CANADA Predicted path of Florence Inches of rain observed in past 7 days 1.0 1.5 Urban areas 2.0 2.5 3.0 4.0 5.0 6.0 8.0 10.0 As of 11 a.m., Sept. 17, 2018 Observed path of Florence ATLANTIC OCEAN 200 mi 200 km RILEY D. CHAMPINE, NG STAFF SOURCE: NATIONAL WEATHER SERVICE

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The catastrophic rains accompanying Hurricane Florence along the U.S. East Coast can be blamed squarely on climate change, new research shows. The rainfall was projected to be more than 50 percent worse than it would have been without global warming, a team of scientists said before the storm made landfall. The hurricane’s size was predicted to be about 50 miles (80 kilometers) wider for the same reason. In parts of North Carolina, as much as 30 inches of rain has already been recorded, setting a state record for the highest rainfall received from any one storm.

The reason: warmer ocean and atmospheric temperatures, caused by the warming Earth.

The slow-moving storm pushed storm surges as high as 10 feet onto the shore when it makes landfall Friday morning. It was described as one of the worst hurricanes to hit the coastal Carolinas since Hurricane Hugo battered Charleston in September 1989. But it is the potential for days of drenching rainfall, already causing flooding, that has officials most worried.

Scientists made a similar, though less drastic finding about the effects of climate change on Hurricane Harvey, after the storm stalled and dumped more than 40 inches of rain on Houston last year.

But the ability to make such a projection ahead of a storm is a first. (Learn more about hurricane hazards.)

Florence Atlantic Ocean Replay Animation Replay Animation Hurricane Florence approaches the United States Brian T. Jacobs, NG Maps. Source: NOAA GOES-East



“This is the first time we’ve done this predictively,” says Michael Wehner, a climate scientist at the Lawrence Berkeley National Laboratory. “Climate change increases the amount of water in the atmosphere that can rain out in a hurricane. It also changes the structure of the storm to make it more efficient at precipitation.”

Wehner was part of a team that also included scientists from Stony Brook University and the National Center for Atmospheric Research. They compared the real-time forecasts for Florence to what could have occurred had the temperatures of ocean waters and the atmosphere been cooler.

Hurricanes 101

CANADA Predicted path of Florence Inches of rain predicted in next 5 days Urban areas 1 2 3 4 5 10 20 As of 5 p.m., Sept. 14, 2018 Observed path of Florence ATLANTIC OCEAN 200 mi 200 km RILEY D. CHAMPINE, NG STAFF SOURCE: NATIONAL WEATHER SERVICE Example Headline This is an example of text in a dek. Header for note This is an example of text in a note. This is the smallest size recommended for mixed-case text or labels. Labels in all caps can be 11pt. TK mi TK km GRAPHIC EDITOR, NG(M) STAFF. ADDITIONAL CREDIT SOURCE(S): EXAMPLE SOURCE; ADDITIONAL SOURCE RILEY D. CHAMPINE, NG STAFF SOURCE: NATIONAL WEATHER SERVICE

Their findings also say much about what may be coming in future hurricane seasons.

“Climate Change Is Here”

“There is a very clear message here. Dangerous climate change is here and now. It is not something in the future,” Wehner says. “If this storm had happened in a world where humans had not interfered in the climate system, there wouldn’t be as much rain. By a large amount.”

Scientists have long been reluctant to attach a single extreme weather event to climate change. But Wehner says that’s no longer the case. Science has caught up.

“We can do this for individual storms. We’ve been doing it for heatwaves and seasonal flooding for several years now. What is new is our ability to do it for hurricanes. Science marches on.”

New Normal?

Regardless of how finely tuned projections are becoming, the overall storyline of coastal erosion from hurricanes and rising sea levels is repetitive and familiar. And Florence offers yet another lesson about coastal vulnerabilities and people’s penchant for living near the sea.

North Carolina, with 300 miles of barrier islands, is one of the most vulnerable places on the Atlantic Coast to shoreline erosion from hurricane and storm damage. Yet state officials were prohibited by the Republican-controlled state legislature from planning for sea-level rise—even in 2016, after Hurricane Matthew’s floodwaters reached far inland, saturating fields of crops and small towns along Pamlico Sound near the Inner Banks, which stand behind the Outer Banks.

The surge from Florence will wash over the front side of the islands, eating away beach sand, as flood waters on the back side will fill it in.

The most fragile places are the towns of South Nags Head, Hatteras and North Topsail. All have a history of erosion.

“Hugo was powerful enough and did enough damage that we thought people were finally going to pay attention,” says Orrin Pilkey, a coastal scientist emeritus at Duke University in Durham, North Carolina.