Hurricane Fiona, hurricanes some of the wettest storms caused by climate change

Hurricane Fiona, hurricanes some of the wettest storms caused by climate change

Powerful storms hit three different, far-flung corners of the globe over the weekend, but they had one thing in common: they got stronger and wetter because of climate change.

From Hurricane Fiona bearing down on Puerto Rico and the Dominican Republic to Typhoon Nanmadol battering Japan to the remnants of Hurricane Merbok wreaking havoc in Alaska, the past 72 hours have demonstrated the devastating effects of heavy rain and of floods.

The weekend’s three storms add to a trend of wetter storms in a warmer future, said Michael Wehner, a senior scientist at Lawrence Berkeley National Laboratory.

“The worst storms are going to get worse,” he said.

With climate change making storms wetter and more intense, the weekend’s extreme weather offers a taste of what could become more common in the future, experts say.

One of the most pronounced ways storms have been affected by climate change in recent years can be measured in increases in precipitation, said Kevin Reed, an associate professor of atmospheric science at Stony Brook University in New York.

As the world’s oceans warm, they provide more energy for storms, allowing them to intensify as they form. A warmer atmosphere can also hold more moisture, Reed said.

“If you have warmer water, you’re going to have more evaporation, which means you have more moisture in the atmosphere, which means you can have more precipitation,” he said.

Until the weekend, the Atlantic hurricane season was unusually quiet, but Reed said mid-September is usually the peak of the season, meaning other powerful storms could still be on the way.

“Hurricane Fiona is a reminder that even though it’s been relatively quiet, things can change and strong storms can have a really big impact,” he added.

Image: Hurricane Fiona in Cayey, Puerto Rico (Stephanie Rojas/AP)

Image: Hurricane Fiona in Cayey, Puerto Rico (Stephanie Rojas/AP)

Scientists have calculated that for every 1 degree Celsius of temperature rise, the atmosphere can hold 7% more moisture that evaporates. The planet has warmed about 1.1 degrees Celsius since the pre-industrial era.

Hurricane Fiona, which hit Puerto Rico on Sunday and caused power outages across the island, is already drenching the region with high levels of rainfall.

In an update early Monday morning, the National Hurricane Center warned of “heavy rainfall and catastrophic flooding” across much of Puerto Rico. Multiple locations on the island received more than 20 inches of rain in the last 72 hours.

A day earlier, one of the strongest storms in at least a decade hit Alaska. The remnants of Typhoon Merbok produced hurricane-force winds, high seas and rain that caused widespread flooding along the coast. (Hurricanes and hurricanes are both tropical cyclones but are named differently depending on where they occur.)

Image: Flooding in Nome Alaska (Peggy Fagerstrom/AP)

Image: Flooding in Nome Alaska (Peggy Fagerstrom/AP)

And thousands of miles away, in Japan, Typhoon Nanmadol became one of the strongest storms to hit the country in years. Weather stations on the island of Kyushu recorded nearly 20 inches of rain in 24 hours Sunday, according to weather experts at Yale Climate Connections.

More than 8 million people were told to evacuate before the typhoon made landfall. The Japan Meteorological Agency warned on Monday that heavy rains, gales, high waves and storm surges are expected to continue as the storm moves towards the coast. Heavy rainfall warnings remain in place across much of the country.

Lawrence Berkeley National Laboratory’s Wehner and Stony Brook University’s Reed collaborated on a paper published in April in the journal Nature Communications that examined rainfall in the 2020 Atlantic hurricane season, which was one of the most active hurricane seasons on record . They found that climate change made the entire season wetter overall and measured a 10% increase in rainfall rates during the heaviest three-hour rainfall period during storms.

“That means the storm got 10 percent more rain because of climate change than it would have without,” Reid said.

These increases in extreme rainfall can be devastating for people living in the areas affected by supercharged storms. In Puerto Rico, for example, communities have yet to fully recover from Hurricane Maria in 2017.

“These storms are certainly interesting scientifically,” Wehner said, “but the human tragedy part is much more important.”

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