I’ve been doing some more than usual research as of late to answer for myself a specific question about CO2 respiration and the amount of man-made CO2 that is reatined versus naturally generated CO2. In doing so I’ve been in some discussion with some people I share an email list with.
One of them pointed out this ESRL (Earth Systems Research Laboratory) animation to me. I immediately found it intriguing because of the disparity between hemispheres:
CO2 (C13) January 1996 to December, 2007
This movie shows the latitude distribution (from south-to-north) of average monthly values derived from the GLOBALVIEW extended records. Cyan circles are average monthly values from sampling locations thought to be regionally representative; pluses are average values from locations thought to be influenced by local sources and sinks. A smooth curve is fitted to the representative measurements when sufficient data exist.
Isotopic measurements from NOAA air samples are made by the University of Colorado (CU), Institute of Arctic and Alpine Research (INSTAAR), Stable Isotope Laboratory (SIL).
They caution that this is a derived product, (due to processing, smoothing etc) and does no longer represent raw data on CO2C13, along with other caveats such as this:
These and other measurements have been widely used to constrain atmospheric models that derive plausible source/sink scenarios. Serious obstacles to this approach are the paucity of sampling sites and the lack of temporal continuity among observations from different locations. Consequently, there is the potential for models to misinterpret these spatial and temporal gaps resulting in derived source/sink scenarios that are unduly influenced by the sampling distribution. GLOBALVIEW-CO213 is an attempt to address these issues of temporal discontinuity and data sparseness and is a tool intended for use in carbon cycle modeling.
But still, it is quite informative. Here is a map of the ESRL station distribution. Not all of them are CO2 surface monitoring stations.
Note how the southern hemisphere’s (90S to EQ)CO2C13 content remains nearly steady over the 12 year period, while the northern hemisphere shows major seasonal variation. The greatest variation is at the northernmost latitude, with data that likely comes from the Alert, Nunavut, Canada and the Ny-Alesund, Svalbard ESRL monitoring station.
You can see by the seasonal variation in the movie that when it is warmer, more CO2C13 is being released into the atmosphere, when it is colder, more CO2 C13 is taken out. It demonstrates a short term linkage between CO2 and temperature. While the “paucity of sampling” in the Southern Hemisphere is evident from the map, I find it curious that there is virtually no seasonal variation there, compared to the dance of the datapoints north of the equator, the ones south of the equator are wallflowers.
h/t to Allan Siddons