Algal blooms are getting worse and the climate crisis is largely to blame

Published: November 27, 2019

Canada geese swim between large algal blooms in a lake Photo by Ken Schulze/Shutterstock

This year saw algal blooms in Lake Erie and a number of cottage-country lakes. Don’t expect things to be much different in coming years.

Anna Michalak, a University of Guelph alum who’s now a researcher at the Carnegie Institute for Science, professor at Stanford, and a co-author of a study recently published in Nature, noticed a dearth of data related to water quality around the world. The bulk of attention has been focussed on quantity, she says, in large part due to drought and flooding.

But together with a team, Michalak, who spent time as a professor at the University of Michigan in Ann Arbor studying algal blooms on the Great Lakes, compiled close to three decades worth of satellite measurements. The data showed that a common denominator affecting water quality around the world was warmer waters, a consequence of climate change.

Part of the problem in gathering global data, however, has been that lakes in China or Africa, for example, didn’t have a lot of on-the-ground measurements. In North America, however, “there’s a lot more data we can actually work with,” says Michalak. Which means, she says, that they can also better pinpoint contributors to algal blooms.

A dominant factor in North American lakes is how many nutrients end up in the water, says Michalak. “Storms are becoming more intense, and a higher fraction of them are occurring in the spring, which also happens to be when a lot of fertilizer application takes place,” she says.

Consequently, algal blooms are much more intense. Factor in warming water, and “you essentially have to do more to maintain the water quality than you would have had to do if we didn’t have these changes in climate happening at the same time,” Michalak says. “We have to be more aggressive in limiting nutrient inputs to, in effect, compensate for the ways in which climate change is pushing things in the other direction.”

Which means…what exactly? “Anything that slows water down is good,” says Michalak. Out with bare shorelines, fertilizers, and lawns, and in with natural shorelines, wetlands, and bogs.

How to prevent algal blooms at your lake

As Michalak puts it, “The shoreline needs to be even more resilient than it used to be.”

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