Dave Andrews wonders:



Tamino, For all your pretty graphs aren’t you missing something here? The Mauna Loa, et al, figures show a roughly steady increase in atmospheric CO2 but there has been a massive increase in the burning of fossil fuels since 1990, especially, but not restricted to, India and China. This huge increase is not being reflected by the Mauna Loa figures.





Each year we emit lots of CO 2 into the atmosphere, but not all of it remains there. A substantial amount (about 45% net) is absorbed by the oceans, biosphere, and other sinks that a real expert could elaborate. But if emissions have grown as rapidly as Dave Andrews implies, why hasn’t the growth rate of CO 2 grown in step?

The answer is, it has.

I found emissions data from the Energy Information Agency. Figures are given in Mt CO2 (million tonnes CO2) but we can convert that to “ppmv” (parts per million by volume in the atmosphere) by noting that 7800 Mt CO2 (7.8 Gt CO2) is about 1 ppmv. Of course we can get CO2 concentration from Mauna Loa. Then we can compute, for each year, the annual change in CO2 (which I estimated as the difference between the annual average and the previous year’s annual average). Then we can compare CO2 growth to emissions directly.

Since only about 55% of emissions remain airborne, I actually compared CO2 annual change to 55% of emissions:

Emissions have indeed grown, and if you want to call the growth “massive” that’s OK with me. But if you do, you also have to refer to the increase in annual CO2 growth rate as “massive.” They certainly are comparable.

We can also, for each year, compute the fraction of emissions which equals the annual increment, i.e., the “airborne fraction” for emissions that year. And here it is:

Linear regression fails to detect any significant trend; it’s obvious that the airborne fraction fluctuates a lot from year to year, but there doesn’t seem to be any trend.

So no, it’s not true that the “increase is not being reflected by the Mauna Loa figures.”