Estimates for the amount of man-made CO₂ absorbed by the oceans is estimated at around 30 > 40%. The processes which govern the rate of absorption are extremely complex and poorly understood.

Examples:

• As the ocean warms, its capacity to absorb CO₂ decreases, tending to release pre-dissolved gases as the temperature rises.

• Warmer oceans lead to increasingly unstable weather patterns and windspeeds which mean higher waves and more sea-spray bubbles - affecting the absorption ( and release ) of CO₂

• As the temperature rises, sea plants and microorganisms which absorb CO₂ become more prolific.

Recent measurements of oceanic CO₂ have not followed the 'expected' rates - so the carbon-sink model must be inaccurate in some as-yet-unknown way(s).

Despite the importance of the ocean carbon sink to climate, our understanding of the causes of its interannual‐to‐decadal variability remains limited. This hinders our ability to attribute its past behavior and project its future. A key period of interest is the 1990s, when the ocean carbon sink did not grow as expected.
Source : AGU Advances

Further reading Wikipedia

Also see : Marine calcium carbonate balanceplugin-autotooltip__plain plugin-autotooltip_bigMarine calcium carbonate balance

"The chemistry of the oceans has varied significantly over the past several billion years, and it is changing at an unprecedented rate today in response to anthropogenic burning of fossil fuels. [...] Calcium carbonates are among the most abundant and reactive minerals on Earth, and their dissolution/preservation in the ocean helps to regulate changes in atmospheric pCO

Importance Rating