The annual oscillations in the "Keeling" curve are driven by:

Question

Accepted Answer

the seasonal uptake in Spring and Summer and release in Autumn and Winter of carbon by trees and other biomass

Answer

the seasonality in demand for aviation fuel (e.g. peak travel during holiday periods)

Answer

the seasonality in carbon emissions due to changes in demand for heating in winter and summer

Answer

no one knows - just one of those mysteries of the universe.

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