Hurricane Fiona, a typhoon as part of wetter storms due to climate change

Hurricane Fiona, a typhoon as part of wetter storms due to climate change

Powerful storms hit three different corners of the planet over the weekend, but they had one thing in common: they were made stronger and wetter by climate change.

From Hurricane Fiona barreling over Puerto Rico and the Dominican Republic to Typhoon Nanmadol hitting Japan, to the remnants of Typhoon Merbok wreaking havoc in Alaska, the past 72 hours have shown the devastating effects of heavy rain and flooding.

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

“The worst storms will get worse,” he said.

As climate change makes it rain harder and harder, the weekend’s extreme weather events provide a glimpse into what could become more common in the future, experts say.

One of the most significant ways climate change has affected storms in recent years can be measured in increases in rainfall, 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 to storms, allowing them to intensify as they form. A warmer atmosphere can also hold more moisture, Reed said.

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

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

“Hurricane Fiona, although relatively quiet, is a reminder that things can change and strong storms have a big impact,” he said.

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

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

Scientists have estimated that the atmosphere can withstand 7% more evaporative moisture for every 1 degree Celsius of temperature rise. The planet has warmed by about 1.1 degrees Celsius since pre-industrial times.

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

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

A day earlier, Alaska was hit by one of the strongest storms in at least a decade. The remnants of Typhoon Merbok brought hurricane force winds, high seas and rain that caused widespread flooding along the coast. (Typhoons and hurricanes are tropical cyclones but are named differently based on their location.)

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

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

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

More than 8 million people were asked to evacuate before the typhoon made landfall. The Japan Meteorological Agency warned on Monday that heavy rain, hail, high waves and storm surges are expected to continue as the storm moves up the coast. A heavy rain advisory is in place for much of the country.

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

“That means the storm had 10% more rain because of climate change than it would have without it,” Reed said.

These increases in extreme rainfall can be devastating for the people who live in the areas hit by overloaded storms. In Puerto Rico, for example, communities have not yet fully recovered from Hurricane Maria in 2017.

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

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