i remember an article stating that the melting ice at the poles is accelerating global warming because the white of the ice used to reflect the light coming towards the water
The problem is specifically the ultraviolet photons in the sunlight, which photoactivate the reaction between bromine ions and ozone to form bromate [1].
The visible color shouldn't matter as much as strong absorbance or reflectance in the UV band. I would guess that they're using a plastic that absorbs UV, or contains a dye that does so.
Because white reflects, black absorbs. White balls wouldn't reflect all light upwards. To put it another way, if you were in the water, looking at the surface, which would be brighter? White balls or black balls?
