A Quality of Ice Problem

“Lake ice has a memory.”

—Sapna Sharma of York University, noting that changes in the weather are reflected in the quality of lake ice, creating increasingly hazardous conditions in a warming world. Sharma was part of a recent study that found warmer temperatures sometimes create thinner layers of black ice and thicker layers of white ice. As black ice has fewer air pockets and larger ice crystals than white ice and therefore is stronger, the new findings highlight the dangers changes in ice can pose to users ranging from skaters to ice truckers. The unstable conditions even interfered with the research itself, as measurements on two Canadian lakes had to be halted earlier than scheduled because of thinning ice. Sharma notes that changes in the weather “are stored in the ice. If the temperature was over 0°C for a period of time, if there was rain or if there were extremely sunny conditions, all of that can affect the safety of the ice for human use.” The researchers explain that changing precipitation resulting from unseasonably warm temperatures is driving much of the variability in ice conditions. Sharma notes that for humans to skate or play on ice requires about 10 centimeters (4 inches) of black ice, but “what we're seeing and what we're predicting is that climate change is contributing to more white ice conditions. . . . You might get periods of time when people are on the ice and they think it's safe, but it really isn't. It's not sufficiently thick enough given the changes in the quality.” The study, which was published in Nature Reviews Earth and Environment, is one of only a few that goes beyond ice thickness to also look at quality of the ice. “The thing that stuck out to me first is the surprising lack of data that we have on ice quality broadly,” says coauthor Joshua Culpepper, also of York. “We were diving into what data [were] available, but trying to find exactly what we could work with in terms of data [that are] available in the Northern Hemisphere was pretty challenging.” [Source: York University]