Is the idea of a “climate haven” under water? » Yale Climate Connections

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Asheville, North Carolina, seemed like a good place to escape the worst of a warming world. The city’s appealing four-season climate includes summers with a typical daily high around 84°F – unusually low for the Southeast U.S. – and winters that aren’t too frigid. There’s typically plenty of moisture throughout the year, but with a mountain rain shadow that keeps Asheville a bit less wet than most of its neighbors. And the city takes climate seriously: findings from a climate resilience assessment have already been incorporated into Asheville’s comprehensive planning document.

In a 2018 Rolling Stone article, Jeff Goodell profiled one climate refugee who had considered the Tampa area before settling on Asheville. “No place is without risk, but in Asheville, the risks seem manageable,” Jeff Kaplan told Goodell. A 2021 Blue Ridge Public Radio segment portrayed Asheville as a climate “winner.”

Then came Hurricane Helene. After striking the Florida Panhandle at Category 4 strength, the storm took a quirky left hook across the southern Appalachians, pushing mammoth amounts of moisture upslope. Making matters worse, a predecessor rain event ahead of Helene had dumped six to 12 inches of rain across the region a day before the storm itself arrived.

Here’s how #Helene biblical flooding evolved. Was a perfect storm – a convergence of natural atmospheric & geological (terrain) features that came together. A preceding rain event common b4 US hurricanes, but with mountains, a fast hurricane & rain rates spiked by climate change!

Jeff Berardelli (@weatherprof.bsky.social) 2024-10-01T02:51:17.418Z

The result was one of the most devastating, prolonged, and deadly hurricane-related U.S. flood disasters since the cataclysm of Katrina in 2005. Across the southern Appalachians – including Asheville – Helene destroyed roads, knocked out power and water lines, crippled communications, and took dozens of lives.

Helene isn’t the first hurricane to cause more trouble over the Appalachians than it did where it came ashore. In August 1969, Hurricane Camille – one of just four Category 5 landfalls on record along the U.S. Gulf or Atlantic coast – slammed into the Mississippi Gulf Coast full force, with top sustained winds estimated at 175 mph. Yet Camille’s remnants were just as catastrophic over the mountains of western Virginia, where they dumped up to 27 inches of rain. Of the 259 U.S. deaths from Camille, more than half – 153 – were caused by landslides and flooding in Virginia.

Less than three years later, in June 1972, Hurricane Agnes struck the Florida Panhandle at Category 1 strength and then reached New York City as a tropical storm. But Agnes inflicted most of its fatalities and damage in Pennsylvania, the result of record rainfall and widespread catastrophic flooding.

It’s also not the first time Asheville and the region has confronted epic flooding. Most of the rainfall records topped by Helene were from 1916, which produced what the city has dubbed “the flood by which all other floods are measured.” And as recently as 2004, severe flooding struck the area after a one-two inland punch from Hurricanes Frances and Ivan.

Among the things that make Helene different is that it arrived at a time when hurricane behavior is being measurably amped up in multiple ways by human-caused climate change. And it hammered a place now widely viewed to be at least somewhat insulated from the worst impacts of that changing climate.

New rapid attribution by Mike Wehner and colleagues at LBL shows that climate change increased Hurricane Helene’s rainfall by up to 50% in some parts of Georgia and the Carolinas, and made the event up to 20x more likely. Read: drive.google.com/file/d/14oq6…

Katharine Hayhoe (@katharinehayhoe.com) 2024-10-01T15:16:57.475Z

Many folks seeking out climate-change-protected places in the U.S. have leaned toward small, progressive cities in relatively cool parts of the Midwest and East. Spikes in heat, drought, and wildfire that have plagued the West seem more likely to be tempered in these apparent havens. And in many of them, climate adaptation efforts are already underway.

As it turns out, most of the country east of the Rockies is getting wetter. Especially over the central and southern Appalachians, some locations saw a 5 to 10% rise in official annual precipitation when their 1980-2011 climate averages were replaced by the 1991-2020 figures. In Asheville, a typical year’s precipitation jumped from 37.32 to 40.61 inches.

Figure 1. Change between 1958 and 2021 in the amount of precipitation falling on the wettest 1% of all days. (Image credit: Climate Central, based on NOAA data).

The character of the rain and snow in these moister climates is also changing. In general, dry spells are intensifying, punctuated by more intense downpours, which means the landscape can lurch more sharply from parched to inundated and back again. Although longer-term drought is not becoming more frequent in the Southeast, it’s tending to be more intense when it does strike, according to the most recent U.S. National Climate Assessment. The report also notes that flash droughts (those that develop especially quickly) are more common in the Southeast than in any other region.

Parts of the southern Appalachians were hit by an exceptional, fast-intensifying drought in autumn 2016, which culminated in vicious November wildfires across Tennessee’s Great Smoky Mountains. The fires destroyed more than 2000 structures and claimed 14 lives – the deadliest outcome from Eastern U.S. wildfire in almost 70 years.

Flood catastrophes have struck several of the most famous climate havens

Among all regions of the nation, the Midwest and Northeast are seeing the biggest increase in the amount of rain that falls on the wettest 1% of all days (see Fig. 1 above). The Southeast isn’t far behind.

Figure 2. Change between 1958 and 2021 in the amount of precipitation falling on the wettest 1% of all days. (Image credit: Climate Central, based on data from the Fifth National Climate Assessment, 2023).

Along with Asheville, a couple of other often-cited climate-change oases in the U.S. Midwest and East have experienced landmark rains and floods in recent years.

  • Duluth, Minnesota, referred to in a 2023 New York Times writeup as “climate-proof Duluth” (and the subject of a study on how climate migration might change the city), experienced the worst flooding in its history on June 19-20, 2012, when the city was swamped by a record 7.24 inches of rain in 24 hours. Colossal rains were even more widespread across northeast Minnesota on June 18, 2024, when a number of stations reported 5-7.5 inches of rain – a daily total with an expected recurrence interval of 500 to 1,000 years, according to the National Weather Service.
  • Vermont has long stood out as a potential U.S. climate refuge, with its environmentally friendly reputation, ample greenery and mountains, and normally mild summers. But when former Hurricane Irene ripped across the state as a tropical storm in August 2011, it brought massive rainfall that triggered one of Vermont’s worst disasters on record, rivaling or exceeding the notorious floods of 1927 in some areas. Then in 2023, weeks of early-summer wildfire smoke filtering south from Canada were followed by the Great Vermont Flood of July 10-11. Triggered by up to 9.61 inches of rain, the floods caused more than $2.2 billion in damage across northern New England and triggered the region’s first-ever flash flood emergency.

In describing the motivations of local climate refugees she had interviewed, the University of Vermont’s Cheryl Morse told the nonprofit news service VTDigger: “In their imagination, Vermont presented a safer climate with plenty of water, access to land and small community settlement.” But after the 2023 disaster, Jared Ulmer, the climate and health program manager at the Vermont Department of Health, told VTDigger: “This summer has maybe burst the bubble a little bit in what probably was more of just a myth, of Vermont being [an] ideal climate refuge.”

Likewise, the widespread view of Asheville as immune, or nearly so, from the vagaries of a human-changed climate will no doubt go through some painful revision.

To be sure, there are iron-clad ways to eliminate or reduce some climate-change risks. Moving well away from the shoreline will obviously protect you from rising sea levels. And many of the best-publicized climate havens are indeed less prone to brutal heat waves and massive wildfires.

But “less prone” doesn’t equal “immune,” and impressions of safety can be faulty. As it turns out, northern Vermont has seen the largest number of disaster declarations of any U.S. location over the past 23 years, as noted by Dr. Jeff Masters in “What should you do to prepare for the climate change storm?” published on this website on August 20.

Masters also emphasizes that there are angles beyond climate to consider:

…some of these places may not be great places to move to if the government, city infrastructure, or social and economic conditions are flawed. For example, I like to tout my home state of Michigan as a climate haven. But Michigan has a poor electrical grid and suffers the second-highest number of power outages of any state, behind Texas — a much larger state (Fig. 1). Thus, it is good to consider the quality of the infrastructure of a state you are considering moving to.

Geographic “cures” to problems do tend to have limits. The tendrils of a human-altered climate, interwoven with natural variability, have a way of touching us even when we think we’re beyond their grasp. All the more reason, then, to work toward major emission cuts sooner rather than later, and to redouble a commitment to climate adaptation – including timely warnings and nimble response when a black-swan event looms on the horizon.

Tired: The entire concept of there existing a region that can be a refuge from extreme climate-driven weather events.Wired: We should help each other mitigate and adapt as quickly as we can. The way we do that best is through a well-funded federal government enacting smart science-backed policy.

Robert Ferry (@robertferry.bsky.social) 2024-10-01T02:21:29.689Z

Postscript: Whether it’s in climate havens or hot spots, solid weather guidance is critical

On Tuesday afternoon, September 24 – more than two days before Helene arrived – the National Weather Service’s Weather Prediction Center warned of the risk of landslides and numerous flash floods over the southern Appalachians. By Wednesday, the local National Weather Service office in Greenville-Spartanburg, South Carolina, was warning that “the potential for major to catastrophic flooding over parts of our [forecast] area is looking more likely,” And by Wednesday afternoon, the Weather Prediction Center had placed parts of the Helene-affected area under a rare High Risk outlook for excessive flood-producing rain (see embedded tweet below).

The first round of torrential rain arrived just a few hours later. One can only hope that residents and officials took these warnings as seriously as possible and responded as best they could. For people in apparent climate-change havens, as well as those on the turbulent front lines of a warming climate, the guidance provided by the National Weather Service can be a literal lifesaver.

Dr. Jeff Masters contributed to this post. We’ll have a full update on the Atlantic tropics in our next Eye on the Storm writeup.

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