Wednesday, April 10, 2019

Ancient Climate Change

The huge problems of climate change in prehistory are frequently invoked when discussing the peoples living in those times and how hard it was to adapt quickly.  At the beginning of the Younger Dryas around 12,700 years ago, the temperature dropped 6 degrees in about 30 years in Europe.  It may have dropped two degrees in a single year. People could not move south fast enough to survive.

Yet so far I can't help but notice that the catastrophes seem to have occurred because of rapid cooling or rapid drying.  Increased warmth and increased moisture do not seem to be a problem (with at least one exception on the moisture, because of flooding).

Don't quote me.  Someone may know better than I on this.


james said...

That 6C change was in Greenland.

"The Younger Dryas was a period of climatic change, but the effects were complex and variable. In the Southern Hemisphere and some areas of the Northern Hemisphere, such as southeastern North America, there was a slight warming"

I have no good feel for how far people ranged or communicated then. Since the yearly change would fall within the normal range, the first year or two wouldn't bite harder than they were used to, but eventually one harvest would be way too small, and the survivors would probably up stakes in the spring.

But how far would they range? I'd guess they'd move roughly in the direction of other people, partly because we're social and partly because the others presumably are alive because they found food. If a thousand miles represent dT=10C, 600 miles is the 6C change (which is probably less pronounced over Europe anyhow). Suppose our heroes don't move until the 4th year, and then up stakes every couple of years after that--that's about 14 moves. The first couple will be fairly random, but after that it should be clear that there are more people southward, so 12 x maybe 20 miles? That makes up about half that temperature shift. It might be more if people figure they can "chase the Sun" to the south. Birds do, and people are observant.

I think a fair fraction of the people would be able to migrate to "safety."

dmoelling said...

If you have a chance visit the Natural history museum in Cincinnati. It has a great exhibit on that time period when the glaciers just started retreating. The Cincinnati regions was the farthest extent of the north American glacier. Basically everything south was a tundra type environment. Although the megafauna were still there, the human population was small and had a hard life. If such a change in climate (entering an ice age not ending) were to occur today much of the temperate zone farm belts would be in trouble.

While you are visiting the Cincinnati region there are some excellent paleolithic mounds from a later era to see. Much like the more famous Nazca lines in Peru, the mounds represent a wide variety of animal and geometric shapes only recognizable from above. Early Americans needed to court the favor of the gods in a much tougher world than today.

Assistant Village Idiot said...

@dmoelling - good to know. I am going to a state park in SE Ohio for a 40th anniversary of a fantasy football league (yes, they used to play by phone and postcard!) live draft this August, and was wondering some other things I might do which were not too many hours away. I went to the Hall of Fame in Canton already and was wondering what else I might like. This is right up my alley.

We went through Cincinnati several times during the nine years our boys were at Asbury, but did not stop, and have not been back.