by Trish Zornio, Colorado Newsline
August 4, 2021

Without a doubt, one of the largest threats to American infrastructure is climate change.

This was illustrated yet again as upwards of 10 landslides ravaged sections of Colorado’s Interstate 70 corridor, closing the Glenwood Canyon portion of the highway indefinitely. This came after weeks of intermittent slides that have exhausted personnel and had a chilling effect on local economies.

Yet despite the impacts, few have sought to elaborate on the relationship between extreme debris flows and the burning of fossil fuels.

This is a grave oversight.

Dismissing the role of climate change in infrastructure resiliency fails to appreciate the inherent relationship between infrastructure and environment. As global temperatures rise, so, too, will the number of extreme events. This places existing structures and byways in new dangers, ranging from some damage to full destruction.

In the case of mudslides, as wildfires burn bigger and hotter due to rising temperatures and severe drought, ground vegetation of the forest floor is burned off at alarming rates. This creates a layer of dusty ash over bare, scorched soil, resulting in a decreased ability of the soil to absorb water.

While healthy forest floors can hold several inches of water per hour, high or moderately burned areas might only hold one-third of an inch. This results in top layers that can be easily washed away, at least until enough ground vegetation is reestablished — roughly the first year or two post-burn. Meanwhile, even small amounts of rainfall can result in dangerous runoffs, posing great risks to structures and byways located in slide paths. Combined with more intense rainfall — also due to climate change — landslides may occur more frequently and over larger areas with greater force and debris.

This dynamic is consistent with recent events on I-70. Based on post-fire assessments conducted by the Burned Area Emergency Response team, the Grizzly Creek Fire — which was fueled by especially hot and dry conditions last year — burned areas surrounding the canyon. Soil testing revealed that 55% of this area had incurred moderate to high soil burns, leaving the region with unusually high risks of extreme runoffs. Only 12% of the 32,370 acres were estimated to be unburned.

Certainly, mudslides are possible in any canyon so steep — and it’s happened before. However, the size and severity of this particular burn created enhanced risks for severe infrastructure damage. Accordingly, at the recommendation of BAER, mitigation efforts were made.

Shortly after the fire, one large, natural berm was created to protect the most critical infrastructure in the canyon — a mostly hidden command center in the heart of Glenwood Canyon that serves to monitor the interstate. As predicted, less than a year later, some 100,000 cubic yards of debris was diverted with that very berm. John Lorme, the Colorado Department of Transportation director of maintenance and operations, hailed the effort as saving the state millions of dollars and extensive closed highway time — a testament to the role of climate research in protecting infrastructure.

There are, however, limits to our current preventative measures — as evidenced by the current debris damage. During a 47-minute press conference with CDOT, Region 3 director Mike Goolsby acknowledged the lack of radar technology and understanding in predicting slides with enough time to close or protect the highway.

According to the U.S. Geological Survey — the only science agency to exist within the U.S. Department of Interior — much additional research funding and efforts regarding landslides are needed as climate change intensifies. Especially relevant are the needs to better understand debris flow mechanisms, forecasting and mitigation strategies, all efforts that would help safeguard core infrastructure.

One Colorado-based hydrologic engineer, Kelsey McDonough, agrees, adding that some in the private sector may also have access to better, more localized technology. “This could be really useful in a state like Colorado where local knowledge can be utilized to build better regional monitoring and modeling systems than are currently available at the national scale,” she says.

Certainly, Colorado has a number of cutting-edge national laboratories and private companies that may be inclined to help find solutions with the right incentives. Securing these funds is just one of many roles local representatives can play in helping the state navigate the new challenges.

Still, perhaps the most important thing we must do is disentangle the notion that discussions of human-driven climate change during extreme events are signals of political interference. They are not. Climate change is well established in scientific literature, as is its impact to structural integrity. Addressing the role of reducing fossil fuels in related press conferences and articles is therefore necessary to serve the long-term goal of infrastructure stability.

Colorado Newsline is part of States Newsroom, a network of news bureaus supported by grants and a coalition of donors as a 501c(3) public charity. Colorado Newsline maintains editorial independence. Contact Editor Quentin Young for questions: info@coloradonewsline.com. Follow Colorado Newsline on Facebook and Twitter.

Here’s a short video (~4 minutes) from CDOT to give you an overview of the slide area.

From The Fort Collins Coloradoan (Miles Blumhardt):

For the past month, Coloradans have been inundated with flash flood watches and warnings and a weather event — called a monsoon…

Neither flash floods nor the annual monsoon season have grabbed Colorado headlines the past several years because neither had much impact on the state.

That changed this year.

“This year is more normal of what we would expect from monsoon season compared to the past couple of years,” said Jennifer Stark, a meteorologist who manages the National Weather Service office in Boulder. “We are seeing bigger impacts, and people are really beginning to take notice because it is impacting their ability to recreate and move across the state and affecting homes.”

A series of events that has led to devastation started last year when the state experienced its worst wildfire season in its recorded 145-year history…

This summer, those burn scars, largely left denuded, have been continually saturated with abundant monsoonal moisture, resulting in large debris slides.

Those slides have continually closed Interstate 70 in Glenwood Canyon, which remains closed Monday due to what the Colorado Department of Transportation has called “extreme damage” to the major transportation corridor. It also resulted in the deaths of three people with a fourth still missing and six residences destroyed in the Poudre Canyon…

The Colorado Climate Center said the monsoon pattern is created by abundant moisture that builds in the atmosphere from the Gulf of Mexico and Pacific Ocean.

A shift in wind pattern results from a high pressure system with clockwise flow over the Rocky Mountains and low pressure near the Gulf of Mexico with a counterclockwise flow that settles over the region and squeezes moisture northward into the atmosphere.

In Colorado, the moisture is more prevalent on the Western Slope but can spill over the Continental Divide, which is happening this year.

This creates persistent afternoon thunderstorms that park over areas that can produce large amounts of rain, sometimes in a short period of time…

When that happens on burn scars, soil that repels water is washed down canyons, gullies and ravines that act as funnels of accumulating water. As it gains momentum, the slide brings with it large boulders and burned trees.

Stark said many of the state’s most devastating floods have taken place during the monsoon season, including the 1976 Big Thompson flood and 1997 Spring Creek flood in Fort Collins, both of which occurred in late July.

Susan J. Prichard, University of Washington; Keala Hagmann, University of Washington, and Paul Hessburg, United States Forest Service

After so many smoke-filled summers and record-setting burns, residents of Western North America are no strangers to wildfires. Still, many questions are circulating about why forest fires are becoming larger and more severe – and what can be done about it.

Is climate change fueling these fires? Does the long history of fighting every fire play a role? Should we leave more fires to burn? What can be done about Western forests’ vulnerability to wildfires and climate change?

We invited 40 fire and forest ecologists living across the Western U.S. and Canada to examine the latest research and answer these questions in a set of studies published Aug. 2, 2021. Collectively, we are deeply concerned about the future of Western forests and communities under climate change.

So, why are wildfires getting worse?

Climate change is a big part of it. Summer wildfire seasons are already 40 to 80 days longer on average than they were 30 years ago. Annual droughts are more pronounced, making it easier for fuels to dry out and fires to ignite and spread. Extreme weather events, marked by dry fuels, lightning storms and strong winds, are also increasingly common and provide essential ingredients for rapid fire growth, as witnessed by the Bootleg Fire burning in Oregon and record-setting fires in California and Colorado in 2020.

Ironically, a chronic lack of fire in Western landscapes also contributes to increased fire severity and vulnerability to wildfires. It allows dry brush and live and dead trees to build up, and with more people living in wildland areas to spark blazes, pressure to fight every forest fire has increased the risk of extreme fire.

The problem with fighting every wildfire

Historically, fire was a regular visitor to most Western forests, except moist locations like those along the Pacific Northwest coast and in British Columbia. Frequent or periodic fires from Indigenous burning and lightning strikes created patchworks of grasslands, shrublands and regenerating forests of all ages.

Past fires influence the way subsequent fires burn and what they leave behind. For example, Indigenous burning practices not only enhance cultural resources and wildlife habitat but also reduce the amount and connectedness of fuels that drive large, severe wildfires. Similarly, patchy burns from lightning ignitions create forest landscapes that are less likely to burn all at once.

The U.S. and Canada effectively suppress all but 2%-3% of wildfire starts. However, this small percentage of fires burn at the height of each fire season, when dry conditions and extreme fire weather thwart even the most aggressive attempts to suppress them.

Unintentionally, by focusing on short-term risks of wildfires, the U.S. is predisposing forests to burn under the very worst conditions. Active fire suppression contributes to what is often referred to as the wildland fire paradox – the more we prevent fires in the short term, the worse wildfires become when they return.

In one of the new studies, Paul Hessburg and co-authors explain how fire managers can mitigate the severity of future fires by managing fire-excluded forests to foster resilience to wildfires and drought. Management approaches include thinning dense forests, reducing fuels through prescribed burning and managing wildfires to restore more typical patterns of forests, meadows, shrublands and woodlands.

In a second paper, Keala Hagmann and her co-authors describe how more than a century of fire exclusion and past forest management practices have jeopardized forest biodiversity and social and ecological values, including culturally important resources, the quantity and quality of water, stability of carbon stores, recreation and air quality.

For example, fire exclusion has compromised aspen stands – biodiversity hot spots for everything from bears to butterflies. Increased forest cover diverts water from downslope meadows, allowing conifer forests to further encroach on aspen habitat.

A path forward

Amid the daunting reality of climate change and severe wildfires, there is a path forward for Western forests.

In a third article, Susan Prichard and her co-authors examine which adaptive forest management approaches have worked to increase resilience to wildfires and climate change. There is strong scientific evidence that fuel reduction treatments – including forest thinning, prescribed burning, Indigenous cultural burning and managed wildfires – are effective approaches for mitigating future fire impacts to Western forests. However, land managers can’t expect these treatments to work if they are applied to only a small fraction of Western forest landscapes.

When combined, forest thinning and prescribed burning in dry ponderosa pine and in dry and moist mixed-conifer forests have been shown to be highly effective at reducing the fire damage to forests. However, this type of treatment is not appropriate for all forest types. Fire managers in some wilderness areas and national parks have allowed fires started by lightning to burn in some wind and weather conditions. Over the past 40-plus years, these wildfires have been allowed to burn and reburn landscapes, generally limiting the size and severity of subsequent wildfires.

Given the immense diversity of Western forests, there is no one-size-fits-all solution. However, in forests that historically supported more frequent fire, revitalizing and continuing cultural burning practices, prescribed burning, and forest thinning combined with prescribed burning can reduce overcrowding and the potential for severe fires. Thinning and prescribed burning aren’t appropriate or feasible everywhere. In reality, only a portion of landscapes can be treated this way. Allowing wildfires to burn in more areas under moderate weather conditions is also part of the solution.

Promoting resilient Western forests will require that our society builds a new relationship with fire by creating fire-adapted communities and looking for opportunities to restore fire to Western forest landscapes.

In this era of warmer, drier summers and longer fire seasons, there are no fire- or smoke-free solutions. The current approach to fire management poses unnecessarily high stakes for Western forests. There is no doubt that the future of Western forests is a fiery one. How we choose to live with fire is still up to us.

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Susan J. Prichard, Research Scientist of Forest Ecology, University of Washington; Keala Hagmann, Affiliate Assistant Professor, University of Washington, and Paul Hessburg, Research Ecologist, United States Forest Service

This article is republished from The Conversation under a Creative Commons license. Read the original article.