The oceans naturally absorb a quarter to a third of human carbon dioxide (CO₂) emissions, slowing the impacts of climate change but also causing detrimental impacts to ocean ecosystems by altering seawater chemistry. Quantifying the uptake of anthropogenic CO₂ and the resulting ocean acidification is challenging due to the high levels of accuracy and precision required of observations that must span decades and are often conducted by multiple laboratories with a variety of methods. In addition, natural variability in the marine carbon cycle combined with sparse observations further compounds the uncertainties. Recently, enhancing the ocean’s ability to take up CO₂ (marine CO₂ removal or mCDR) as a way to combat climate change and meet emissions targets has received growing attention. Monitoring, validation, and reporting of any mCDR strategy will require a detailed understanding of uncertainties in observations along with a well-designed measurement plan. Here we use new laboratory experiments and direct ocean observations to evaluate uncertainties from the perspective of mCDR observational requirements and challenges.
 

mCDR,ocean acidification,Uncertainties