Recently I commented on CO2 concentration as a function of temperature. This paper is my attempt to answer comments and reactions for which I am grateful. I wrote: It appears that CO2 concentrations follows temperature with approx 6-9 months. The interesting part is off course that the CO2 trends so markedly responds to temperature changes.

To some, this is “not possible” as we normally see a very smooth rise on CO2 curves. However, the difference in CO2 rise from year to year is quite different from warm to cold years, and as shown differences are closely dependent on global temperatures.

See larger image here

The relatively rough relationship between CO2 growth per year and global temperatures (UAH) is:

1979: CO2 growth (ppm/year) = 3.5 * Temp.anomaly(K) + 0.7
2008: CO2 growth (ppm/year) = 3.5 * Temp.anomaly(K) + 1.2
1979-2008: CO2 growth (ppm/year) = 3.5 * Temp.anomaly(K) + 0.95

For 2007, a UAH temperature anomaly near - 0.32 K should lead to CO2 rise/year = 0 , that is, CO2-stagnation.

These equations are useful for overall understanding, but so far they don’t give a fully precise and nuanced picture, of course. On the graph, I have illustrated that there is a longer trend difference between CO2 and Temperature. Thus, the “constant” of the equation should be a variable as it varies with time (1979: 0.7 2008: 1.2).

The trend difference means, that from 1979 to 2008 the CO2-rise per year compared to the global temperatures has fallen 0.5 ppm/year, or the other way around: It now takes approx. +0.15 K global temperature anomaly more to achieve the same level of CO2 rise/year as it did in 1979. How can this be? The CO2 rise/year now takes higher temperatures to achieve? With the human emissions rising in the time interval 1978-2008, one could imagine that it would be the other way around, that CO2 rises came with still smaller temperature rises needed. But no, its becoming “harder and harder” to make CO2 rise in the atmosphere.

So generally, the human emissions effect appears inferior to other effects in this context at least. Which effects could hold CO2 rise/year down as we see?The fact that we today have higher CO2 concentration in the atmosphere than in 1978 does not favour more CO2 release from the oceans. However the fact that we approx 500 million years ago had almost 7000 ppm CO2 in the atmosphere implies that the 385 ppm today hardly makes a difference. Read much more here.