<p>Since CO2 concentration is responsible of temperature, that trend is related to <a href="https://en.wikipedia.org/wiki/Little_Ice_Age#Possible_causes" rel="nofollow noreferrer">the little ice age</a>, where Earth cooled a little. Wikipedia article describes several possible causes for that, one of the is the answer of Keith, but others might be orbital cycles, solar activity, volcanic activity and ocean circulation.<br>
Also is possible that is just a <a href="https://en.wikipedia.org/wiki/Bond_event" rel="nofollow noreferrer">cycle</a> that repeats itself each 1000 or 1500 years.</p>

CC BY-SA 4.0
2019-12-19T16:32:39.240Z
Thank you for your answers, I see that there are several strong theoretical positions which seem to be explications.
Rico1990
CC BY-SA 4.0
2019-12-21T04:41:03.740Z
"orbital cycles, solar activity, volcanic activity and ocean circulation" might affect the temperature, but would not directly affect CO2-concentrations (except that volcanic activity would increase it, which appears to be the opposite of what the plot shows).
Keith McClary
CC BY-SA 4.0
2019-12-19T13:48:00.570Z
2019-12-19T13:48:00.570Z
Santiago
<p>One theory:<br>
<a href="https://www.vice.com/en_us/article/bjqnqq/european-genocide-of-indigenous-peoples-in-the-americas-cooled-earths-climate" rel="nofollow noreferrer">European Genocide of Indigenous Peoples in the Americas Cooled Earth’s Climate</a></p>

<blockquote>
  <p>The mass deaths of Indigenous American peoples 500 years ago—caused by disease and violence spread by European colonizers—was so extreme that it cooled Earth’s climate, according to a new study in Quaternary Science Reviews.<br>
  Led by Alexander Koch, a graduate student in geography at University College London, the authors said that a period of global cooling that lasted from the 16th to 19th centuries was partly caused by epidemics and warfare that killed 90 percent of the Indigenous population in just 100 years.<br>
  The devastating loss, known as the Great Dying, left 56 million hectares of farmland unattended, enabling forests and other vegetation to grow over agricultural terrains. The rewilded landscapes drank in much more carbon dioxide than the preceding farms, which reduced levels of the greenhouse gas in the atmosphere by 7-10 parts per million.</p>
</blockquote>

<p>Original research this article references:<br />
<a href="https://www.sciencedirect.com/science/article/pii/S0277379118307261" rel="nofollow noreferrer">Earth system impacts of the European arrival and Great Dying in the Americas after 1492</a></p>

CC BY-SA 4.0
2019-12-22T14:29:12.237Z
there were many many flaws with this study, including using modern farming practices as models of indigenous farming climatic effects.
John
CC BY-SA 4.0
2019-12-18T22:45:10.417Z
2019-12-19T12:44:45.680Z
2019-12-19T12:44:45.680Z
Keith McClary
<p>I plotted the atmospheric CO2-concentrations to see trends and wondered especially about the phase around 1600 in the plot which I find very interesting. Etienne Godin already told me some facts in the comments of another thread, but I'm curious about more details, since I'm a newbie in this area.</p>

<p><a href="https://i.sstatic.net/2QxYZ.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/2QxYZ.png" alt="enter image description here"></a></p>

<p>source: <a href="https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/smoothedco2.txt" rel="nofollow noreferrer">https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/smoothedco2.txt</a></p>

<p>Where I plotted the column ALL_50_full.</p>

<p>What do you say?</p>

CC BY-SA 4.0
2019-12-19T16:33:43.837Z
I plotted it myself with data of the IAC in Switzerland which published an excel sheet with that data.
Rico1990
CC BY-SA 4.0
2019-12-20T13:41:47.007Z
That's true. I used another source now and edited the article so that we can talk about the paramteres of the study too. See https://www.ncdc.noaa.gov/paleo-search/study/10437 for the source and all wanted metadata. The measurement used ppmv to access CO2-concentrations from 1000-2004.
Rico1990
CC BY-SA 4.0
2019-12-20T20:28:50.930Z
I think your new plot is the same as the black curve in Fig. 1b of [Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate](https://www.researchgate.net/publication/41174277_Ensemble_reconstruction_constraints_on_the_global_carbon_cycle_sensitivity_to_climate)
Keith McClary
<atmosphere><climate-change><co2>
Trends in atmospheric CO2
Rico1990
# Trends in atmospheric CO2

(Asked by: username_0 on 2019-12-18)

I plotted the atmospheric CO2-concentrations to see trends and wondered especially about the phase around 1600 in the plot which I find very interesting. Etienne Godin already told me some facts in the comments of another thread, but I'm curious about more details, since I'm a newbie in this area.

[![enter image description here](https://i.sstatic.net/2QxYZ.png)](https://i.sstatic.net/2QxYZ.png)

source: <https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/frank2010/smoothedco2.txt>

Where I plotted the column ALL\_50\_full.

What do you say?

**Tags:** atmosphere, climate-change, co2

> **Comments:**
> **username_0**: I plotted it myself with data of the IAC in Switzerland which published an excel sheet with that data.  
> **username_0**: That's true. I used another source now and edited the article so that we can talk about the paramteres of the study too. See https://www.ncdc.noaa.gov/paleo-search/study/10437 for the source and all wanted metadata. The measurement used ppmv to access CO2-concentrations from 1000-2004.  
> **username_1**: I think your new plot is the same as the black curve in Fig. 1b of [Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate](https://www.researchgate.net/publication/41174277_Ensemble_reconstruction_constraints_on_the_global_carbon_cycle_sensitivity_to_climate)  

---

## 2 answers

### Answer by username_2 on 2019-12-19. Score: 1

Since CO2 concentration is responsible of temperature, that trend is related to [the little ice age](https://en.wikipedia.org/wiki/Little_Ice_Age#Possible_causes), where Earth cooled a little. Wikipedia article describes several possible causes for that, one of the is the answer of username_1, but others might be orbital cycles, solar activity, volcanic activity and ocean circulation.  
Also is possible that is just a [cycle](https://en.wikipedia.org/wiki/Bond_event) that repeats itself each 1000 or 1500 years.

> **Comments:**
> **username_0**: Thank you for your answers, I see that there are several strong theoretical positions which seem to be explications.  
> **username_1**: "orbital cycles, solar activity, volcanic activity and ocean circulation" might affect the temperature, but would not directly affect CO2-concentrations (except that volcanic activity would increase it, which appears to be the opposite of what the plot shows).  

---

### Answer by username_1 on 2019-12-18. Score: -1

One theory:  
[European Genocide of Indigenous Peoples in the Americas Cooled Earth’s Climate](https://www.vice.com/en_us/article/bjqnqq/european-genocide-of-indigenous-peoples-in-the-americas-cooled-earths-climate)

> The mass deaths of Indigenous American peoples 500 years ago—caused by disease and violence spread by European colonizers—was so extreme that it cooled Earth’s climate, according to a new study in Quaternary Science Reviews.  
> Led by Alexander Koch, a graduate student in geography at University College London, the authors said that a period of global cooling that lasted from the 16th to 19th centuries was partly caused by epidemics and warfare that killed 90 percent of the Indigenous population in just 100 years.  
> The devastating loss, known as the Great Dying, left 56 million hectares of farmland unattended, enabling forests and other vegetation to grow over agricultural terrains. The rewilded landscapes drank in much more carbon dioxide than the preceding farms, which reduced levels of the greenhouse gas in the atmosphere by 7-10 parts per million.

Original research this article references:  
[Earth system impacts of the European arrival and Great Dying in the Americas after 1492](https://www.sciencedirect.com/science/article/pii/S0277379118307261)

> **Comments:**
> **username_3**: there were many many flaws with this study, including using modern farming practices as models of indigenous farming climatic effects.  

---

