Extracting CO2 from the air likely requires some energy, and seafloor organisms are almost certainly energy-constrained. We could beat the seafloor simply by providing more energy, if we get within the ballpark of their efficiency. We have plenty of deserts and solar panels.
> if we get within the ballpark of their efficiency
In all likelihood, we can get ~10x better efficiency without trying very hard.
Living beings don't focus much on growing. They are usually less than 1% efficient on that, with more complex life being on the order of 0.1% efficient.
