The oceanic flora (viz. seagrasses, seaweed) and the ocean floor itself holds
ancient carbon stores.
Washington state is a bit ahead of that curve because
ancient carbon stores in the deep ocean are periodically churned up by local currents.
Not exact matches
The burning of fossil fuels essentially reintroduces
ancient carbon that is
stored in the depths of the earth back into the
carbon cycle.
When those
stored molecules eventually return to the surface, pH can be lowered due to respiration of
ancient carbon, independent of atmospheric CO2.
In contrast, fossil fuels come from
ancient photosynthesis, thus the
carbon released by burning had been
stored for ages and thus represents a net addition into the atmosphere.