Devastation in Western North Carolina shows nowhere is safe from climate change
When Helene swept through western North Carolina late last week, the rain fell heavy and fast enough to start washing away mountainsides. Rivers overflowed, and a chunk of one of the state’s major highways collapsed, cutting off communities; floods slung mud and muck into buildings. Cars, trucks, dumpsters, entire homes and bridges—these and more were carried away in the floods as if they weighed nothing. Much of what managed to stay in place became submerged in brown water. Thousands of people in Asheville remain without power, and boil-water advisories are in effect; evidence suggests that the city’s water system was severely damaged. Asheville’s River Arts District has been destroyed. At least 35 people in the region have died, and with cell service down, hundreds more are unaccounted for.
When a hurricane barrels toward land, “we really focus on the coast,” Michael Lowry, a hurricane specialist in Miami, told me as Helene headed toward the continental United States. But the inland impact “can’t be overstated,” especially in heavily wooded areas, where fallen trees can exacerbate the destruction. Before the giant hurricane even came ashore, North Carolina had endured a miserable amount of rainfall. On Friday morning, rivers in western North Carolina were already at record levels, and officials for a time feared that a dam at Lake Lure, which is surrounded by dense forest, would fail. Helene had weakened to a tropical storm by the time it reached the mountains, but this much more water was simply too much.
Excessive rainfall can weaken soil and force once-sturdy ground to slide away with terrifying swiftness; scientists have linked both extreme rainfall and increased risk of landslides to climate change. (A recent study found, for instance, that the rainfall that triggered a series of landslides in India this summer, killing hundreds, was made 10 percent heavier as a result of human-caused climate change.) That Helene affected western North Carolina so dramatically may force more people to incorporate those dynamics into their understanding of climate effects. For years, climate scientists warned that rising sea levels would worsen coastal flooding during hurricanes, and indeed, Helene broke storm-surge records along Florida’s Gulf Coast, some of which were set only a year ago. But one of the places still reeling most dramatically from Helene’s wrath are the southern Appalachian Mountains.
Helene bore some of the hallmarks of a hurricane in a too-warm world, such as rapid intensification. The hurricane drew fuel from abnormally warm waters in the Gulf of Mexico, which likely helped extend the storm’s life. A study examining hurricanes that made landfall between 1967 and 2018, for example, found that modern-day hurricanes extend farther inland because they contain more moisture collected during their journey over warmer seas. Hurricanes are now decaying at a slower rate after traveling inland. [Continue reading…]
The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, [Ed] Clark [head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama], [Ryan] Maue [a former NOAA chief scientist] and [Kristen] Corbosiero [University of Albany hurricane expert] said.
North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.
Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”
Storms are getting wetter as the climate changes, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.
Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.
In a quick analysis, not peer-reviewed but using a method published in a study about Hurricane Harvey’s rainfall, three scientists at the Department of Energy’s Lawrence Berkeley National Lab determined that climate change caused 50% more rainfall during Helene in some parts of Georgia and the Carolinas.
For [North Carolina state climatologist, Kathie] Dello, the “fingerprints of climate change” were clear. [Continue reading…]