Physical and Environmental Sciences

Canadian Institute for Theoretical Astrophysics

Astronomy

Astrophysics

Climate Change

Faculty of Arts & Science

Physics

Subheadline

An atmospheric tide driven by the sun countered the effect of the moon, astrophysicists say

A team of astrophysicists from the ��߲ݴ�ý has revealed how the slow and steady lengthening of Earth’s day caused by the tidal pull of the moon was halted for over a billion years.

They show that from approximately two billion years ago until 600 million years ago, an atmospheric tide driven by the sun countered the effect of the moon, keeping Earth’s rotational rate steady and the length of day at a constant 19.5 hours.

Without this billion-year pause in the slowing of our planet’s rotation, our current 24-hour day would stretch to over 60 hours.

Drawing on geological evidence and using atmospheric research tools, the scientists show that the tidal stalemate between the sun and moon resulted from the incidental but consequential link between the atmosphere’s temperature and Earth’s rotational rate.

The study was published in the journal Science Advances.

The paper’s authors include Professor Norman Murray, a theoretical astrophysicist with the Faculty of Arts & Science’s Canadian Institute for Theoretical Astrophysics (CITA); graduate student Hanbo Wu, with CITA and the department of physics; Kristen Menou, associate professor in the David A. Dunlap department of astronomy and astrophysics and the department of physical and environmental sciences at U of T Scarborough; Jeremy Leconte, a CNRS researcher at the Laboratoire d’astrophysique de Bordeaux and a former CITA postdoctoral fellow; and Christopher Lee, assistant professor in the department of physics.

Murray and his collaborators relied on geologic evidence in their study, like these samples from a tidal estuary that reveal the cycle of spring and neap tides. Thick bands correspond to spring tides, and thin bands to neap tides (image by G.E. Williams)

When the moon first formed some 4.5 billion years ago, the day was less than 10 hours long. But since then, the moon’s gravitational pull on the Earth has been slowing our planet’s rotation, resulting in an increasingly longer day. Today, it continues to lengthen at a rate of some 1.7 milliseconds every century.

The moon slows the planet’s rotation by pulling on Earth’s oceans, creating tidal bulges on opposite sides of the planet that we experience as high and low tides. The gravitational pull of the moon on those bulges, plus the friction between the tides and the ocean floor, acts like a brake on our spinning planet.

“Sunlight also produces an atmospheric tide with the same type of bulges,” says Murray. “The sun's gravity pulls on these atmospheric bulges, producing a torque on the Earth. But instead of slowing down Earth’s rotation like the moon, it speeds it up.”

For most of Earth’s geological history, the lunar tides have overpowered the solar tides by about a factor of ten – hence the Earth’s slowing rotational speed and lengthening days.

But some two billion years ago, the atmospheric bulges were larger because the atmosphere was warmer and because its natural resonance – the frequency at which waves move through it – matched the length of day.

The atmosphere, like a bell, resonates at a frequency determined by various factors, including temperature. In other words, waves – like those generated by the enormous eruption of the volcano Krakatoa in Indonesia in 1883 – travel through it at a velocity determined by its temperature. The same principle explains why a bell always produces the same note if its temperature is constant.

Throughout most of Earth’s history that atmospheric resonance has been out of sync with the planet’s rotational rate. Today, each of the two atmospheric “high tides” take 22.8 hours to travel around the world. Since that resonance and Earth’s 24-hour rotational period are out of sync, the atmospheric tide is relatively small.

But during the billion-year period under study, the atmosphere was warmer and resonated with a period of about 10 hours. Also, at the advent of that epoch, Earth’s rotation – slowed by the moon – reached 20 hours.

When the atmospheric resonance and length of day became even factors (ten and 20), the atmospheric tide was reinforced, the bulges became larger and the sun’s tidal pull became strong enough to counter the lunar tide.

“It’s like pushing a child on a swing,” Murray says.

“If your push and the period of the swing are out of sync, it’s not going to go very high. But, if they’re in sync and you’re pushing just as the swing stops at one end of its travel, the push will add to the momentum of the swing and it will go further and higher. That’s what happened with the atmospheric resonance and tide.”

Along with geological evidence, Murray and his colleagues achieved their result using global atmospheric circulation models (GCMs) to predict the atmosphere’s temperature during this period. The GCMs are the same models used by climatologists to study global warming. Murray says the fact they worked so well in the team’s research is a timely lesson.

“I've talked to people who are climate-change skeptics who don't believe in the global circulation models that are telling us we’re in a climate crisis,” he says. “And I tell them: We used these global circulation models in our research, and they got it right. They work.”

Despite its remoteness in geological history, the result adds additional perspective to the climate crisis. Because the atmospheric resonance changes with temperature, Murray points out that our current warming atmosphere could have consequences in this tidal imbalance.

“As we increase Earth's temperature with global warming, we’re also making the resonant frequency move higher – we’re moving our atmosphere farther away from resonance. As a result, there's less torque from the sun and therefore the length the day is going to get longer – sooner than it would otherwise.”

Award-winning science student – who started university at 13 – graduates from U of T Scarborough

siddiq22 — Tue, 06 Jun 2023 20:33:44 +0000

Award-winning science student – who started university at 13 – graduates from U of T Scarborough

siddiq22 Tue, 06/06/2023 - 16:33

Cutline

Charlotte Wargniez, 17, is a new graduate and this year's recipient of the Rose Sheinin Award, given to the highest performing woman student in science across U of T’s three campuses (photo by Chai Chen)

Alexa Battler

Topic

Convocation 2023

Subheadline

Now a sustainability advocate, Charlotte Wargniez was inspired to switch her major to environmental geoscience after taking a first-year geology course

Charlotte Wargniez’s rapid academic climb – one that will see her graduate from the ��߲ݴ�ý Scarborough this month at just 17 – began the day she broke her leg.

When she was 10, Wargniez was a competitive skier with a packed schedule – eight hours on the slopes and one hour studying – until a fall left her in bed with nothing to do but learn.

She had been homeschooled all her life through virtual education – a necessity for her family as they bounced around the world every summer, spending six months travelling across the United States, India, Malaysia and Mexico, then living in ski resorts for the rest of the year.

“I got really eager to learn in that time,” says Wargniez. "My parents gave me this legacy to be open-minded to new theories, experiences, ideas and perspectives.”

Her school’s online curriculum let her go at her own pace, and within three months she had finished eighth-grade math – four grades ahead of her age bracket. She took an entrance exam to enrol in a French virtual high school and from then on completed a grade per year.

Wargniez graduated high school at age 13 and was soon enrolled at U of T Scarborough for neuroscience – she’d watched her brother grow up with Epidermolysis bullosa simplex, a genetic condition that made his skin extremely fragile, and picked her program accordingly.

“It made me want to go into medicine, because I saw people like my brother and I really wanted to help them,” she says.

After studying environmental geoscience, Wargniez became a staunch proponent of sustainability (submitted photo)

Her academic goals shifted after a first-year geology course taught by Nick Eyles, former professor of geology in U of T Scarborough's department of physical and environmental sciences (DPES). She says a fascination with the Earth had been brewing after visiting almost every national park in America – and the course inspired her to embrace that interest. She switched her major to environmental geoscience and never looked back.

“I’d wanted to go to medical school to help people, but then I realized how much of what’s happening in the world is about climate change,” she says. “I realized I could also help people through environmental geoscience.”

Eyles became a mentor to Wargniez, teaching several of her courses and enjoying chats during office hours.

“She’s exceptional – not just academically, but in being a competitive skier and the breadth of experience she has,” Eyles says. “It was a real pleasure to work with her. I think she’s got a fantastic future – students like her are why you teach.”

Environmentalism was the cornerstone of Wargniez's extracurricular life too – largely through Regenesis UTSC, a student group dedicated to creating and raising awareness of environmental and sustainability initiatives. She led the team as co-president to revive U of T Scarborough’s free store and create a bike-sharing centre on campus – projects that won Adams Sustainability Grants from U of T.

She also became vice-president of academic affairs with the Environmental and Physical Science Students’ Association, a group that works with the department to host programming, outreach, tutoring and field trips.

Wargniez says starting university so young didn’t present many challenges during her undergraduate experience. While the pandemic hit during her first year, she still made lasting friendships while living on campus and partook in research projects.

She says she did sometimes feel the need to hide her age – particularly from students when she became a teaching assistant. She notes that many of the people she connected with at university may only learn how young she is by reading articles such as this one.

Wargniez is the first and only student to graduate with U of T Scarborough’s new minor in applied climatology. She was also this year’s recipient of the Rose Sheinin Award, given to the highest-performing woman student in science across U of T’s three campuses, and received a DPES excellence and leadership award.

In the fall, she’ll head to the University of Oxford to pursue a master’s of science in sustainability, enterprise and the environment, a unique program examining how businesses and organizations can reach net-zero carbon emissions.

“I think she’s just the sort of person we need in the realm of policymaking for environmental problems and issues – someone who has a thorough understanding of science, how the world works, is experienced, has met a lot of people and has that discipline,” Eyles says.

As she looks to the future, Wargniez has no specific career path in mind yet, just a resolve to create change – and plans to join Oxford’s ski team.

“I want to keep my mind open to anything that will come,” she says. “I know how I want to impact this world, and whatever I find that will work best for me, I’ll take it.”

Pollution disrupts water fleas' 'chemical conversations,' disrupts food chain: U of T study

Christopher.Sorensen — Tue, 09 Mar 2021 15:31:38 +0000

Pollution disrupts water fleas' 'chemical conversations,' disrupts food chain: U of T study

Christopher.Sorensen Tue, 03/09/2021 - 10:31

Cutline

A new study by U of T Scarborough's Myrna Simpson shows how low levels of pollution can disrupt communication, via "info-chemcials," between water fleas and other species (photo by iStockPhoto via Getty Images)

Topic

Environmental Science

Researchers at the ��߲ݴ�ý have shown that pollution can disrupt the “chemical conversations” water fleas rely on to communicate with other species.

Daphnia, more commonly known as water fleas, live in all sorts of aquatic environments – from swamps to freshwater lakes and ponds. They’re crucial to the aquatic food chain, feeding on algae, while also serving as food for insects, water mites and small fish.

The water fleas navigate by releasing bio-molecules, or info-chemicals, that interact with other species, helping them detect prey or potential mates.

“It’s these info-chemicals that species use to communicate with each other – they’re basically like messengers,” says Myrna Simpson, a professor of environmental science in U of T Scarborough's department of physical and environmental sciences and associate director of the Environmental NMR Centre.

It’s been thought that “chemical conversations” between species are disrupted when one of the species is affected by pollution. But a new study by Simpson and former post-doctoral student Tae-Yong Jeong, now an assistant professor at Hankuk University of Foreign Studies in Seoul, that was recently published in the journal Environmental Science & Technology documents the first time this disruption between two species has been observed because of exposure to such low levels of pollution.

The study found that info-chemicals between water fleas and algae could be disrupted by a small amount of fenoxycarb (200 nanograms per one litre of water), which is a type of pesticide. Fenoxycarb is also an endocrine disruptor – a chemical that can mimic or disrupt hormones in the body – which is important because the endocrine system is believed to play an important role in producing info-chemicals in water fleas.

Simpson, a Canada Research Chair in Integrative Molecular Biogeochemistry, says the disruptions may cascade throughout the entire food web. If water fleas can’t reproduce or find food it means there will be less of them, she says, and fewer water fleas means less food for larger predators, but also more algae, which can lead to algae blooms that can harm fish and deteriorate water quality.

“Daphnia are an excellent indicator of aquatic ecosystem health,” says Simpson, whose research program focuses on the effect of environmental change in water and soil at the molecular level. “If they’re unhealthy, other organisms living in that ecosystem are also likely unhealthy as well.”

Simpson and Jeong developed a novel technique that relies on a powerful instrument called a tandem mass spectrometer to detect the info-chemical disruption. They pioneered the approach by using a method called metabolomics that’s able to detect rapid changes in tissues and cells almost instantaneously. This approach is both fast and highly sensitive to any stress or biochemical changes within an organism.

Simpson says the fact the info-chemicals of daphnia and algae were disrupted so quickly, and at such a low concentration of exposure, demonstrates that these pollutants may pose a greater ecological risk than is currently recognized. She adds that most water monitoring focuses on how relatively large amounts of a toxin will affect a water flea’s ability to reproduce.

“This shows we may need to look at things more broadly because there is this disruption taking place, and we know that these types of pollutants are commonly found in the environment at these low levels.”

The research, which received funding from U of T Scarborough’s Research Excellence Faculty Scholars award, offers the potential of developing a rapid way of assessing the health of an ecosystem.

Simpson says the overall goal is to create a framework where these novel techniques can be easily used in environmental monitoring programs.

“Currently, water pollution tests are time-consuming and they analyze only a certain number of pollutants,” Simpson says. “But there are many pollutants and by-products that are undocumented. By using metabolomics to study how daphnia are affected, it can offer a rapid way of assessing water quality through this critically important organism.”

Pregnant Inuit women exposed to higher levels of chemicals found in consumer products: U of T study

Christopher.Sorensen — Mon, 02 Nov 2020 17:16:39 +0000

Pregnant Inuit women exposed to higher levels of chemicals found in consumer products: U of T study

Christopher.Sorensen Mon, 11/02/2020 - 12:16

Cutline

A U of T study found that pregnant Inuit women had concentrations of PFAAs, found in non-stick coatings for cookware and cleaning products, that were twice as high as those in a representative sample of Canadian women (photo by Halfpoint via Getty Images)

Topic

Inuit

Pollution

Quebec

Pregnant women living in Nunavik in northern Quebec are increasingly being exposed to potentially harmful chemical compounds commonly found in consumer products.

This is one of the findings of new study by a group of Canadian researchers including Élyse Caron-Beaudoin, an assistant professor in the department of health and society and the department of physical and environmental sciences at the ��߲ݴ�ý Scarborough.

The study, published in the journal Environment International, focused on perfluroalkyl acids (PFAAs), which are used in a wide range of consumer products including non-stick coatings for cooking ware, water and stain repellents, food packaging, paints, cosmetics and cleaning products. It found that PFAA concentrations in pregnant Inuit women were twice as high as those in a representative sample of Canadian women.

“It’s an environmental injustice because people’s food in the Arctic is being contaminated by chemicals made far away from their homes,” says Caron-Beaudoin, an expert on toxicology as well as public and environmental health.

PFAAs do not biodegrade easily, and as a result, can persist for a long time in the environment. They can also be carried over long distances in the atmosphere and in oceans, where they accumulate in the tissues of living organisms in the Arctic food chain, according to Caron-Beaudoin.

She says that exposure to these compounds, including during fetal development, is associated with changes in hormonal, kidney, cardio-metabolic and immune function.

The study involved measuring changes in the concentration of PFAAs in the blood of 279 pregnant women living in the Nunavik region of northern Quebec from 2004 to 2017. The researchers found that one of the likely sources of PFAAs concentrations in the blood is the consumption of country foods, particularly marine wildlife.

Caron-Beaudoin says that many living in the north experience food insecurity and rely on the nutritional and cultural value provided by country foods, which make up the traditional Inuit diet.

“The benefit of consuming traditional foods still outweigh the negatives,” she says. “[But] we need adequate regulations that protect these country foods from harmful contaminants because these communities rely on them, especially pregnant women who need the nutritional value.”

While most PFAAs are regulated in North America, they do get imported by consumer products that contain them. The researchers found there’s been a drop in concentrations of legacy PFAAs – those banned by various international and North American treaties – but found that concentrations of long-chain PFAAs, which are more recent and can come from the degradation of other currently-used similar compounds such as Fluorotelomer alcohols (FTOHs), are on the rise.

“These long-chain PFAAs are even more persistent and have an even greater potential to accumulate in the food chain than the older PFAAs,” says Caron-Beaudoin.

Caron-Beaudoin says compounds like FTOHs not only travel long distances from their site of production, they also travel in consumer and industrial products that get imported into North America.

“It’s important to stay on top of this and make sure these new chemical compounds are tightly regulated as well,” she says.

The unexpected link between the ozone hole and Arctic warming: U of T expert

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

The unexpected link between the ozone hole and Arctic warming: U of T 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

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 ��߲ݴ�ý Scarborough.

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

U of T researchers turn McDonald's deep fryer oil into high-end 3D printing resin

Christopher.Sorensen — Thu, 30 Jan 2020 21:40:45 +0000

U of T researchers turn McDonald's deep fryer oil into high-end 3D printing resin

Christopher.Sorensen Thu, 01/30/2020 - 16:40

Cutline

Rajshree Biswas, a PhD student in the lab of U of T Scarborough Professor Andre Simpson, shows off biodegradable plastic butterflies made using a 3D printer and resin derived from McDonald's waste cooking oil (photo by Don Campbell)

Topic

3D Printing

Graduate Students

Researchers at the ��߲ݴ�ý Scarborough have, for the first time, turned waste cooking oil – from the deep fryers of a local McDonald’s – into a high-resolution, biodegradable 3D printing resin.

Using waste cooking oil for 3D printing has significant potential. Not only is it cheaper to make, the plastics made from it break down naturally unlike conventional 3D printing resins.

“The reasons plastics are a problem is because nature hasn’t evolved to handle human-made chemicals,” says Andre Simpson, a professor at U of T Scarborough’s department of physical and environmental sciences who developed the resin in his lab.

“Because we’re using what is essentially a natural product – in this case fats from cooking oil – nature can deal with it much better.”

The plastic butterfly printed from the researchers’ cooking oil-derived resin showed features down to 100 micrometres and was structurally and thermally stable (photo by Don Campbell)

Simpson first became interested in the idea when he got a 3D printer about three years ago. After noting the molecules used in commercial resins were similar to fats found in cooking oils, he wondered whether one could be created using waste cooking oil.

One challenge was finding old cooking oil from a restaurant’s deep fryers to test in the lab. Despite contacting several major national fast food chains, the only one that responded was McDonald’s. The oil used in the research was from one of the hamburger chain’s Scarborough restaurants.

Simpson (left) and his team used a straightforward one-step chemical process in the lab, using about one litre of used cooking oil to make 420 millilitres of resin. The resin was then used to print a plastic butterfly that showed features down to 100 micrometres and was structurally and thermally stable, meaning it wouldn’t crumble or melt above room temperature.

“We found that McDonald’s waste cooking oil has excellent potential as a 3D printing resin,” says Simpson, an environmental chemist and director of the Environmental NMR Centre at U of T Scarborough.

Used cooking oil is a major global environmental problem, with commercial and household waste causing serious environmental issues, including clogged sewage lines caused by the build-up of fats.

While there are commercial uses for waste cooking oil, Simpson says there’s a lack of ways to recycle it into a high value commodity such as a 3D printing resin. He adds that creating a high value commodity could remove some of the financial barriers with recycling waste cooking oil since many restaurants have to pay to dispose it.

Conventional high-resolution resins can cost upwards of US$525 per litre because they’re derived from fossil fuels and require several steps to produce. All but one of the chemicals used to make the resin in Simpson’s lab can be recycled, meaning it could be made for as low as US$300 per tonne, which is cheaper than most plastics. It also cures solid in sunlight, opening up the possibility of pouring it as liquid and forming the structure on a work site.

Another key advantage is biodegradability. The researchers found that burying a 3D-printed object made with their resin in soil lost 20 per cent of its weight in about two weeks.

“If you bury it in soil, microbes will start to break it down because essentially it’s just fat,” Simpson says.

“It’s something that microbes actually like to eat and they do a good job at breaking it down.”

The results of the research are published in the journal ACS Sustainable Chemistry & Engineering. Simpson received funding from the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, the Government of Ontario and the Krembil Foundation.

A local #ScarbTO @McDonaldsCanada gave the researchers the old oil to test it out—and it WORKED! https://t.co/524Vhxx9WV #UTSC #UofT pic.twitter.com/XRFNSOSLZn
— ��߲ݴ�ý Scarborough (@UTSC) January 30, 2020

Substances that created hole in ozone may account for half of Arctic warming, U of T 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, U of T 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)

Topic

Arctic

Climate Change

Global

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 ��߲ݴ�ý.

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 U of T 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 U of T 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.”

Science and art history students at U of T join forces to uncover museum collection's secrets

Christopher.Sorensen — Tue, 10 Dec 2019 21:47:34 +0000

Science and art history students at U of T join forces to uncover museum collection's secrets

Christopher.Sorensen Tue, 12/10/2019 - 16:47

Cutline

Students in Associate Professor Alen Hadzovic's (seated) class brought their expertise in technology and chemistry to examine artifacts from The Malcove Collection, a large museum collection that spans prehistory to the 20th century (photo by Chai Chen)

Tina Adamopoulos

Topic

City & Culture

Jackman Humanities Institute

Art History

Chemistry

Humanities

Undergraduate Students

University College

A group of ��߲ݴ�ý students from two very different disciplines have teamed up to uncover secrets behind a museum collection that spans prehistory to the mid-20th century.

The academic detective work was done on selected pieces from The Malcove Collection, a permanent display of art located at U of T’s Art Museum. The goal was to help fill some of the blanks in the collection by a true merger of the arts and sciences.

The collection itself was donated by Lillian Malcove, a Freudian psychoanalyst who had gathered more than 500 objects over a 50-year period. However, little was known about the history behind many of the museum’s artifacts. A detailed material analysis was needed to help trace its history – a challenge that was tackled through two Jackman Scholars-in-Residence (SiR) projects. The SiR program is an intensive four-week interdisciplinary residency in social science research for upper-year graduates.

“When basic information is missing, it means researchers and teachers don’t use it because they want to be able to tell their class about its history,” says Erin Webster, an associate professor, teaching stream, in U of T Scarborough’s department of arts, culture and media. “Having that concrete, factual identification is going to make it easier to use the collection in the future.”

(photo by Chai Chen)

While Webster’s group had knowledge of art history, a group of students led by Alen Hadzovic, an associate professor, teaching stream, in U of T Scarborough’s department of physical and environmental sciences, was able to lend their expertise in technology and chemistry to identify materials used in a few of the collection’s pieces.

Webster had used pieces from the collection in her classes before, but the more she worked with the collection the more she realized the need for collaboration.

“We really wanted to showcase the knowledge that could be developed by students working across disciplines,” Webster says.

One of the technologies used was an X-ray fluorescence (XRF) hand-held spectrometer, which offers a safe and non-destructive look at the chemical elements of a sample, particularly metals in objects such as sculpture, jewelry and decorative pieces. Certain blending of materials are unique to specific time-periods, which helps to identify when and where they were made, and also allows for proper conservation of objects and their full description.

Rashana Youtzy studied Christian objects, including an oval-shaped pendant. The pendant, which has a raised image of the Virgin Mary holding a post-crucifixion Jesus on its surface, is carefully lined with leaves around its frame.

“Holding an object that is centuries-years-old amazes me,” says Youtzy, a fifth-year U of T Scarborough art history student. “I found it really enticing that I could contribute to the field and not only mark a check-point in my academic career, but also in the lives of the artworks.”

(photo by Chai Chen)

Working with Liam Bryant, a third-year art history specialist at University College, the group used XRF analysis and digital microscopy to accurately date the pendant down to the half-century, rather than a hundred-year gap, predicting that the two objects they studied were from the European Renaissance – and likely produced in Italy.

“Initially we had read that the pendant was created in the 17th century and made with white bronze, then on a different file it had silver written as the material,” Youtzy says. “Through our analysis we established the material as silver, and after studying silver-working processes alongside the stylistic analysis we could claim it was made in the 16th century.”

Le Anh Chau Tran, a third-year arts management student, studied features of a manuscript from a Dutch prayer book. While it was suspected they contained gold, no one had ever done a material analysis on them before. The group figured out that parts of the manuscript were made with real gold, meaning it was likely made for elite patrons.

“The intersection between the humanities and chemistry worlds has the potential to be a discipline in itself,” Chau Tran says.

(photo by Chai Chen)

Hadzovic says there’s potential for an interdisciplinary approach beyond the program itself.

“I’ve had chemistry students tell me, ‘I didn’t know I could work in an art museum,’ but you can,” Hadzovic says. “I want to constantly show students the possibilities they have in the field and the different challenges they may meet as they navigate the space of chemistry.”

Bryant hopes to become an art conservator in the future. Since it’s hard to find art conservation classes at the undergraduate level, he used the opportunity as a way to get experience in a related field.

“The Scholars-in-Residence program allowed me to really see what my future could look like in a sincerely palpable way,” Bryant says.

“I suggest applying. Depending on the project, you really have the opportunity to distill a very abstract idea of your future down to an academic reality.”

Hadzovic and Webster are offering a joint fourth-year research-based seminar this winter that has grown out of the SiR project. It will bring art history and chemistry students together for further study of Malcove objects.

'It's a great honour': Eleven U of T faculty named fellows of the Royal Society of Canada

perry.king — Tue, 10 Sep 2019 13:53:13 +0000

'It's a great honour': Eleven U of T faculty named fellows of the Royal Society of Canada

perry.king Tue, 09/10/2019 - 09:53

Cutline

From left to right: Pamela Klassen, Kathleen Gallagher and Heinz-Bernhard Kraatz are three of 11 U of T researchers named fellows of the prestigious Royal Society of Canada (all photos by Perry King)

Perry King

Topic

Ecology and Evolutionary Biology

Awards

Drama

Faculty of Applied Science & Engineering

Faculty of Arts & Science

Faculty of Medicine

History

Hospital for Sick Children

Humanities

Laboratory Medicine and Pathobiology

Mechanical & Industrial Engineering

Ontario Institute for Studies in Education

Physics

Psychiatry

Religion

Royal Society of Canada

St. Michael's Hospital

surgery

Theatre