Research Day 2023

2019 was an unprecedented year of profound momentum for the climate movement. Fridays for the Future and Climate Strikes united young people around the globe as did visions for a Green New Deal. Alliances were forming across activist groups and political coalitions around the idea of an economic "just transition" from fossil fuels to renewable energy that centered climate justice. At the same time, news media began to report on the climate crisis like never before. In 2019, journalists from different national newsrooms committed to new initiatives such as the Covering Climate Now media collaborative that promised not only more climate coverage, but also better climate coverage that included the perspectives of young activists who were often belittled or excluded from reporting. A lot has changed, however, in the past four years. In this talk, I will discuss how the COVID-19 pandemic has had a hugely consequential impact on both the collective ties that previously united a growing climate movement, and on climate journalism. In particular, I will focus-in on how news media are increasingly reporting on climate justice activists as threatening to the nation and as preventing a desired sense of security, safety, and normalcy following the disruption of the pandemic. Indeed, the construction of a "militant climate justice warrior" stereotype has become a common trope used to report on (post)-pandemic climate politics. Ultimately, in this talk I will critique these shifts in climate reporting and argue that different modes of climate journalism are required to move away from this fear-mongering and "Othering" that currently animate climate coverage.

Hanna E. Morris, Ph.D. is an assistant professor at the School of the Environment at the University of Toronto. Her research focuses on climate change media and communication, culture and climate politics, transnational climate movements, and authoritarianism and the climate crisis. She recently co-edited the book entitled Climate Change and Journalism: Negotiating Rifts of Time (Routledge, 2021) and is currently writing a new book entitled Apocalyptic Authoritarianism: Climate Crisis, Media, and Power (forthcoming).

How species respond to habitat loss and fragmentation depends in part on the flexibility of their niche requirements. Species with a specialized, narrower breadth of niche requirements relative to more generalized taxa are predicted to experience higher vulnerability for extirpation or even extinction. Empirical tests of this prediction between sympatric congenera allow us to examine the importance of niche requirements relative to their conservation risk. In this study, we compared the distribution and ecological niche patterns of sympatric common brown lemur (Eulemur fulvus) and mongoose lemur (E. mongoz) in northwestern Madagascar. We hypothesized that Critically Endangered E. mongoz would exhibit a narrower breadth of niche requirements resulting in a smaller distribution than Vulnerable E. fulvus. We used MaxEnt v3.4.4 to develop species distribution models (SDMs) using presence-only data collected between 2015 and 2020 and ten independent background covariates. The comparison of our two models (EF-AUC=0.73 and EM-AUC=0.89) provides strong support for our hypothesis. The top 10th percentile of the E. mongoz probability distribution estimates an effective habitat of 17,757ha – much smaller than the predicted effective habitat of E. fulvus (48,591ha). Although the two species exhibited a significant degree of niche overlap, our E. mongoz model predicts a somewhat narrower niche breadth when compared to the E. fulvus model. The association of our results with the conservation status of E. fulvus and E. mongoz suggests that a relatively more generalized niche breadth enables E. fulvus to better respond to habitat loss and fragmentation.

Background: Although an established carcinogen for cancers of the skin, bladder and lungs, the relationship between arsenic exposure and breast cancer risk is not known. Studies to date have been conducted in populations with endemically high levels of arsenic, have been limited by small sample sizes and have methodological concerns. The impact of chronic exposure to low levels of arsenic remains unclear. This project aimed to evaluate the association between urinary arsenic levels and breast cancer risk among Canadian women.

Methods: Demographic information and urinary arsenic biomarkers (µg/L) from Cycles 1-5 (2007-2017) of the Canadian Health Measures Survey (CHMS) were used. Incident breast cancers were ascertained through linkage to the Canadian Cancer Registry. Female participants were eligible if they were older than 18 at time of CHMS participation, had no personal history of cancer, and had urinary arsenic and creatinine levels available. Arsenic exposure was described using weighted percentiles and then categorized by tertiles. Cox proportional hazards regression was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) of arsenic exposure and breast cancer risk.

Results: This study included 5,100 women with a mean age of 44.6 years and an average follow-up of 6.6 years. The median total urinary arsenic level was 7.8 µg/g of creatinine. Women in the highest tertile of urinary arsenic levels (> 13.0 µg/L) had a significant two-fold increased risk of developing breast cancer compared to the referent group, after adjusting for confounders (HR= 2.05; 95%CI 1.05-3.94, P-trend = 0.035).

Significance: This is the first analysis of arsenic levels and breast cancer risk in a pan-Canadian cohort. Our findings suggest that exposure to arsenic, even at low levels, is associated with an increased risk of breast cancer and are important for informing population-level interventions to reduce the breast cancer burden.

Carbon monoxide (CO) is released during biomass burning events, resulting in decreased air quality and leading to the formation of climate forcing pollutants. An increase in wildfires has resulted in a change to the CO seasonal cycle of the North American Pacific Northwest, when comparing 2012-2018 to 2002-2011. This trend was reported using data from the Measurements of Pollution in the Troposphere (MOPITT) instrument on NASA’s Terra satellite. Similarly, an increase in summertime CO values was identified with the Fourier Transform Infrared (FTIR) spectrometer at the University of Toronto Atmospheric Observatory (TAO), over the same time period. Studies have shown correlations between wildfire smoke exposure and healthcare utilization for cardiovascular and respiratory conditions. Monthly counts of Emergency Department admissions for cardiovascular and respiratory diseases for Alberta and Ontario are investigated in relation to wildfire events in Canada and the USA. MOPITT and TAO FTIR CO columns, the Moderate Resolution Imaging Spectroradiometer (MODIS) burned area product, and provincial burned areas from Natural Resources Canada are assessed to estimate wildfire smoke exposure in the study region. This work aims to evaluate if CO can be used as a complementary tracer for health impacts from wildfire smoke exposure.

Objectives: Diesel engine exhaust (DEE) is a known lung carcinogen and a common occupational exposure in Canada.The use of diesel-powered equipment in the construction industry is particularly widespread, but little is known about DEE exposures in this work setting.The objective of this study was to determine exposure levels and identify and characterize key determinants of DEE exposure at construction sites in Ontario.

Methods: Elemental carbon (EC, a surrogate of DEE exposure) measurements were collected at seven civil infrastructure construction worksites and one trades training facility in Ontario using NIOSH method 5040. Full-shift personal air samples were collected using a constant-flow pump and SKC aluminium cyclone with quartz fibre filters in a 37-mm cassette. Exposures were compared with published health- based limits, including the Dutch Expert Committee on Occupational Safety (DECOS) limit (1.03 μg m−3 respirable EC) and the Finnish Institute of Occupational Health (FIOH) recommendation (5 μg m−3 respirable EC). Mixed-effects linear regression was used to identify determinants of EC exposure.

Results: In total, 149 EC samples were collected, ranging from <0.25 to 52.58 μg m−3 with a geometric mean (GM) of 3.71 μg m−3 [geometric standard deviation (GSD) = 3.32]. Overall, 41.6% of samples exceeded the FIOH limit, mostly within underground worksites (93.5%), and 90.6% exceeded the DECOS limit. Underground workers (GM = 13.20 μg m−3, GSD = 1.83) had exposures approximately four times higher than below grade workers (GM = 3.56 μg m−3, GSD = 1.94) and nine times higher than above ground workers (GM = 1.49 μg m−3, GSD = 1.75). Training facility exposures were similar to above ground workers (GM = 1.86 μg m−3, GSD = 4.12); however, exposures were highly variable. Work setting and enclosed cabins were identified as the key determinants of exposure in the final model (adjusted R2 = 0.72, P < 0.001). The highest DEE exposures were observed in underground workplaces and when using unenclosed cabins.

Conclusions: This study provides data on current DEE exposure in Canadian construction workers. Most exposures were above recommended health-based limits, albeit in other jurisdictions, signifying a need to further reduce DEE levels in construction. These results can inform a hazard reduction strategy including targeted intervention/control measures to reduce DEE exposure and the burden of occupational lung cancer.

Climate models predict that the Brewer-Dobson Circulation (BDC) will accelerate due to the warming atmosphere. This would increase trace gas transportation from the tropics to higher latitudes and result in further changes to the radiative properties of the atmosphere, creating a feedback effect. Stratospheric age of air can be used to determine whether this acceleration is occurring. Age of air is defined as the time that has elapsed since a stratospheric air parcel left the troposphere. It is a useful diagnostic for atmospheric transport: air that is too young at higher latitudes indicates rapid transport, while old air indicates slow transport. Changes in age of air can therefore signal changes in the BDC. Detecting such changes requires a long-term observational record of age of air, which until now has been difficult to obtain due to low availability of measurements. The trace gas SF6 provides a reliable way to calculate age of air, but it is difficult to measure due to its small concentrations. The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) provides the longest available record of SF6, spanning 2004 to the present. I will discuss how monthly age of air is calculated using ACE-FTS SF6 measurements and show comparisons with the existing observation-based age of air datasets. The results are promising, indicating that the new ACE-based age of air dataset can likely be used to detect whether there is a significant trend in stratospheric age of air.

The precise identification of predominant toxic disinfection byproducts (DBPs) from disinfected water is a longstanding challenge. We propose a new acellular analytical strategy, the ‘Thiol Reactome’, to identify thiol-reactive DBPs by employing a thiol probe and nontargeted mass spectrometry (MS) analysis. Disinfected/oxidized water samples had reduced cellular oxidative stress responses of 46 ± 23% in Nrf2 reporter cells when preincubated with glutathione (GSH). This supports thiol-reactive DBPs as the predominant drivers of oxidative stress. This method was benchmarked using seven classes of DBPs including haloacetonitriles, which preferentially reacted with GSH via substitution or addition depending on the number of halogens present. The method was then applied to chemically disinfected/oxidized waters, and 181 tentative DBP-GSH reaction products were detected. The formulas of 24 high abundance DBP-GSH adducts were predicted, among which nitrogenous-DBPs (11) and unsaturated carbonyls (4) were the predominant compound classes. Two major unsaturated carbonyl-GSH adducts, GSH-acrolein and GSH-acrylic acid, were confirmed by their authentic standards. These two adducts were unexpectedly formed from larger native DBPs when reacting with GSH. This study demonstrated the “Thiol Reactome” as an effective acellular assay to precisely identify and broadly capture toxic DBPs from water mixtures.

Persistent chemicals are commonly used in everyday life; in non-stick materials, in personal care products, and in fire-retardants. These chemicals often end up circulating in environmental and anthropogenic systems, and many of these compounds pose risks to both human and environmental health. A common feature of persistent chemicals is halogenation, the presence of chlorine, fluorine, or bromine atoms in the chemical structure, which greatly contributes to their resistance to degradation.

A group of organisms called organohalide respiring bacteria (OHRB) are able to utilize halogenated compounds for energy and growth. In doing so, the OHRB remove the halogen atoms from these contaminants transforming them into harmless hydrocarbons. These microorganisms are particularly useful for bioremediation of halogenated contaminant sites and has been employed in the cleanup of toxic chlorinated compounds. All OHRB produce a particular group of enzymes called reductive dehalogenases (RDases) that carry out the dehalogenation of these compounds, each enzyme is specific for degradation of one or a handful of compounds. I have built tools to expedite the production and characterization of these RDases. Understanding how these enzymes work and manipulating which compounds they can readily degrade will allow for better remediation strategies to remove some of the most damaging pollutants from the environment.

Many cities, including Toronto, have pledged to reduce their greenhouse gas emissions. However, in order to accurately monitor their progress, it is important to estimate emissions using observation-based approaches. These methods, however, often do not account for fluxes from vegetation in and around the cities. Our research aims to use remote sensing and vegetation models to estimate biogenic fluxes of CO2 in the Greater Toronto Area To do this we use Solar-Induced Fluorescence (SIF), a by-product of photosynthesis which can be detected from satellite instruments, and two vegetation models: the SIF for Modelling Urban biogenic Fluxes (SMUrF) model and the Urban Vegetation Photosynthesis and Respiration Model (UrbanVPRM). We have made several updates to each model to optimize their use over the Greater Toronto Area. We validate the results from these models against ground-based measurements of biogenic CO2 fluxes in Southern Ontario and compare the results from each of the models in the Greater Toronto Area. The results from this research will help to constrain both urban biogenic and anthropogenic fluxes of CO2.

The subsistence practices of Later Stone Age (LSA) foragers and herders living in Namaqualand South Africa are often difficult to differentiate based on their archaeological signatures but characterizing their dietary choices is vital to understand the economic importance of domesticates. However, ethnohistoric accounts have provided information on the cooking/boiling of marine mammal fat, mutton, plants, and milk by early herders and foragers across the Western Cape. To further investigate these reports, we use lipid residue analysis to characterize 106 potsherds from four open-air LSA sites, spanning in time from the early first millennium to the late second millennium AD. Two sites (SK2005/057A, SK2006/026) are located on the Atlantic coast whereas sites Jakkalsberg K and Jakkalsberg M are located further inland on the southern bank of the Orange River. Notably, at the coastal sites, the presence of marine biomarkers suggests the intensive and/or specialized processing of marine products in many vessels. The dominance of ruminant carcass products at inland sites and probable sheep remains confirms the importance of stockkeeping. Furthermore, and in good agreement with ethnohistoric accounts for its use, our results provide the first direct chemical evidence for the use of dairy products in LSA western South Africa.

This study investigated the relationship between carbon literacy (knowledge) and pro-environmental actions taken to reduce greenhouse gas emissions among undergraduate engineering students at the University of Toronto. The choice of engineering students seems apt given the importance of this profession to sustainability and the limited number of studies being conducted with engineering students as participants. The participants’ carbon literacy and carbon footprints data were collected using an instrument designed to request information about their view on how impactful certain actions are (high, moderate or low), and their personal choices regarding those actions. Participants’ carbon literacy was calculated based on the accuracy in identifying the high, moderate and low impact actions and their pro-environmental actions were captured by calculating their carbon footprint using a life cycle assessment approach. The pro-environmental actions by the participants produced an average carbon footprint of 4.8 tCO2 which was lower than Toronto residents, Ontario and Canada overall (~20 tCO2) but still higher than the global 2030 target (~2.8 tCO2). The carbon literacy by participants was more accurate for high impact actions like ground transportation and dietary choices but less so for air travel and there was mixed awareness for the moderate and low impact actions. The relationship between pro-environmental action and carbon literacy showed that for high impact, there was a slight positive correlation between carbon literacy and pro-environmental action whereas for moderate and low impact actions, there was a negative correlation. These results indicate that there may be some misconceptions around actions that are pro-environmental, specifically for air travel in the high impact action category and for the moderate and low impact actions. For those pro-environmental actions that correlated positively to carbon literacy like ground transportation choices and meat consumption, the reasons for this positive correlation could be the lack of barriers to encourage this type of behaviour including accessibility to reliable public/active transportation options and a variety of food types in Toronto.

Silence in the international climate change negotiations is widely understood as an agreement. If countries do not voice their concerns, influence an outcome, or vote, they ultimately agree with decisions taken by other Parties to the UNFCCC. Recent studies in norm contestation have started to problematize the role and meaning of silence. Using the differential treatment norm as a case study, we ask if silence can have any other role or meaning beyond agreement through a lens of norm contestation. We found that the differential treatment norm has been contested even after the adoption of the Paris Agreement, although this contestation has taken a subtler form, silence. Our study also shows that silence can be an indication of capacity and political power constraints and barriers that hinder the capability of countries to influence outcomes or even participate in the international climate change negotiations. Our study contributes the norm contestation scholarship by elucidating how silence can have intentions to provide new meanings, or even to weaken or delegitimize a norm. Our study also finds that ignoring the silence of Parties can contribute to barriers to fairness, justice, and equity in the international climate regime.

The neighborhood of Regent Park in the City of Toronto is currently going through a “Revitalization” which is a 5-stage, market-driven, public-private partnership that will completely alter the material, social, and economic interactions that take place therein. The Revitalization Plan was approved in 2002, and construction started in 2006. Construction was initially planned to last between 15-20 years, but has subsequently been delayed. Costing approximately $1 billion, the project is leading to no net gain in numbers of rent-geared-to-income units (Brail and Kumar 2017:2; Silver 2011:11). The Regent Park Revitalization is taking place through a public-private partnership between the municipality of Toronto, its non-profit public housing authority Toronto Community Housing Corporation (TCHC), and a private developer (The Daniels Corporation for phases 1-3 and in December 2020 Tridel Builders Inc. was selected for phases 4-5).

Mixed-income planning aims to integrate public housing communities economically, spatially, and socially into the fabric of the city, and this planning approach results in radically changed social and material environments (Walks and Maaranen 2008). This presentation will examine the unique planning styles of the Garden City and the Radiant City which were used in the initial 1950's iteration of urban renewal, and will contrast them with the New Urbanist style currently being used in the Revitalized Regent Park. In both iterations, the marketing of a relationship with the natural world has been a key tool to promote interest in, and support for, the urban renewal projects.

How have environmental design approaches evolved from the postwar period to the present? More specifically, how have scientific and technical knowledge and methods informed design efforts to understand and act within dynamic natural environments? This presentation offers an overview of several case studies from the 1970s to the 1990s, including a variety of research groups and laboratories connected to architecture departments at North American universities. Suggesting connections across these cases, the presentation outlines a contribution to interdisciplinary histories environmental thought and action.

Municipal waste is a small but significant contributor to greenhouse gas (GHG) emissions for countries worldwide. In Toronto, while it accounts for only a small percentage of the city’s GHG emissions, primarily methane emissions from landfills, reducing waste sent to landfill is important for helping the city achieve its net zero goal for GHG emissions by 2040 and for reducing the need for future landfills. However, municipal waste diversion in Toronto is an uneven landscape, with type of housing having a significant influence on diversion performance. In single family homes, 63% of waste generated in the home was diverted from landfill to recycling and composting in 2021 while only 26% was diverted in multi-residential homes. In this presentation, I discuss the findings from a research collaboration with the Toronto Environmental Alliance on interventions to improve diversion in the latter type of housing. The study examines the perceptions held by residents of multi-residential buildings about the convenience of waste work, their waste sorting practices, and their knowledge about and attitudes towards sorting. Interventions included making improvements to building infrastructure, to waste services and to resident education. The impact of the interventions was assessed by comparing the intervention buildings to ‘model’ buildings in the city that have achieved high diversion rates.

Virginia Maclaren is an Associate Professor Emerita from the Department of Geography & Planning. Her research has focused on waste studies, most recently for communities in Canada and previously in Southeast Asia. Her current research is on waste diversion in multi-residential buildings in Toronto. She has had several advisory roles on public waste organizations, including Waste Diversion Ontario, the Advisory Group for Toronto’s Long Term Waste Management Strategy, and the Mayor’s Towering Waste Challenge Committee in Toronto.