European colonization of Americas caused climate change

Aug 2011
107
The Castle Anthrax
#11
Huh... I always understood that it was the earth's precession that causes annual climate changes and ocean temperatures which affect a broader climate cycle. All along it was those pesky European settlers! Who knew? Add that to the list of apologies. Now if we could just figure out how those hooligan European settlers killed off all of the dinosaurs!
 
Likes: Belgarion
Mar 2018
593
UK
#13
The worse of the little ice age occurred in the 1600, after the population of the Americas had stopped declning and was probably rising again. And the Little Ice Age had ready started by 1300, long before the Americas were discovered.

And if there was a drop.after the European colonization due to the loss of people, there should have been a loss due to the Black Death, yet the Little Ice preceded the Black Death by around 40 years.

If there was a drop in CO2 , by how much? Did their claims.od drop.comd from actual measurements, as from the ice core samples, or is it just speculation ? The article doesn't say.
You can't expect details from a news website. However, the research article is linked to in the first paragraph, which is actually pretty good. Quantitative evidence is presented here:

https://www.sciencedirect.com/science/article/pii/S0277379118307261#

The whole paper is open access, so you can read to your hearts content. The abstract presents the case fairly well. The most interesting part is:

"We investigate whether the decline in global atmospheric CO2 concentration by 7–10 ppm in the late 1500s and early 1600s which globally lowered surface air temperatures by 0.15∘C, were generated by natural forcing or were a result of the large-scale depopulation of the Americas after European arrival, subsequent land use change and secondary succession."
"Accounting for carbon cycle feedbacks plus LUC outside the Americas gives a total 5 ppm CO2 additional uptake into the land surface in the 1500s compared to the 1400s, 47–67% of the atmospheric CO2 decline. Furthermore, we show that the global carbon budget of the 1500s cannot be balanced until large-scale vegetation regeneration in the Americas is included"

So they seem to be saying that the reforrestation that occurred after the depopulating of the Americas removed between 2-5ppm of CO2, with an associated temperature change of 0.03-0.08C. Considering how broad they inter quartile ranges are everywhere in their data, I'm somewhat sceptical that they can identify such a minute effect. People studying the modern climate, where we have far better data, don't try and make predictions that accurate!

I'll stick with my original assessment: it's a plausible result, but not convincing.
 
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Likes: Ichon
Mar 2018
593
UK
#14
Huh... I always understood that it was the earth's precession that causes annual climate changes and ocean temperatures which affect a broader climate cycle. All along it was those pesky European settlers! Who knew? Add that to the list of apologies. Now if we could just figure out how those hooligan European settlers killed off all of the dinosaurs!
Annual climate change is the seasons... That's caused by the earth's tilt, not by its procession.

Now changes in climate are caused by a great deal of factors: astronomical changes (i.e. changes in the sun and the orbits), geological factors (volcanoes, plates moving), and biological factors (changes in land use, atmospheric composition, etc...)
 

Bart Dale

Ad Honorem
Dec 2009
7,095
#15
Note, that CO2 levels reached a pre-modern peak of 320 ppm around 1300, which was the start of the Little Ice Age.

The CO2 record is characterized by high-frequency variability. Focussing on centennial-scale changes (the 3 point moving average), prominent minima in CO2 of about 260 ppmv are present around 860 AD and 1150 AD, and smaller minima of 275-280 ppmv occur around 1600 AD and 1800 AD. In between, CO2 maxima of 300 ppmv around 1000 AD, 320 ppmv around 1300 AD, and 300 ppmv around 1700 AD are recorded.
Start of Little Ice Age

The Little Ice Age was a period of regionally cold conditions between roughly AD 1300 and 1850. Little Ice Age
So the earth was cooling as CO2 levels were at their pre-modern peak in the last 1000 years.



A study of the Medieval Warming period

In conclusion, and considering the full spectrum of studies included in this Summary, it would appear that a goodly portion of the Medieval Warm Period throughout Russia was somewhat warmer than what has so far been experienced there during the Current Warm Period. And since the MWP held sway when the atmosphere's CO2 concentration was something on the order of 285 ppm, as compared to the 400 ppm of today, it would appear that the air's CO2 content has had essentially nothing to do with earth's near-surface air temperature throughout the entire Holocene, when the air's CO2 concentration at times dropped as low as 250 ppm. Other factors have clearly totally dominated. CO2 Science
 
Nov 2011
8,845
The Dustbin, formerly, Garden of England
#16
The Mississippi mound building cultures prospered from c.900 AD to 1500AD driven by a global warm and moist period that allowed good corn crops to be harvested--it's decline on the eve of European contact co-incided with a cold period and drought that would, presumably, have caused lower plant growth and thus lower CO2 levels.
 

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