Research

Some tropical land may experience stronger-than-expected warming under climate change (CU Boulder Today)

David J Lubinski — Wed, 04 Feb 2026 23:03:58 +0000

Some tropical land may experience stronger-than-expected warming under climate change (CU Boulder Today) David J Lubinski Wed, 02/04/2026 - 16:03

Lina Pérez-Angel and Julio Sepúlveda led a team to study a sediment record millions of years old from the tropical Andes. They found that the region heated up dramatically when atmospheric CO2 levels were similar to today’s.

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Breaking ice, moving earth: Greenland will release more sediment into the ocean as the climate warms

Gabe Allen — Mon, 02 Feb 2026 13:00:00 +0000

Breaking ice, moving earth: Greenland will release more sediment into the ocean as the climate warms Gabe Allen Mon, 02/02/2026 - 06:00

Gabe Allen

Ethan Pierce aboard the Porshild, the research vessel of the Arctic Research Station in Disko, Greenland. (Irina Overeem)

Greenland’s winding, rocky fjords are no strangers to research vessels. Usually, these boats give icebergs a wide berth, because they can roll over unexpectedly.

That wasn’t the case, though, for the boats carrying INSTAAR fellow and CU associate professor Irina Overeem and her former PhD student Ethan Pierce during the 2019 and 2022 summer field seasons. They were there for the icebergs.

Relying on the caution and expertise of Greenlander captains, the scientists sidled up to the floating monoliths aboard small dinghies and carefully chipped off samples before returning to the main boat.

A small dinghy carries Irina Overeem, Tom Marchitto, and Mia, a Greenlandic deckhand, out to sample an iceberg. (Nora Matell)

“We really were relying on the Greenlanders a lot for their sense of what was safe and what was not,” Pierce said.

“They fish in that environment themselves, so they have a ton of experience doing that risk calculation,” Overeem added.

Five years later, that calculated risk is paying off. Pierce, Overeem and �Թ�� of Copenhagen associate professor emeritus Bent Hasholt published a new paper in Nature Communications documenting how icebergs bring sediment from Greenland out to sea.

Tom Marchitto paddles a packraft out to sample a dirty iceberg in Nuup Kangerlua (Irina Overeem)

The investigation is the first to unravel the complex process underlying a phenomenon that has an outsized impact on the Arctic Ocean’s chemistry. The scientists estimate that icebergs account for around one third of all of the sediment leaving Greenland (the rest comes from meltwater). That sediment unloads nutrients into Arctic waters, which support organisms at every scale — from phytoplankton to whales.

Irina Overeem poses with her catch in a Greenlandic fjord. (Tom Marchitto)

Importantly, the scientists were also able to determine the effect of climate change on this process. As the planet warms, icebergs will deposit more and more sediment into the ocean.

“This is the first modern study of this process that can say, ‘with a warming climate we’re going to see more transport of ice-rafted debris,’” Pierce said.

A back-of-the-envelope calculation

Greenland contributes around 15 percent of the sediment that ends up in the ocean each year — an exceptionally high figure for a landmass of its size. Nearly a decade ago, Overeem published another paper characterizing the amount of sediment coming from Greenlandic meltwater rivers. She found that these waterways were unloading a vast amount, but they didn’t account for all of Greenland's sediment export.

At the time, Overeem already knew that icebergs might be the missing piece of the puzzle. For years, she had seen dark stripes of debris crisscrossing icebergs in Greenlandic fjords. And, ice-derived debris has long been found in sediment cores pulled from the bottom of the Atlantic Ocean. But, scientists had yet to figure out how exactly the debris got in the ice or how much of it left the continent this way.

On the flight home from her 2016 field season, Overeem started jotting down rough equations based on previous research from colleagues. The numbers shocked her.

“At the time, I did a back-of-the-envelope calculation,” she said. “I was shocked at how much it could be.” “I pitched the idea to the CU Research and Innovation Office and they funded a pilot project.”

By 2019, Overeem brought Pierce on as a PhD student and put him on the project. Unfortunately, the pandemic delayed multiple field seasons, but Pierce used the extra time to drill down on a mathematical model of how the debris ends up in the ice in the first place.

According to Pierce’s model, the weight of the massive Greenland ice sheet creates pressure points where the ice comes into contact with individual grains of sand on the earth below. These pressure points create heat, which melts the ice. The meltwater then refreezes around the grain of sand. As the ice sheet slides downhill toward the ocean, this process sucks up more and more sediment into the bottom layer of ice. Eventually, the ice reaches the waters edge and breaks off, forming a sediment-laden ice berg.

Pierce's model combined with the field sample data produce the central insight of the new paper — that icebergs contribute about one third of Greenland’s sediment export.

“There are lab experiments and grain-scale models that show that these processes happen, but Ethan is the first person who put together a numerical model that can then be extrapolated out on the scale of the Greenland ice sheet,” Overeem said.

Powering new research

Now that Overeem’s back-of-the-envelope calculation has grown into a sophisticated model, it’s time for the researchers to pass their data on to other scientists. The model could be useful for myriad other projects, including offering hints into ancient climatic conditions.

Another potential application is more forward looking. As sediment in the Arctic Ocean increases, it will increase the abundance of minerals like iron and silicon. Those are minerals used by phytoplankton, the microscopic foundation of the Arctic marine food web.

“People who are good at observing phytoplankton over the long-term record have seen an uptick in Greenland,” Overeem said. “There’s definitely some interest in this from that community.”

It’s not yet clear exactly how an increase in sediment might affect life in the ocean, but the question could spark further collaborations within the Institute of Arctic and Alpine Research. Tom Marchitto’s laboratory excels at precise measurements of dissolved chemicals, a capability that could further resolve the contents of Greenlandic sediment. On the biological side of things, INSTAAR director Nicole Lovenduski’s lab specializes in modeling phytoplankton blooms in the Arctic.

“This is just one part of a number of potential connections,” Overeem said.

For now, Pierce will move onto other projects as a postdoctoral researcher at Dartmouth, and Overeem will turn her attention to other pressing surface process models. Both can rest easy knowing they placed another puzzle piece in the answer to a question that has loomed over generations of Greenlandic science.

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 paper from Irina Overeem and Ethan Pierce describes how icebergs export Greenlandic sediment into the Arctic Ocean — and how that process might change in the future.

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An iceberg sheds sediment as it melts into Torsukattak Fjord in Greenland. (Irina Overeem)

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Research highlight: Dr. Keith Musselman and the EcoTram (MRS News)

Gabe Allen — Wed, 14 Jan 2026 16:53:42 +0000

Research highlight: Dr. Keith Musselman and the EcoTram (MRS News) Gabe Allen Wed, 01/14/2026 - 09:53

INSTAAR fellow Keith Musselman and collaborators have constructed an "EcoTram" that continuously measures hydrological and ecological variables across a 400-foot transect high in the Indian Peaks. The system provides a wealth of data for investigations into shifting mountain systems.

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INSTAAR’s most read news stories of 2025

Gabe Allen — Fri, 02 Jan 2026 22:00:13 +0000

INSTAAR’s most read news stories of 2025 Gabe Allen Fri, 01/02/2026 - 15:00

It’s officially 2026, which means the Institute of Arctic and Alpine Research is celebrating its 75th year as an institute. In honor of the occasion, we’re launching an anniversary webpage, putting on an event series, and launching a fundraising effort to support groundbreaking arctic and alpine science, laboratories and scientists.

Later this year, we’ll take a deep dive into the history of how INSTAAR grew from a tiny field station in the Indian Peaks into a global leader in interdisciplinary environmental science. But, before we do that, we wanted to take a more brief look back — just at the past year.

In 2025, we published stories about innovative investigations, grassroots public outreach projects, award-winning scientists and groundbreaking publications. According to our audience data, a few stood out.

Here are INSTAAR’s most read news stories of 2025.

The top five

Air pollution and warming are changing Colorado’s remote alpine lakes

This summer, INSTAAR communications specialist Gabe Allen followed Bella Oleksy’s lab for a day of work high in Rocky Mountain National Park. The group leverages year-round backcountry fieldwork and a 42-year biogeochemical record of alpine lakes to investigate how alpine watersheds are changing in the 21st century.

The data is in: Colorado’s snowpack is lagging behind the 21st century average in 2025

Last spring all eyes were on The Mountain Hydrology Group’s new Western U.S. snow water equivalent (SWE) reports. The news from this article is old now, but it’s a good reminder of the excellent hydrological modeling work here at INSTAAR. You can check out frequent updates on snow cover from Karl Rittger’s Snow Today website. The Mountain Hydrology Group will also once again begin putting out SWE reports in the next month or so.

Spotlight: Hunter Geist-Sanchez is pioneering restoration methods for Colorado grasslands and reconnecting with his ranching roots

Hunter Geist-Sanchez is a master’s student in Katharine Suding’s lab studying restoration ecology with a particular focus on grasslands. Geist-Sanchez is following his life-long love of nature to develop new methods for preserving Colorado natural areas and rangelands. As a sixth-generation Coloradoan, he hopes his research can help ranchers preserve their livelihoods in the face of climate change.

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

INSTAAR senior research associate Robert Brakenridge is always looking for ways to tie-in his life-long interest in astrophysics to his career in geologic and hydrologic research. In a groundbreaking paper published earlier this year, he uncovered potential links between stellar explosions and ancient climate changes.

Beneath crumbling walls: how rock glaciers took over the southern rockies

The last of Colorado’s true glaciers are small and disappearing fast. Yet, rock glaciers, stable ice sheets locked between layers of rock and debris, are prevalent across the Colorado Rockies. In a new paper this year, Robert and Suzanne Anderson, along with their mentees, uncover the geologic history of this phenomenon.

The runner up

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

Over the past three decades, INSTAAR’s Katharine Suding has become one of the most influential voices in the field of restoration ecology. Her work is locally relevant to Colorado, yet it has influenced scientists around the world. This year, the Franklin Institute awarded her the Bower Award for Achievement in Science. Past winners include Jane Goodall, Stephen Hawking, Albert Einstein and Marie Curie.

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.

Between ambitious projects, big awards and groundbreaking publications, it’s been a newsy year at the Institute of Arctic and Alpine Research. Here are our top stories of 2025.

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Precious waterways: how contaminated mountain streams could power American-made technology

Gabe Allen — Tue, 16 Dec 2025 16:45:07 +0000

Precious waterways: how contaminated mountain streams could power American-made technology Gabe Allen Tue, 12/16/2025 - 09:45

Gabe Allen

Most people have never heard of neodymium, a strong, silvery rare-earth metal, yet almost all of us carry around a little bit of it in our pocket every day.

“Your cell phone, your computer — all of these things run on lanthanides, a series of 14 elements that are relatively heavy metals,” Institute of Arctic and Alpine Research (INSTAAR) geochemist and CU professor Tom Marchitto said.

Though these elements are rare, they are found in unusually high concentrations in certain streams here in Colorado. The phenomenon occurs along Colorado’s “mineral belt,” where acidic waterways pick up metals trapped in bedrock. With Marchitto’s help, INSTAAR biogeochemist and CU distinguished professor Diane Mcknight and collaborators have spent the past decade investigating this process at old mining sites and natural “acid rock” deposits around the state.

Now, their efforts could lead to another exciting discovery. McKnight and Marchitto are part of a new $2.8 million project, funded by the U.S. Department of Energy and led by the �Թ�� of Missouri, that seeks a method for extracting rare earths from acid rock drainage for industrial uses.

The project comes at a fortuitous moment. Recently, the Trump administration has sought ways to decrease America’s reliance on China for rare earths by subsidizing U.S. production. At the same time, metal contamination from acid rock drainage is increasing in Colorado and causing environmental harm. If the new project is successful, it could improve water quality by removing metal while simultaneously producing essential raw materials for personal electronics, electric vehicles and military technologies.

“Improving water quality impacts associated with acid mine and rock drainage is really expensive,” McKnight said. “If there’s a valuable commodity that could be recovered through that process, it could change the equation.”

Master's students Athena Bolin and Adam Odorisio collect water samples from a creek near Aspen. (courtesy photo)

An unexpected finding

�Թ�� a decade ago, rare earth metals weren’t yet on Diane McKnight’s radar. For years, she and her students had characterized processes leading to metals like copper and zinc leaching into waterways along Colorado’s mineral belt. But, a serendipitous accident that led to a further discovery.

“A colleague happened to put my student, Garrett Rue’s, samples at the end of a run testing for rare earths,” McKnight said. “Afterward, he got in touch with Garrett and asked, “where are these samples from? There’s 200 micrograms per liter of neodymium!”

Later, Rue published a paper in Environmental Science and Technology based on these findings. In the years since, a steady stream of passionate students have scrounged funding to continue investigating the presence of rare earths in mountain watersheds. Marchitto has supported these efforts through his lab’s powerful mass spectrometer, capable of measuring trace amounts of metals in water samples.

One insight from this work is that metal concentrations in Colorado are increasing over time as warming summer temperatures thaw previously frozen sites containing acid-forming bedrock. This result is alarming from an ecological perspective. If metal concentrations climb too high, they can kill aquatic species, as evidenced by one mountain lake that washed up hundreds of dead fish this summer.

But, these increased concentrations may also present an opportunity. That’s according to Baolin Deng and Pan Ni, two distinguished researchers at the �Թ�� of Missouri’s Missouri Water Center, who are now working to unlock an efficient process capable of extracting rare earths from acid rock drainage.

Molecular puzzle pieces

For the proposal to work, the process must be both efficient and selective. The inputs required must be low enough to make the method economically viable, while the outputs must be concentrated enough to provide a high-quality source of rare earth metals.

That’s why Deng and Ni have decided to target these elements at a molecular level. They propose creating ion-imprinted polymers, made from seafood byproducts. These polymers will act like jigsaw puzzle pieces. Most molecules will bounce right off them, but the targeted element will fit perfectly into the ion-imprinted cavity, allowing the researchers to conserve target elements and filter out the rest.

Designing these polymers is a monumental task. To increase their chances of success, the researchers will deploy artificial intelligence to help them iterate and refine.

“These elements are like twin brothers when it comes to telling them apart,” Ni said. “Maybe one weighs just a little more than the other. It’s incredibly challenging to differentiate them, but Professor Deng and our research team have proven it’s possible. Now, AI will further enhance the selectivity of our material.”

While the �Թ�� of Missouri team is busy refining polymers, Marchitto, McKnight, and a to-be-hired PhD student will have their work cut out for them in Colorado. The team will work to identify potential sites for extraction, while also continuing to probe questions about the geochemical processes activated in these waterways.

“We’re also interested in the natural aspects of acid rock drainage that haven’t been explored much, like ‘what controls rare earth concentrations? And, ‘how are they precipitating out in the stream bed?’” Marchitto said. “Knowing more about the fundamentals of the geochemistry will inform what kind of recovery efforts can be used. It’s all connected.”

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.

Diane McKnight and Tom Marchitto are collaborators on a new project looking for a way to extract rare earth metals from contaminated Colorado streams. The goal is to improve water quality while also increasing the domestic supply of raw materials for advanced technologies.

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Changing Winters Leave Indigenous Alaskans on Thin Ice (Eos)

Gabe Allen — Mon, 15 Dec 2025 13:00:00 +0000

Changing Winters Leave Indigenous Alaskans on Thin Ice (Eos) Gabe Allen Mon, 12/15/2025 - 06:00

INSTAAR's Arctic Rivers Project is blending Indigenous knowledge with climate science to describe a shifting arctic environment. Eos news reports on the project's unique blend of methodologies, including participatory mapping, remote sensing and biological modeling.

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How an experiment in the mountains could reveal the future of alpine plants (KUNC)

Gabe Allen — Fri, 12 Dec 2025 13:00:00 +0000

How an experiment in the mountains could reveal the future of alpine plants (KUNC) Gabe Allen Fri, 12/12/2025 - 06:00

Researchers in Nancy Emery's lab are investigating how alpine plants respond to climate change at Niwot Ridge. Anticipated funding cuts could threaten the long-term ecological records that make this research possible.

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What can a mile-long stick of ice, stored away for 33 years, tell us about Earth’s climate?

Gabe Allen — Thu, 11 Dec 2025 17:43:41 +0000

What can a mile-long stick of ice, stored away for 33 years, tell us about Earth’s climate? Gabe Allen Thu, 12/11/2025 - 10:43

Gabe Allen

After years as a professional research assistant at INSTAAR’s stable isotope lab, Valerie Morris estimates she’s processed more than 10 kilometers of ice from around the world.

“You’ve done more ice than the Bolder Boulder,” co-principal investigator Tyler Jones joked around a table at the lab recently. “She’s done more high-resolution ice measurements than just about anyone in the world.”

Valerie Morris loads an ice core sample into a carousel in the stable isotope lab at INSTAAR. The carousel is the front end of a continuous flow analysis system developed by Morris and Bruce Vaughn, which continuously measures isotopic ratios for hydrogen and oxygen as the ice core melts. (Gabe Allen)

This fall, Morris loaded yet another chunk of ice into the one-of-a-kind ice analysis system at the lab. But, this one was significant. It was the final sample for a project that she and other lab members began a year-and-a-half before — to reanalyze an ice core that was drilled 33 years ago in Greenland using modern techniques.

The ice core in question was extracted at the Greenland Ice Sheet Project Two (GISP2) from 1988 to 1993. It took scientists five years to drill down from the top of the ice sheet to the bedrock. They were left with a cylinder of ice more than a mile long.

Though the effort was great, the payoff was worth it. Within the ice were chemical signatures of past temperatures, climate shifts and volcanic eruptions. The deeper those signatures, the older. At its base, the ice core dated back more than 100,000 years.

Brooke Chase looks at a readout of isotopic ratios from an ice core as Bradley Markle (left) and Tyler Jones (right) look on. (Gabe Allen)

Shortly after the ice core was extracted, researchers analyzed the chemical contents of samples spanning its length. Their results, combined with other records, provided a better understanding of Earth’s climate history from the start of the last ice age to today.

Yet, this earlier analysis was also limited. Sampling methods at the time required the scientists to melt down meter-long chunks of ice at a time. That meant, at best, each data point represented an average over about a decade of history.

Today, technicians at the stable isotope lab use a system developed by Morris and INSTAAR fellow emeritus Bruce Vaughn in 2009. Instead of measuring large, discrete chunks of ice, the system melts each sample slowly from tip to tail. As the sample melts, the water is quickly sucked into a matrix of instruments. The technique allows the scientists to analyze the ice millimeter by millimeter — literally.

The team of scientists that reconstructed the length of the GISP2 ice core poses at the NSF-Ice Core Facility. From Left to Right: Rhys-Jasper Leon, Richard Nunn, Ella Johnson, Valerie Morris, Adira Lunken, Brooke Chase, Tirso Jesus Lara Rivas, Max Eshbaugh, Megan Erskine, Theo Carr.

Using this method, lab members knew they could unlock new information in what was left of the GISP2 ice core, which has been stored in the National Ice Core Facility in Lakewood for the past three decades. Though much of the volume of the ice core was consumed by previous analyses, almost all of its length was preserved in the archive. Over the past year-and-a-half, Morris, PhD student Brooke Chase, and a team of research assistants reconstructed more than a mile of ice from GISP2 and ran it through the instruments at the lab.

The data they gathered has the potential to answer pressing questions about Earth’s past climate. Last winter, the lab published a new paper identifying periods of climatic stability preceding abrupt warming events during the last ice age. That analysis relied on data from the newer East Greenland Ice-Core Project. Chase is now busy processing and analyzing the data from GISP2, and the preliminary results seem to contradict these earlier findings.

“Brooke has some preliminary results suggesting that we are not getting the same answers,” Jones said. “But we only have a small chunk of time so far, so we’re sitting here waiting until we have the final data.”

Resolving these contradictions might unlock a new understanding of these abrupt warming events in the past, or it might further muddy waters. Either way, the researchers now have much more detail to parse through than before. The new project provided around 1,000 times more data points per meter of ice than the previous sampling effort. At its best, each value now represents a few months of climate history.

“What were trying to do with this project is see what Earth was capable of at higher frequencies,” Jones said. “You lose the ability to look at variability in the climate when you only measure every meter. But if you can look at a higher resolution, you can see those changes.”

Although ancient history may seem far removed from the pressing concerns of modern climate change, it's more relevant than it appears. Understanding how Earth’s climate evolved is essential to scientist’s ability to understand current climate dynamics and predict future outcomes.

“We only have about 40 years of satellite observations of Earth’s climate, and a few hundred years of people standing around with thermometers,” co-principle investigator Bradley Markle explained. “The time scales that people care about are on the order of decades and centuries, but to understand variability on those time scales you have to look at records of Earth’s climate over thousands of years.”

Learn more:

What do ice cores reveal about the past? (National Snow and Ice Data Center)

Thawing the Mysteries of ancient climate changes (INSTAAR)

Inside an ice stream (Science)

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.

Researchers at the stable isotope lab just finished resampling more than a mile of ice from Greenland. Further analysis will probe unanswered questions about climate change, sea ice and Earth’s history.

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Brooke Chase stands in the main storage area of the National Science Foundation Ice Core Facility. This part of the facility is held at -36 degrees Celsius and houses over 30,000 meters of ice from polar regions around the world.

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Brief: New funds for student research at the Mountain Research Station

Gabe Allen — Wed, 03 Dec 2025 13:00:00 +0000

Brief: New funds for student research at the Mountain Research Station Gabe Allen Wed, 12/03/2025 - 06:00

The Maxwell/Hanrahan Foundation has pledged $75,000 to support student research projects at the Mountain Research Station. The donation will fund three years of research expenses and stipends for undergraduate and graduate students working on scientific investigations in the alpine.

The foundation already contributed $15,000 toward five undergraduate research grants in 2024 and 2025. These research experiences allow students to take a first step toward a career in science.

Ecology and evolutionary biology student Isabella Manning spent a summer studying plant-pollinator interactions in a subalpine meadow above the station. Earlier this year, Manning authored a paper covering the investigation in Oecologia — an enormous accomplishment for an undergraduate researcher.

According to Mountain Research Station director Scott Taylor, the Maxwell/Hanrahan Foundation grants serve a dual purpose. They provide seed funding for important research in a rapidly changing alpine environment, while also giving students valuable experience in field science.

“This is a unique opportunity for undergraduate and graduate students to pursue independent research — and to build hands-on skills in the field,” he said.

The Maxwell/Hanrahan Foundation has pledged $75,000 to support student research at the Mountain Research Station. The donation will fund three years of research expenses and stipends for undergraduate and graduate students.

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Hymenoxys grandiflora, also known as old man of the mountain, blooms on Niwot Ridge above the Mountain Research Station. (Courtesy, Scott Taylor)

Scientists predict a sea change in Arctic ecosystems by the end of the century

Gabe Allen — Wed, 19 Nov 2025 13:00:00 +0000

Scientists predict a sea change in Arctic ecosystems by the end of the century Gabe Allen Wed, 11/19/2025 - 06:00

Gabe Allen

The lush greenery of the Amazon rainforest is often called the “lungs of the planet,” but really land plants are just half of the equation. The other lung dwells in the sea. Single-celled photosynthetic algae, known collectively as phytoplankton, produce about half of the oxygen in Earth’s atmosphere.

Phytoplankton are especially abundant at high latitudes, where seasonal sea ice retreat leads to explosive summer blooms.

“Polar regions can experience rapid growth,” INSTAAR postdoctoral fellow Courtney Payne explained. “They have a pretty short window, but phytoplankton can grow like crazy over a period of weeks or months.”

According to a new paper from Payne and collaborators, that cycle may soon be disrupted in the Arctic Ocean. Using a suite of modeling tools, the researchers predicted the state of phytoplankton blooms 80 years into the future — in the year 2100 — and compared them to records from the 1970s. They found that summer blooms will start more than a month earlier on average by the end of the century.

Unfortunately, the models predict that this change in seasonal timing will disrupt the foundation of the marine food web, leading to scarcity at every trophic level. It’s a change that will impact marine animals and the Indigenous communities that rely on them for sustenance.

Payne kneels on sea ice in the Chukchi Sea during a research cruise in 2023. (Courtesy, Courtney Payne)

Mismatches in the food web

The first time Payne saw a phytoplankton bloom, she was behind a pair of oars in a boat off the coast of Maine. It was just another day of practice for her collegiate rowing team, but the water, which had remained deep blue all winter, had turned green.

“Each spring, someday it would turn this violent green color,” Payne said. “Several years we would have these big swarms of jellyfish come through to consume the phytoplankton.”

These days, Payne spends most of her working hours behind a computer, but her history on the water allows her to visualize the ecosystems she studies. Just like the jellyfish in Maine, phytoplankton in the Arctic provide food for drifting grazers known collectively as zooplankton. This interaction forms the base of a rich marine food web. The zooplankton feed fish and whales, and the nutrients trickle their way up to seals, sea birds, polar bears and other Arctic animals.

The earlier spring bloom predicted by Payne and her collaborators may not seem like a bad thing. In fact, the researchers predict that the bloom will last more than a month-and-a-half longer on average by the end of the century. But, marine organisms have adapted to the current cycle over millennia, and they are ill prepared for it to change so quickly and drastically.

The researchers predict that scarcer sea ice will lead phytoplankton to bloom during the cold early-summer months. Zooplankton struggle to multiply at these temperatures and thus will not be able to take advantage of the bounty. Each spring, a large proportion of the bloom will go uneaten and sink to the ocean floor.

“If the spring bloom happens earlier and at these colder temperatures, the things that feed on the phytoplankton aren’t able to grow as much in response,” Payne said. “That means that whales and other animals that migrate to the area won’t have as much food to feast on.”

Maps of the Arctic Ocean showing the change in the average start date of the spring phytoplankton bloom from 1970 to 2020 (left) and from 1970 to 2100 (right). So far, the change has been subtle, but Payne and her collaborators predict a much earlier bloom by the end of the century. (Courtesy of Courtney Payne)

The culprit is clear

Overall, the new study paints an alarming picture for the future of Arctic marine ecosystems. But, there is a silver lining. Payne and her collaborators proved the efficacy of a methodology seldom seen in ecological research.

While previous studies have relied on limited observational data or single model simulations, the new study took a more comprehensive approach. The researchers worked off of an Earth system model that had been tweaked 50 times to produce 50 different, equally likely, future scenarios.

“If we used real world observational data, we would have to rely on one example of what the Earth is doing over a short period, which may not be representative of changes in the long run,” Payne said. “One of the benefits of using an Earth system model is that you can run the same years over and over again and use the mean to figure out, on average, what is going on.”

By comparing this “ensemble” of outcomes, the researchers were able to separate out the effects of anthropogenic climate change from natural climate variability. In short, they could identify a culprit: greenhouse gas emissions.

“With our methodology, we are able to specifically isolate the impact of climate change on the timing of the bloom,” Payne said. “Thus far it has only led to a shift of about 5 days, but we see a much more substantial impact by the end of the century.”

INSTAAR director Nicole Lovenduski, NCAR scientists Alice Duvivier, Marika Holland and Kristen Krumhardt are coauthors on this report.

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, led by INSTAAR’s Courtney Payne, used a powerful methodology to predict outcomes for life in the Arctic Ocean in the year 2100. Their results predict disrupted phytoplankton blooms, which will ripple throughout the ecosystem.

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A phytoplankton bloom in the Barents Sea, north of Norway and Russia, as seen from space in July, 2021. (NASA Earth Observatory)

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A phytoplankton bloom in the Barents Sea, north of Norway and Russia, as seen from space in July, 2021. (NASA Earth Observatory)

Research

Some tropical land may experience stronger-than-expected warming under climate change (CU Boulder Today)

Related Articles

Breaking ice, moving earth: Greenland will release more sediment into the ocean as the climate warms

Off

Research highlight: Dr. Keith Musselman and the EcoTram (MRS News)

Off

INSTAAR’s most read news stories of 2025

The top five

Air pollution and warming are changing Colorado’s remote alpine lakes

The data is in: Colorado’s snowpack is lagging behind the 21st century average in 2025

Spotlight: Hunter Geist-Sanchez is pioneering restoration methods for Colorado grasslands and reconnecting with his ranching roots

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

Beneath crumbling walls: how rock glaciers took over the southern rockies

The runner up

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

Off

Precious waterways: how contaminated mountain streams could power American-made technology

Related Articles

Changing Winters Leave Indigenous Alaskans on Thin Ice (Eos)

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How an experiment in the mountains could reveal the future of alpine plants (KUNC)

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What can a mile-long stick of ice, stored away for 33 years, tell us about Earth’s climate?

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Brief: New funds for student research at the Mountain Research Station

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Scientists predict a sea change in Arctic ecosystems by the end of the century

Mismatches in the food web

The culprit is clear

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