[QA] Why do we need white ice?

Sea ice (white ice) is heat-deflecting as it reflects nearly all of the sunlight that hits it back into the atmosphere. This helps keep the polar regions cold, because the sunlight reflected back into space does not warm the surface. Melting sea ice means that the polar regions have less of a reflective surface and more heat is absorbed, which causes more melting, which in turn amplifies the warming. This cycle is known as a positive feedback loop.