I wonder if they realize that, according to the laws of physics and thermodynamics, the amount of heat and energy they consume and put into the world in order to produce those ice blocks, actually exceeds the amount they're removing. So making ice blocks might help in the short term, but in the long term, they might actually make it worse, if not for the arctic, than for other places on the planet. Unless they're doing other stuff like planting trees, the best they could ever hope for is to simply break even; to cancel themselves out.
The ice isn't to cool the water, the ice is to reflect most of the incoming light.
Sea ice keeps the polar regions cool and helps moderate global climate. Sea ice has a much brighter surface compared to many other Earth surfaces, particularly the surrounding ocean. The darker ocean reflects only 6 percent of the sun’s energy and absorbs the rest, while sea ice reflects 50 to 70 percent of the incoming energy.