Research

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)

New pika research finds troubling signs for the iconic Rocky Mountain animal (�� Boulder Today)

Gabe Allen — Tue, 18 Nov 2025 22:37:44 +0000

New pika research finds troubling signs for the iconic Rocky Mountain animal (�� Boulder Today) Gabe Allen Tue, 11/18/2025 - 15:37

A new study from INSTAAR's Chris Ray and Jasmine Vidrio sounds the alarm for pikas in the Rocky Mountains. The paper provides the first empirical evidence for a theory long held by wildlife biologists — that pikas are struggling to adapt to warming temperatures.

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New insight into how sunlight transforms legacy mining pollution in mountain wetlands (CSU)

Gabe Allen — Tue, 11 Nov 2025 18:04:02 +0000

New insight into how sunlight transforms legacy mining pollution in mountain wetlands (CSU) Gabe Allen Tue, 11/11/2025 - 11:04

Lauren Magliozzi has published a new analysis of an INSTAAR experiment conducted by Diane McKnight and Sabre Duren. The researchers characterized daily chemical fluctuations in wetlands downstream from an inactive Colorado mine.

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Global Leaders Unite to Protect Ross Sea (Tasmanian Times)

Gabe Allen — Wed, 29 Oct 2025 17:45:34 +0000

Global Leaders Unite to Protect Ross Sea (Tasmanian Times) Gabe Allen Wed, 10/29/2025 - 11:45

Leaders from 26 countries and the European Union offered support for a new research and coordination network focused on the Ross Sea in Antarctica this week. INSTAAR fellow and Antarctic scientist Cassandra Brooks leads the steering committee for the NSF-funded network.

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Researchers granted $1.6 million to study microbes' influence on alpine tundra (Niwot Ridge LTER)

Gabe Allen — Tue, 28 Oct 2025 16:56:23 +0000

Researchers granted $1.6 million to study microbes' influence on alpine tundra (Niwot Ridge LTER) Gabe Allen Tue, 10/28/2025 - 10:56

A team, led by INSTAAR scientist Will Wieder, received an NSF grant to study the role of microbes in shrub encroachment in the alpine tundra. The project will be based at Niwot Ridge.

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Researchers aim to identify pika calls through 'acoustic fingerprinting'

Gabe Allen — Tue, 28 Oct 2025 12:30:00 +0000

Researchers aim to identify pika calls through 'acoustic fingerprinting' Gabe Allen Tue, 10/28/2025 - 06:30

Gabe Allen

On a foggy, cool morning earlier this fall, wildlife biologist Chris Ray and PhD student Rachel Mae Billings sat down at the edge of a rock-strewn mountain slope and listened — just listened. All was quiet aside from the scratching of pencils in field notebooks, the occasional chickadee twitter and, most importantly, squeaking pikas.

Chris Ray writes in a field notebook beside rocky pika habitat near Mitchell Lake in the Indian Peaks Wilderness on Sept. 13, 2025. (Gabe Allen)

Pikas — small herbivorous mammals related to rabbits — are easily recognizable by their staccato, piercing calls. They squeak to warn others of impending danger, shoo away neighbors that stray too far into their turf, and attract potential mates.

Some day in the future, Ray and Billings hope to use these vocalizations to study the animals on a scale never before possible. Their collaboration began with this goal in mind — if you could find a way to distinguish between individual pika calls, you could gather more information with an audio recorder than was previously possible from a full day of trapping.

“My life would be so much easier if I could just take a microphone out and sit in each territory and get a few calls.” Ray said. “Then I could go back and sit on those same rocks and see whether I get the same individual next year.”

Heralds of change

Ray has studied pikas since 1988, when she was an undergraduate student at the University of California, San Diego. Over the past 37 years, she has amassed countless days in the field.

Much of her work has focused on how climate change is impacting the diminutive mammals. Pikas are adapted to rocky slopes high in the mountains, where it stays cool through the summer. As temperature and precipitation has shifted across the American West, some pika populations have become small and isolated, or even disappeared. Others, like the populations here in the front range, have remained stable despite showing signs of stress.

A study published by Ray and collaborators a decade ago predicted that warming temperatures could extirpate pikas from large parts of their current habitat by the end of the century. But, those same researchers are continually learning more about how the animals adapt to environmental change.

“I’m interested in whether or not that’s actually happening,” Ray said. “Pikas are really good at finding microclimates that suit them.”

To answer these questions, Ray has continued monitoring pika populations across the American West. Each year, she returns to the mountains to trap the animals and collect health, survival and genetic data with help from a rotating cast of collaborators, volunteers, field technicians and students.

Click to zoom

Acoustic fingerprints

When Billings asked Ray to mentor her through her PhD candidacy, Ray saw an opportunity. She knew, from spending time with the animals, that individual pikas sounded slightly different from each other. Billings, who previously studied electronics engineering and is doing a PhD in quantitative biology, had the skills to develop technological tools that could identify those differences.

“She has the right background to work on a bioacoustic project — and she’s really good at it too,” Ray said.

This summer, Ray and Billings began making audio recordings of pikas that had previously been trapped, tagged and characterized. The next step will be to try to find “acoustic fingerprints” within these recordings. To do this, Billings will analyze digital visualizations of the calls. She may even employ machine learning tools to assist.

Chris Ray and Rachel Billings check a pika trap near Mitchell Lake in the Indian Peaks Wilderness on Sept. 13, 2025. (Gabe Allen)

“If you look at a graphical representation of a pika call, known as a spectrogram, it sort of looks like a thumbprint,” Billings said. “The goal is to collect enough recordings to see, are these really unique enough to tell them apart?”

If Billings can unlock an acoustic fingerprinting technique, the research potential is great. Already, the team has stationed solar-powered audio recorders that passively record pika calls at field sites on Niwot Ridge.

“We have terabytes of acoustic data from Niwot Ridge already,” Billings said. “The hope is to eventually use that data to infer population trends and track individual survival from year to year without observing and tagging them through an invasive trapping process.”

Of course, acoustic fingerprinting is, for now, theoretical. This winter, Billings will hang up her field gear and spend her days behind a computer working out the methodology.

But, even if it doesn’t work, Ray, Billings and their collaborators are trying other noninvasive methods to expand their pika observation powers. One option is to analyze pika scat for “DNA fingerprints,” a technique that is becoming cheaper as genetic analysis evolves.

A third project, which has been ongoing since 2010, leverages Coloradans’ fondness for the animals. The Colorado Pika Project employs teams of volunteers to keep track of pikas around the state. And, as of 2022, citizen scientists can upload observations to a mobile app called Pika Patrol.

No matter the method, their goal is clear. To better understand these charismatic little mammals, and safeguard their future in a changing environment.

“The pika has been singled out as one of the animals more sensitive to climate change,” Ray said. “We're trying to find out how they survive in some of the most challenging climates on earth, and whether they're nearing their limits.”

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An American pika in Alberta, Canada. Photo courtesy of Alan D. Wilson, Creative Commons Attribution-Share Alike 3.0 Unported.

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An American pika in Alberta, Canada. Photo courtesy of Alan D. Wilson, Creative Commons Attribution-Share Alike 3.0 Unported.

North Atlantic dolphins are dying younger, new study shows (�� Boulder Today)

Gabe Allen — Mon, 13 Oct 2025 22:53:58 +0000

North Atlantic dolphins are dying younger, new study shows (�� Boulder Today) Gabe Allen Mon, 10/13/2025 - 16:53

Common dolphins in the Bay of Biscay aren't living as long as they were in the '90s, according to a new paper led by INSTAAR postoc Etienne Rouby. The study used a novel sampling method to update inaccurate estimates and propose solutions.

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Snow melts earlier in burned forests, new Science Advances study finds (Mines Newsroom)

David J Lubinski — Thu, 25 Sep 2025 17:49:53 +0000

Snow melts earlier in burned forests, new Science Advances study finds (Mines Newsroom) David J Lubinski Thu, 09/25/2025 - 11:49

Wildfires are causing earlier snowmelt across the western U.S., and this effect would only be exacerbated by projected warmer winters. For the new research, INSTAAR Fellow Karl Rittger teamed with Arielle Koshkin and Adrienne Marshall of the Colorado School of Mines.

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A walk across Alaska’s Arctic sea ice brings to life the losses that appear in climate data (The Conversation)

Gabe Allen — Tue, 23 Sep 2025 19:41:36 +0000

A walk across Alaska’s Arctic sea ice brings to life the losses that appear in climate data (The Conversation) Gabe Allen Tue, 09/23/2025 - 13:41

INSTAAR fellow Alexandra Jahn has spent more than a decade studying how sea ice is changing in the 21st century. In an op-ed for the Conversation, she recounts a trip arctic communities that are feeling those changes firsthand.

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200 dead fish in Colorado reservoir have local groups concerned over climate change’s impact on mountain waters (CO Sun)

Gabe Allen — Mon, 15 Sep 2025 20:15:50 +0000

200 dead fish in Colorado reservoir have local groups concerned over climate change’s impact on mountain waters (CO Sun) Gabe Allen Mon, 09/15/2025 - 14:15

Dead fish piled up on the shore of Grizzly Reservoir last month, prompting officials to look for a cause. Research from INSTAAR fellow Diane McKnight's lab indicates that high metal concentrations from the reservoir's inflows could have poisoned the water.

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Research

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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Mismatches in the food web

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