Alternate History Another Ice Age begins in Historical Times.

[Sailor.X]

In this scenario around the year 1,000 BC a change in the climate triggers another Ice Age globally. Sea levels fall to where they were during the last Ice Age. As a result the Bering Land Bridge is reestablished between Eurasia and North America. Glaciers advance into much of the Northern Hemisphere putting Northern North America and much of Northern Eurasia in a deep freeze. This Ice Age will last until the year 1980 AD. How does this sudden change in the climate affect the various civilizations of the time? And how will the rest of human history play out?

 

[raharris1973]

At one extreme, unpredictability of weather destroys agricultural civilization, and anything that's ever been written is burned for fuel or recycled as construction material by people with no literacy in its symbols. Maybe agricultural civilization could start again from hunter gatherer/hunter gardeners after 1980.

 

[Sailor.X]

Agriculture would more than likely move into the now lower in size Mediterranean Sea Area for Europe. A lot of land that is covered by ocean will be opened up for humanity to use again.

A lot of fertile ground will be for the taking. And Irrigation can help with crops.

 

[Buba]

We ARE in an Ice Age. But in an interglacial. These last a few tens of thousands of years, followed by glaciations of several hundreds of thousands of years. This had been the state of affiars for the last few millions of years, since the Drake Passage opened and the ACC formed.
End OTL current interglacial in 1000BC? 3kya? As changes occur at a glacial pace (bad pun, sue me, see if I care!) it'd be colder than today, the vegetation zones slightly more southernly (and prolly narrower), but no noticeable change in sea level. It took 20 (TWENTY!!!!!!) thousand years or so for enough ice to melt to rise asl by 100 metres. Growing the glaciers takes longer.
Some places will be affected significantly as, even if rainfall remains same, colder=less evaporation, and thus will be wetter.
Nevertheless things should be drier. This OTL cooling is what you are looking for:

https://en.wikipedia.org/wiki/Younger_Dryas

or

https://en.wikipedia.org/wiki/8.2-kiloyear_event

Civilization might proceed like in OTL, yet simply does not reach as far north as in OTL.
Nevertheless history is very different, with e.g. Scotland being tundra and England or Germany taiga. Maybe agriculture kicks off in central Sudan, not Egypt?

Speculation about such a scenario prepared by well paid people (which does not necessarily make it correct ):

Wayback Machine

 

[Skallagrim]

One stand-out issue with the premise of "populations have to migrate, but then agriculture comes back elsewhere" is that our currunt interglacial has a high degree of long-term climate stability. There is a lot of evidence that during the glacial period, the entire planets saw a mucht higher frequency of climate shifts.

Meaning within time-frames of mere centuries.

The current theory is that this is one reason why agriculture kicked off about as soon as we entered the interglacial. The opportunity was there. Finally, the climate was stable, which meant a society could settle in one place where the living was good... and it stayed good. So they didn't have to up and get going a few hundred years later. This gave them the prerequisite time to develop a more sedentary modus vivendi.

There is good reason to believe that this is a pretty fundamental pattern, which means that a new ice age will cause renewed climate instability, which means -- well, that humanity goes back to the hunter-gatherer stand-by. Because under such conditions, that's the only sensible and viable way to exist.

If the new interglacial starts in 1980, then the next centuries will see small bands of humans settle down in favourable locations, and invent agriculture.

In other words: the period 1000 BC - AD 1980 is a second Younger Dryas.

 

[Buba]

In other words: the period 1000 BC - AD 1980 is a second Younger Dryas.

Yup.
Even the milder 8,2 ky event - going by wiki - caused a reversal to hunting-gathering.

Still, by 1000BC/3000 kya agriculture was quite well established. Some agricultural societies will be wiped out, others revert to (or reinforce that aspect of their lives) to pastoralism and/or hunting, but there should be refuges, no? As mentioned, irrigation is a game changer here.

 

[Sailor.X]

Yup.
Even the milder 8,2 ky event - going by wiki - caused a reversal to hunting-gathering.

Still, by 1000BC/3000 kya agriculture was quite well established. Some agricultural societies will be wiped out, others revert to (or reinforce that aspect of their lives) to pastoralism and/or hunting, but there should be refuges, no? As mentioned, irrigation is a game changer here.

Many of the Civilizations in the Levant and Fertile Crescent had long established methods of Irrigation. They will get through the climate shift more better than others that didn't have Irrigation techniques.

 

[Skallagrim]

Yup.
Even the milder 8,2 ky event - going by wiki - caused a reversal to hunting-gathering.

Still, by 1000BC/3000 kya agriculture was quite well established. Some agricultural societies will be wiped out, others revert to (or reinforce that aspect of their lives) to pastoralism and/or hunting, but there should be refuges, no? As mentioned, irrigation is a game changer here.

There could probably be some hybrid societies, although I have my doubts about irrigation as a lasting crutch. We see that if the climate changes are too volatile, irrigation can delay the inevitable, but typically not stop it.

In any case, I imagine it to be a marginal affair, with the main advantage being that once the global climate stabalises as we enter a new interglacial, and societies that retained agricultural traits will be in an excellent position to expand upon that.

(Indeed, a case can be made that the rapid expansion of agriculture after the Younger Dryas may have been due to such societies. In that hypothetical scenario, agriculture was established before the Younger Dryas, then reduced to a marginal role during, only to rapidly bounce back afterwards. This is of course just one possibility, but not one I'm ready to discount.)

 

[History Learner]

Personally, I've always found a contemporary Ice Age an interesting hypothetical; by that I mean media like The Day After Tomorrow, SM Stirling's The Peshawar Lancers, etc. It's much easier to speculate how Humanity would respond, given by then we had enough well developed knowledge and capabilities to do so.

 

[WolfBear]

Personally, I've always found a contemporary Ice Age an interesting hypothetical; by that I mean media like The Day After Tomorrow, SM Stirling's The Peshawar Lancers, etc. It's much easier to speculate how Humanity would respond, given by then we had enough well developed knowledge and capabilities to do so.

We'll just warm the planet more in such a scenario to compensate for this lol!