The surprisingly rapid decline in air - sea partial pressure difference (ΔpCO2) is primarily a response to
an elevated water column inventory of dissolved inorganic carbon (DIC), which, in turn, reflects mostly anthropogenic CO2 input rather than natural interannual variability.
This is because seagrasses take up CO2 in the
water column through photosynthesis and
elevate the aragonite saturation state, potentially offsetting ocean acidification impacts at local scales.