« on: 04/07/2013 11:29:11 »
Reverting to Mauna Loa, they do publish an annual CO2 cycle with the underlying trend removed. I'm baffled as to why the CO2 level rises whilst the trees are growing, reaches a peak in summer, and decreases as photosynthesis shuts down. When I was a lad, we were taught that photosynthesis extracts CO2 from the atmosphere, so I'd expect exactly the opposite behaviour if your model is correct (and they haven't moved Hawaii!). Where does the summer CO2 come from? Certainly not human activity, unless you Aussies have found some way of exporting your winter barbie smoke across the equator and halfway round the world.
Alan please check this diagram and tell me if that is the graph you are referring to: http://commons.wikimedia.org/wiki/File:Mauna_Loa_Carbon_Dioxide.png
If so, then you must appreciate two things:
firstly that the maximum and minimum are in May and October respectively, not June and December.
secondly that the amount of photosynthetic activity is reflected in the rate of change (slope) of the mixing ratio graph rather than the mixing ratio per se.
The months of maximum negative gradient (high photosynthetic activity) are June and July -- summer months -- while those of maximum negative gradient (low photosynthetic activity) are December, January, and February, the winter months.