Research led by physicist and mathematician Leif Ristroph looked at how vertical cylinders of ice melt in water baths between 2°C to 10°C. Below 4°C, the ice whittled into a pointy and smooth hanging tooth structure—slightly warmer water settled to the bottom of the water bath, accelerating melting lower down the ice compared to upper parts of the structure. At temperatures of 7°C or higher, the geometry flipped: This time, a spire appeared instead, due to warmer water rising and hastening melting higher up the ice. Intermediate water temperatures between 4°C and 7°C gave rise to more complicated shapes. Pockets of warmer water and only marginally colder liquid created complex flow patterns, such as a vertical column of vortices near the surface of the ice. As a result, imprinted on the ice were rolling crests and troughs. The research not only sheds light on the intricacies of the melting process, but also allows scientists to infer an ice block’s environmental conditions simply by taking stock of its shape. In the larger context of climate change, the research might help inform how soaring temperatures affect natural ice formations. As icebergs and glaciers shed meltwater, the icy structures they leave behind may encode information on its environment, hinting at their surrounding temperatures that are in turn dictated by the rising influences of a warming world.
