The Keeling Curve and modern CO2 data

From Wikipedia
The Keeling Curve also shows a cyclic variation of about 5 ppmv in each year corresponding to the seasonal change in uptake of CO₂ by the world's land vegetation. Most of this vegetation is in the Northern hemisphere, since this is where most of the land is located. From a maximum in May, the level decreases during the northern spring and summer as newplant growth takes carbon dioxide out of the atmosphere through photosynthesis. After reaching a minimum in October, the level rises again in the northern fall and winter as plants and leaves die off and decay, releasing the gas back into the atmosphere.^[13]

When C.D. Keeling published his 1960 paper, there did not appear to be any evidence of oceanic absorption. Keeling conjectured that this might be attributable to fluctuations in the causation of the seasonal variation, within the small number of years since his measurements had begun. However it is now understood that allowance should be made for about 50% absorption by the oceanic sinks.^[17]

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Satellite derived data of seasonal CO2