<p>We call this the <a href="https://en.wikipedia.org/wiki/Airborne_fraction" rel="noreferrer">airborne fraction</a>, although as the name suggests, it's normally expressed as a fraction rather than a percentage.</p>

<p><a href="https://www.biogeosciences.net/11/3453/2014/" rel="noreferrer">Raupach et al (2014)</a> is an (open access) example of it being used in the literature, and in that paper they quote a long-term 1959 to 2012 value of 0.44, so in the same ball-park as your estimate.  Similarly, here's an example of it's use in <a href="https://ipcc.ch/publications_and_data/ar4/wg1/en/ch7s7-3-5-2.html" rel="noreferrer">Chapter 7 of the IPCC AR4</a> with a range of modelled values from 0.4 to 0.5.  It's also often calculated over single years, as in your example, to look at the trends and variability.</p>

<p>As an aside, the 2 ppm in your calculation is called the <a href="https://www.newscientist.com/article/2112153-a-pause-in-growth-rate-of-atmospheric-co2-is-over-heres-why/" rel="noreferrer">atmospheric CO2 growth rate</a> and the total mass of CO2 in the atmosphere would be the atmospheric CO2 <em>burden</em>.</p>

CC BY-SA 4.0
2018-10-27T11:59:46.970Z
2018-10-27T11:59:46.970Z
Deditos
<p>I have a theoretical exercise where I calculated the amount of CO2 that is released to the atmosphere per year (4.6 ppm). We assume that the relative increase of CO2 is 2 ppm, hence the percentage of CO2 that stays in the atmosphere is around 2/4.6 ~ 40 %.</p>

<p>What is the technical term for this percentage?</p>

CC BY-SA 4.0
2018-10-21T07:52:31.833Z
Possibly residual or accumulated CO2.
Fred
CC BY-SA 4.0
2018-10-23T14:37:30.113Z
Atmospherically persistent CO2?
Zeitsperre
CC BY-SA 4.0
2018-10-27T16:39:50.820Z
Mauna Loa CO2 data shows the actual amount in the atmosphere and the continuing increase ; one does not need to assume anything. Unless you are separating "good" from "bad" CO2.
blacksmith37
<atmosphere><climate-change><co2><climatology>
Technical term for percentage of CO2 remaining in the atmosphere
andreas
# Technical term for percentage of CO2 remaining in the atmosphere

(Asked by: username_0 on 2018-10-20)

I have a theoretical exercise where I calculated the amount of CO2 that is released to the atmosphere per year (4.6 ppm). We assume that the relative increase of CO2 is 2 ppm, hence the percentage of CO2 that stays in the atmosphere is around 2/4.6 ~ 40 %.

What is the technical term for this percentage?

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

> **Comments:**
> **username_1**: Possibly residual or accumulated CO2.  
> **username_2**: Atmospherically persistent CO2?  
> **username_3**: Mauna Loa CO2 data shows the actual amount in the atmosphere and the continuing increase ; one does not need to assume anything. Unless you are separating "good" from "bad" CO2.  

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## 1 answers

### Answer by username_4 on 2018-10-27. Score: 6 | Accepted answer

We call this the [airborne fraction](https://en.wikipedia.org/wiki/Airborne_fraction), although as the name suggests, it's normally expressed as a fraction rather than a percentage.

[Raupach et al (2014)](https://www.biogeosciences.net/11/3453/2014/) is an (open access) example of it being used in the literature, and in that paper they quote a long-term 1959 to 2012 value of 0.44, so in the same ball-park as your estimate. Similarly, here's an example of it's use in [Chapter 7 of the IPCC AR4](https://ipcc.ch/publications_and_data/ar4/wg1/en/ch7s7-3-5-2.html) with a range of modelled values from 0.4 to 0.5. It's also often calculated over single years, as in your example, to look at the trends and variability.

As an aside, the 2 ppm in your calculation is called the [atmospheric CO2 growth rate](https://www.newscientist.com/article/2112153-a-pause-in-growth-rate-of-atmospheric-co2-is-over-heres-why/) and the total mass of CO2 in the atmosphere would be the atmospheric CO2 *burden*.


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