Carbon Dioxide Will Cease To Be a Problem
By Ed Caryl
We do have the real world measurements of CO2, resolved to a monthly measurement with a well established seasonality that I will not describe here. We also know fairly accurately how much carbon we are injecting into the atmosphere from fossil sources.
Figure 1 is a plot of annual fossil carbon emissions (green trace), the annual atmospheric carbon increase (red trace) computed from Mauna Loa CO2 figures, and emissions minus the ocean and biosphere flux.
In Figure 1, the blue trace (fossil carbon emissions with all the biospheric carbon uptake subtracted) should equal the red trace, and in the long term average (pink trace), it comes close, so our simple model is reflecting the real world in that half the carbon emissions are being taken up by the ocean and the biosphere. The other half is contributing to the atmospheric CO2 increase. The difference between the pink and the green curves in 1977 is about 2.5 Gigatons and is increasing at an ever faster rate. The current difference is about 5 Gigatons. An increasing amount of CO2 is disappearing into the biosphere.
The part that remains is called the “air-borne fraction”. If this part is charted as a percentage you get a plot that looks like this (from James Hansen’s paper here. His Figure 3, is my Figure 2. Hansen’s caption is quoted.
Figure 2: Hansen’s Figure 3 “Fossil fuel CO2 emissions (left scale) and airborne fraction, i.e., the ratio of observed atmospheric CO2 increase to fossil fuel CO2 emissions. Final three points are 5-, 3- and 1-year means.”
I duplicated Hansen’s figure in the next figure, extended, and showed the un-averaged data. The heavy red trace is Hansen’s blue trace above:
Figure 3 above duplicates Hansen’s Figure 3 using the original data. The narrow red trace is the un-averaged computation. The black trace is a 2nd order polynomial trend line.
Note in Figure 3 that the airborne fraction of fossil-fuel carbon polynomial trend line goes to zero in about 30 years. When this happens, atmospheric CO2 will stop increasing. This roughly agrees with the atmospheric CO2 increase ceasing in mid-century as found in the previous article.