Each summer, more lake beaches shut down as toxic algae blooms spread across the water and while climate change is often blamed, new research revealed a deeper culprit: humans.
Researchers from Michigan State University used open data to study climate change in 24,000 U.S. lakes. Using new methods and satellite data, they found climate-driven patterns in algae levels across freshwater lakes.
Patricia Soranno, professor of ecology at Michigan State University and co-author of the study, has spent nearly 30 years researching what affects water quality. While climate change plays a role, she said human activity is the true driving force behind the growing problem.
“We know what causes lakes to be greener,” Soranno pointed out. “It’s agriculture runoff, urban runoff, extra nutrients that come from lawns. All of those things we’ve known for decades, that’s what causes lakes to be green.”
Soranno and her team found climate affected algae in a third of the lakes, but not as expected. Only 4% had lasting algae growth, while 71% saw short-term spikes.
The study revealed sudden algae spikes often go unnoticed, making climate effects harder to track. Researchers said their method helps fill this gap. Soranno added while human activity drives more blooms, lakes with less human impact are more vulnerable to climate change.
“It’s affecting the lakes that are fairly pristine now and are in pretty good shape,” Soranno noted. “This influences Michigan lakes actually, because Michigan lakes have fairly good water quality already.”
Soranno stressed the need for strong policies and regulations to protect waterways. Her team has a goal to study every U.S. lake using satellite imagery. However, she is deeply concerned federal cuts could threaten their research.
