An interesting paper on rapid return to ice age conditions. I almost put this in the chaos thread as it would appear to be a sudden change to another attractor.
"ICE AGE the Return Updated: Oct 11, 2018
During the last 2 decades there seems to be a growing number of misconceptions and Theories when evaluating previous Ice Ages, in this paper we look back at the Last five Ice Ages in an attempt to understand Climate and events which preceded them.
Geologically speaking talking about the last 10 million years, the last 10,000 years is part of an extended warm period at the end of a long cooling trend. Geologically there have been several extended hot periods, where the earth was covered in tropical swampy lands with shallow warm seas which changed little for tens of million years- up to around 120 million years. The Mississippian and Pennsylvanian periods best illustrate that, In recent history there have been 5 well documented glacial periods (two more less well documented periods preceded those 5), interrupted by warm interglacial periods.
We can see from the above graph that Glacial periods (in time scales) are getting shorter (Logarithmic bases). So let us take a look at the last 65 million years.
65 Million years
The Vostok Greenland and Antarctic ice cores when analysed year by year show a temperature spike of VERY short duration at the start of major glacial periods. It appears that the start of the glacial period is precipitous, lasting no more than a decade. For example the Dover straits between England and France froze solid in less that a decade at the start of the last Wurm glacial period. That was preceded by a 9°c spike lasting about 20 years, followed by a crash of over 7°c that lead to total glaciation. In the below graph - note the spikes.