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The Keeling curve is very well approximated with an exponential function with an offset $256$ [ppm] $$256+A\cdot e^{\alpha\cdot t}$$ where $A=1.095\cdot10^{-12}$ and $\alpha=0.0161$ ($t$ is in years b.c.)

In the graph below the raw data for the blue sawtooth curve is from NOAA, from the columns 'decimal date' and 'monthly average'.

enter image description here

From the very beginning 1958 the curve has an unbreaked tendency of emissions from fossil fuels and fossil materials and from the sees and the ground. Even the increased global warming the last 50 years must have affected the emissions but still the trend is untouched. How come? Which are the main sources of emissions and why is the trend so stable?

To limit the temperature raise below $1.5-2.0$ °C the pledges from the COP conferences must have an effect on the emissions that is unseen since 1958.

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  • $\begingroup$ and here we see the difference of a linear curve vs a logarithmic one,here is the one commonly used nationalgeographic.org/encyclopedia/keeling-curve $\endgroup$
    – trond hansen
    Nov 13, 2021 at 6:12
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    $\begingroup$ The trend isn't stable, it's exponentially increasing. A straight line in a lin-log plot is an exponent in reallife. $\endgroup$
    – AtmosphericPrisonEscape
    Nov 13, 2021 at 6:55
  • $\begingroup$ @trondhansen - Different representations of the same data. $\endgroup$
    – Lehs
    Nov 13, 2021 at 7:08
  • $\begingroup$ @Lehs yes that is my point. $\endgroup$
    – trond hansen
    Nov 14, 2021 at 6:08

2 Answers 2

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The Keeling Curve - the measured growth of atmospheric CO2 - appears directly related to global economic growth over the relevant period. This is because such growth has been highly dependent on growth of fossil fuel burning.

Attempts to sustain economic growth without increasing fossil fuel use and to reduce existing dependence are a recent phenomena, with a lot of resistance within the economic sectors that produce and use them to any constraints on their future use; growth of their use still continues. Whilst new energy generation is now predominately "renewables" (wind and solar), exceeding the growth of fossil fuels and presumed to be reducing the rate of that growth we have still not reached the point where fossil fuel use stops growing.

an unbroken tendency of emissions from fossil fuels and fossil materials and from the sees and the ground.

Seas and vegetation are taking up (not adding) some of the excess atmospheric CO2.

This diagram shows The Global Carbon Cycle -

Global Carbon Cycle

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  • $\begingroup$ Maybe the planet itself and the law of big numbers equalize the differences and the pledges from year to year? $\endgroup$
    – Lehs
    Nov 14, 2021 at 13:38
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The trend has actually not been stable. Per the Scripps CO2 Group, which along with NOAA monitors CO2 levels at Mauna Loa:

[> The rate of growth in carbon dioxide concentrations in the atmosphere

has accelerated since the beginnings of the Keeling Curve. The rate has gone from about 0.75 parts per million (ppm)/yr in 1959 to about 2.25ppm/yr today.]2

"Today" being in 2015, when this item was originally posted to the Keeling Curve website.

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    $\begingroup$ The Keeling curve as such has a growing rate and so does any curve $A+B\cdot e^{\alpha\cdot t}$. But $\alpha$ is stable. The Keeling curve is not approximately an exponential function, but an exponential function with offset. $\endgroup$
    – Lehs
    Nov 16, 2021 at 20:32

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