Extend the Epipelagic zone with (floating or fixed) fiber optic lenses in order to increase capacity for photosynthesis, carbon dioxide recapture, and oceanic productivity. Planet Earth indicates that vast stretches of ocean are like [relatively unproductive] deserts. Typically I'm not a fan of altering ecosystems, but increasing the productivity of the bottom of the [oceanic] food chain while increasing the capacity for CO2 recapture seems like it might be a good idea, especially considering what we've been doing to the oceans. One concern I have is that the process I suggest might increase ocean temperature -- not sure how to get around that one, yet.