Freshwater can exist under sea ice at around 0 C. Without much salt it is less dense and will float on warmer saline ocean water. It has been described as protective, aiding the existence of the ice. I am of the opinion that sea ice mostly melts from below. Record warm Arctic air temperatures are not necessarily the driver of sea ice loss. I think it’s more the result of variable warm ocean water intrusion from the Gulf Stream into the Arctic Ocean. Sea ice loss may be a significant cause of the record warm Arctic air temperatures. Sea ice does slow down the ocean’s venting of heat to the atmosphere.