Illinois State University’s Catherine O’Reilly is one of the lead authors of a new international study showing lake ice in the Northern Hemisphere is vanishing due to climate change.

The newest study, published in the journal Nature Climate Change, predicts the loss of ice on lakes could impact more than 650 million people. The study used long-term ice datasets that exist for 345 lakes around the Northern Hemisphere.

We’re not talking about lakes getting a little warmer. We are talking about lake ice being gone in the winter. — Catherine O’Reilly

“We’re not talking about lakes getting a little warmer. We are talking about lake ice being gone in the winter,” said O’Reilly, an associate professor of geology who has spearheaded past studies on the impact of climate change on rapidly warming lakes around the world. “Our children and grandchildren would not see something we have taken for granted.”

Authors looked at whether a lake had an ice-free year, determined influencing factors, and then applied this information to a global lake database. The goal was to determine how many lakes would be affected periodically by a loss of ice cover, using climate projection models to determine when this might happen. “We found currently 15,000 lakes along the edge of the cold winter zone periodically do not have ice cover,” said O’Reilly, who added this number would more than double, even if the world is able to meet the Paris Agreement’s climate goals to hold average temperature warming to 2 degrees C.

The rate of warming surpassed anything we anticipated. — Catherine O’Reilly

The disappearance of lake ice could endanger everything from freshwater supplies and commercial industries, to tourism and long-standing recreation and traditions. “This would mean a dramatic shift in the cultural identity for millions of people,” said O’Reilly.

The rapid nature of the change surprised the team, which consists of several members who have been studying freshwater supplies and global lakes for decades. “The rate of warming surpassed anything we anticipated,” said O’Reilly. She noted the sudden loss of ice in lakes could lead to lower oxygen levels, which could affect the survivability of fish and other lake life. “At the moment we realized how fast this is happening, we saw how urgent our message was.”

Internationally known as an expert in the field of freshwater ecology, O’Reilly’s studies have been supported with millions of dollars in grants from the National Science Foundation (NSF), the National Aeronautics and Space Administration (NASA), the Danish International Development Agency, the Nutrient Research and Education Council, and Environmental Protection Agency.

The international team was comprised of 11 researchers from across the globe who collaborate as part of the Global Lake Ecological Observatory Network (GLEON).

Funding for the lake ice study was provided by the Ontario Ministry of Research, Innovation, and Science’s Early Researcher Awards, York University Research Chair program, and the Natural Sciences and Engineering Research Council of Canada.