This animation shows the biosphere represented as phytoplankton concentration over the ocean and vegetation index over land. Corresponding carbon dioxide concentrations from ground measurements in Hawaii are shown in the foreground.

As each year progresses, notice how the greening of the land changes in correspondance with the CO₂, which decreases as the northern hemisphere greens up.

Despite these annual oscillations in the CO₂ graph, the overall trend is upward.

Question: Why are time series so interesting ?