Arctic

Kent Moore, a professor of atmospheric physics at �Թϱ�� Mississauga, collaborated with scientists from Environment and Climate Change Canada to study the North Water polynya

A new study by scientist Kent Moore shows that the unique marine ecosystem supporting a web of diverse natural life in the frozen Arctic is managing to sustain itself against the impacts of climate change – so far.

His findings, in partnership with researchers from Environment and Climate Change Canada, were recently published in the journal Scientific Reports.

Kent Moore (supplied image)

A professor of atmospheric physics in the department of chemical and physical sciences at the University of Toronto Mississauga, Moore is studying an 85-000-square-foot expanse known as a polynya – the name for a year-round open-water area surrounded by sea ice.

Located in north Baffin Bay between Canada and Greenland, it creates a relatively warmer microclimate with melted freshwater, which triggers an abundant bloom of phytoplankton each spring.

The site attracts diverse species of fish, birds, walruses, narwhals, whales, seals and polar bears who come to feed, mate and rest. For several millennia, the polynya has also been a source of traditional food for local Indigenous peoples.

Scientists refer to this site as the North Water (NOW) polynya, while it is known among some Inuit in Canada and Greenland as Pikialasorsuaq. Whatever name is used, Moore wants to underscore its ecological importance.

“The Arctic is mostly like a desert – it's difficult for a lot of wildlife to survive," Moore said. “But the North Water is quite amazing, because it’s the most biologically productive ecosystem in the region … You can think of it as an oasis in the Arctic."

The Nares Strait region, including northern Baffin Bay (NBB); Smith Bay (SB); Inglefield Fjord (IF); Smith Sound (SS); Kane Basin (KB); Humboldt Glacier (HG); Kennedy Channel (KC); Hall Basin (HB): Robeson Channel (RC); and Lincoln Sea (LS). Blue lines show the approximate location of the North Water polynya. (Map: Scientific Reports)

The NOW is below the Nares Strait, a waterway separating northwest Greenland from Ellesmere Island, surrounded by the oldest and thickest sea ice in the world.

Each winter, ice arches up to 100 kilometres in length from along the northern and southern ends of the strait. They stabilize the ice for seven or eight months, preventing any breaking ice floes from traveling down into the NOW.

To understand how the warming Earth is affecting the region, Moore collaborated with two scientists from Environment and Climate Change Canada to study the ice arches. Their 2021 study found that thinning ice is causing these arches to collapse earlier each year.

“There’s been a lot of work suggesting that without the arches, the NOW will dramatically change,” Moore said. “That change would mean a reduction in productivity, fewer species in the region and just a general decline in the richness of the ecosystem.”

Recently, Moore partnered again with the same scientists to examine satellite data showing patterns of ice arch formation and disintegration each winter since 2007. They also developed weather prediction models to estimate how, in the absence of ice arches, winds will blow ice downstream into the NOW.

They found that when arches do not form, the presence of sea ice tends to be about 10 per cent higher than usual. However, despite variations in ice arch activity, biological productivity in the NOW has held steady.

Moore said this may be because the region’s strong winds push the ice into – and then out of – the polynya, leaving them no time to disturb the ecosystem.

“It’s kind of a good news story that the polynya appears to be more stable than people thought,” Moore said. “We can breathe a bit easier about the NOW for the next few years.”

But as climate change intensifies, the NOW could be at risk. As a critical habitat for so many diverse species, and a key contributor to the food security of nearby Indigenous communities, it needs to continue to be monitored, Moore noted.

“The underlying issue is that we’re still warming the planet up. And there are many other stresses on the environment and the animals in that region,” he said.

“If you go to a scenario where we lose all the ice in the Arctic, then the NOW won’t be there anymore.”

�Թϱ�� grad student tracks 70 years of snow and ice data in the High Arctic

Christopher.Sorensen — Wed, 08 Mar 2023 14:53:13 +0000

�Թϱ�� grad student tracks 70 years of snow and ice data in the High Arctic

Christopher.Sorensen Wed, 03/08/2023 - 09:53

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Brianna Lane, a master's student at �Թϱ�� Mississauga, is developing an accessible method to monitor lake ice and snow levels in the High Arctic amid a changing climate (photo courtesy of Brianna Lane)

Tina Adamopoulos

Topic

Our Community

Black Research Network

Arctic

Climate Change

Research & Innovation

Sustainability

�Թϱ�� Mississauga

Brianna Lane, a second-year master’s student studying physical geography at the University of Toronto Mississauga, is developing an accessible method for snow and ice data quantification using ground-based trail cameras in the Central Canadian High Arctic – making vital research underway easier for experts to assess.

Working with Laura Brown, an associate professor in �Թϱ�� Mississauga’s department of geography, geomatics and environment, Lane is monitoring lake ice and snow in the Central Canadian High Arctic in Nunavut.

Her research will provide insight into the historical changes in the region when compared with climate data from 1953 to the present day.

“If the air temperatures are getting warmer, then we will expect that the lake ice duration is shrinking – so less time that the lakes are staying frozen,” Lane says. “If it’s staying the same, that may just be an indication that nothing has changed in the area.”

Lane is one of five recipients of the 2022 Black Graduate Scholar Award in Geography and Planning. The initiative, a partnership between the Black Research Network and the university’s tri-campus Graduate Geography and Planning, recognizes the exceptional academic and professional achievements of Black graduate students.

Lane is conducting research on five lakes: Hunting Camp Lake in the Nanuit Itillinga National Wildlife Area; Resolute Lake, Small Lake, Plateau Lake and North Lake near the community of Resolute/Qausuittuq, Nunavut.

The lakes – each about one-square-kilometer – are located near the town of Resolute, one of Canada’s northernmost communities. Typically, the lakes are used by local communities for fishing and, when frozen, transportation.

In the Central Canadian High Arctic, lakes stay frozen for up to a 10-month period from September to June.

Students install a ground-based camera near Resolute, Nunavut (photo courtesy of Brianna Lane)

The ground-based cameras Lane is using allow researchers to determine how much of the lake is snow, ice or water. The cameras take pictures twice daily, which allows Lane to monitor when lake ice forms and melts, including the spatial distribution of the snow and the ice. Rather than manually reviewing images from the trail cameras, the method digitizes data. A Shallow Water Ice Profiler (SWIP) is also used to measure lake ice.

“Ground-based cameras provide a way for us to consistently monitor the lakes,” Lane says. “The field sites we are looking at are inaccessible and hard to get to. A lot of recent research is using satellite imagery, but the lakes that I’m looking at are small and it’s hard to distinguish what is happening on the lakes because the resolution isn’t great.”

There are two vital periods that Lane is measuring – the freeze-up and break-up of a lake. Lane explains that lake features such as size and depth determine the freeze-up period, while the break-up period happens when temperatures rise above 0 C and is also controlled by lake features.

With a surface area of 540 square kilometers, Lake Hazen, the High Arctic’s largest freshwater ecosystem and the world’s biggest High Arctic lake is rapidly responding to climate changes – experiencing warming and shorter lake ice coverage over the last 10 years.

Lane says there haven’t been dramatic changes at her research sites so far, but noted she is still sorting through data.

“In the past few years, there haven’t been any drastic changes,” she says. “We aren’t seeing that the timing is changing dramatically, which over a long period of time is what we expect with climate change and the warming temperatures.”

Researchers identify mechanism responsible for temperature and salinity 'staircases' in Arctic Ocean

Christopher.Sorensen — Wed, 28 Sep 2022 19:08:56 +0000

Researchers identify mechanism responsible for temperature and salinity 'staircases' in Arctic Ocean

Christopher.Sorensen Wed, 09/28/2022 - 15:08

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Understanding how temperature and salinity “staircases” form could shed more light on the causes and consequences of rapid Arctic sea ice loss amid climate change (photo by imagebear via Getty Images)

Topic

Faculty of Arts & Science

Graduate Students

Physics

Research & Innovation

Sustainability

Researchers at the University of Toronto have identified the mechanism responsible for the formation of temperature and salinity “staircases” in the Arctic Ocean, resolving a mystery that has confounded oceanographers and climatologists alike for more than half a century.

Understanding how these vertical structures work promises to shed more light on the causes and consequences of rapid Arctic sea ice loss amid climate change.

“Our discovery of a new mechanism of hydrodynamic instability provides insights into the formation of staircase-like structures resulting from the mixing of warm salt water and cooler fresh water,” said Yuchen Ma, a PhD candidate in the department of physics in the Faculty of Arts & Science and lead author of a study published in Physical Review Fluids describing the findings.

“These structures were first observed in the late 1960s but the mechanism responsible for their existence has never been explained.”

Known as thermohaline staircases, these step-like variations of temperature and salt concentration are common in a wide range of regions of the global ocean.

A simulation depicts the strongly defined changes in temperature and salt that form staircase-like structures within the Arctic Ocean (image courtesy of Yuchen Ma and W. Richard Peltier)

The findings reported in Physical Review Fluids – which have attracted significant positive response from the research community – fully verify a previous analysis by the same authors published in the Journal of Fluid Mechanics in 2020 that documented the existence of this new hydrodynamic instability. The verification was accomplished by designing a series of direct numerical simulations of turbulence in the Arctic Ocean to better understand global ocean circulation.

“The ocean is typically thought of as a highly chaotic and turbulent environment, so it is striking to see such strongly defined layers of salt and heat within it,” says Ma.

The flow of heat out of the ocean into the overlying sea ice is strongly enhanced by the presence of thermohaline staircases. Thus, understanding the staircase formation process in the polar oceans is important for developing future global warming projections and informing efforts to mitigate sea ice loss.

“In this era of global warming, it is a well-recognized fact that the loss of Arctic Ocean sea ice cover is a critical aspect of this global process,” said University Professor W. Richard Peltier, of the department of physics who is a co-author of the studies and Ma’s PhD supervisor.

“While the extent to which staircase formation is contributing to this loss has yet to be quantified, we can certainly say that the ocean component of the climate models employed to make projections of the global warming process are not able to resolve the staircase formation process.”

The research builds on previous work that focused on understanding global ocean circulation under the ice age conditions from 30,000 to 70,000 years ago.

In the previously developed model of glacial climate, the rapid transitions from cold to warm weather were shown to be caused by an extensive “hole” in the sea ice cover of the North Atlantic Ocean resulting from heat flow out of the ocean into the sea ice. The magnitude of this heat flow was determined by the assumption that a staircase had formed in the ocean below.

Support for the research was provided by the Natural Sciences and Engineering Research Council of Canada. The computations on which the study is based were performed on the Niagara supercomputer cluster at the SciNet High Performance Computing facility at �Թϱ��, which is funded by the university, the Canadian Foundation for Innovation and the Province of Ontario.

Climate change slows reduction of methylmercury levels in Arctic: �Թϱ�� researchers

Christopher.Sorensen — Fri, 19 Feb 2021 18:31:22 +0000

Climate change slows reduction of methylmercury levels in Arctic: �Թϱ�� researchers

Christopher.Sorensen Fri, 02/19/2021 - 13:31

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Igor Lehnherr, a researcher at �Թϱ�� Mississauga, assessed the build-up of methylmercury, a dangerous neurotoxin, in Lake Hazen, one of Canada’s northernmost lakes (photo by Igor Lehnherr)

Topic

Research & Innovation

Sustainability

�Թϱ�� Mississauga

Climate change may be slowing the reduction of methylmercury – a dangerous organic neurotoxin created by microbes that metabolize mercury – in Arctic waters despite a global movement to reduce industrial mercury emissions.

That is among the findings of Igor Lehnherr and his research team at the University of Toronto after assessing the build-up of methylmercury in Lake Hazen, one of Canada’s northernmost lakes.

The study is published in the journal Environmental Science & Technology.

“Mercury pollution has gone down in the atmosphere,” says Lehnherr, an assistant professor of geography at �Թϱ�� Mississauga. “We’re doing things to tackle it, but climate change is throwing things for a loop [because] it can actually undo some of the benefits from emission reductions.”

Methylmercury levels rise only indirectly from human activity. Burning fossil fuels, mining and other industrial processes release unmethylated mercury into the atmosphere. As the mercury settles into aquatic ecosystems, certain types of microbes metabolize it to form the much more dangerous methylmercury.

A “persistent organic pollutant,” Methylmercury becomes more concentrated as it moves up the food chain – from bacteria to fish, predators and people. It affects the nervous system and can also cause cardiovascular damage. The toxin is especially dangerous for pregnant women and for fetuses, babies and young children whose nervous systems are still developing.

While the area where the �Թϱ�� team collected samples is not close to any northern communities, Lehnherr says the work is relevant for Indigenous people who hunt and fish for food.

“What we’re learning is not constrained to that location,” he says. “We put a lot of import on understanding mechanisms that affect methylmercury, so we can apply what we learn in one place somewhere else.”

Igor Lehnherr, an assistant professor of geography at �Թϱ�� Mississauga, says the field work for his latest study spanned several seasons and involved collaboration with other research teams in order to expand sampling (photo by Igor Lehnherr)

Arctic methylmercury levels depend on a complex mix of factors, including industrial emissions, precipitation patterns, microbial numbers and activity, as well as changes in seasonal sea ice. The complexity, along with the remoteness of northern ecosystems, make Lehnherr’s work particularly challenging.

“The field work spanned a few seasons,” he says of his latest study. “Some years we were there in the spring when it’s all snow and ice cover, some years in the summer, some years for both. By combining efforts with other teams, we expanded the sampling. Arctic research by nature is fairly collaborative – we share costs, time and ideas.”

Igor Lehnherr and his research team take water samples through the ice (photo by Igor Lehnherr)

In general, methylmercury-producing microbes are more active in warmer environments, implying a direct correlation between global warming and increased toxicity. But climate change also has many other effects that can exacerbate, mitigate and further complicate the situation.

“Temperature in the Arctic also controls permafrost thaw. It affects the amount of precipitation by controlling cloud cover, sea ice cover, rates of evaporation and these kinds of things,” Lehnherr says.

Changing weather patterns also affect how much methylmercury builds up in specific isolated areas and how efficiently it flows from one lake to the next, creating more widespread problems. In the short term, Lehnherr says it looks as though reduced emissions have not fully translated into cleaner Arctic ecosystems. However, Lehnherr says it should not necessarily be interpreted as a sign that efforts to reduce mercury aren’t worth it.

“I mostly think it validates the ongoing efforts to reduce anthropogenic mercury emissions,” he says. “Countries have shown this is something they’re willing to take on. These results allow us to have reasonable expectations about how long it will take for mercury levels to go down and stabilize.”

Lehnherr also wants to reassure people in northern communities who may be concerned about the safety of their food supply.

“Whenever I talk about the risks of mercury and negative health impacts, I always stress that the benefits of consuming traditional foods vastly outweigh the risks of contaminants. Locally caught Arctic char has better nutritional value than dried goods and flown-in goods,” he says.

Lehnherr plans to continue his study of methylmercury in the Arctic region to get a better sense of the long-term impacts of climate change.

Ice arches holding Arctic's ‘Last Ice Area’ in place are at risk, �Թϱ�� researcher says

Christopher.Sorensen — Tue, 05 Jan 2021 14:21:49 +0000

Ice arches holding Arctic's ‘Last Ice Area’ in place are at risk, �Թϱ�� researcher says

Christopher.Sorensen Tue, 01/05/2021 - 09:21

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Sea ice in the Nares Strait as seen from a NASA P-3B turboprop during a 2013 survey flight (photo by Christy Hansen/NASA)

Topic

Research & Innovation

�Թϱ�� Mississauga

Snugged up against the upper edges of the Canadian Arctic Archipelago and Greenland lies the oldest and thickest sea ice in the world, covering hundreds of thousands of square kilometres of ocean. Arctic sea ice grows and shrinks with the seasons, but this ice has so far lasted even through the warmest summers on record.

Scientists call this region “The Last Ice Area.” They say it could endure even after the rest of the Arctic becomes ice-free in the warmer months, providing a vital refuge for polar bears, walruses and other species that rely on sea ice to survive.

But recent research at the University of Toronto Mississauga suggests the Last Ice Area may be in more peril than previously thought. In a recent paper published in the journal Nature Communications, Professor Kent Moore and his co-authors describe how this multi-year ice is at risk not just of melting in place, but of floating southward into warmer regions. This, in turn, would create an “ice deficit” and hasten the disappearance of the Last Ice Area.

“This very old ice is what we’re concerned about,” says Moore, who is in �Թϱ�� Mississauga’s department of chemical and physical sciences. “The hope is that this area will persist into the middle part of this century or even longer. And then, hopefully, we'll eventually be able to cool the planet down. The ice will start growing again, and then this area can act as a sort of seed,”

Using satellite data, Moore has been studying ice arches that form along Nares Strait, a 40-kilometre-wide, 600-kilometre-long channel that runs between Greenland and Ellesmere Island from the Arctic Ocean into Baffin Bay.

Moore had already observed warning trends in earlier research that indicated this ice is increasingly on the move.

“The Last Ice Area is losing ice mass at twice the rate of the entire Arctic,” Moore says. “We realized this area may not be as stable as people think.”

His most recent analysis of satellite data says the problem may be getting even worse. The arches along Nares Strait that historically have held the Last ice Area in place have become less stable, according the study.

“The ice arches that usually develop at the northern and southern ends of Nares Strait play an important role in modulating the export of Arctic Ocean multi-year sea ice,” he and his authors write.

“The duration of arch formation has decreased over the past 20 years, while the mass of ice exported through Nares Strait has increased.”

The ice arches form as the weather cools. Multiple ice floes converge as they funnel into the relatively narrow strait, forming huge structures that look like bridge supports turned on their sides. The arches span the full width of the passage, blocking the movement of multi-year ice from north to south.

“It's really quite profound to imagine a 100-kilometre-long barrier of ice that remains stationary for months at a time. That's more than twice as long as Louisiana’s Lake Pontchartrain Causeway – the world’s longest continuous bridge over water,” Moore says. “It speaks to the strength of ice.”

But that strength is diminishing. Ice arches only form for part of the year. When they break up in the spring, ice moves more freely down the Nares Strait. And that breakup is happening sooner than in the past.

“Every year, the reduction in duration is about one week,” Moore says. “They used to persist for about 200 days and now they’re persisting for about 150 days. There’s quite a remarkable reduction.

“We think that it’s related to the fact the ice is just thinner and thinner ice is less stable.”

The impact of losing the Last Ice Area would extend far beyond photogenic species like polar bears. Ice algae flourishes below the ice and in brine channels that run through its cracks and fissures, supplying carbon, oxygen and nutrients that underpin an elaborate but vulnerable ecosystem.

In 2019, the Canadian government designated a section of the Last Ice Area as the Tuvaijuittuq Marine Protected Area. Tuvaijuittuq is Inuktut for “the place where the ice never melts.”

Moore remains hopeful that his analysis of the Nares Strait ice arches will focus more attention on this important region of the Arctic. However, he says action targeted specifically at preserving the arches won’t be sufficient to solve the problem. A global solution is needed.

“The scale is so huge and the region is so remote,” he says. “The only thing we can do is cool the planet down. Then the arches will hopefully naturally form again.”

Inset: Images of the ice arch that formed at the southern end of Nares Strait in 2020. The upper image shows the arch holding back the ice while the lower image shows the ice streaming southwards after the arch collapses (Sentinel-2 satellite imagery courtesy of the European Space Agency)

Virginia Isaac, a �Թϱ�� Social Work grad, is helping Nunavut residents quarantine during COVID-19

Christopher.Sorensen — Tue, 17 Nov 2020 14:31:58 +0000

Virginia Isaac, a �Թϱ�� Social Work grad, is helping Nunavut residents quarantine during COVID-19

Christopher.Sorensen Tue, 11/17/2020 - 09:31

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Virginia Isaac, who is graduating with a master's degree in social work, is currently supporting Nunavut residents who must quarantine at an isolation centre in Ottawa before returning to the territory (photo by Dale Duncan)

Topic

Factor-Inwentash Faculty of Social Work

Nunavut

Virginia Isaac, a community social worker with the Government of Nunavut, is working out of Ottawa these days as she supports returning residents who must complete a 14-day quarantine in the territory’s isolation hubs.

The isolation hubs, which also exist in Winnipeg, Edmonton and Yellowknife, serve as entry points to Nunavut and have played a key role in helping it avoid the first wave of COVID-19.

Yet, while the strategy has been successful – the territory’s first case was identified Nov. 6 – Isaac says the experience can take its toll on residents.

“My job is to welcome new guests to the hubs, help them with their adjustment to quarantine, and do whatever I can to ease their stress during their stay,” Isaac says. “Isolation can be difficult, whether you’re travelling alone or managing the pressures of having your spouse and children living together in one room.”

Isaac, who is graduating this fall from the University of Toronto’s master of social work program in the Factor-Inwentash Faculty of Social Work, does daily check-ins to monitor guests’ needs, which include meals that cater to their cultural and dietary requirements, safety, support and mental health services. Guests at the isolation hubs are reminded to adhere to public heath regulations, which include wearing a mask, practising social distancing, staying in their bubble and washing their hands frequently.

“When people are struggling with the demands of quarantine, I remind them that they’re making a positive contribution to preventing the spread of the virus,” Isaac says. “Remembering the broader value and purpose of their sacrifice often helps.”

As for her own safety, Isaac also takes a big-picture perspective.

“I’m very proud to be among those making a difference in people’s lives during the pandemic,” she says.

Isaac says her education and experience have served her well in her current role. As an advanced standing student, she pursued the faculty’s social justice and diversity field of study.

“A central emphasis in the program is recognizing clients’ unique life experiences and treating them as equal partners,” she says. “This is the way I approach my relationship with every new guest at the hub.”

Isaac was a social worker with the Government of Nunavut for more than six years before studying for her master’s degree at �Թϱ��. When she arrived in the territory in 2012, it was her first time in Canada’s Arctic. “It was a bit shocking at first in terms of the vast and untamed landscape,” she says. “But I took the time to get to know the culture and traditions of the Inuit, and their close relationship to the land.”

She says she soon saw similarities with her own childhood on the Caribbean island of Saint Lucia, where people in her rural village also have strong ties to their surroundings.

Isaac was a teenager when she immigrated to Toronto, which she now considers home. But she spent several years in British Columbia studying, working and vounteering with an intercultural and immigrant aid society – work that inspired her to becoming a social worker. There, she forged strong connections with local Indigenous communities. Before moving to British Columbia, Isaac worked for several years in health care in Toronto.

“I’ve always had a strong interest in learning about and working with Indigenous Peoples in Canada,” she says. “My own experience as a Black woman and that of my ancestors is very parallel in terms of marginalization, poverty, discrimination and stigma.”

For her master of social work practicum, Isaac worked at a community organization serving the Black community in Toronto, where many of the clients were coping with such issues.

Isaac is not sure what she’ll do once the isolation hubs are no longer needed. But she says the uncertainty doesn’t bother her.

“My ambitions are many, but wherever I am and whoever I’m working with, I approach things with an open mind and a passion for helping people.”

�Թϱ�� researchers, students travel to high Arctic to conduct atmospheric research

Christopher.Sorensen — Mon, 28 Sep 2020 15:46:58 +0000

�Թϱ�� researchers, students travel to high Arctic to conduct atmospheric research

Christopher.Sorensen Mon, 09/28/2020 - 11:46

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The PEARL Ridge Lab is located on Ellesmere Island at Eureka, Nunavut, about 1,100 kilometres from the North Pole (photo by Ramina Alwarda)

Ellen Eckert

Topic

Our Community

Arctic

Faculty of Arts & Science

Physics

Research & Innovation

Ellen Eckert is a post-doctoral researcher in the Faculty of Arts & Science’s department of physics and a member of the department’s Earth, atmospheric and planetary physics group. Below she shares a first-person account of what it was like to conduct research at the Polar Environment Atmospheric Research Laboratory (PEARL).

For just over two decades, students and post-doctoral researchers working with the University of Toronto’s Kimberly Strong and Kaley Walker have traveled to Eureka, Nunavut, in the Canadian High Arctic each spring to make unique measurements of atmospheric trace gases.

Strong is chair of the department of physics and Walker is a professor in the department. Together with department colleagues and researchers from Dalhousie University and York University, the team had another extraordinary opportunity last winter to work at the Polar Environment Atmospheric Research Laboratory (PEARL).

The three-week campaign yielded valuable measurements obtained using a wide variety of instruments. The measurements are used to validate data gathered by satellites and to investigate a variety of atmospheric phenomena. This year, the team observed record low levels of Arctic ozone and is currently analyzing these results to understand why conditions were so different.

But why go to this remote location? At 80 degrees north, PEARL is 1,100 kilometres from the North Pole. And why at this time of the year when temperatures can plunge to -50 C before windchill?

At the 80 degrees north sign on the way from Eureka to PEARL (photo by Pierre Fogal)

PEARL is in a sweet spot for atmospheric research for several reasons: it is located in an area of the world that is crucial for understanding the global atmosphere; and there are no other stations anywhere nearby, meaning there’s a lack of data for polar regions.

Another reason is that satellites like the Canadian-led Atmospheric Chemistry Experiment frequently pass over this area, so data collected during these campaigns can be used to make sure the satellites are working properly.

Ice crystals in the atmosphere result in spots of light on either side of the sun, a phenomenon known as a sun dog (photo by Ellen Eckert)

Also, campaigns at this time of year coincide with the transition between the season in which the sun never rises to the season in which it never sets. This transition only takes about seven weeks at Eureka. Since some of the instruments operate at night and some need sunlight to operate, this time of year is ideal for comparisons between the different instruments to determine if there are biases between their measurements.

Team members joined PEARL site manager Pierre Fogal in the radio room (photo by Ramina Alwarda)

This year’s team included myself, graduate students Ramina Alwarda, Kristof Bognar, Beatriz Herrera Gutierrez and Tyler Wizenberg, as well as post-doctoral researcher Ali Jalali – all from the department of physics. They were joined by �Թϱ�� senior research associate and PEARL site manager Pierre Fogal, operator John Gallagher, research associate Alexey Tikhomirov from Dalhousie and Professor Emeritus Tom McElroy from York University.

When the team arrived at Eureka this year, the sun was only above the horizon for about two hours. When they left, daylight hours had exceeded nine hours. The team lived at Environment and Climate Change Canada’s Eureka Weather Station, where they enjoyed the hospitality of the permanent staff, amazing food and recreational activities.

To do their research, the team drove about 20 to 25 minutes to the PEARL Ridge Laboratory each day, weather permitting, to take measurements. They also performed maintenance and repair tasks when necessary. This work can be interrupted by poor weather such as storms, so the team had to always be aware of the meteorological conditions.

Working in the high Arctic is challenging but very rewarding. Frigid temperatures mean that seemingly simple tasks such as tightening screws and adjusting components need to be done quickly and carefully, with fingers well protected.

The cold takes its toll on the instruments, but the lab is well stocked with tools and spare parts so things can often be fixed on site. On rare occasions, specific spare parts are shipped north and instruments are sometimes brought south for major repairs.

This year’s campaign was a success, as the team was able to get all the instruments running and to keep them collecting data that will provide insight into Arctic atmospheric phenomena. In addition to measuring ozone, the team also monitored atmospheric trace gases associated with ozone destruction, which allows them to better understand the chemical and dynamic processes behind the event.

The team encountered several members of the local wildlife community during this year’s trip (photos by Ellen Eckert, Guillaume Gamache and Ramina Alwarda)

Visiting Eureka is a unique and fantastic experience – not only for the scientific research, but also for the mind-blowing scenery and the wildlife. This year, the team was lucky to encounter a couple of foxes close to the Ridge Laboratory, a musk ox that had made itself comfortable around the Eureka weather station and even a pack of wolves that strolled by the station on the last day of the campaign.

Predator loss, climate change combine to devastate Alaskan reefs: �Թϱ�� study

Christopher.Sorensen — Thu, 17 Sep 2020 15:40:39 +0000

Predator loss, climate change combine to devastate Alaskan reefs: �Թϱ�� study

Christopher.Sorensen Thu, 09/17/2020 - 11:40

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Massive reefs, built slowly over centuries to millennia, are now rapidly eroding because of overgrazing by sea urchins amid predator loss and climate change (photo by J. Tomoleon)

Topic

Alaska’s living reefs – which house an entire ecosystem – are collapsing thanks to climate change and the disappearance of sea otters, new research published in the journal Science reveals.

Weakened by warming waters and increased acidity, the centuries-old reefs are being ground down by sea urchins, whose population has exploded following the functional extinction of their predator, the Aleutian sea otter.

“It’s basically a top down relationship,” says Jochen Halfar, a paleoclimate and paleontology professor at the University of Toronto Mississauga who studies sea floor algae and was one of the study’s authors.

He says that, with the loss of their original food source due to hunting, orcas now prey on sea otters, seals and other smaller marine animals. The adaptation has, in turn, led to the removal of sea otters from the system and their main food source – sea urchins – are now proliferating unchecked.

“It’s amazing the amount of sea urchins on the sea floor,” Halfar says, noting there were sometimes layers of urchins stacked on the seabed when he was diving. “I had to use knee pads to get down to the sea floor so the sea urchins wouldn’t puncture my dry suit.”

Bioeroded alga with numerous sea urchins of different sizes grazing on the dead tissue (photo by Jochen Halfar)

Sea urchins prefer to eat kelp, but with so many dining on the once-abundant underwater forests, they’ve had to turn to an alternate food source: the coralline algae that form the reef.

Attached to the sea floor, the algae grow over thousands of years, one calcified layer after another, much like tree rings, with the living tissue on the surface. Halfar says the massive reef-like structures cover the Aleutian sea floor at a depth of between 10 to 30 metres.

This isn’t the first time the sea otter population has plummeted and sea urchin numbers have spiked. Halfar explains that, during the fur trade in the late 1700s and early 1800s, sea otters were hunted almost to extinction. By 1840 the population had declined so much that hunting them was no longer economical.

Yet, the reefs were nevertheless able to hold their ground against the urchins.

What makes the loss of sea otters so devastating this time around are changes to water temperature and acidity.

Oceans are warming and, according to Halfar, the acidity is rising with increased concentrations of carbon dioxide from burning fossil fuels.

To test the impact of temperature and acidification, the researchers put live algae and urchins in controlled environments that replicated preindustrial and current seawater conditions, plus those expected at the end of the century. Halfar says they found that the density of the calcified algae skeleton decreased and the urchin bites were deeper with higher levels of C02 in the water.

“The sea urchins, which might not have been able to attack the algae so easily maybe 50 years ago when it was colder and less acidic, are now able to inflict deeper bites,” Halfar says.

Experiments were performed to test how climate change has altered the intensity of sea urchins grazing on algae (photo by D. Rasher)

He explains that algae are built for grazing. They are able to repair their wounds and regenerate tissue. But if the bites are deep, large or numerous, the algae can’t heal.

Researchers found that lethal grazing under current conditions was about 35 per cent to 60 per cent greater than in preindustrial conditions. The rates grew by an additional 20 per cent to 40 per cent under future conditions. The results confirm that climate change has recently allowed urchins to breach the algae’s defences, pushing the system beyond a critical tipping point.

“You get what’s called bioerosion,” Halfar explains. “The entire surface of the algae is eroded and the algae ultimately die.”

The coralline algae play a vital role in the Aleutian Islands’ marine ecosystem. Different species depend on the algae substrate to live in, find shelter and reproduce.

“These structures house millions of organisms. If these reefs disappear, we’re changing the entire ecosystem – bottom up,” Halfar says.

An end of whaling could see orca shift back to their original diet, leading to the return of sea otters, which would help reduce sea urchin populations and mitigate the bioerosion that’s taking place.

That, however, is only part of the puzzle.

“Obviously temperatures are going to keep increasing,” Halfar says. “And as long as we use fossil fuels, acidity is going to keep on increasing.”

The research was funded by the U.S. National Science Foundation and the Natural Sciences and Engineering Council of Canada.

The unexpected link between the ozone hole and Arctic warming: �Թϱ�� expert

Christopher.Sorensen — Wed, 19 Feb 2020 14:59:47 +0000

The unexpected link between the ozone hole and Arctic warming: �Թϱ�� expert

Christopher.Sorensen Wed, 02/19/2020 - 09:59

Cutline

Temperatures are warming faster in the Arctic than anywhere else in the world. Water and sewer pipes in Iqaluit, Nunavut, are cracking during the winter as the ground shifts (photo by Sean Kilpatrick/CP)

Karen Smith

Topic

Our Community

Physical and Environmental Sciences

One of the earliest climate model predictions of how human-made climate change would affect our planet showed that the Arctic would warm about two to three times more than the global average. Forty years later, this “Arctic amplification” has been observed first-hand.

Record-breaking Arctic warming and the dramatic decline of sea ice are having severe consequences on sensitive ecosystems in the region.

But why has the Arctic warmed more than the tropics and the mid-latitudes?

We now know that this is due, in part, to tiny concentrations of very powerful greenhouse gases, including ozone-depleting substances such as chlorofluorocarbons (CFCs).

A wonder gas?

The ozone layer is the protective layer in the stratosphere, roughly 20-50 kilometres above the Earth, that absorbs harmful ultraviolet radiation from the sun. Ozone-depleting substances are potent greenhouse gases, but they are more commonly known for their devastating effect on the ozone layer.

These chemicals were invented in the 1920s. They were touted as “wonder gases” and used as refrigerants, solvents and propellants in refrigerators, air conditioners and packing materials. It wasn’t until the 1980s when scientists discovered a hole in the ozone layer above Antarctica that they realized the full extent of the ozone-depleting nature of these chemicals.

In 1987, 197 countries agreed to phase out their use of ozone-depleting substances by ratifying the Montréal Protocol. The success of this historic international agreement has reduced the emissions of CFCs to nearly zero; however, the recovery of the ozone hole has been slower as CFCs remain in the atmosphere for decades.

Due to the effect of ozone-depleting substances on the ozone layer, climate scientists who study these chemicals and their climate impacts have been focused on the consequences of ozone depletion. The climate impact of ozone-depleting substances themselves has been typically considered small given the very tiny concentrations of these gases in the atmosphere, and has been largely unexplored.

Experimenting with climate models

My colleagues and I were interested in understanding how ozone-depleting substances might have influenced late-20th century warming from 1995 to 2005. We specifically chose this time period in order to capture the rapid rise in ozone-depleting substances in the atmosphere over this time. Since the early 2000s, atmospheric concentrations have been declining.

One way that climate scientists approach problems like this one is to use computer models of the Earth to understand what the effects of different phenomena, such as volcanic eruptions and greenhouse gases such as methane, might have on air temperatures, ocean circulation patterns, rainfall and so on.

A snowmobiler navigates the ice near Iqaluit, Nunavut (photo by Sean Kilpatrick/CP)

To explore the contribution of ozone-depleting substances to late-20th century warming, we ran a climate model over the period from 1955 to 2005. One of the simulations incorporated all of the various historical climate drivers – those that warm the climate, like carbon dioxide, methane, nitrous oxide and ozone-depleting substances, and those that cool the climate, like volcanic particulate matter. The second simulation had all the historical climate drivers, except the ozone-depleting substances.

This is one of the first times the role of ozone-depleting substances had been isolated. Typically, climate model experiments that examine the roles of different climate drivers will lump all greenhouses gases together.

Comparing the two model simulations revealed that global warming was reduced by a third and Arctic warming by half when the ozone-depleting substances were not included in our simulation.

Arctic amplification

Why do ozone-depleting substances have such a large impact despite their very small atmospheric concentrations? First, these chemicals are very potent greenhouse gases, a fact that we have known for a long time. Second, in the late-20th century, warming from carbon dioxide was partially cancelled out by the cooling that comes from particulate matter in the atmosphere, allowing CFCs and other ozone-depleting substances to contribute substantially to warming.

Finally, when it comes to Arctic amplification, we know that this phenomenon arises from feedbacks within the climate system that act to enhance warming, and this is exactly what we find in our model simulations. In the simulation without ozone-depleting substances, the climate feedbacks were weaker than in the simulation with them, resulting in less Arctic amplification.

Climate warming could extend the growing season in Nuuk, Greenland, by two months by the end of the 21st century (photo by David Goldman/AP)

Understanding why the feedbacks differ is the aim of our future research but, in the meantime, our work clearly demonstrates the significant impact of ozone-depleting substances on Arctic climate.

Thirty years ago, those who signed the Montréal Protocol were not thinking about climate change. Yet, research such as ours underscores the important role this agreement will play in mitigating future warming as the concentrations of ozone-depleting substances decline over time.

That said, without massive reductions in carbon dioxide emissions in the coming decades, the gains we will achieve through the Montréal Protocol will be quickly overwhelmed. Further action is needed to protect the Arctic – and our planet.

Karen Smith is an assistant professor, teaching stream, in the department of physical and environmental sciences at the University of Toronto Scarborough.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Substances that created hole in ozone may account for half of Arctic warming, �Թϱ�� researchers find

Christopher.Sorensen — Mon, 20 Jan 2020 18:08:04 +0000

Substances that created hole in ozone may account for half of Arctic warming, �Թϱ�� researchers find

Christopher.Sorensen Mon, 01/20/2020 - 13:08

Cutline

While fears over ozone depletion were initially associated with potential increases in skin cancer, researchers say the compounds have also proven to be a significant contributor to climate change (photo by Jan Sieminski via Getty Images)

Don Campbell

Topic

Breaking Research

Physical and Environmental Sciences

Arctic

Climate Change

Global

Research & Innovation

Sustainability

The substances responsible for creating a massive hole in the Earth’s ozone layer may account for nearly half of Arctic warming over a 50-year period, according to a new study by researchers at the University of Toronto.

The research, published in Nature Climate Change, highlights how ozone-depleting substances (ODS) are a significant and unrecognized source of 20^th-century Arctic climate change.

“Ozone depleting substances in many respects have been an under-appreciated contributor to climate change,” says Karen Smith, an assistant professor, teaching stream, in the department of physical and environmental sciences at �Թϱ�� Scarborough and one of the authors of the study.

“These are potent greenhouse gases that stay in the atmosphere for a long time, and there’s still a lot we don’t know about their broader impact on climate.”

The compounds in question eat away at the protective layer of ozone located in the Earth’s upper atmosphere. They were commonly used throughout most of 20th century in refrigerants, solvents and propellants like those found in hairsprays.

Karen Smith, a researcher at �Թϱ�� Scarborough, says ozone-depleting substances are “potent greenhouse gases that stay in the atmosphere for a long time” (photo by Don Campbell)

Smith, along with colleagues at Columbia University, including lead author Lorenzo Polvani, used a climate model to estimate what amount of warming can be attributed to ODS. They ran two separate simulations – one with natural and human emissions measured from 1955 to 2005, and another with ODS and their ozone impacts removed.

“We found that ODS may have caused about half of Arctic warming and sea ice loss during that period,” says Smith, whose research focuses on climate variability in the polar regions.

Out of the four main sources of human-made greenhouse gas emissions – carbon dioxide, nitrous oxide, methane and ODS – ODS ranked second behind only carbon dioxide in terms of its contribution to climate change during the 50-year period. ODS emissions have been reduced dramatically thanks to the 1987 Montreal Protocol banning their use, and as a result the ozone layer has slowly been recovering.

While fears over ozone depletion were initially associated with potential increases in skin cancer and other biological effects, Smith says there have since been discoveries about how these substances contribute to climate change.

Smith, who received a grant from the National Science Foundation (NSF) for her research, says an important next step is explore the mechanisms behind how ODS amplify Arctic warming despite their very low atmospheric concentrations compared to other greenhouse gases.

“The focus of greenhouse gas emissions and their contribution to climate change has been on carbon dioxide, and rightfully so based on concentration,” says Smith, who is the director of the master of environmental science climate change impacts and adaptation program.

“In terms of the global average, ODS do not play as big of a role as carbon dioxide in causing global warming, but in Arctic regions we see about double the warming.”

If there is a silver lining, Smiths says the decline in ODS could be a good news story for climate change.

“Thanks to the Montreal Protocol, ODS emissions have been dramatically reduced and their atmospheric concentrations are decreasing, so the phasing out of these chemicals will help mitigate future Arctic warming and sea ice loss.”

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The unexpected link between the ozone hole and Arctic warming: �Թϱ��� expert

A wonder gas?

Experimenting with climate models

Arctic amplification

Substances that created hole in ozone may account for half of Arctic warming, �Թϱ��� researchers find

�Թϱ�� grad student tracks 70 years of snow and ice data in the High Arctic

Climate change slows reduction of methylmercury levels in Arctic: �Թϱ�� researchers

Ice arches holding Arctic's ‘Last Ice Area’ in place are at risk, �Թϱ�� researcher says

Virginia Isaac, a �Թϱ�� Social Work grad, is helping Nunavut residents quarantine during COVID-19

�Թϱ�� researchers, students travel to high Arctic to conduct atmospheric research

Predator loss, climate change combine to devastate Alaskan reefs: �Թϱ�� study

The unexpected link between the ozone hole and Arctic warming: �Թϱ�� expert

Substances that created hole in ozone may account for half of Arctic warming, �Թϱ�� researchers find