well scaling a natural process will change the chemistry of the ocean. Since the ocean is such a huge component of our planetary system it would be foolish of us to approach it without monitoring and planning for the consequences of this scale of engineering.
most of the plans to sequester carbon in the ocean make me worry about how that would impact the broader ecosystem. As I understand it, it would change the chemistry of the ocean, which might trade one disaster for another. Not to mention ideally sequestration would last for millennia.
i've found https://www.annualreviews.org/doi/pdf/10.1146/annurev.energy... to be a pretty good overview.