More children and young adults are drowning in winter lakes because of warming temperatures that create unstable lake ice, a new study finds.
A team of international researchers examined several decades of data, including 4,000 drownings and population information from throughout Canada, 14 U.S. states, Estonia, Germany, Latvia, Finland, Russia, Sweden and regions of Italy and Japan. They collected temperature and precipitation data for each month and area for each drowning from University of East Anglia's Climatic Research Unit in Britain.
The study found that when winter air temperatures reached between -10 degrees Celsius (14 degrees Fahrenheit) and -5 degrees C (23 degrees F), drownings rose substantially. When they were nearing 0 degrees C (32 degrees F), drowning numbers were five times higher than usual. At 0 degrees C or higher, the number of drownings fell drastically, probably because the ice was gone or visibly unsafe.
"The time when the risk of drowning is greatest is at the beginning and the end of winter, which also corresponds to the weakest ice, when it is less stable and less thick," said lead researcher Sapna Sharma, an associate professor in the Faculty of Science at York University in Toronto.
"In this study, we also looked at who was drowning, when, and what kind of activities they were doing at the time," Sharma said in a York news release. "Almost 50% of drowning victims are children less than 9 years old playing on the ice, while the majority of victims drowning while in vehicles, such as snowmobiles, are young adults less than 24 years old."
The study was published Nov. 18 in the journal PLOS One.
For some countries, the number of winter drownings were 15% to 50% of the total annual number of drownings. Canada had the highest number of winter drownings.
"Because we also examine trends in lake ice over hundreds of years, we know that ice-on is much later in the season and ice-off is much earlier. We are seeing these trends in lakes and rivers across the Northern Hemisphere, and we found that the highest number of drowning events correspond to these times of ice-off and ice-on," Sharma said.
The complexities of changing winters are destabilizing the ice on freshwater lakes and rivers in countries across the Northern Hemisphere, according to researchers. Countries with strong regulations about who can go on the ice, when, and for what activity had lower incidences of winter drownings.
Sharma suggested incorporating winter ice safety in swimming lessons for children.
"The climate is changing and it's affecting when you can be on the ice safely. Individuals need to take that into account, especially this winter when more individuals will be out enjoying winter ice activities," Sharma said. "Times have changed, and climate has changed. Winters are among the fastest warming season, especially in Northern countries, and we're seeing the impacts of that on our lakes, and it's also contributing to tragedies each winter."
The World Health Organization's Health and Environment Linkages Initiative has more information on climate change-related deaths.
SOURCE: York University, news release, Nov. 18, 2020