I’ve seen ideas re sprinkling iron across ocean surfaces, to enhance plankton growth in bid to soak up more carbon dioxide. But, maybe not a great idea after all:
… The researchers were able to track what happens to carbon that comes up from the deep and how it supports the local plankton populations. They found that a lot of the carbon fails to sink back down to the depths. Instead, it is recycled as organic matter, where it remains in the surface waters and can even be ejected into the atmosphere as carbon dioxide, says chemical oceanographer Claudia Benitez-Nelson of the University of South Carolina in Columbia and lead author of the Hawaii paper.
Don’t Bet on the Bloomin’ Plankton – Science news; need subscription to view after a month.