“It is an unbelievable honor to become a fellow of the Royal Society of Canada,” says Dahl-Jensen. “It means a lot to me to be acknowledged for the research I do at the University of Manitoba.”

A Leader in Arctic Research

A Canada Excellence Research Chair at the UM Centre for Earth Observation Science, in the Clayton H. Riddell Faculty of Environment, Earth, and Resources, Dahl-Jensen leads groundbreaking climate research. Her latest project on the Müller ice cap of Axel Heiberg Island made headlines in May 2025, after drilling the deepest ice core ever pulled in Canada.

At 613 metre deep ice core at Axel Heiberg Island, Nunavut is the deepest ever drilled in Canada.

“Dr. Dahl-Jensen is one of the foremost accomplished and influential scientists in glaciology and climate science, deciphering past climate by drilling and studying ice cores from Greenland, Antarctica, and most recently northern Canada,” says Dr. Feiyue Wang, Professor, Canada Research Chair and Associate Dean Research of the Riddell Faculty.

“Her extraordinary leadership is evident in her organization and execution of complex logistical operations in the harsh environments on the summit of ice sheets and ice caps. As a mentor, she has fostered an incredibly large number of students and scientists who are now leaders in their own fields.”

Dahl-Jensen’s findings have been widely published in prestigious academic journals including Nature, Science, and Proceedings of the National Academy of Sciences. Her publications in collaboration with co-authors all over the world have achieved a high impact, having been cited more than 23,000 times.

In Denmark, Dahl-Jensen is a Professor at the Niels Bohr Institute of the University of Copenhagen. She was recognized as a Knight of Danneborg 1st Order and with the International Glaciology Society’s Seligman Crystal in 2023, and the prestigious Banco Bilbao Vizcaya Argentaria (BBVA) Frontiers of Knowledge Award in 2024.

Canada Excellence Research Chair, Dr. Dorthe Dahl-Jensen (right), discovers ancient plant fossils during a polar ice core expedition.

Research Impacts from Pole to Pole

Dahl-Jensen’s leadership in polar climate science through the Physics of Ice, Climate and Earth at the Niels Bohr Institute has achieved truly global reach in understanding the ongoing human causes of climate change.

In 2023, Dahl-Jensen led a team who drilled a 2670-meter ice core, reaching bedrock for the first time on the North Greenland Ice Stream. The international team, including researchers from 12 countries, proved definitively that ice is melting at the base of the Ice Stream, improving predictions for the rate of sea level rise worldwide.

At the beginning of 2025 Dahl-Jensen again earned international attention, this time in Antarctica with a team that drilled to a depth more than 1.2 million years old. At 2800 meters deep, this was the oldest ice core ever retrieved.

Dorthe Dahl-Jensen and team of international researchers celebrate milestone in climate change research in Greenland.

“The multinational collaborations led by Dr. Dahl-Jensen exemplify the UM Strategic Research priority for sea ice exploration and Arctic access, while positioning the Centre for Earth Observation Science at the forefront of glaciological science worldwide,” says Dr. Mario Pinto, Vice-President (Research and International).

“Her pioneering ice core research is greatly advancing public understanding of Earth’s complex climate system and provides critical insights that are informing the response to climate warming by decision makers around the world. She is a true explorer.”

Dahl-Jensen will join the Earth, Ocean & Atmospheric Sciences Division of the RSC Academy III at the induction ceremony in November 2025. Two other UM community members are honoured by the Royal Society in 2025:

• Sean Carleton, Associate Professor, Department of History and Department of Indigenous Studies in the Faculty of Arts is elected as a College Member.
• Humaira Jaleel, a recent graduate of the Faculty of Law, has received the Justice Rosalie Silberman Abella Prize.

Published in Science, the UM-led study predicts a near-unrecognizable Arctic landscape by 2100 if global commitments to reduce greenhouse gas emissions (GHGs) remain unchanged.

Led by Julienne Stroeve, Canada 150 Research Chair in Climate Forcing of Sea Ice, and Dorthe Dahl-Jensen, Canada Excellence Research Chair in Arctic Sea Ice, Freshwater-Marine Coupling and Climate Change, the research highlights that the Arctic is heating at four times the global average rate, posing significant environmental and socio-economic challenges.

Dr Julienne Stroeve

Accelerating Changes and Their Consequences

“The Arctic is warming at four times the rate of the rest of the planet,” said Stroeve. “At 2.7 degrees Celsius of global warming, this scenario would dramatically reshape the Arctic, the fastest-warming region on earth.”

Key projections of the study include:

• Almost every day will be hotter than the extreme temperatures of the past.
• The Arctic Ocean will be ice-free for several months each summer.
• The part of Greenland’s ice sheet that stays above freezing for over a month will be four times larger than before, accelerating rising sea levels.

While these transformations pose severe risks, the researchers emphasize that immediate and coordinated global action can help mitigate the impacts and preserve the Arctic’s crucial role in the Earth’s climate system.

Solutions for a Sustainable Future

This study underscores the opportunities for proactive intervention to avoid these dire environmental consequences. Governments, industries, and individuals all have roles to play in reducing GHGs, expanding conservation areas, and integrating Indigenous knowledge into climate strategies.

“If we act now with bold climate policies and innovative technologies, we can still make a difference,” says Stroeve. “The Arctic is a key part of the global climate system, and its future truly lies in our hands.”

Continued scientific research is crucial in shaping effective policies. Monitoring Arctic changes will improve climate models and adaptation strategies.  

“We must combine scientific advancements with community-driven solutions,” Stroeve says. “By working together, we can develop strategies that not only protect Arctic ecosystems but also support the people who depend on them.”

Global Climate Action and Collaborative Research Needed

The research, supported by funding from the Canada 150 Research Chairs Program and other institutions, utilized data from NSIDC’s Sea Ice Today and Ice Sheets Today projects to provide a comprehensive overview of Arctic changes. Collaborators included the University of Ottawa, Northern Arizona University, and the University of Hamburg.

While these transformations pose severe consequences, the researchers emphasize that immediate and coordinated global efforts can help mitigate the impacts and preserve the Arctic’s crucial role in the Earth’s climate system for future generations.

#1 Grolar bears-what are they and how common are they?

The topic of Grolar bears (hybrid of Polar Bears and Grizzly bears) showed up a few times on this list. The first time was after a group of researchers published their study on how common hybridization might be in Conservation Genetics Resources journal. The team of scientists from Polar Bears International, Environment and Climate Change Canada, MacEwan University, also included UM researcher Ruth Rivkin, from the Department of Biological Sciences. Some of the media outlets that featured the story included, Advnture.com, Yahoo! News, BBC.com, CBC, and Canadian Geographic.

#2 The Kyrenia shipwreck, UM expert perspective

CNN tapped Mark Lawall, UM professor in the department of Classics to give his insights on the how improvements to carbon dating and other techniques helped decipher exactly when the Greek-Hellenistic Kyrenia ship came to rest on the ocean floor. Lawall has studied ancient Greek containers used for shipping wine, olive oil and other goods from the Kyrenia shipwreck. The reach of this story was furthered after it ran on Yahoo! News, as well.

#3 Grolar bears hybrids traced to same ‘strange’ female Polar Bear

As more stories around climate change grabbed headlines around the world, media came back to the Grolar bear topic and how it may be an indicator of climate change. Researchers including UM’s Ruth Rivkin, who also works with Polar Bears International, talked about how most hybridizations could be traced back to one female polar bear.  “Rivkin suggested the initial mother may have been ‘pretty strange’ but also pointed out that while female polar bears do have ‘some level of choice’ about who they mate with, size makes a difference.” This story appeared in a number of places including, Yahoo! News, MSN, and The Guardian. Many stories also talked about the new genetic sequencing chip, which was used to track and gather information on the Grolar bears and could be used in the future to track more hybridization cases.  Some of these stories also linked to a study published in Nature by UM researchers Alex Crawford and Julienne Stroeve from Clayton H. Riddell Faculty of Environment, Earth, and Resources. 

#4 UM expert weighs in on case of serial killer, Jeremy Skibicki

The trial of Winnipeg serial killer, Jeremy Skibicki, and the lives of the women he admitted to killing caught the attention of many people worldwide and media outlets came to Brandon Trask, Assistant Professor in the Faculty of Law and adjunct fellow, St. John’s College, for his perspective. Some of the media outlets that featured the story with Trask’s insights included BBC, CBC, Winnipeg Free Press, Globe and Mail, and CTV Winnipeg

#5 Can a DNA analysis help improve your fitness?

Can DNA analysis help improve your fitness? UM jumped into the discussion for CNN’s Fitness, But Better series. UM’s Dylan MacKay, Assistant Professor, Department of Food and Human Nutritional Sciences, suggested people may want a level of skepticism when thinking Grandpa’s ability to throw a wicked caber toss at the annual Highland Games naturally gets passed down to them. Mackay noted while the accuracy in actual genetic testing is likely good, the science behind how the companies are interpreting the results could be problematic. This story was also picked up by Yahoo! News, intriguing readers across search engines and moving it into the top 5 most viewed news stories featuring UM experts.

#6 Are You A Bad Parent For Using Sarcasm Around Your Kids? Experts Have Thoughts

Tell me something we don’t know! So many thoughts to unpack in this interesting look at how children learn sarcasm. Melanie Glenwright, a Associate Professor of Psychology at UM, should know. She studied it and told HuffPost  “…it isn’t until ages 7 to 10 where children living in Canada begin to understand that a sarcastic speaker intends to be funny.” So, are you a bad parent for using sarcasm? Click the link above to find out. This story also ran on Yahoo! Life.

#7  and 8 A woman bought a vintage dress at an antique store. It had a secret pocket with a mysterious note

This story took two places in the Top 10 countdown because this story went big when it was first written and pitched to news outlets in December 2023, but then really took off in publications in 2024. It was covered everywhere from the New York Times, Washington Post, and CNN. When Rivers Cofield purchased the vintage dress—made in the 1880s— from an Antique mall in Maine, she found a code in a secret pocket. She posted a blog about it and for years she looked for someone to help her crack the code. Enter Wayne Chan, who is actually a data analyst at UM’s Centre for Earth Observation Science, but who also loves to solve mysteries in his spare time. So, if you missed what the code revealed, click on the story link above. 

#9 Mutated strain of mpox with ‘pandemic potential’ found in DRC mining town

UM is known for its world-renowned experts doing groundbreaking research to track and find solutions to some of the world’s most complicated viruses and pathogens. In the number nine position, is a story that features Dr. Jason Kindrachuk, Associate Professor in infectious disease at UM’s Max Rady College of Medicine in the Rady Faculty of Health Sciences. He was the co-author of a paper that looked at the ‘pandemic potential’ of a certain strain of Mpox. The story was featured in the UK’s Telegraph, and shared in Yahoo! News.

#10 UM apologizes for housing Indigenous remains and artefacts, develops repatriation policy

This story was the final story on our list that received a lot of media coverage. First, for the apology  and recognition by UM for the harms it caused First Nations, Métis and Inuit descendant communities for housing remains and artefacts without permission. Second, for developing the Respectful Rematriation and Repatriation Ceremony to coordinate next steps to return these artefacts and remains to affected communities. It was covered in a variety of outlets, including MSN and The Canadian Press.

This list was compiled by UM’s Media Relations team, based on data provided by the media-monitoring platform, Cision.

The report, “Ice-free period too long for Southern and Western Hudson Bay polar bear populations if global warming exceeds 1.6 to 2.6C”  published June 13, 2024, in Communications Earth and Environment was developed in collaboration with researchers from the University of Toronto Scarborough, National Snow and Ice Data Center, The Arctic University of Norway, Fisheries and Oceans Canada, Environment and Climate Change Canada, and Polar Bears International.

As it is increasingly unlikely that the world will meet the most ambitious Paris Agreement target of limiting global warming to 1.5°C, the team of biologists and climate scientists came together, using the latest science, to reevaluate the future of Hudson Bay’s sea ice, polar bears, and seals. The report analyzes various climate warming scenarios if greenhouse gas emissions continue and we surpass 2°C warming above pre-industrial levels, the upper limit set in the Paris Agreement.

“If we fail to limit global warming to less than two degrees Celsius, we will lose Hudson Bay’s populations of polar bears,” says lead author Professor Julienne Stroeve, University of Manitoba, adding, “The disappearance of the Southern Hudson Bay polar bears is imminent, with Western Hudson Bay not far behind. Our research underscores the rapid changes human activity imparts to our climate. It’s incumbent upon us to understand the impending impact on our natural world, so that we can make policy decisions informed by science.”  

A Comprehensive Approach for an Interconnected Ecosystem

This report offers the first holistic look at the future of Hudson Bay’s ecosystem—encompassing polar bears and seals alike—and predicts a polar bear extirpation, which means a localized extinction, between the 2030s and 2060s. Unlike previous reports analyzing partial regions, often looking retrospectively at historical data, this report provides a comprehensive examination of the future of the Hudson Bay area. This shift addresses changes in sea ice thickness and snow thickness, which are critical for polar bear hunting, polar bear denning, and seal pup denning. 

This study analyzes sea ice thickness to determine polar bear survival, which has never been done before. Previous approaches assessed sea ice coverage, which authors found could overestimate polar bear survival by 50 days. Sea ice is not always thick enough for a polar bear to use for successful hunting, as seen in this video clip, therefore this report analyzes ice thickness of at least 10 cm – minimum for supporting a male polar bear hunting.

Key Results: Polar Bear Survival Depends on Melting Ice

Polar bear survival is directly related to Arctic sea ice, as they need the ice platform to hunt their main prey, seals. When polar bears are forced onto land by melting ice, terrestrial food is an insufficient replacement, with prior research finding that survival and reproduction are constrained by bears’ capacity to fast. This new report finds that under 2°C of warming, southern Hudson Bay will be ice-free for 174 to 182 days, which would impair reproduction and strain survival. Western Hudson Bay will maintain sea ice for longer, with 163 to 168 ice-free days. Analyzing the projections from 20 climate models, the Western Hudson Bay region becomes an unsuitable habitat at 2.2°C or 2.6°C. The southern Hudson Bay sub-population faces a more dire projection, with ice-free periods becoming excessively long for most bears at 1.6°C to 2.1°C. Therefore, if the Paris Agreement is breached, and the world surpasses 2°C of warming, this report finds that the southern population will disappear, and the whole of Hudson Bay’s polar bears will be at or near their survival limit. If we do surpass 2°C global warming, the timing of that breach and localized extinction depends on the rate of greenhouse emissions by human activities over the coming decades. 

“Unregulated emissions could mean we see the disappearance of the Southern Hudson Bay subpopulation as early as the 2030s,” says assistant professor and co-author, Alex Crawford.
“Changing policies to achieve more aggressive emissions reductions could delay the breach of the 2°C threshold to the 2060s, maintaining the survival of Hudson Bay’s polar bears.”

This map illustrates the boundaries of the Western Hudson Bay and Southern Hudson Bay polar bear populations (Credit: Alex Crawford)

Significance of Hudson Bay’s Polar Bears

Hudson Bay is home to two of the world’s 19 polar bear subpopulations, representing the world’s southernmost polar bear populations, which have long been considered an indicator of how the rest of the world’s polar bear subpopulations will fare in the future. Hudson Bay’s polar bears are the best-studied polar bears in the world, and this report includes models using over 50 years of data since monitoring of Hudson Bay’s polar bears began in the 1970s. Beyond serving as a “canary in the coal mine” for other Arctic regions, these polar bears hold significant cultural value for communities around Hudson Bay.

“This report is more detailed and alarming than previous studies, reinforcing that Hudson Bay’s polar bears are not on a good trajectory unless significant emissions mitigation measures are implemented,” says co-author Geoff York, senior director of research and policy at Polar Bears International, adding, “This cross-disciplinary, forward-looking and comprehensive analysis of all of Hudson Bay provides more actionable insights for policymakers and wildlife managers.” 

Implications for Seals and Other Species: 

As rainfall, rather than snowfall, increases in the Subarctic and Arctic, it will be more difficult for both seals and polar bears to make dens to give birth to offspring, with rain potentially washing away their dens. There are three seal species in Hudson Bay, of which the ring seals are polar bears’ preferred prey. This report highlights how less snow can impact seal pup survival, as ring seals need at least 32 cm of snow depth to dig lairs for their pups. Future studies could look at the sea ice thickness needed for other species, like caribou and walrus that travel across the ice. Future research may analyze future sea ice roughness, which determines where snow sticks and accumulates, and therefore where seals can den. 

This research underscores the importance of swift greenhouse gas emissions reduction, and multi-disciplinary, holistic approaches to research, management, and policy. 

Contaminants detected included total mercury (THg), major and trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and per and polyfluoralkyl substances (PFASs). These findings show that pollution effects leave a long legacy in the environment and include both local and long-range effects.

Read more

What you should know about Feiyue Wang and his research:

• As Tier-1 Canada Research Chair in Arctic Environmental Chemistry, he looks at current and emerging contaminants in the Arctic and global environments and how they interact with climate change.
• Wang is a researcher at the Centre for Earth Observation Science and leads the Churchill Marine Observatory and Sea-Ice Environmental Research Facility.
• Building upon his pioneering research on mercury in sea ice, his research team is studying how oil spills and other emerging contaminants associated with Arctic development can affect the Arctic ecosystem and human health. Ultimately, his research will provide critical knowledge and tools to improve policies and practices for sustainable development in the Arctic.

Recent honours and honourable mentions:

• Holds an Honorary Professorship at Aarhus University (Denmark)
• Serves as a national expert for Canada on mercury assessment for the Arctic Monitoring and Assessment Program and the United Nations Environment Program
• In 2021, The Chemical Institute of Canada recognized him with the Dima Award for distinguished contributions to research and developments in the field of environmental chemistry or environmental chemical engineering
• Winnipeg Free Press: U of M receives research awards

Must-read or Must-see:

Conversation Canada: How we solved an Arctic mercury mystery 

UM Knowledge Exchange-Now You Sea Ice

What’s next:

• The Grand Opening of the Churchill Marine Observatory (summer 2024)
• A new major research initiative, “Reimagining Arctic and Central Canada Accessibility through Hudson Bay (REACH)”

UM Faces & Spaces is a monthly feature showcasing the people and places across UM that are transforming the student experience, advancing innovation in research, driving change and creating a lasting impact here in Manitoba and globally. For more stories go to our YouTube playlist.

“Congratulations to Dr. Dahl-Jensen on receiving this international award for her invaluable research into climate change and its impacts around the globe,” said Dr. Mario Pinto, Vice-President (Research and International) at UM. “The University of Manitoba is proud to advance research excellence to increase scientific understanding of society’s most pressing issues while providing solutions for the betterment of future generations.”

Dahl-Jensen, along with French scientists Jean Jouzel and Valérie Masson-Delmotte and Swiss scientists Jakob Schwander and Thomas Stocker have received this award discovering of the link between greenhouse gases and rising global temperatures enclosed within the polar ice through their analysis of ice cores in Greenland and Antarctica.

“It is an honour to receive this award for research that is fundamentally significant to the sustainability of our global climate,” said Dahl-Jensen.

Dahl-Jensen and her colleagues’ research involved examining concentrations of carbon dioxide (CO2) trapped within layers of polar ice over time. Their research on the natural variability of the earth’s climate contextualizes current GHG concentrations in the midst of human-induced global warming.

“My research has been primarily concerned with reconstructing past climates by studying polar ice cores in Greenland,” said Dahl-Jensen. “These ice cores can tell us what temperatures were like when they were formed, as well as CO2 concentrations in the atmosphere at the time. I found that, even though we had warm periods over the last 800,000 years, CO2 concentrations were never as high as they are today. These findings signify the potential impacts of escalading temperatures and rising sea levels if measures are not taken to further reduce GHG emissions.”

This year is the sixteenth edition of the BBVA Foundation Awards, which has honoured the likes of Noam Chomsky, Philip Glass, and Stephen Hawking.

UM Knowledge Exchange is a continuation of the former UM Café Scientifique program and is an important opportunity for UM researchers to share emerging knowledge with members of the public and the wider UM community. UM Knowledge Exchange is hosted by the Office of the Vice-President (Research and International), with support from the UM Learning for Life Network.

Now You Sea Ice..

November 22, 7pm-8:30pm (CDT) at Degrees Diner. UM Knowledge Exchange is a hybrid event with in-person and online options to attend.

Please register by November 17^th to join the discussion.

With global temperatures on the rise polar sea ice is disappearing, having a profound effect on ecosystems and ways of life in the Canadian North. What can the decline in sea ice tell us about the future of climate change, and what will it mean to live in our warmer world?

Global experts and researchers at UM are working together with Northern communities to understand and prepare for the impacts of climate change, because a Manitoba without sea ice is closer than we think.

Moderator

• Dr. Feiyue Wang, Associate Dean (Research and Innovation), Clayton H. Riddell Faculty of Environment, Earth, and Resources

Panelists

• Dr. Julienne Stroeve, Professor and Canada 150 Research Chair, Clayton H. Riddell Faculty of Environment, Earth, and Resources
• Mike Spence, Mayor of Churchill Manitoba
• Dr. Dorthe Dahl-Jensen, Canada Excellence Research Chair, Center for Earth Observation Science, Clayton H. Riddell Faculty of Environment, Earth, and Resources

Add Now You Sea Ice.. to your calendar. Coffee and other refreshments will be provided, and the kitchen at Degrees Diner will be open for specialty coffee and full food service. Parking available is available with registration.

Or join us for online viewing 7 pm CST to watch the live stream. Participate during the live session by asking your questions via email to: Research [dot] Communications [at] UManitoba [dot] ca

The seven-part UM Knowledge Exchange panel-discussion series will take place between November 2023 and May 2024. More details to come soon on the UM Knowledge Exchange webpage.

Due to intensifying sea-ice melting in the Arctic, sunlight is now penetrating deeper and deeper into the ocean. Since marine zooplankton respond to the available light, this is also changing their behaviour – especially how the tiny organisms rise and fall within the water column. An international team of researchers led by the Alfred Wegener Institute, which included Julienne Stroeve from the University of Manitoba, has now shown that in the future this could lead to more frequent food shortages for the zooplankton, and to negative effects for larger species including seals and whales. The study was just released in the journal Nature Climate Change.

In response to anthropogenic climate change, the extent and thickness of the Arctic sea ice are declining; the mean sea-ice extent is currently decreasing at a rate of 13 percent per decade. As early as 2030 – as the latest studies and simulations indicate – the North Pole could see its first ice-free summer. As a result, the physical conditions for organisms in the Arctic Ocean are changing just as visibly. For example, due to less and thinner sea ice, sunlight can penetrate much farther below the surface. As a result, under certain conditions, the primary production – i.e., the growth – of microalgae in the water and ice can increase substantially. How these changing light conditions are affecting higher trophic levels in the food chain – like zooplankton, which feed in part on microalgae – remains poorly understood. In this regard, an international team of researchers led by Dr Hauke Flores from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) has now gained valuable insights.

Buoy deployment (photo by Folke Mehrtens)

According to Flores: “Every day, the largest-scale mass movement of organisms on our planet takes place in the ocean – the daily migration of the zooplankton, which include tiny copepods and krill. At night, the zooplankton rises near the water’s surface to feed. When the day comes, they migrate back to the deep, keeping them safe from predators. Although the individual organisms are minuscule, taken together this constitutes a tremendous daily vertical motion of biomass within the water column. But in the polar regions, the migration is different – it’s seasonal; in other words, the zooplankton follow a seasonal cycle. During the months-long brightness of the Polar Day in summer, they remain in the deep; during the months-long darkness of the Polar Night in winter, part of the zooplankton rise and remain in the near-surface water just below the ice.”

Both the daily migration at lower latitudes and the seasonal migration in the polar regions are predominantly dictated by sunlight. The tiny organisms usually prefer twilight conditions. They like to stay below a certain light intensity (critical irradiance), which is usually quite low and lies well into the twilight range. When the intensity of sunlight changes in the course of a day or the seasons, the zooplankton go where they can find their preferred light conditions, which ultimately means they rise or sink in the water column. “Particularly when it comes to the topmost 20 metres of the water column, just below the sea ice, there was no available data on the zooplankton,” Flores explains. “But it’s precisely this hard-to-reach area that’s most interesting because it’s in and just below the ice where the microalgae that the zooplankton feed on grows.” In order to take readings there, the team designed and built an autonomous biophysical observatory, which they moored below the ice at the end of the MOSAiC expedition with the AWI research icebreaker Polarstern in September 2020. Here – far from any light pollution due to human activities – the system was able to continually measure the light intensity below the ice and the zooplankton’s movements.

Copepod Paraeuchaeta (Photo taken by Mario Hoppmann)

“Based on our readings, we identified an extremely low critical irradiance for the zooplankton: 0.00024 watts per square metre,” says the AWI researcher. “We then fed this parameter into our computer models for simulating the sea-ice system. This allowed us to project, for a range of climate scenarios, how the depth of this irradiance level would change by the middle of this century if the sea ice grew thinner and thinner due to climate change.” What the experts found: Due to the steadily declining ice thickness, the critical irradiance level would drop to greater depths earlier and earlier in the year and wouldn’t return to the surface layer until later and later in the year. Since the zooplankton fundamentally remains in waters below this critical level, their movements would mirror this change. Accordingly, in these future scenarios, they remain at greater depths longer and longer, while their time near the surface below the ice in winter grows shorter and shorter.

“In warmer future climates, the ice will form later in the autumn, resulting in reduced ice-algae production,” Flores explains. “This, in combination with their delayed rise to the surface, could lead to more frequent food shortages for the zooplankton in winter. At the same time, if the zooplankton rise earlier in the spring, it could endanger the larvae of ecologically important zooplankton species living at deeper levels, more of which could then be eaten by the adults.”

“Altogether, our study points to a previously overlooked mechanism that could further reduce Arctic zooplankton’s chances of survival in the near future,” says Flores. “If that comes to pass, it will have fatal consequences for the entire ecosystem, including seals, whales and polar bears. But our simulations also show that the impact on vertical migration will be much less pronounced if the 1.5-degree target can be reached than if greenhouse-gas emissions rise unchecked. Accordingly, every tenth of a degree of anthropogenic warming that can be avoided is critical for the Arctic ecosystem.”

Buoy installation (Photo taken by Folke Mehrtens).

Original publication: H. Flores, G. Veyssiere, G. Castellani, J. Wilkinson, M. Hoppmann, M. Karcher, L. Valcic, A. Cornils, M. Geoffroy, M. Nicolaus, B. Niehoff, P. Priou, K. Schmidt, J. Stroeve: Sea-ice decline makes zooplankton stay deeper for longer; Nature Climate Change (2023). DOI: 10.1038/s41558-023-01779-1

Today’s Arctic sea ice is more likely to resemble a snow-covered parking lot than the chaotic ice blocks Nansen saw. Two years of tanking summer sea ice—in 2005 and 2007—exposed the dark ocean surface to more heat from the sun, further reducing sea ice and increasing heat in an ongoing cycle, says co-author Laura de Steur. The new study’s findings are consistent with satellite observations and other research, says Julienne Stroeve, a sea ice remote sensing expert with the U.S. National Snow and Ice Data Center and the University of Manitoba.