I know this has probably been asked to death, but does anyone know of a ice age worlda map with climate already superimposed? If not, I'll make one. Just don't want to have to reinvent the wheel if there's already one out there.
I'd like to see one of those myself, and it sort of exists I suppose.
The thing to remember is that the "Ice Age" is a period (one of dozens since Earth tipped over into having periodic glaciations some millions of years ago) some ten times longer than the roughly 10,000 year Interglacials between them, and furthermore, a claim I have seen alleged, supported and believe from other posters on this site, the Glaciations are characterized by relatively rapid climate fluctuations all across the globe, not just in the regions near the ice sheets--this is an explanation why agriculture did not develop any time during the most recent glaciation anywhere we can identify, but then popped up in a dozen or so centers all around the world within a couple thousand years of the start of our current Interglacial. With local climates shifting within a few hundred years or less significantly, proto-cultivars that gatherer-hunter bands tend to favor unintentionally would be disfavored in the new climate, and the GH people would shift their gathering toward other varieties that in turn go out of favor in the next climate shift, and so the tendency for varieties to become both more productive with human attention and therefore also more vulnerable without it which characterizes crops would be repeatedly frustrated, resetting the prevailing genome mix of wild plants toward wild norms as humans keep rotating their attentions toward different varieties. When the climates stabilize, as they did with the settling of new Interglacial conditions, the process goes forward and various groups shift over to increasing dependency on these new crops and voila, we get agricultural civilization.
Whereas during the glaciation, if it is true that regional climates do shift rapidly, within the limits of their overall general climate zones (we won't get snowfall in tropical sea level places, for instance; I suppose in the tropics the major variable causing ecosystems to shift is about rainfall patterns, nor can we get tropical conditions in high latitudes which must be affected by the highly variable sunlight over the year) any sort of Koppen or other school classification has to be kind of vague. One could have a blurred, generalized Koppen-lite coloring where each color does not so much show the detailed pattern as the range of possibilities over thousands of years, or one could arbitrarily pick a given year and attempt to work out detailed maps with the understanding that some thousands of years later or earlier the map would be quite different.
One often hears for instance that the Sahara was even more severe a desert during the glaciation, but I think the fact is that just as in the current interglacial it would alternate between harsh aridity and somewhat moister grassland/savannah conditions, with a cycle of its own on a much shorter time scale.
Pick your year, and draw your map, and it might be accurate for a couple centuries plus or minus--except that some zones would be in process of rapid change which you happened to come down in the middle of, while others are in the middle of a fairly long fairly stable period. I'd guess if we had the ability to closely sample many areas over many points in time we'd find empirical correlations, that moistening in one area is always correlated with desiccation of another area, warming here always coincides with cooling over yonder, and so on, so there is some method to the madness, but on the other hand the interlocking patterns are kaleidoscopic and confusing. Thus some maps one might draw are it turns out logically impossible while others are kosher, but it would require a scientific career in paleontological climatology to be able to make the judgement of which is which.
In addition to the general problem of this fluctuation which might be patterned but in a complex way, we have the fact that the Glaciations are not uniform from beginning to end. It is currently my impression, possibly wrong of course, that the ice sheets trend to thicken and broaden over the entire period, and then are suddenly checked and start melting back rapidly from their peak just before the period ends and the Interglacial starts. So a glaciation begins relatively subtly, with "Fimbulwinter" in many core high latitude zones (Canada and Scandinavia, basically) where the snow of last winter does not melt during summer, but the ice cover is only a tiny fraction more than in the Interglacial, and this snow cover just accumulates year to year, taking many thousands of years to accumulate to glacial thickness and start spreading as glacial ice sheets. If this is true, the world undergoes shift to glacial era climate patterns, which as noted fluctuate rapidly, right away, but the sea levels do not drop at any rapid rate; they very slowly go down, down and down as the ice caps slowly thicken but don't reach their maximum depression until just before the whole thing reverses and then they surge back up relatively very rapidly over just a handful of thousands of years.
One of the fascinations of ATL or future history of humanity in an Ice Age is the different world resulting from the lowered sea levels, and if my impression is correct then we only get that in maximal form just before the whole world is going to tumble over into the next interglacial. If you pick a time spang in the middle, some 60,000 years ago or some 50,000 years hence, the sea level will probably be only halfway down.
Or maybe not exactly that. It makes sense to suggest that the rate of ice accumulation might be a lot higher earlier on since there is more open sea and moist land area to supply heavier snowfall, and as the glaciers thicken and broaden the rate of snow deposit slows down. That would shift the rate of ice formation and sea level drop toward the earlier tens of thousands of years, but I think overall it is still true that the maximum lowering of sea levels and maximum burden of ice on land is still just a handful of thousands of years before the interglacial starts, and that while halfway through the glaciation the sea might be lower than halfway down, it will still be higher than its lowest point which would be some 40,000 years later.
Anyway the glacial period is so long that one could write an AH spanning more time than OTL Interglacial agricultural based history and still have a lot of margin to spare even crowding it in toward the end.
As noted the problem I have is that humanity was spread out over most of the habitable Old World, excepting the Americas but including Australia, and the most recent estimate of "Modern Mentality" of our species is 40,000 years ago, so we have a good 30,000 years with humans spread out everywhere from the tundras bordering the European ice sheet clear down to Tasmania and the Siberian shores of the Pacific, as well as throughout most of Africa or even all of it, and this spans a whole heck of a lot of very different climate zones and ecologies, and we have not one shred of evidence that in a time span some 4 times longer than the whole history of agricultural civilization that any of these populations created any agricultural crops whatsoever. Then kaboom within a period less than a tenth of this time, we get at least half a dozen clearly independent inventions of some set of core crops or other scattered all over the world, including a fewin the Americas which had no hominids at all until the Interglacial started. I think it is unlikely some common mutation transformed such widespread populations simultaneously in the same way to give them abilities their ancestors lacked, nor is it plausible the "message" of the general idea of cultivation spread culturally, certainly not to the New World. Nope, humans had the innate ability to invent farming but not the opportunity, and when that opportunity came it came to the whole world all at once and was taken by people of essential identical abilities, all at once.
Therefore I am very skeptical of the idea that it is plausible that some precocious group could invent it any time during the prior glaciation.
Now on the other hand, if we have people who already have a high degree of dependency on crops, who are suddenly catapulted into glacial era conditions but in a habitable climate zone, they will face tough challenges but I do think some portion of them would hang on to farming by various tough expedients. The trick would be to invest effort in sustaining the survival of varieties that are not favored in current climate conditions but will be once again favored in new ones that will be coming along many generations hence, and of course then sustaining the once and future staples disfavored in the new interim, and so on. One way to accomplish this would be to spread the zone of settlement of these people over many regional climates, with some specializing in some crops and others in others to suit their various zone current conditions, and sustaining contact and trade over these diverse regions so that there is a source for substitution of new crops as a given zone shifts from one climate to another; the "reserved for the future" crops are sourced from other regions where they happen to be profitable at the time, and someday this crop goes out of cultivation there but is restored there even later when the climate shifts back again.
If we had an ISOT type situation where a large diverse region loosely tied together with trade is plopped down in a glacial age, I can see it stumbling on such solutions, via a period of general disorientation and loss--though the "Vlad Tepes" dieback might be mitigated, or even pretty well absorbed, by the opportunities many people would have to expand into neighboring territories inhabited only by downtime gatherer-hunters--who would suffer themselves to be sure by being displaced. Or more likely absorbed, but it would be unpleasant for them even if they don't suffer demographic genocide, and realistically they will die back exposed to the disease pool of agricultural peoples tied together by trade links. So for a time we have a Dark Age of sorts where the uptimers disperse and many of them even abandon agriculture and become GH peoples themselves, and the general population density drops as they disperse in a wave front leaving the core agricultural zones with depleted population--which buffers the adverse conditions in which they must discover what crop mixes suit the new local climates, and then the disconcerting future climate shifts that change that mix.
So it would be possible for a broad region containing many subregional climates and a diverse mix of crops to hit bottom while still sustaining most of these somewhere or other, and then learn to shift them around as climates shift, and thus with somewhat greater labor intensiveness at lower population densities, resume progress at a slower rate, and start expanding opportunistically until eventually they cover the globe, having probably invented some new crops over the many thousands or tens of thousands of years this happens. Against this, they do have time, depending on just how far back before the Glaciation ends they have been set, and their learned habits of opportunistic crop shifting will help them survive the rapid global changes of the shift from Glacial to Interglacial when it comes, and then they'd be set up pretty when the new Interglacial settles to make the most of it.
But I think you can see why I think it more likely that any ISOT of Interglacial agriculturalists will end with all its peoples one by one abandoning agriculture completely and merging with the downtime GH peoples and forgetting all about farming save in vague legend, and have to reinvent all the wheels in the next Interglacial on the same terms as OTL.
And I think it is massively improbable though perhaps not impossible to postulate an ATL invention of agriculture against these steep odds, when OTL history demonstrates that the barrier must be formidable indeed for no one to have done it OTL. Many people suggest, "Oh, it could have been developed in some place that is now submerged!" but the problem I have with that idea is that if the tough challenge of developing farming in rapidly changing climate conditions could be met, the people who did it would perforce be opportunists who spread out to grab every chance they can find and are accustomed to migrating to new sites, so when the Interglacial comes on and the seas start rising, they'd just spread uphill and survive--and then they'd be precociously placed to dominate the Interglacial early and we'd know all about them, being the obvious founders of civilization as we know it, and many thousands of years before the most ancient OTL civilizations too.
Indeed given the long odds against even one such society forming can be beat, it and its successors might be marginal versus the lusher prospects of stable Interglacial climates, but slow and steady they'd survive, advance, prevail over GH populations, and spread around the world and develop more and more advanced tech until eventually we'd have industrialism and space travel and nukes and so forth before the Glacial period ends. It might take them 3-5 times as long for a variety of reasons, and might involve much lower population densities, but again, they have time, nor will the transition to an Interglacial wipe them out--might eliminate the majority of the established populations, who do seem likely to be located in places that would go under the sea, but branches and outliers would be above the new sea levels and sitting pretty to enjoy the more stable new climates when they emerge, and rapidly consolidate control over the whole world.
I'm guessing you might be interested in such a TL. But while I grant it is possible, it does seem very very very unlikely to me, or it would have happened OTL, which is to say some very very alternate versions of ourselves would have Internet level societies having this dialog maybe 10,000 years ago! Their discussion might be more on the lines of "WI agriculture were founded 10,000 years earlier" and it would be plausible to ask that, the constraints being largely about the development of modern human mentality and demographic spread of our species out of East Africa. For them the next Interglacial would be a matter of far off eras--unless of course human generated climate change threatens to tip it over early! As it might or might not plausibly do; I don't think we understand the mechanisms involved yet well enough to guess what kind of monkey wrench current OTL elevations of greenhouse gases would throw into the cycle.