Climate change and migrations

With fires raging and people fleeing to the sea in Australia, and evacuations in the Philippines in the face of volcanoes, I think about all the instances of weather and climate that have changed the shape of world populations. The few that I know about are certainly samples of many.

I started thinking about this when I read that half of the European immigrants to North America from Plymouth to the formation of the U.S. were indentured servants. Europe was caught in the throes of the Little Ice Age. It was cold and crops failed or yielded little. Fathers would take their sons and daughters to the dock and turn them over to a ship’s captain. The captain would sail them to the “new” world and recover their passage with their sale to waiting farmers and settled and prosperous families.

In my research, I read Brian Fagan’s The Great Warming, a history of population ebbs and flows with planet warming circa 800-1400. The Vikings went across the seas, colonizing Iceland, Greenland, and Newfoundland. European populations swelled as farmers grew wheat in Norway and wine grapes in England. The moldboard plow was invented to turn up new ground with the exploding populations.

But in the Americas at that time, indigenous populations were decimated by heat and drought. Half the people of the California coast died as their acorn-based diet died. The Mayan cities, reliant on sophisticated irrigation systems, collapsed with drought and the people scattered and survivors scratched livings in small villages. And I think this was the time that the very sophisticated society at Chaco Canyon collapsed. People dispersed; we have no record of where they went, and how many died in getting there.

The mound cities, including Cahokia, near present day city of St. Louis, and circa 1100 c.e., larger and more sophisticated than London with 10,000-40,000 people, grew and collapsed during the Warming—overuse of resources? Floods? Climate? Not sure.

The planet cooled, populations in Europe shrunk rapidly with the plague, and the generations of survivors literally shrunk in size. Charlemagne, King of the Franks in the late 700s and early 800s—the very beginning of that Great Warming period, commanded an army of six-footers. Napoleon, who ruled, fought, and lost with an army of soldiers of five-footers, had his run towards the end of what is called the Little Ice Age, the period from roughly 1300-1850.

Which is of course a period that encompasses the colonization of the Americas by Europeans (and the demise of the Vikings settlements in Newfoundland and Greenland). North America apparently recovered with the cooling. Population, including that of the Mound cities and the Pacific coast, might have fallen rapidly, but corn and agriculture had moved from Central America north; agriculture, and very sophisticated hunting, fishing, and gathering, served populations well. As crops and agriculture moved, so did people. And until modern genetics, we best traced that with linguistics. John Wesley Powell commissioned a language study in the late 1800s at the Smithsonian, and came up with 45 or 48 language families in North America. Alvin Josephy started with languages in The Indian Heritage of America, published in 1968, long before modern genetics. The language maps show Athabaskan—or dene—languages in present day Canada, the North Pacific Coast, and in the Southwest, with Navajo and Apache among others. It would be interesting to correlate Athabaskan languages and peoples from north to the south, and the Algonquins from the Northeast to the Pacific coast with climate and weather events.

There were of course conflicts and wars too. But even wars can own to climate. There is now good evidence that the turmoil of the Arab Spring and upheavals and eventually war in Syria had to do with drought. Drought chased farming rural people into cities, where jobs and food were scarce for many and created a swelling population ready for any radical change that might mean bread.

Now the people of Middle East, sub-Saharan Africa, and Central America scurry north, to milder climates where agriculture and industry still thrive. We can blame mass migrations on corruption, mismanagement, overpopulation, and wars, but somewhere in the mix is drought and hunger.

With heat and drought come fire and sporadic flooding of vulnerable lands. With rising tides, more dramatic shifts of rains, snows, and temperatures; with winds, hurricanes, typhoons, fire and flood (add earthquakes and volcanoes), the populations of the world are probably in the beginning of rapid transformations. What parts of Australia will survive—and where will its populations go? How many islands in the Philippines will go under? How long can New Orleans stay above water? How much air conditioning can Phoenix afford? Where will Phoenix—and much of California—get its water as the Colorado gets overtaxed and evaporation sucks its waters? And where will all the people go?

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