Nothing that could potentially scale without unintended consequences. Next
It’s all the ships from China spewing carbon into the ocean
Yea
So how do you install 250k km2 of underwater umbrellas, and who stands to get filthy rich from this?
Stopping direct sunlight exposure to help stop coral bleaching is an awesome idea.
Have to nitpick though, umbrellas protect you from falling water, parasols block light.
Unfortunately stony corals also face a grave threat from ocean acidification due to rising CO2 in the atmosphere. They need alkalinity to make their skeletons.