More—and more intense—storms are in the forecast

Published: July 22, 2020 · Updated: July 27, 2020

Summer storm over a lake Photo by Mariusz Hajdarowicz/Shutterstock

A new study shows that North America can expect to see more storms and greater precipitation as the planet warms.

Those of us who summer on a lake are often dazzled by the storms that move across the water.

We might have noticed that those storms are increasing in frequency and intensity. And now, a recent study published in Proceedings of the National Academy of Sciences confirms what many of us were noticing anecdotally: the storms are becoming wilder and occurring more often.

“With additional warming we will see further increases in the frequency and severity of heavy rainfall,” says Megan Kirchmeier-Young, a research scientist with Environment Canada and one of the co-authors of the study. “With warmer air, you have more moisture, so if it’s going to rain, it’s going to rain more.”

She and colleagues looked at data as far back as 1961 to gauge the heavy rain events that occurred in each year. “[Scientists have] identified trends globally in terms of extreme precipitation much easier than we were able to find robust trends on the continental scale,” she says. “And locally this is even more challenging. But as we continue learning, as we continue having increases in extreme precipitation, the magnitude of those changes will be more noticeable.”

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She’s right, of course. It was hard for many to ignore their docks and boathouses underwater in the spring of 2019. The time between flooding events, referred to as the return period, is also growing shorter, says Kirchmeier-Young. What used to be considered 100-year events, she says, with our current rate of warming—with the global average temperature at 1°C above pre-industrial levels—is now roughly once every 20 years on average. With another degree of warming, which we’re getting close to, we can expect those extreme events to occur every five years on average, and with a further 1°C of warming—an overall increase of 3°C—those events will occur every other year.

The conclusions from this study could inform everything from infrastructure to insurance to public policy. “Looking at extreme precipitation in the past and extreme precipitation in the future [provides] information relevant to a lot of different interests,” says Kirchmeier-Young. In other words, expect more intense storms, and prepare for them.

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