Research

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

Gabe Allen — Tue, 10 Jun 2025 20:15:29 +0000

Supernovae may have kicked off abrupt climate shifts in the past, and they could again Gabe Allen Tue, 06/10/2025 - 14:15

Gabe Allen

Robert Brakenridge

When a star explodes, it sends high-energy particles out in all directions. This burst of energy can travel through space for thousands of light-years, traversing solar systems and even galaxies.

In a recent paper, published in the Monthly Notices of the Royal Astronomical Society, INSTAAR senior research associate Robert Brakenridge argues that supernovae may be the key to understanding a series of abrupt climate shifts in recent geologic history. The analysis models how such radiation could collide with Earth’s atmosphere, changing its composition. Brakenridge also matches a number of known supernovae to climate shifts preserved in geologic records.

“We have abrupt environmental changes in Earth’s history. That’s solid, we see these changes,” Brakenridge said. “So, what caused them?”

Brakenridge says that, if nearby supernovae caused such changes, further research could help scientists predict similar events in the future and prepare accordingly.

“When nearby supernovae occur in the future, the radiation could have a pretty dramatic effect on human society,” he said. “We have to find out if indeed they caused environmental changes in the past.”

Brakenridge’s recent paper is actually one of many he and others have published on the topic since the 1980s. But, in the past, the idea has rested mainly in the realm of theoretical physics. Brakenridge’s new publication is an effort to link the theory to empirical observations, both in space and here on Earth.

Telescopes and tree rings

In recent years, high-powered, orbital telescopes have offered unprecedented information about the contents and character of supernova radiation. Using these observations, Brakenridge created a more precise model of how this radiation might interact with Earth’s atmosphere than previously possible.

According to the model, a sudden influx of high energy photons from a supernova would thin the ozone layer, which shields the Earth from the Sun’s rays. Simultaneously, the radiation would degrade methane in the stratosphere, a major contributor to the greenhouse effect that keeps the Earth warm. Put together, these interactions would dampen greenhouse warming and increase the amount of ultraviolet radiation that reaches Earth from the sun. Brakenridge predicts that knock-on effects could include selective animal extinctions, increased wildfires and global cooling.

Since supernova radiation isn’t arriving on Earth today, the model can’t yet be tested in situ. Instead, Brakenridge looked to records of the past for further evidence. Specifically, he looked at tree rings. Because trees incorporate atmospheric carbon into their trunks as they grow, scientists can look to these records for a glimpse into ancient atmospheric conditions.

In the new paper, Brakenridge parses tree ring records spanning 15,000 years and identifies 11 spikes in radioactive carbon. He argues that these spikes may have been caused by 11 corresponding supernovae.

“The events that we know of, here on earth, are at the right time and the right intensity,” Brakenridge said.

Predicting supernovae

For now, supernovae are just one possible explanation for these phenomena — solar flares are the most prominent alternative. But, Brakenridge says the evidence is mounting behind his argument. He hopes that further efforts can refine models of environmental effects and correlate them with geologic records — from ice cores to marine sediment to tree rings.

A better understanding of supernova radiation could do more than just satiate curiosity, it could help humans prepare for abrupt climate shifts that could arrive any day. For example, astronomers predict that Betelgeuse, a nearby red supergiant star perched on the shoulder of the Orion constellation, will meet its end in a supernova explosion sometime soon — it could be tomorrow, or any time in the next 100,000 years.

“As we learn more about our nearby neighboring stars, the capability for prediction is actually there,” Brakenridge said. “It will take more modeling and observation from astrophysicists to fully understand Earth’s exposure to such events.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

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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The Vela supernova remnant, the remains of a supernova explosion 800 light-years from Earth in the southern constellation Vela, as seen from the Dark Energy Camera on the Víctor M. Blanco Telescope at Cerro Tololo Inter-American Observatory. In his latest paper, Robert Brakenridge identifies a radioactive carbon anomaly in tree ring records that may have been caused by radiation from the vela supernova entering Earth's atmosphere nearly 13,000 years ago.

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The Vela supernova remnant, the remains of a supernova explosion 800 light-years from Earth in the southern constellation Vela, as seen from the Dark Energy Camera on the Víctor M. Blanco Telescope at Cerro Tololo Inter-American Observatory.

Researchers model a dangerous glacial lake in the Himalayas and propose solutions

Gabe Allen — Tue, 27 May 2025 20:42:35 +0000

Researchers model a dangerous glacial lake in the Himalayas and propose solutions Gabe Allen Tue, 05/27/2025 - 14:42

Gabe Allen

INSTAAR senior research associate Alton Byers has organized frequent research expeditions to the Himalayas for more than 50 years. Last summer, he returned to the remote Kanchenjunga region in Nepal, an area he has visited three times since 2019. His team was there to gather more data for an ongoing study of glacial, ecological and socioeconomic changes in the region. But, his attention was soon diverted when a friend, a young man from the local Tibetan community, brought an emerging issue to his attention.

The man told Byers that locals had noticed large meltwater ponds forming at the toe of the Kanchenjunga Glacier, upstream from the villages of Ghunsa and Kambachen. He worried that the ponds could trigger a flood — a scenario that has played out in nearby areas more than once.

“He asked if we could go take a look at it,” Byers said. “We were on our way up to the Kanchenjunga base camp, so we made a detour. Sure enough, you could see these considerable lakes, perhaps a half-a-square-mile and growing.”

Byers sprung into action. First, he interviewed other community members about the ponds — they confirmed the observations and growing concern. Then, over the ensuing months, he assembled a team of experts to conduct a study of how the ponds were changing. The study was published in Water earlier this month.

The new paper outlines a number of potentially dangerous flood scenarios that could be triggered at the site in the future. In order to protect local communities, the researchers urge regional authorities to implement mitigation measures, including a monitoring program and an early warning system for flooding.

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Modeling disaster

Byers’ first call for collaboration was to Sonam Wangchuk, an expert in snow and ice research via satellite imagery at the International Centre for Integrated Mountain Development. Wangchuck, now onboard, gathered satellite images of the site. The images were striking. From 2022 to 2024, the ponds grew from puddles to large, interconnected bodies of water.

“It’s sort of an indicator of how these melting processes are accelerating,” Byers said.

Next, Byers and collaborators levied statistical methods to look to the future. They estimated that the meltwater ponds could form a large glacial lake. That lake, if it forms, will be vulnerable to outburst flooding, which could be triggered by melting processes, structural collapse or rockfall from surrounding slopes.

Finally, the researchers focused their efforts on modeling potential floods. They identified four scenarios, from small to large.

Under the mildest scenario, the flood surge would travel 75 miles down the Tamor River, flooding 16 existing buildings and 30 bridges along the way. Under the worst-case scenario the flood would travel at least 175 miles and impact 90 buildings and 44 bridges. According to the authors, the flooding would also likely impact livestock, crops and tourism infrastructure.

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Mitigating disaster

Byers warns that, without adequate preparation, glacial outburst flooding can be deadly. In 1941, a glacial lake in Peru collapsed and sent a surge of water into the downstream city of Huaraz killing thousands.

In light of events like this, some regional governments around the world have developed early warning systems for potential outburst floods. Others have also implemented novel mitigation measures. In Peru, government engineers drained water from a number of dangerous glacial lakes in efforts spanning decades.

Byers and his coauthors advise local and regional authorities in the Kanchenjunga region to take similar measures to prevent a flood originating from the study site. Their recommendations include establishing early warning systems for flooding, partnering with research organizations in Kathmandu to monitor the site and adapting zoning laws to prevent new buildings in flood zones.

According to Byers, one of the cheapest and most effective early warning systems is deceptively simple: cell phones.

“Not everyone can afford multi-million dollar early warning systems that rely on laser readings of water depth,” he said. “But, studies have shown that cell phones, at least during the daytime, are one of the better early warning systems out there.”

In the end, Byers hopes the study can help the same people that brought the issue to his attention.

“The goal was always to share the research with the local community,” he said. “Then they have all of the information they need to make the best decisions possible.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

Alton Byers and his coauthors identify dangerous glacial melt in the Kanchenjunga Conservation Area in a new paper. The researchers model potential flood scenarios and suggest mitigation measures.

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Imja Lake, a glacial lake in the Mount Everest region of Nepal, began as meltwater ponds in 1962 and now contains 90 million cubic meters of water. Its water level was lowered to protect downstream communities. Alton Byers

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Sediment records provide a glimpse into Iceland’s past, and hope for its future

Gabe Allen — Tue, 13 May 2025 21:38:08 +0000

Sediment records provide a glimpse into Iceland’s past, and hope for its future Gabe Allen Tue, 05/13/2025 - 15:38

Gabe Allen

Just a couple of kilometers inland from the coast of Northern Iceland, lie Torfdalsvatn, a small, deep freshwater lake. Winters here are frigid, snowy and dark, save a few hours of muted daylight. Lucky visitors might catch a glimpse of the Northern Lights when the clouds clear.

Most travelers opt to visit the region in the summer, when conditions are more temperate, but for paleoclimate researchers, winter is the perfect time for a trip to Torfdalsvatn. That’s because the mud that lies below the lake holds an exceptionally detailed record of Earth’s past. And, in the winter, researchers can bring the cumbersome equipment needed to drill down into the mud right out on the ice with them.

“You can drive right out onto the ice and drill through with an ice auger,” CIRES research scientist and INSTAAR affiliate David Harning explained. “It’s much harder in the summer when you’re out in a little boat trying to anchor it and it’s windy and our boat is getting dumped on.”

Last month, Harning, along with American and Icelandic collaborators, published a new analysis built on decades of research at Torfdalsvatn. The study brings diverse analytical methods together to provide a highly detailed picture of past climatic conditions, soil stability and plant life at the site.

One clear takeaway was that Torfdalsvatn’s soils and plant communities remained exceptionally resilient, when compared to other sites in Iceland. It’s an insight that is more than a piece of history—it could help conservationists better plan for the future.

“Soil erosion is one of the biggest problems in Iceland right now,” Harning said. “Understanding the resilience or fragility of certain areas to future changes in soil erosion is really important to conserving these landscapes.”

Fire and ice in the mud

Since 1992, researchers have looked to the sediments below Torfadalsvatn to understand the past 12,000 years of climatic conditions in Iceland. The site is an exceptionally good model of the past for two reasons.

Firstly, sediment piles up at the bottom of Torfadalsvatn at an unusually high clip, leaving researchers more mud to analyze. Secondly, Torfadalsvatn was one of the first lakes to emerge, when the giant ice sheet that once stretched across Iceland began to retreat 12,000 years ago. As a result, the lakebed houses some of the oldest sediment in the country.

The winter 2020 field team operates a sediment coring device on a clear day. Left to right: Jonathan Raberg (Postdoc, University of Wyoming and former INSTAAR PhD), Gifford Miller, and Áslaug Geirsdóttir. Photo courtesy of David Harning.

Over the past three decades, much of the work on Torfadalsvatn’s sediment record has been done by two researchers and their students: INSTAAR faculty fellow Gifford Miller and University of Iceland professor of geology Áslaug Geirsdóttir.

Harning, a former student of both, was brought in on the project during his PhD studies at INSTAAR. Between other projects, he worked to identify layers of volcanic ash in the sediment (Iceland is known as “the land of fire and ice” because of its plentiful active volcanoes).

Over the lifetime of the project, several other researchers devoted countless hours to other analyses. These included identifying algal pigments and geochemical markers, proxies for past plant communities and climate respectively.

In the new study, Harning pairs these previous analyses with a suite of techniques meant to place each data point more precisely in time.

Áslaug Geirsdóttir prepares the sediment coring device at Torfdalsvatn. Due to the lake’s high sedimentation rates, this 3 meter long tube will only recover around 3,000 years of mud. Multiple subsequent cores are then required to collect the entire 12,000 year history. Photo courtesy of David Harning.

“By establishing the chronology and locking sedimentary history in time, we could start to ask some of these longstanding questions that our group has been interested in,” he said.

One of these questions, perhaps the most controversial one, concerns soil erosion and human settlement. There is a longstanding theory that Norse settlers caused widespread soil erosion and ecological degradation when they arrived in Iceland a millenia ago. Recent research has called this narrative into question, suggesting that these changes could have been kicked off by environmental changes even further in the past.

Harning’s analysis, though, complicates the theory even further. The researchers estimated that erosion and vegetation changes at Torfadalsvatn didn’t escalate until around 200 years after the arrival of settlers. Perhaps something about the site made it more resistant to whatever factors caused degradation elsewhere.

“We weren’t expecting that,” Harning said. “This implied that the site, which is coastal and at a low elevation, had some sort of natural resilience to the processes that were causing soil erosion elsewhere.”

Looking Forward

Harning urges that further research should look into what made Torfadalsvatn so resilient. The question is still relevant today, as Icelandic land managers and farmers search for ways to combat soil erosion and deforestation on the landscape.

Harning and his colleagues’ recent paper could also provide useful information for other scientific fields. The analysis provides an exceptionally detailed record of past volcanic events, many of which had not been previously identified. If corroborated, these markers could provide, essentially, a time stamp in the sediment record to aid future research.

“It’s a ton of information about volcanic history,” Harning said. “Maybe someone else finds another link, and then you have new marker layers.”

Finally, the new analysis provides a huge amount of information relating past climatic conditions to ecological conditions. This information isn’t only useful for researchers curious about ancient history, it could also help scientists look to the future.

“These high resolution records are a key data constraint for any Earth system model that’s trying to predict future climate change,” Harning said. “If you have a good understanding of the physics of the system, you can run that model forward.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

A new investigation, led by INSTAAR affiliate David Harning, uncovers a story of ecosystem resilience at a lake in coastal Iceland. The analysis could aid future conservation and climate modeling efforts.

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INSTAAR and University of Iceland researchers extracting a sediment core from an Icelandic lake in February 2020. Photo courtesy of David Harning.

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INSTAAR and University of Iceland researchers extracting a sediment core from an Icelandic lake in February 2020. Photo courtesy of David Harning.

An apple a day? It’s the 51��ý way (Colorado Arts and Sciences Magazine)

Gabe Allen — Mon, 12 May 2025 22:04:54 +0000

An apple a day? It’s the 51��ý way (Colorado Arts and Sciences Magazine) Gabe Allen Mon, 05/12/2025 - 16:04

The 51��ý Apple Tree Project, led by INSTAAR fellow Katharine Suding, has broken ground on a new apple orchard on 30th Street in 51��ý. The orchard will provide shade, fruit and a site for agroecology research. It is supported by a $90,000 sustainable CU grant.

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Spring runoff is older than you think (University of Utah)

Gabe Allen — Thu, 08 May 2025 15:56:27 +0000

Spring runoff is older than you think (University of Utah) Gabe Allen Thu, 05/08/2025 - 09:56

INSTAAR alum Paul Brooks led this study, which found that more of the Rocky Mountain spring runoff comes from groundwater than previously thought. The results could help water managers, cities and farmers. INSTAAR faculty Holly Barnard is a coauthor.

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Arctic plants react unexpectedly to climate change, study says

Gabe Allen — Wed, 07 May 2025 20:42:43 +0000

Arctic plants react unexpectedly to climate change, study says Gabe Allen Wed, 05/07/2025 - 14:42

Gabe Allen , Rhona Crawford

Rapid climate change is upending plant communities in the Arctic, with species flourishing in some areas and declining in others, according to a new study in Nature.

The decades-long investigation, led by researchers at the University of Edinburgh, compiled data from 1981 to 2022 on more than 2,000 plant communities across the Arctic tundra. Analysis revealed shifting patterns in plant species composition, abundance and growth during a period of unprecedented change.

Researchers use a point frame while surveying plant species on Qikiqtaruk-Herschel Island in the Canadian Arctic. Photo courtesy of Jeff Kerby.

Sarah Elmendorf, an INSTAAR faculty fellow and research associate in the department of Ecology and Evolutionary Biology, was a coauthor on the paper. She stressed the outsized importance of Arctic environments to both people and life on Earth.

“The Arctic holds a huge amount of the world’s carbon,” she said. “It also has resources that are used by animals and people, and a vast amount of biodiversity that isn’t found anywhere else.”

According to Elmendorf, a better understanding of Arctic plant community’s responses to climate change could help us conserve them down the line.

“If we understand how biodiversity is changing over time, and the relationship to climate change, we can understand how it might change in the future,” she said.

The Nature paper identified a few key trends. In many areas shrubs and grasses are proliferating and shading out fragile flowering plants. The result is an overall decrease in plant diversity at these sites.

Interestingly, the researchers found evidence against a oft-cited hypothesis—that climate change would cause Arctic plant communities to become more similar to each other.

“In fact, they’re changing in all sorts of directions. It’s a little less cut and dry,” Elmendorf said.

Though Arctic plant communities aren’t becoming more homogenous, yet at least, Elmendorf warns against seeing this with rose-tinted glasses. In totality, the analysis revealed widespread change. And, according to the authors, these vegetation changes can be an early warning signal for ecosystem-level changes with knock-on effects for animals, humans and the planet’s natural carbon storage systems.

“Often when we think about climate change impacts on the planet we think about biodiversity loss, but in the temperature-limited tundra, climate change is multi-faceted,” said Isla Myers-Smith a coauthor on the Nature paper and professor at the Universities of Edinburgh and British Columbia. “Taken together, our study indicates that biodiversity can follow diverging trajectories in the rapidly warming Arctic.”

Rhona Crawford is the PR & Media Manager for the University of Edinburgh

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

A team of 54 researchers, including Sarah Elmendorf, analyzed more than 42,000 field records of Arctic plant communities over a span of 41 years. Their insights are essential to understanding how Arctic environments are changing in the modern era.

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Tundra plants make the most of the short summer in Ellesmere Island, Nunavut. Photo courtesy of Anne Bjorkman.

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Tundra plants make the most of the short summer in Ellesmere Island, Nunavut. Photo courtesy of Anne Bjorkman.

INSTAAR faculty among those awarded undergraduate research grants (UROP)

Gabe Allen — Wed, 30 Apr 2025 20:44:19 +0000

INSTAAR faculty among those awarded undergraduate research grants (UROP) Gabe Allen Wed, 04/30/2025 - 14:44

The Undergraduate Research Opportunities Program committed $77,000 in grants for CU undergraduates to work with INSTAAR faculty this summer and next school year. The awards will catalyze opportunities for students to contribute to critical research in earth and environmental science.

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The ocean may be absorbing less carbon, but it may not be due to climate change—yet (CU 51��ý Today)

Gabe Allen — Tue, 29 Apr 2025 21:05:38 +0000

The ocean may be absorbing less carbon, but it may not be due to climate change—yet (CU 51��ý Today) Gabe Allen Tue, 04/29/2025 - 15:05

An INSTAAR-led study found that recent dips in the ocean’s carbon absorption are likely due to natural variability instead of global warming. Institute director Nicole Lovenduski urges that future research needs to employ remote devices to gather more field samples.

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Earth Day: 6 sustainability stories from INSTAAR in 2025

Gabe Allen — Tue, 22 Apr 2025 23:41:24 +0000

Earth Day: 6 sustainability stories from INSTAAR in 2025 Gabe Allen Tue, 04/22/2025 - 17:41

Gabe Allen

INSTAAR researchers investigate fundamental questions about ecosystems, climate systems and landscapes.

Today marks the 55th annual Earth Day, a global celebration of our planet, its natural systems and the idea of a sustainable future. In honor of the occasion, INSTAAR is sharing stories from the first four months of 2025 about INSTAAR’s environmental research.

As mountain glaciers melt, risk of catastrophic flash floods rises for millions (The Conversation US)

Last month, INSTAAR faculty research scientist Alton Byers and Wesleyan University professor of earth science Suzanne OConnell wrote a guest article in the Conversation US. The pair, a mountain geographer and earth scientist respectively, described how melting glaciers are amplifying the risk of catastrophic flooding in mountain communities around the world. Some governments and organizations, including the U.N., have focused efforts on research into mitigation tactics and early effective warning systems.

Franklin Institute selects Katharine Suding for the Bower Award for Achievement in Science

Next month, INSTAAR faculty fellow and professor of distinction in ecology and evolutionary biology Katharine Suding will officially receive the Bower Award for Achievement in Science from the Franklin Institute. The award honors prominent scientists and innovators who have changed the world for the better. Suding is a preeminent restoration ecologist who has left an indelible mark on the concepts of ecosystem resilience, restoration and biodiversity.

Desert reservoirs capture and store organic carbon, according to new research

Dams have long been a controversial topic among environmentalists. While they can sometimes harm aquatic ecosystems, they can also provide benefits, like increased water storage. Recently, a group of INSTAAR researchers uncovered another potential benefit of certain reservoirs. In a recent paper, they describe how one large reservoir in New Mexico captures and stores carbon beneath layers of sediment during droughts and flash floods.

Drone experiment reveals how Greenland ice sheet is changing (CU 51��ý Today)

Kevin Rozmiarek is a drone enthusiast, but he’s not just a hobbyist. He’s using unmanned aircraft to do science. In a recent publication, Rozmiarek and his colleagues documented changes in Greenland’s ice sheet. Their study relied on samples of atmospheric water vapor collected by drones, an approach that could improve simulations of sea level rise.

International research collaboration uncovers key driver of Himalayan glacier melt

This winter, INSTAAR research scientist Karl Rittger lent his talents to an intercontinental team of scientists seeking to understand exactly how and why Himalayan glaciers are melting. Rittger’s unmatched methodology for analyzing dust-covered snow from satellite imagery led the team to key insights. They found that dust storms were picking up pollution from heavily populated areas and depositing it on the mountains.

New research demystifies carbon cycling in freshwater lakes around the world

Back in 2019, INSTAAR faculty fellow Isabella Oleksy, then a PhD student, put out a call to collaborators for data on phytoplankton activity in freshwater lakes. In the end, researchers from all over the world contributed to the dataset. Oleksy and collaborators then used the data to refine a mathematical model of primary productivity for freshwater lakes. The new model could help earth scientists better understand the carbon cycle, which could lead to better climate predictions.

INSTAAR researchers investigate fundamental questions about ecosystems, climate systems and landscapes. These six stories highlight the environmental research that the institute is doing in 2025.

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Major dust-up for water in the Colorado River (University of Utah)

Gabe Allen — Mon, 21 Apr 2025 20:13:39 +0000

Major dust-up for water in the Colorado River (University of Utah) Gabe Allen Mon, 04/21/2025 - 14:13

A new study unveils a powerful dataset quantifying snow darkening and its impacts on snowmelt across the Colorado River Basin in real time. INSTAAR research scientists Karl Rittger and Sebastian Lenard are co-authors on the University of Utah-led paper.

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Research

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

Telescopes and tree rings

Predicting supernovae

Related Articles

Researchers model a dangerous glacial lake in the Himalayas and propose solutions

Modeling disaster

Mitigating disaster

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Sediment records provide a glimpse into Iceland’s past, and hope for its future

Fire and ice in the mud

Looking Forward

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An apple a day? It’s the 51��ý way (Colorado Arts and Sciences Magazine)

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Spring runoff is older than you think (University of Utah)

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Arctic plants react unexpectedly to climate change, study says

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INSTAAR faculty among those awarded undergraduate research grants (UROP)

Related Articles

The ocean may be absorbing less carbon, but it may not be due to climate change—yet (CU 51��ý Today)

Related Articles

Earth Day: 6 sustainability stories from INSTAAR in 2025

As mountain glaciers melt, risk of catastrophic flash floods rises for millions (The Conversation US)

Franklin Institute selects Katharine Suding for the Bower Award for Achievement in Science

Desert reservoirs capture and store organic carbon, according to new research

Drone experiment reveals how Greenland ice sheet is changing (CU 51��ý Today)

International research collaboration uncovers key driver of Himalayan glacier melt

New research demystifies carbon cycling in freshwater lakes around the world

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Major dust-up for water in the Colorado River (University of Utah)

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