In less than 20 years.
The Younger Dryas, also referred to as the Big Freeze, was a geologically brief period of cold climatic conditions and drought that was in sharp contrast to the preceding period of warming.
The Big Freeze began approximately 12,800 years ago and ended about 11,500 years ago – about 1,300 years, according to Wikipedia.
The Younger Dryas began catastrophically, with the climate in the higher latitudes of the Northern Hemisphere rapidly descending into glacial conditions.
Scientists think the transition occurred over a period of a decade or so, perhaps even faster.
Ten years. Or even faster.
My own research shows that all – all! – ice ages in the last 250,000 years began in less than 20 years, sometimes in less than three years.
At the end of the Eemian Period, for example, the climate descended from a period of warmth as warm as, or even warmer than today’s, into full-blown glaciation in less than 20 years.
Can you imagine how unprepared our world would be if we descended into an ice age in less than 20 years?
It has happened before, time after time after time. It’s not a question of “if,” only “when.”
Wikipedia description of the Younger Dryas:
Thanks to Steven Rowlandson for this link
- Berger, W. H. (1990). “The Younger Dryas cold spell – a quest for causes”. Global and Planetary Change 3 (3): 219–237. Bibcode:1990GPC…..3..219B. doi:10.1016/0921-8181(90)90018-8.
- Alley, Richard B. et al. (1993). “Abrupt accumulation increase at the Younger Dryas termination in the GISP2 ice core”. Nature 362 (6420): 527–529.Bibcode:1993Natur.362..527A. doi:10.1038/362527a0.
- Choi, Charles Q. (2 December 2009). Big Freeze: Earth Could Plunge into Sudden Ice Age.
***************Interestingly, the Younger Dryas began at about the same time as the Gothenburg magnetic reversal.
(See “Magnetic Reversals and Glaciation” chart)