Curiosities: What makes ice slippery?

When ice is under pressure, a thin surface layer melts, and this causes slipperiness, says Jonathan Martin, professor of atmospheric and oceanic sciences at UW-Madison. “All our body weight is concentrated on the bottom of your shoe, and that exerts enough pressure to melt the ice, creating a layer of liquid water on the surface. Thatâ??s the substance on which we slide.”