "ice ages" are actually the flip of a switch in the planet's resolution of surplus heat (and I believe it is only available WHEN ICE CAPS ARE EXTANT but I could be wrong on this point too -- in any case we are bounded by such a condition). The switch from deflecting insolation at the Pole to deflecting it across the continents results in a much more EFFICIENT resolution of heat, so paradoxically the state is entered when the planet is at its warmest, and enough surplus heat accumulates to melt the bulk of the Arctic Sea Ice.