Climate & Environment

Groundwater levels in the US Southwest more sensitive to climate shifts than in the Pacific Northwest

Megan Maneval — Mon, 16 Jun 2025 17:45:10 +0000

Groundwater levels in the US Southwest more sensitive to climate shifts than in the Pacific Northwest Megan Maneval Mon, 06/16/2025 - 11:45

CIRES

Scientists used fossil groundwater and model simulations to identify regional differences in aquifer response during the Last Glacial Termination, a period of warming, ice sheet loss and major environmental change that occurred between 20,000 and 11,000 years ago.

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Rainy spring may be bad news for fire season. Here’s what you can do about it

Yvaine Ye — Mon, 16 Jun 2025 15:35:30 +0000

Rainy spring may be bad news for fire season. Here’s what you can do about it Yvaine Ye Mon, 06/16/2025 - 09:35

Yvaine Ye

This May, Denver saw more than 4 inches a rain, doubling the city’s historic average and outpacing famously rainy places like Seattle.

While the additional moisture has painted the Front Range a lush green, to grassland ecologist Katharine Suding, it’s concerning.

“Wet springs mean more plant growth,” said Suding, distinguished professor in the Department of Ecology and Evolutionary Biology and the Institute of Arctic and Alphine Research. “That growth would turn into fuel later in the season.”

Without interventions to reduce the amount of dry vegetation in the fall and winter, the region could face intense and fast-spreading wildfire if one breaks out.

Katharine Suding. (Credit: Casey A. Cass/University of Colorado)

To Suding, this spring felt all too familiar. In 2021, a wet spring set the stage for the Marshall Fire later in December. The fast-moving fire destroyed more than 1,000 homes in Boulder and its surrounding suburbs like Louisville and Superior.

While forest fires tend to receive more attention, grassland fires are becoming a bigger problem nationwide. Research has suggested that in the United States, grassland and shrubland fires are burning more land and destroying more homes than forest fires.

“We should think about grasslands far differently than forests,” said Suding, standing in front of a grassland in Superior that the Marshall Fire swept through. “Knowing how to manage forests for fires does not necessarily mean that we can take that knowledge and apply it to the grassland system at all.”

As out-of-control wildfires rage in places like the Canadian prairies, Suding spoke to CU Boulder Today about these fast-moving grassland fires and potential ways to manage them.

What makes grassland fires so dangerous?

People might think forests are riskier, because there’s more biomass to burn. And that’s absolutely the case. But in grasslands, fires can burn really fast under hot, windy conditions. They can also spread very quickly and even jump barriers we once thought would stop them, like paved roads.

For example, the Marshall Fire crossed the U.S. Interstate 36. Some of the intense, fast-moving fire characteristics that we thought were mostly a forest fire problem are now occurring in grassland fires as well.

For states like Colorado with elevated grassland fire risks, when does the fire season begin?

In grasslands, fires typically start when the green vegetation turns brown at the end of their growing season. That’s usually August, with peak fire danger in October and November. But as the climate warms, we’re now extending the fire season into winter. The Marshall Fire happened in December. Fires are even popping up in early spring, before new green growth has a chance to return.

Where else are grassland wildfires becoming a growing concern?

Many places are starting to realize they face grassland fire risks, with Colorado seeing some of the earliest impacts. But it’s happening in California, Texas, Oklahoma, and throughout the Southwest as well.

How is climate change shifting the fire patterns?

Colorado and many other grasslands regions are getting hotter and drier. That means plants may stop growing, or senesce, earlier when it’s too dry, leaving behind dry, dead material that sits on the landscape for longer. That’s what happened the year of the Marshall fire, and it’s happening more and more often.

We are also seeing increasing wind speed in the fall and winter in areas like Colorado and California. The combination of high wind and dry vegetation is the riskiest situation for grasslands.

What can be done to reduce fire risks in grasslands?

It isn't quite clear what exactly we can do to make these grasslands less risky for the people that live right next to them, because we’re just starting to understand these fires.

At CU Boulder, we’re working with a group of local partners, including Boulder County, the city authorities of Boulder, Superior and Louisville, to try out some techniques. For example, we have tested grazing, which uses cattle or goats to eat down tall grasses. We’re also testing out mowing, as well as prescribed burning to reduce fuel in a controlled way.

Unlike forests, where you might thin trees and not have to return for years, grass regrows quickly. So, all of these interventions have to happen multiple times in a summer.

Some preliminary research suggests a combination of grazing and prescribed burning may work better than either alone, but there’s still a lot to learn. With funding from the Joint Fire Science Program, we are just on the cusp of trying to figure out how we can manage fires without removing all the grasses and turn the area into just a dust bowl.

For those living near fire-prone grasslands, is there something they can do to make their home more resilient?

One thing to do is avoid having tall, dead plants, as well as plants that catch on fire quickly, around their homes. The City of Boulder is encouraging people to remove junipers, highly flammable shrubs, from their yards. Planting native wildflower plants instead would be helpful, because they tend to be less flammable. Also, reducing vegetation density around homes can reduce risk.

CU Boulder Today regularly publishes Q&As with our faculty members weighing in on news topics through the lens of their scholarly expertise and research/creative work. The responses here reflect the knowledge and interpretations of the expert and should not be considered the university position on the issue. All publication content is subject to edits for clarity, brevity and university style guidelines.

Ecologist Katharine Suding shares insights on the increasing risks of grassland fire across the country.

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Large plumes of smoke from the Marshall Fire were visible over Superior, CO. (Credit: Tristantech/Wikimedia)

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Large plumes of smoke from the Marshall Fire were visible over Superior, CO. (Credit: Tristantech/Wikimedia)

Supernovae may have kicked off abrupt climate shifts in the past, and they could again

Megan Maneval — Fri, 13 Jun 2025 14:46:33 +0000

Supernovae may have kicked off abrupt climate shifts in the past, and they could again Megan Maneval Fri, 06/13/2025 - 08:46

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Robert Brakenridge has spent decades trying to understand how distant exploding stars may have affected Earth's atmosphere in the past. A new analysis indicates the need for continued research in the field.

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'Fall back in love with nature': A climate forum's call to lead with heart

Megan Maneval — Tue, 10 Jun 2025 13:24:43 +0000

'Fall back in love with nature': A climate forum's call to lead with heart Megan Maneval Tue, 06/10/2025 - 07:24

Yvaine Ye

Left to right: Graduate student Naia Zulueta, moderator and journalist Lakshmi Singh, Sheila Watt-Cloutier, graduate student John Ecklu and Professor Amanda Carrico. Photos by Casey Cass/CU Boulder.

When asked what she would do if every government around the world became aligned on climate action, with unlimited resources for one year, Sheila Watt-Cloutier, longtime advocate for the rights of the Arctic’s Inuit peoples and Indigenous groups worldwide, didn’t hesitate.

“I would continue doing what I’ve been doing for 30 years but in much more of a full force,” said Watt-Cloutier. “I would build a team and get the younger generation mobilized in bigger ways than we have. They're the ones who have given me a lot of inspiration, and they're fighting for their future.”

Watt-Cloutier delivered a powerful plenary keynote Thursday in Boulder. She was also a featured speaker at the inaugural Right Here, Right Now Global Climate Summit held at CU Boulder in 2022.

The day’s conversation centered on climate change’s disproportionate burden on women, youth, Indigenous people and communities who are historically unseen—and the need to ensure solutions focus on those most affected. NPR Newscaster Lakshmi Singh moderated the discussions.

Watt-Cloutier said she believes that educating people about the human impacts of climate change can bring the world together, even in times of political uncertainty and conflict.

“We're all in this together as a common humanity,” Watt-Cloutier said.

Joined by three other members of the CU Boulder community, including environmental studies professor Amanda Carrico, environmental human rights graduate student Naia Zulueta and environmental engineering graduate student John Ecklu, Watt-Cloutier and the group outlined three ideas to guide the work toward climate solutions.

“Do things that bring you back to nature, and you will start to protect what you love.”

Turn research data into tools for change

Around the world, about 3.6 billion people are living in areas highly susceptible to climate change. Despite contributing minimally to global emissions, those in low-income and marginalized communities bear most of the impact.

A persistent problem is the lack of data for these communities. Zulueta noted that over a third of countries worldwide still lack routine indoor air quality monitoring.

“No data means no visibility, and no visibility means no accountability,” she said.

At the same time, the panelists emphasized that the world has enough data to understand the scale of the climate crisis and to mobilize action. An important step is making that information accessible and actionable.

Ecklu at CU Boulder’s Mortenson Center in Global Engineering & Resilience has been working on water well monitoring in Kenya. Prolonged droughts have forced local people to rely heavily on deep water wells called boreholes. But frequent breakdowns in Kenya’s boreholes are severely threatening water access for the communities.

To address the issue, Ecklu and team installed sensors that can detect signs of borehole failure and alert local engineers before wells completely collapse.

“We need to be more intentional about how the data we are collecting can better serve local communities,” he said. “Accessible data is helping communities become more resilient.”

Put a human face to the issues

But statistics alone are not enough. More than once during the event, the group returned to the idea that reframing climate change as a human rights issue is essential.

“We can no longer just think our way through these issues of climate change,” Watt-Cloutier said. “We have to feel our way through, and we've got to connect as a common humanity.”

Sheila Watt-Cloutier gives keynote remarks at the 2025 Right Here, Right Now Global Climate Summit plenary event in Boulder.

She described how melting Arctic sea ice isn’t just an environmental loss. It’s the disappearance of an entire way of life for Indigenous communities. “The ice is our life force. It’s our highway that brings us out to the supermarkets. It’s our organic farms, which bring us highly nutritious food we need.”

For Watt-Cloutier, one solution is leadership rooted not in anger and force but in empathy and connection.

“We can never underestimate the impact when we take a big action toward something that we feel is so important to us. Don’t let the politics of things stop us,” she added.

She will be speaking more about conscious leadership in her upcoming podcast, A Radical Act of Hope.

Embrace nature-based solutions

Finally, speakers urged a shift away from carbon-heavy, industrial responses to climate change to solutions from nature.

Ecklu highlighted a Colorado-based example along the Yampa River, where restoring wetlands is helping to filter water runoff from nearby farms before it reaches the river. Nature-based solutions like this improve water quality while supporting biodiversity and ecological health.

Watt-Cloutier echoed the importance of reconnecting with nature, which holds the wisdom needed to sustain it.

“In the Arctic, we just absolutely love our land, and Indigenous peoples around the world are the same. We love nature because of what it gives us, and the love allows us to be stronger in our fight to defend our way of life,” she said.

She urged city dwellers to rediscover that bond.

“Do things that bring you back to nature, and you will start to protect what you love.”

At a regional plenary of the Right Here, Right Now Global Climate Summit, co-sponsored by CU Boulder, speakers called for action that centers human stories, local wisdom and nature-based solutions to break the cycle of environmental injustice.

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First-ever airborne toxin detected in Western Hemisphere

Megan Maneval — Mon, 09 Jun 2025 18:35:06 +0000

First-ever airborne toxin detected in Western Hemisphere Megan Maneval Mon, 06/09/2025 - 12:35

CIRES

A field campaign on an Oklahoma feedlot that aimed to measure aerosols in the atmosphere yielded surprising results.

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Honeybees are dying in record numbers. This scientist is racing to save them

Yvaine Ye — Fri, 06 Jun 2025 15:35:34 +0000

Honeybees are dying in record numbers. This scientist is racing to save them Yvaine Ye Fri, 06/06/2025 - 09:35

Yvaine Ye

The first sign something was wrong came from the silent beehives.

When Samuel Ramsey visited his family in Maryland this March, he and his father, an avid beekeeper, approached the 10 bee boxes in his grandmother's yard. They were expecting to hear the familiar hum of insects awakening from their winter rest. They pictured the smell of warm, sweet beeswax.

Instead, the Ramseys found thousands of lifeless bees piling up at the bottom of the hives.

As an entomologist in the Department of Ecology and Evolutionary Biology and the BioFrontiers Institute, Ramsey studies honeybees and why they haven’t been doing so well lately.

Samual Ramsey co-designed an observation beehive so the team can monitor how the honeybees without opening the box. (Credit: Yvaine Ye)

“When you open the top of the box, and there's a silence of the bees that you're greeted with, it’s a very upsetting scene for beekeepers and bee researchers to see,” said Ramsey.

Ramsey is not alone. Across the United States, beekeepers are reporting the same grim discovery as unprecedented honeybee losses sweep through the nation’s colonies. Researchers predict that beekeepers in the country have lost more than 62% of their colonies over the winter. In some places, the number could reach 70%.

“Since we've started measuring honeybee losses, this is the worst that we have ever seen,” Ramsey said. “We now have net losses of honeybees that will impact everything from honey production to foods that we consume on a regular basis.”

Losing over half of the colonies passes a critical threshold where beekeepers can no longer divide the surviving colonies and wait for each new group to repopulate, a strategy that has worked when losses hovered below 50%.

Scientists say that a range of factors, including climate change, pesticides and, particularly, parasites are likely contributing to the massive die-off. Ramsey is racing to identify the causes and find solutions. He thinks bees on the other side of the world might hold clues to prevent the tragic decline from happening again next year.

Collapsed colonies

Honeybees are among the most efficient pollinators in nature, contributing to about $18 billion worth of crops in the United States. A decline in honeybee populations could threaten the yields of crops like apples, peaches and almonds. It would also affect livestock production, because the plants that make animal feed also rely on pollination.

Normally, about 10% of bees die as they brave the winter months due to natural causes like cold weather.

In 2006, U.S. beekeepers began noticing their bees dying off or vanishing in much larger numbers, resulting in colony losses of about 30% to 50% in a phenomenon known as colony collapse disorder. But around 2011, the disorder mysteriously disappeared, so quickly that scientists never identified a cause.

Strangely, U.S. honeybee colonies continue to suffer even after the disorder disappeared.

A bee colony in an observation beehive in Samuel Ramsey's lab. (Credit: Yvaine Ye)

“The bees never bounced back, and it’s incumbent on us as scientists to figure out what’s holding them back from returning to their healthiest state,” Ramsey said. He added that many factors are stressing out honeybees, but at the center of the crisis is a parasitic mite, Varroa destructor.

These tiny mites attack a honeybee’s fat body, an important organ that manages the insect’s metabolism, immune system, body temperature and its ability to break down pesticides.

Scientists have found that more than 98% of colonies in the United States already have varroa mites.

The parasite also makes all the other problems bees are dealing with worse. For example, the mites damage the honeybee’s ability to handle extreme temperatures. They also weaken the bee’s ability to fend off other bacterial or viral infections.

At the same time, a changing climate is causing wildflowers to bloom earlier than usual, often before bees emerge from winter to collect food. Infected bees are even less likely to survive when resources are scarce.

“These mites were already present last year and the year before and the year before and the year before, going all the way back to 1987. The reason why mites may be a greater issue now is because they compound everything else happening around them,” Ramsey said.

Natural immunity

Traditional methods of mite control often involve pesticides, but varroa mites have developed resistances to these chemicals and are becoming more virulent over time.

Ramsey and his team are searching for a solution. In recent years, they have traveled around the world to collect genetic data from every existing species of honeybee and to observe how they interact with their native parasites.

He has previously discovered that some honeybees in Southeast Asia, where varroa originated, are resistant to mites. The secret could lie in genes.

“Nature has done a spectacular job of solving problems that we are still trying to figure out how to solve. So instead of reinventing the wheel, it would be a much better idea for us to better conserve the organisms that have already figured out how to solve life's problems and study them,” Ramsey said.

He added that if scientists could transfer these genes to honeybees in the United States, it might help them develop immunity against varroa.

This summer, Ramsey had planned to travel to Vietnam, Borneo and Thailand where he hasn’t yet collected DNA from honeybees. But because of funding issues, he had to postpone the trips.

“In order for us to do what we can to make sure that this level of die-off never happens again, we need better funding for research. This is the worst possible time for us to be reducing funding for agricultural and bee research,” Ramsey said.

There are also some actions people can take, he said. For example, planting native wildflowers around homes could provide much-needed food for bees.

“It’s endearing to think that these little insects have increased the carrying capacity of our country so we can thrive. I’m determined to figure out how to make them thrive too,” Ramsey said.

American honeybee colonies have declined by more than 60% this year. A CU Boulder entomologist is racing to find a solution.

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Honeybees fly into beehive. (Credit: Kai Wenzel/Unsplash)

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Honeybees fly into beehive. (Credit: Kai Wenzel/Unsplash)

Why Brazil’s quilombola communities are still fighting for the land they’re owed

Yvaine Ye — Tue, 03 Jun 2025 16:40:00 +0000

Why Brazil’s quilombola communities are still fighting for the land they’re owed Yvaine Ye Tue, 06/03/2025 - 10:40

Yvaine Ye

Brazil’s quilombola people, the descendants of Africans who escaped slavery, have lived in the nation’s vast Amazon and Atlantic rainforests for centuries. Today, the quilombolas number about 1.3 million people in the country and have cultivated deep ties to their ancestral territories, where they raise their families and steward the land.

But these communities remain largely unseen in the eyes of the government and neglected in scientific research, especially when it comes to their legal rights to the land they call home.

A new study published in World Development Sustainability sheds light on this critical gap. Previous research has shown that Indigenous peoples who have secured formal land rights in Brazil have reduced deforestation in their territories. But, according to research from CU Boulder and the Federal University of Rio Grande do Sul in Brazil, the team didn’t see the same pattern in quilombola communities.

Women from Volta Míuda, a quilombola community in Brazil, are conducting a participatory mapping research activity. Read the book "Honoring Ancestry" by community leader Célio Leocádio to learn more about this community's struggles. (Credit: Rayna Benzeev)

While the team was surprised by the result, they said it could point to deeper systemic issues, including a lack of research on the quilombolas and Brazil’s convoluted process for obtaining land rights.

“Our research reveals a significant data gap that has rendered quilombolas less visible in research and reporting,” said Peter Newton, the paper’s senior author and associate professor in the Department of Environmental Studies. “These communities have been significantly less studied than some others, and without data, the plight of these residents often goes undiscussed and unrecognized.”

Traditional peoples and lands

Brazil’s 1988 Constitution recognized that traditional peoples, including quilombola and Indigenous communities, have rights to receive formal recognition of their ancestral lands, known as land tenure.

Prior research from Newton and his colleagues found that Indigenous communities in Brazil’s Atlantic Forest who attained full land tenure reduced deforestation and increased forest cover in their communities between 1985 and 2019. The researchers wondered if the same would hold true for quilombola territories.

“Legally-enforced land rights provide communities the ability to prevent invaders from encroaching and land grabbing,” said Rayna Benzeev, the first author of both papers who earned her doctorate from CU Boulder in 2022. “At the same time, when a community knows they'll be able to access the land for many generations into the future, they have more incentive to care for this land.” For example, quilombola farmers have ancestral traditions involving agro-ecology and crop rotation which allows forests to regenerate.

After analyzing more than three decades of satellite imagery and land tenure data, the researchers found no clear difference in deforestation or reforestation rates between territories that had secured formal tenure and those still awaiting it.

A broken process

The arduous land tenure process for quilombola communities might be one reason for the result.

When Benzeev began collecting data on forest coverage change in quilombola territories, she noticed a shockingly low rate of land tenure more than three decades after the constitution first guaranteed the rights. Out of 5,900 quilombola territories, only 176—or fewer than 3%—have been able to complete the process to obtain formal land rights.

The contrast is striking. �鶹��Ƶ 69% of Indigenous territories in Brazil have secured formal tenure.

Brazil’s National Institute for Colonization and Agrarian Reform (INCRA) oversees quilombola land tenure applications. It requires communities to navigate a complex six-step process to prove their territories are traditional lands.

“For a lot of these communities, it’s been really hard to reach the end of the six-stage process. This could be due to huge recent decreases in the government budget, or because of strong political opposition to recognizing these territories,” Benzeev said.

Rayna Benzeev

Between 2014 and 2019, Brazil cut INCRA’s budget for formalizing land tenure by 89%, effectively paralyzing the process.

In addition, reliable data on land use within these areas is sparse. As a result, the team could only include a total of 313 quilombola territories in their analysis of the 5,900 territories that exist across Brazil, including 98 with full tenure and 215 still in process.

“We could only analyze a very small proportion of all quilombola territories, and that sample might not be representative of the whole picture,” Benzeev said.

More than trees

Even though this study didn’t detect an immediate forest benefit from land tenure among quilombolas, the researchers note that securing land rights for these communities may still be crucial.

Forests in Brazil remain under persistent threats, including from legal and illegal logging, ranching, gold mining and large-scale plantations.

“It’s not that those activities were necessarily legal before a territory gets its land tenure, but once tenure is granted, it becomes clear who owns and manages the land. When those boundaries are fuzzy or can be contested, it’s much easier for others to move in,” Newton said.

Some quilombola community leaders Benzeev has collaborated with said they had been fighting against encroachment from eucalyptus companies for decades. People died in these conflicts, but without land rights, the quilombolas were not able to stop the violence.

“Quilombolas are some of the most marginalized communities in Brazil,” Benzeev said. “The fact that they are entitled to land by law but they’re not receiving this recognition is a violation of rights, and shows there is still a big gap to address.”

Beyond the story

Our research impact by the numbers:

45 U.S. patents issued for CU inventions through Venture Partners in 2023–24
35 startups launched based on university innovations in 2023–24
$1.2 billion raised by companies built on CU Boulder innovations in 2022–24

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CU Boulder research sheds light on communities in Brazil facing ongoing marginalization despite legal land rights.

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Andre Luiz, a member of Ribeirão, a quilombola community, looking at the community's reforestation nursery in Bahia, Brazil. (Credit: Rayna Benzeev)

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Andre Luiz, a member of Ribeirão, a quilombola community, looking at the community's reforestation nursery in Bahia, Brazil. (Credit: Rayna Benzeev)

What makes some homes, neighborhoods more likely to survive wildfire? New research offers insight

Amber Elise Carlson — Tue, 03 Jun 2025 15:33:30 +0000

What makes some homes, neighborhoods more likely to survive wildfire? New research offers insight Amber Elise Carlson Tue, 06/03/2025 - 09:33

Amber Carlson

Editor’s note: This article has been updated to reflect that Erica Fischer and Amy Metz of Oregon State University led this study.

When a wildfire ravages a community, the loss of homes can be one of the most devastating impacts. The destruction displaces residents and can drive businesses and services away from those who still live there.

But fires don’t affect all homes and neighborhoods equally. Some burn to the ground, while others are left untouched.

In a recent study, engineers from Oregon State University and CU Boulder aimed to find out why.

“There's no such thing as fireproof,” said Abbie Liel, a co-author of the study and professor of civil, environmental and architectural engineering at CU Boulder. “But I really believe we can protect our communities better.”

In the study, which was published in Fire Technology, the research team, led by Erica Fischer and Amy Metz of Oregon State University, examined the patterns of destruction left by the December 2021 Marshall Fire, which killed two people and destroyed more than 1,000 homes in Boulder County.

The researchers used machine learning models to predict whether 1,055 homes in the Marshall Fire burn area would have survived based on 23 different factors, such as the homes’ construction year and type, the presence of wooden fencing, nearby vegetation, how isolated the neighborhood was and what jurisdiction it was located in.

When the researchers entered the true data from the fire, the models accurately predicted 99% of the houses that would be destroyed and 54% of the homes left standing. When they removed certain factors, they discovered that some factors, such as where a house is located, mattered more than others.

The characteristics of the homes themselves made a difference — for example, the materials a home is made from or the landscaping nearby — especially in more densely populated wildland-urban interface, or WUI, areas like Louisville and Superior.

In these areas, homes are closer together, and fire spreads more easily from one home to the next. Because the houses themselves act as fuel for a fire, and the most common way fires spread in WUI areas is through embers that can be carried miles away, it’s even more crucial for homes in these areas to be built in ways that reduce risk, the researchers said.

Fischer of Oregon State University said there are a few simple and low-cost ways homeowners can safeguard their homes: They can clean gutters, keep rooftops free of debris that could catch fire and remove easily combustible material, such as bark mulch, from within 5 feet of a home. They can also add screens over attic and crawlspace vents to block embers from getting inside the house and sparking a fire.

Residents can also learn about their risk level for fires. Colorado has a Wildfire Risk Viewer that can help residents learn whether they are in a WUI area.

Abbie Liel is pictured doing field work in areas affected by the Marshall Fire in January 2022. (Credit: Abbie Liel)

Other methods, like upgrading to fire-resistant siding and roofing or removing flammable landscaping, can be more expensive but can also help protect homes. Liel of CU Boulder calls wooden fences a “conduit” for fire spread and recommends changing them out for fire-resistant fencing if possible. The researcher’s study indicated that newer houses were somewhat more likely to survive, indicating the benefit of more modern construction.

Another major takeaway of the study, which was chosen as one of the best studies of 2024 in Fire Technology: Community-level actions and policies can play an even bigger role than individual homeowners’ actions.

The researchers found that during the Marshall Fire, the layout of communities and the spatial arrangement of houses determined which homes survived, especially in Louisville and Superior, which are more densely populated WUI areas.

Houses’ proximity to open space mattered, but so did the distance between houses: Areas like Louisville and Superior with more dense housing and smaller distances between houses were more susceptible to wildfire spread. In unincorporated Boulder County, where lot sizes are larger and homes are farther apart, the fire did not spread in the same way.

But Liel said she doesn’t see reducing housing density as the best lever for mitigating fire risk. Denser housing can create livable, walkable communities and also be more affordable, especially for lower-income people and families.

Homes in denser areas can be built to be more fire-resistant, and these communities can be protected from fires through other means, including vegetation and open space management as well as keeping roads and water sources accessible for firefighters.

Colorado, a home-rule state, has no statewide building code, and local jurisdictions are allowed to set their own standards, although efforts to create a statewide wildfire code are underway. Those standards could include wildfire hardening policies implemented at a city or county level. Numerous cities, including Boulder, are currently weighing such policies.

Broader legislation can also influence which regulations homeowners’ associations can impose on residents. For instance, a new Colorado law passed last year blocks HOAs from prohibiting building with fire-resistant materials, so they can’t require higher-risk features like wooden fencing.

Rebuilding tips

CU engineers have compiled a list of rebuilding recommendations informed by the Marshall Fire for homeowners affected by wildfire.

Additionally, Fischer said, jurisdictions can find ways to shore up their water capacity for fighting fires, and neighborhoods can be designed in a way that makes them easy for firefighters to access.

Even when there’s not a shortage of water in nearby reservoirs, a sudden surge in demand for water can overwhelm municipal water systems and lead to a drop in water pressure, causing fire hydrants to run dry. The Los Angeles wildfires in January offered a painful illustration of this lesson.

“Typical public works departments are built such that they're fighting one house fire at a time. They're not fighting an entire city block or an entire cul-de-sac at the same time,” Fischer said. “The water system is just not made for it.”

Regardless of the means, the researchers agreed that people and communities need to take action to make themselves safer from fires.

“People really do want a safe home, and they really do want their community to be safe,” Liel said. “We need to take individual and collective actions, starting with the things that are most achievable and moving up to things that are harder.”

Beyond the story

Our sustainability impact by the numbers:

First student-run campus environmental center in the U.S.
No. 11 university for environmental and social impact in the U.S.
First zero-waste major sports stadium in the U.S.

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A study of the 2021 Marshall Fire in Boulder County shows that community policies are as important, if not more so, than homeowner actions.

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Abbie Liel and others do field work amid Marshall Fire debris in January 2022. (Credit: Abbie Liel)

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Researchers model a dangerous glacial lake in the Himalayas

Megan Maneval — Fri, 30 May 2025 15:06:58 +0000

Researchers model a dangerous glacial lake in the Himalayas Megan Maneval Fri, 05/30/2025 - 09:06

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In a new paper, Alton Byers and his coauthors identified a rapidly forming glacial lake in the Kanchenjunga Conservation Area. The researchers model potential flood scenarios and suggest mitigation measures.

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CIRES researchers find elevated levels of mercury in Colorado mountain wetlands

Megan Maneval — Thu, 22 May 2025 17:26:22 +0000

CIRES researchers find elevated levels of mercury in Colorado mountain wetlands Megan Maneval Thu, 05/22/2025 - 11:26

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Climate change is increasing sulfate runoff, likely causing soil microbes to produce the most toxic form of mercury.

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Climate & Environment

Groundwater levels in the US Southwest more sensitive to climate shifts than in the Pacific Northwest

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