Climate Change Accelerates Algae Blooms In Canadian Lakes

A study conducted by Laval University highlights the effects of global warming on freshwater reserves and underlines the urgency of taking action to preserve them.

Algal growth has been accelerating in Canadian lakes since the 1960s. A research team co-led by Université Laval and McGill University reveals that this proliferation is seven times faster than in previous decades. Their study, published in the journal Communications Earth & Environment , shows that global warming is the main driver of this trend.

While previous studies of a limited number of lakes or shorter time periods linked algae growth to local pollution, such as fertilizer runoff, this new research highlights a broader dynamic. To the scientists' surprise, even lakes far from any human activity are not immune.

To identify the causes, the team analyzed sediment cores dating back to the 1800s, taken from 80 lakes as part of NSERC's State of Canada's Lakes Network, and used machine learning techniques to detect long-term trends. This data was then compared to historical records of air temperature, sunlight, and human activity near the lakes.

“Our results clearly indicate that global warming is the main driver of the algae dynamics we observed,” says Dermot Antoniades, a professor in the Faculty of Forestry, Geography and Geomatics and one of the study’s co-authors. “Lakes are warming along with the climate, creating ideal conditions for the growth of these aquatic microorganisms.”

Other factors, such as solar radiation and land use, have also had an effect, but rising temperatures remain the most marked influence.

A shared ecological responsibility
The research team emphasizes the importance of this problem and the need for concerted action on a global scale. "Our work shows that local solutions, such as reducing fertilizer runoff, are no longer sufficient. Climate action is imperative to sustainably protect our lakes," says Hamid Ghanbari, a postdoctoral researcher at Université Laval and lead author of the study.

According to scientists, water quality is intimately linked to the well-being of communities. "Lakes," says Dermot Antoniades, "are places where we swim, where we fish, where we get our drinking water, and where many businesses operate. Uncontrolled algal blooms can harm health, kill fish, cause unpleasant odors on beaches, and lead to economic costs."

"Ignoring these issues means exposing ourselves to increased risks for our water, our wildlife, and our economy. It's a collective challenge that requires the commitment of everyone—citizens, governments, organizations, and businesses—to reduce our carbon footprint," concludes Hamid Ghanbari.

The study 's authors are Hamid Ghanbari and Dermot Antoniades of Laval University, Irene Gregory-Eaves of McGill University, and scientists from other Canadian universities.