The authors compared death records and temperature data in Canada, Estonia, Germany, Latvia, Finland, Russia, Sweden, Italy, Japan and the northern United States. They analyzed about 4,000 total records over a span of 26 years, though the time period varied depending on the available data in each country.
The researchers found that more cold-weather drownings occur in spring, when daily low temperatures increase too much to support stable ice structures. At the same time, those warmer temperatures make it more enjoyable to spend time outdoors, meaning more people are spending time on ice.
Northern Canada and Alaska have higher rates of drowning, even in very cold temperatures. Dr. Sharma says that is probably because people there simply spend more time on the ice. Indigenous communities close to the Arctic rely on waterways for food and transportation, which means more time on the ice in winter and an increased risk of drowning.
The coronavirus pandemic could also put more people at risk.
“If this winter is anything like this summer was,” Dr. Sharma said, “a lot of people spent time in cottage country in Ontario because we just can’t go anywhere.”
She said that ice with sitting water, slush or holes in the surface was generally unsafe. “Snow cover is when it gets tricky,” Dr. Sharma said. “People think there’s so much snow on the ice, the ice must be thick,” but snow can also act as insulation, melting the ice more quickly.
“We need to, as individuals, adapt our decision-making,” she added, and focus on how changing winters affect local rivers, lakes and streams. “It may not be as safe now as it was 30 years or 40 years ago.”