Does a sheen of oil atop a large portion of the gulf warm or cool the waters underneath?
For the globe it is a very small area....but I don’t have a direct answer.
There is a product called Solar Pill that coats the top of swimming pool water and supposedly helps the water retain warmth.
I asked the owner of our pool store and she said it worked, but a dome works better. We have a vinyl dome over our above-ground and she added that the Solar Pill would not give us any additional heat.
The thing contains a fluid that *coats* the water. It is placed in the skimmer.