DENVER (AP) – When ominous storm clouds gathered over a large area recently blackened by wildfire in western Colorado, torrential rain fell and the charred land, stripped of vegetation, gave way, creating a torrent of mud and Boulders down steep canyon walls and onto a major highway.

The July 29 mudslides stranded more than 100 people in their vehicles overnight, causing extensive damage that closed Interstate 70 and crowned several weeks of dangerous conditions in a scenic canyon carved through the mountains by the Colorado River.

It was the latest in a series of closures in the past two years for an area that serves as a major transportation corridor between the Rocky Mountains and the west coast. Both forced long detours for semi-trailers delivering fuel and groceries, and created economic problems for companies delivering to tourists in the popular summer destination of Glenwood Springs.

The closings illustrate the damage that scientists have long warned about as a result of forest fires made worse by climate change: dangerous mudslides caused by rain on scorched terrain. Although no casualties have been reported, such landslides have resulted in death and destruction in California and other parts of the western United States in recent years.

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Those who live and work in the Glenwood Canyon area have adapted to the inconvenience of the closure for years, but mudslides have become more frequent and intense since the Grizzly Creek fire burned about 50 square miles (130 square kilometers) last summer.

Traffic officials have closed a 46-mile stretch of the freeway and are urging motorists traveling between Denver and Glenwood Springs at the western end of the canyon to take another route that will add about 402 kilometers to the journey. Meanwhile, long-haul truckers have been advised to head north via Wyoming on Interstate 80 until the canyon reopens, which could take weeks.

According to state transportation authorities, an average of thousands of commercial vehicles drive the interstate through the canyon every day.

Much of the fuel, groceries, and other products distributed in the western part of the state come from Denver on I-70, and the detours add hours to each trip, said Greg Fulton, president and CEO of Colorado Motor Carriers Association.

In some cases, this means truckers can’t make the round-trip trip without breaking state restrictions on how long they can sit behind the wheel.

“It’s a ripple effect because we won’t get the truck back until the next day. … It upsets those drivers, and effectively you need more drivers and more trucks, ”said Fulton, who warned the delays could lead to gas and food shortages, late deliveries and higher prices.

“If we have extra miles and extra time, and then possibly even pay the cost of a motel room, that has to be passed on at some point,” he said.

The mudslides have also had a significant impact on tourism in Glenwood Springs, which typically attracts thousands of visitors for hiking, biking, fishing, and other outdoor activities at this time of year.

Lisa Langer, the city’s tourism director, said many attractions and some hotels were from full occupancy to half full, and some lost between 25% and 50% of their normal income on the weekend after the canyon closed.

The biggest problem is that people from front range cities like Denver are canceling their trips because they don’t want to take the long detour, said Langer, who has shifted her focus to attracting tourists from areas that are still easily accessible.

Meanwhile, whitewater rafting companies have had to reroute their itineraries, and some companies have had staff shortages because employees live on the other end of the blocked interstate, a technical marvel that winds its way through a narrow passage bounded by the Colorado River and cliffs who have favourited hundreds of feet.

Max Vogelman, co-owner of Stoneyard Distillery, said the closure had “quite a big” impact on the finances and logistics of his beet-making alcoholic liquor company.

The company opened a tasting room in Glenwood Springs in May, but the distillery is across the canyon in Dotsero.

Vogelman said the company’s only employee in Glenwood Springs was on extra shifts to keep the tasting room open, and another worker in Dotsero travels nearly an hour down a series of winding country lanes every few days to deliver supplies.

“It definitely gets us into a bit of a puzzle here, but we’re trying to get it to work,” said Vogelman, who is also trying to figure out how to keep distributing to areas west of the canyon and get people to come to the Distillery for tours and drinks.

“We have a lot of motorhome traffic. Many of them stay here on a property. They are all canceled, ”he said.

He and other business owners and local residents are quickly realizing that they need to adjust to what could become the canyon’s new normal.

Scientists say special calculations are needed to determine how much, if any, global warming is responsible for a single extreme weather event. But a historic drought and recent heat waves related to climate change have undoubtedly made fighting wildfires in the American West difficult.

Climate change has made the region much warmer and drier over the past 30 years and the weather is expected to become more extreme and forest fires more frequent and destructive, which could lead to more mudslides if rain falls on burn scars.

Andy Hoell, a meteorologist with the National Oceanic and Atmospheric Administration, said rainfall over the Four Corners states last summer was the lowest on record, and drought conditions were deteriorating.

“In this case, it is really the intensifying and cascading effect of an active fire season last year, followed by heavy rainfall this year, that together have this huge impact on I-70,” said Hoell, who studies drought and extreme events in one changing climate.

A recent study led by researchers from the US Geological Survey mapped susceptibility to landslides in Southern California and found that the area can now expect small landslides after a forest fire almost every year and major events roughly every 10 years. It is said the state is at increased risk of forest fires and landslides, the shifts in its wet and dry seasons caused by climate change.

One particularly devastating post fire slide occurred in southern California in 2018 when a river of mud, trees and boulders crashed into the town of Montecito. More than 20 people died and hundreds of houses were destroyed.

Colorado Governor Jared Polis said Monday he hopes any state or federal infrastructure package has climate resistance “at heart”.

“We need to look at things like fire risk mitigation and retaining walls in a new and different way given the realities we face in Colorado,” he said.