<p>Due to IPCC the climate sensitivity of CO₂ very likely is 3.0 ± 1.5 ℃ for each doubling of the concentration of atmospheric CO₂. </p>

<p>Counting on earlier global warming using the Arrhenius formula [ΔT=λ·α·㏑(C/C₀)], global mean vs emissions of atmospheric CO₂, assumed mostly depending on CO₂, gives:</p>

<ol>
<li>1970-2018 0.9 ℃ 325ppm,408ppm: sensitivity 2.74 ℃</li>
<li>PETM 5 ℃ 700ppm,2000ppm: sensitivity 3.30 ℃</li>
</ol>

<p>The Paleocene–Eocene Thermal Maximum (PETM) is associated with extreme changes in Earth's carbon cycle due to volcanism about 55 million years ago. The warm period lasted for about 200,000 years. (Wikipedia)</p>

<p>Of course, there is an amount of uncertainty in the PETM figures and Earth wasn't quite the same since it was ice free etc, but these two examples support the information from IPCC with a most likely value of about 3 ℃.</p>

<p>The circumstances, the cause of PETM and the coincidence of the today emissions and observed warming, indicate that calculations like this is relevant. </p>

<p>My question is:</p>

<blockquote>
  <p>Are there other geological events that can be used to estimate the
  climate sensitivity?</p>
</blockquote>

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

<hr>

<p>I did an error, the concentration of atmospheric CO₂ 1970 was 325 ppm.</p>

<p>The formula I use is: Climate Sensitivity = ΔT∙㏑ 2/㏑(C/C₀)].</p>

<blockquote>
  <p>I think that the Arrhenius formula is valid only for a solid sphere
  without (especially vertical) currents. Calculating the climate
  sensitivity for global land</p>
  
  <p><a href="https://www.ncdc.noaa.gov/cag/global/time-series/globe/land/1/6/1880-2019" rel="nofollow noreferrer">https://www.ncdc.noaa.gov/cag/global/time-series/globe/land/1/6/1880-2019</a></p>
  
  <p>from the range of the Keeling curve gives sensitivity≈3.48 ℃.</p>
</blockquote>

CC BY-SA 4.0
2019-12-25T17:40:21.210Z
@ebv - "Mass balance calculations indicate that the required carbon mass during the CIE interval *would not exceed* ~28,000 Pg, given that the carbon was released from organic matter, permafrost, thermogenic methane, methane hydrate, or any of their combinations."
Lehs
CC BY-SA 4.0
2019-12-25T18:17:53.480Z
@ebv - It makes an upper limit 0.56 Gt/y. Humans today is about 10 Gt/y. Using the upper limit for calculating sensitivity gives 1.82 ℃ beating the IPCC low limit which is 1.5 ℃.
Lehs
CC BY-SA 4.0
2019-12-26T09:48:21.737Z
@ebv - You are right, it should be "geological events". It is thought that 0.24 Gt carbon was emitted per year and methane in the atmosphere turn into CO₂ in 10-20 years.
Lehs
<geology><climate-change><co2><carbon-cycle>
About climate sensitivity of carbon dioxide: today compared with PETM
Lehs
# About climate sensitivity of carbon dioxide: today compared with PETM

(Asked by: username_0 on 2019-12-25)

Due to IPCC the climate sensitivity of CO₂ very likely is 3.0 ± 1.5 ℃ for each doubling of the concentration of atmospheric CO₂.

Counting on earlier global warming using the Arrhenius formula [ΔT=λ·α·㏑(C/C₀)], global mean vs emissions of atmospheric CO₂, assumed mostly depending on CO₂, gives:

1. 1970-2018 0.9 ℃ 325ppm,408ppm: sensitivity 2.74 ℃
2. PETM 5 ℃ 700ppm,2000ppm: sensitivity 3.30 ℃

The Paleocene–Eocene Thermal Maximum (PETM) is associated with extreme changes in Earth's carbon cycle due to volcanism about 55 million years ago. The warm period lasted for about 200,000 years. (Wikipedia)

Of course, there is an amount of uncertainty in the PETM figures and Earth wasn't quite the same since it was ice free etc, but these two examples support the information from IPCC with a most likely value of about 3 ℃.

The circumstances, the cause of PETM and the coincidence of the today emissions and observed warming, indicate that calculations like this is relevant.

My question is:

> Are there other geological events that can be used to estimate the
> climate sensitivity?

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

---

I did an error, the concentration of atmospheric CO₂ 1970 was 325 ppm.

The formula I use is: Climate Sensitivity = ΔT∙㏑ 2/㏑(C/C₀)].

> I think that the Arrhenius formula is valid only for a solid sphere
> without (especially vertical) currents. Calculating the climate
> sensitivity for global land
>
> <https://www.ncdc.noaa.gov/cag/global/time-series/globe/land/1/6/1880-2019>
>
> from the range of the Keeling curve gives sensitivity≈3.48 ℃.

**Tags:** geology, climate-change, co2, carbon-cycle

> **Comments:**
> **username_0**: @ebv - "Mass balance calculations indicate that the required carbon mass during the CIE interval *would not exceed* ~28,000 Pg, given that the carbon was released from organic matter, permafrost, thermogenic methane, methane hydrate, or any of their combinations."  
> **username_0**: @ebv - It makes an upper limit 0.56 Gt/y. Humans today is about 10 Gt/y. Using the upper limit for calculating sensitivity gives 1.82 ℃ beating the IPCC low limit which is 1.5 ℃.  
> **username_0**: @ebv - You are right, it should be "geological events". It is thought that 0.24 Gt carbon was emitted per year and methane in the atmosphere turn into CO₂ in 10-20 years.  

---

## 0 answers

