Anthropocene initiation: 1610

[Maxx]

So when did human impacts take off on their own trajectory?

1610, it is suggested, when the demographic decline of the New World caused a CO2 dip:

http://phys.org/news/2015-03-epoch-defining-humans-dominate-planet-earth.html

 

[Alessandra Kelley]

Wow.

I find it sobering that the sudden death of some 50 million Native Americans due to introduced disease abruptly stopped nearly all farming activities in the Americas, leading to a regrowth of massive forests and a very noticeable drop in CO2 levels worldwide for some decades.

 

[Maxx]

Wow.

I find it sobering that the sudden death of some 50 million Native Americans due to introduced disease abruptly stopped nearly all farming activities in the Americas, leading to a regrowth of massive forests and a very noticeable drop in CO2 levels worldwide for some decades.

And imagine how productive in terms of food all that farming must have been!
Also, of course, a lot of agriculture involves slash-and-burn techniques.
Also, you see some comparative events on a smaller scale around the Mediterranean with deforestation and erosion altering the environment or the remarkable environmental preservation that a region can have if it harbors enough pirates to keep most human exploitation at a lower level (eg in the Adriatic in early modern times).

 

[King Neptune]

I think the authors are trying to get funding. It appears that according to some evidence there was a drop in CO2 around that time, but I think it was too early to have been caused by Europeans acting in the Western hemisphere. I'm not as familiar with South America, but in North America the epidemics that greatly decreased the numbers of American Indians came in the late 1600's and early 1700's. The cultures of the Southern states were untouched at that time, as was also true of the Indians in Midwest, Indianapolis, around the Great Lakes, etc.

I wouldn't be surprised if something else drank up CO2. Or it might be that the North American Indians stopped burning the underbrush on a regular basis. That burning would have put a fair amount of CO2 into the atmosphere every year; stop it and it would take some time for things to adjust.

 

[Maxx]

I think the authors are trying to get funding. It appears that according to some evidence there was a drop in CO2 around that time, but I think it was too early to have been caused by Europeans acting in the Western hemisphere. I'm not as familiar with South America, but in North America the epidemics that greatly decreased the numbers of American Indians came in the late 1600's and early 1700's. The cultures of the Southern states were untouched at that time, as was also true of the Indians in Midwest, Indianapolis, around the Great Lakes, etc.

I wouldn't be surprised if something else drank up CO2. Or it might be that the North American Indians stop[ped burning the underbrush on a regular basis. That burning would have put a fair amount of CO2 into the atmosphere every year; stop it and it would take some time for things to adjust.

There's a big footnote about the CO2 timing. The drop begins earlier than 1610, which seems right. The model on the social side is somewhat crude. For example, I'd say you don't have to literally kill off 50 million to get the effect -- but a number of things compound the effect, one is simple demographic loss, ie a population that would have been say 40 million in 1600 can't reach that level because 60% of the population died in say 1550 so there just are missing people who otherwise would have been born.
The other is social disruption, which we know for the Americas can mean simply dispersing and doing less agriculture as well as avoiding production for tribute and/or escaping the levels of society that used to level the tribute.
The effect in MesoAmerica of the Europeans was something like the effect of the Mongols on Mesopotamia: massive depopulation, social collapse, destruction of irrigation systems and so on, but on a much greater scale in a region with a much larger potential biomass.

 

[King Neptune]

There's a big footnote about the CO2 timing. The drop begins earlier than 1610, which seems right. The model on the social side is somewhat crude. For example, I'd say you don't have to literally kill off 50 million to get the effect -- but a number of things compound the effect, one is simple demographic loss, ie a population that would have been say 40 million in 1600 can't reach that level because 60% of the population died in say 1550 so there just are missing people who otherwise would have been born.
The other is social disruption, which we know for the Americas can mean simply dispersing and doing less agriculture as well as avoiding production for tribute and/or escaping the levels of society that used to level the tribute.
The effect in MesoAmerica of the Europeans was something like the effect of the Mongols on Mesopotamia: massive depopulation, social collapse, destruction of irrigation systems and so on, but on a much greater scale in a region with a much larger potential biomass.

I was thinking of things like that, but there wasn't enough by 1600 to make a major difference. Most of South America was untouched by invaders, and only a small part of North America was invaded, but it is true that Central America had suffered greatly. There was a great deal of agriculture there, but as a percentage of the whole it is relatively small, and most of it went into other vegetation, so there would have been similar amounts of CO2 being eaten by plants.

 

[Xelebes]

Smallpox spread quite differently because it could exploit the trade networks between the various nations. The Cree were already stricken with smallpox prior to being met by Radisson and Groseilliers but William Tomlison is noted for being able to control the spread of smallpox in York Factory, demonstrating that it was the trade networks that were infecting the aboriginal populations and not simply contact.

 

[Maxx]

Smallpox spread quite differently because it could exploit the trade networks between the various nations. The Cree were already stricken with smallpox prior to being met by Radisson and Groseilliers but William Tomlison is noted for being able to control the spread of smallpox in York Factory, demonstrating that it was the trade networks that were infecting the aboriginal populations and not simply contact.

Yes, there's plenty of evidence (the best being how empty and open the woodlands of North American were when the Europeans arrived up north) that demographic collapse was going strong even in North America by 1600.

Another bit of evidence is the movement of Athapaskan hunter-gatherers around 1550 into areas that had been full of farmers (Puebloans) and the collapse of some Athapaskan (Dismal River for example) and Caddoan farming at about the same time (eg, Pawnee shifting away from agriculture).