Two problems need mention
One, this would do nothing to slow ocean acidification, perhaps the most under-recognized feedback that could produce increasing CO2 levels from the reduced algae growth that more acidic waters contribute to. Two, less sunlight for solar panels, agriculture, as a driver of global winds and other yet to be discovered environmental functions. The concept needs to be studied further since it might prove useful as a short-term way to blunt the effects of extreme heat waves someday, but we should not be deluded into thinking this kind of scheme in any way reduces the need to move to a carbon free energy system globally as quickly as possible.
