Thursday, October 13, 2011

IRCPPs in the Links: Did the European conquest of the Americas contribute to the "Little Ice Age"?

Abandoned Footnotes looks at the possibility of unintended environmental consequences following mass social change (in 1492!):
...Most native peoples in the Americas, lacking iron tools, practised forms of agriculture that made much use of fire. These were not "primitive" forms of agriculture, but complex land-management practices that made possible great population densities, even in places that are today only lightly inhabited (like the Amazon). Low-level burning kept grasslands from turning into forests, helped create forests that looked to Europeans like great parks, and produced charcoal that was used to make thin soils fertile through terra preta. And these practices effectively kept enormous amounts of carbon dioxide constantly in the atmosphere rather than locked into trees and other vegetation. When  native populations collapsed, however, the burning stopped or was greatly reduced, and the carbon dioxide was quickly locked up into forests again. Now, what follows is quite controversial. Mann cites some recent research that argues that this must have made a big contribution to the so-called Little Ice Age: the sudden drop in carbon dioxide in the atmosphere, perhaps in combination with natural variations in solar radiation, generated global cooling from around 1550 to around 1660. And this global cooling in turn appears to have produced a great "general crisis" in Europe: famine, war, and pestilence....