The Urban Heat Island Effect in Montréal

By Claire Suh, Samuel Centre for Social Connectedness Research Fellow

The Samuel Centre for Social Connectedness Fellowship is a program where scholars develop research specific to their partner’s objectives and to social connectedness. SC fellows conduct outreach, research, writing, and analysis on their topic while engaging with the local community.

The worsening state of our environment is looming large in our collective consciousness. We have scientific experts giving us an ever-narrowing window of time to reverse the warming of the earth. Although the more extreme effects of the climate crisis may seem to be decades away, the hard truth is that we are seeing the devastating consequences now, especially in cities. More than half of the world’s population is now living in urban areas, placing an enormous amount of pressure on how we should design and run our cities in order to deal with mounting environmental problems.1Hsu, A., N. Alexandre, J. Brandt, T. Chakraborty, S. Comess, A. Feierman, T. Huang, S. Janaskie, D. Manya, M. Moroney, N. Moyo, R. Rauber, G. Sherriff, R. Thomas, J. Tong, Y. Xie, A. Weinfurter, Z. Yeo (in alpha order). The Urban Environment and Social Inclusion Index. New Haven, CT: Yale University. Available: datadrivenyale.edu/urban.

In cities, the urban heat island effect is already wreaking havoc on residents. It is a phenomenon where some urban areas are significantly higher in temperature than surrounding rural areas.2U.S. Environmental Protection Agency. 2008. Reducing urban heat islands: Compendium of strategies. Draft. https://www.epa.gov/heat-islands/heat-island-compendium. In Montréal, a heat wave caused 66 mortalities over 6 days in June and July 2018, during which vulnerable populations that live in areas with a strong urban heat island effect were twice as likely to die.3Canada. Gouvernement Du Québec. Institut De La Statistique Du Québec. Le Bilan Démographique Du Québec. By Chantal Girard, Anne Binette Charbonneau, Frédéric F. Payeur, and Ana Cristina Azeredo. 2018 ed. 51-79., MHRP4“ Heat Wave Summer 2018 in Montréal.” n.d. Heat Wave Summer 2018 in Montréal.

This effect is inextricably tied with climate change as a whole, with health, and with social equity. However, the climate mitigation and adaptation policies in Montréal do not reflect this interconnection, rendering them much less effective. The sections below will explore the manifold causes of the urban heat island effect, why some populations are more vulnerable to it, and how to make climate policy in Montréal more effective by shifting to an interdisciplinary perspective.

What is the Urban Heat Island Effect?

The urban heat island effect is a result of urbanization.5Hsu et al. Replacing rural, vegetated areas with built-up structures creates areas in a city that are significantly hotter than surrounding rural areas.6Ibid The following properties of cities are the major contributors to the urban heat island effect.

Higher Thermal Capacity

 

Buildings have a high capacity to store heat which contributes to a slower release of heat compared to surrounding areas.7Gutiérrez, Estatio, Jorge E. González, Alberto Martilli, Robert Bornstein, and Mark Arend. “Simulations of a heat-wave event in New York City using a multilayer urban parameterization.” Journal of Applied Meteorology and Climatology 54, no. 2 (2015): 283-301.

 

 

Air Pollution and Waste Heat

 

 

Air pollution and waste heat generated by human activity (e.g. emissions from cars, emissions from air-conditioning units) is a big contributor to urban heat.8Gutiérrez, Estatio, Jorge E. González, Alberto Martilli, Robert Bornstein, and Mark Arend. “Simulations of a heat-wave event in New York City using a multilayer urban parameterization.” Journal of Applied Meteorology and Climatology 54, no. 2 (2015): 283-301.

Decrease in Vegetated Areas

 

 

The decrease in vegetated areas leads to reduced evaporative cooling in cities.9Ibid

Low Albedo

 

The low reflectivity (i.e. low albedo) of road and building surfaces causes them to absorb lots of heat.10Ibid

Airflow

 

 

Urban smog and changes in airflow due to the complex geometry of urban structures further traps heat.11Ibid

“Parking lots are one of the problems that we have with heat and I’ve seen, not only in Québec, but in North America and in rows as well. Everything is constructed around cars, and everybody is driving their cars. So one of the effects is having cities that are constructed mainly for cars and this kind of construction just traps heat in the cities, and it contributes to having more heat in the cities.”

— Mélanie Beaudoin

Mélanie Beaudoin is a Scientific Advisor for Health Adaptation to Climate Change at the National Institute of Public Health in Quebec (INSPQ). She has worked at the INSPQ for nine years, mainly on urban heat islands and green spaces.

Consequences of Extreme Heat and the Urban Heat Island Effect

The urban heat island effect has several ramifications.

During extreme heat events, there is a proliferation of cyanobacteria blooms in water sources and an increase in the number and severity of smog episodes.12Service de l’environnement. 2017. CLIMATE CHANGE ADAPTATION PLAN FOR THE Montréal URBAN AGGLOMERATION 2015-2020. Supervised by Roger Lachance. This leads to reduced air and water quality, causing negative health impacts.13Ibid Residents that live in areas with a stronger urban heat island effect are more vulnerable to these impacts as well as other complications of heat-related health outcomes during heat waves (e.g. heat stroke). In addition, the air pollution that contributes to areas with a stronger urban heat island effect traps heat, creating a vicious cycle of worsening pollution and heat. 14U.S. Environmental Protection Agency. 2008. Reducing urban heat islands: Compendium of strategies. Draft. https://www.epa.gov/heat-islands/heat-island-compendium.

 

 

The higher level of heat creates an increased power demand for cooling and generates heat stress which leads to work absenteeism and productivity loss.15Hsu et al. These consequences place financial stress on those living in urban heat islands.16Service de l’environnement

The Urban Heat Island Effect in Montréal

In Montréal, the western end of the island is less prone to the urban heat island effect because it has a lower population density and has a lot of tree cover.17Chan et al. In contrast, the central portion of the island, which has a high population density, and the eastern portion of the island, which has much less tree cover, are especially vulnerable to the urban heat island effect.18Ibid

Income per capita (local currency) by Borough in Montréal

You can click on the different neighborhoods on the map to see their names.

(Source: UESI)

Areas with a strong Urban Heat Island Effect

(Source: Climate Change Adaptation Plan for the Montréal Urban Agglomeration 2015-2020: 2017 Edition)

Furthermore, in Montréal the burden of the urban heat island effect falls inequitably on lower income populations.19Hsu et al. Three of the city’s neighborhoods who score the lowest on urban heat island effect on the UESI Index are Rosemont-La-Petite-Patrie, Le-Plateau-Mont-Royal, and Saint-Leonard, all of which are central or eastern Montréal and relatively lower income.20Ibid The Urban Environment and Social Inclusion Index measures urban heat island effect performance using the 15-year (2003-2017) mean difference in daytime and nighttime surface temperatures between urban land cover and non-urban land cover within the city in degrees Celsius (°C).21Ibid The index compares each neighborhood’s urban heat island intensity to the overall intensity of the urban heat island effect across the entire city.22Ibid A higher UESI score is better, meaning the urban heat island effect is weaker in that neighborhood.

Correlations

You can hover over each point to see the neighborhood it represents.

treecover1

Tree cover is positively correlated with the UESI urban heat island effect performance score meaning that neighborhoods with higher tree cover tend to have a weaker urban heat island effect in Montreal.

inc1

The neighborhood income per capita (local currency) is very slightly positively correlated with the UESI urban heat island effect performance score meaning that neighborhoods with a higher neighborhood income per capita tend to have a very slight weaker urban heat island effect in Montreal.

imm1

The proportion of residents that are immigrants is negatively correlated with the UESI urban heat island effect performance score meaning that neighborhoods with a higher proportion of immigrant residents tend to have a slightly stronger urban heat island effect in Montreal.

five1

The proportion of the population living in dwellings over 5 stories, which could be considered a measure of built-up structures, is negatively correlated with the UESI urban heat island effect performance score meaning that neighborhoods with a higher proportion of the population living in dwellings over 5 stories tend to have a stronger urban heat island effect in Montreal.

Montréal in Photos

Ville-Marie (Source: Claire Suh)

Ville-Marie (Source: Claire Suh)

Ville-Marie is a borough in the southeast of Montréal that has a low percentage of tree cover, an average level of income within Montréal, and suffers from a strong urban heat island effect.23Hsu et al.

Outremont (Source: Claire Suh)

Outremont (Source: Claire Suh)

Outremont is a borough that has a high percentage of tree cover, high level of income within Montréal, and does not suffer from a strong urban heat island effect.24Ibid

Policies Combating the Urban Heat Island Effect in Montréal

Montréal has an extensive set of policies aimed to adapt to the current effects of the urban heat island effect and heat waves, and to mitigate climate change in the long term. The following section lays out selected policies on the municipal and borough level of government in order to pinpoint specific areas that need improvement.

“I always say that the tree planted today will be your air in 20 years. So what we have to do is to plant right now. With climate change, we expect to have even more heat waves in the future, we expect to have heat waves that will go further in the north and in the east of the province of Québec. That would be mainly the same for the rest of Canada as well. So what we have to do right now is adapt to climate change, we need to work on reducing greenhouse gases. But we need to work as well on adaptation, because we are already living through the climate change effects right now. Mainly, heat as we are discussing right now.” 

— Mélanie Beaudoin

Table of Selected Montreal Policies and Initiatives25Bureau du développement durable, Natacha Beauchesne, Monique Côté, Isabelle Gauthier, Catherine Philibert, Melina Planchenault. 2016. Sustainable Montréal 2016-2020. Sustainable Montréal 2016-2020. http://ville.Montréal.qc.ca/pls/portal/docs/page/d_durable_en/media/documents/plan _de_dd_en_lr.pdf. 26Centre intégré universitaire de santé et de services sociaux du Centre-Sud-de-l’Île-de-Montréal. 2019. CHALEUR ACCABLANTE ET EXTRÊME 2019: Plan Régional De Prévention Et De Protection Et Guide à L’intention Des Établissements De Santé. Gouvernement du Québec. https://ciusss-centresudmtl.gouv.qc.ca/sites/ciussscsmtl/files/media/document/2019_P lanChaleurAccablanteExtreme.pdf. 27Sucar, Daniel. 2019. “Plante Announces Plan to Build Montréal’s Largest Urban Park.” Montréal Gazette, June 16, 2019. https://Montréalgazette.com/news/local-news/plante-announces-plan-to-build-Montréals-largest-urban-park. 28Interview with Valérie Patreau (Outremont borough councillor, Chair of the Standing Committee on Water, Environment, Sustainable Development and Great Parks). July 10th, 2019. 29Canada. Natural Resources Canada. Measures to Reduce the Urban Heat Island Effect in Rosemont–La Petite-Patrie. July 2014. Accessed June 10, 2019. https://www.nrcan.gc.ca/sites/files/earthsciences/pdf/mun/pdf/13-0616-Rosemont-Case-Study_e.pdf.30Interview with Federal Government Employee. July 15th, 2019.

“For a 26°C day, the temperature of a dark roof would be 80°C, a white roof would be 45°C, and a green roof would be 29°C”

— Mélanie Beaudoin

Example: The Initiatives and Policies of Outremont

Many boroughs – such as Outremont — have their own approaches to 
addressing the urban heat island effect and its impact on human health and social 
inclusion.

“In Outremont, we have some îlots de fraîcheur at the community centres and at the library. It’s a place where people can go and have climatized (air-conditioned) spaces, and also we have a swimming pool. It was under construction, but we have been able to open it just before the heat wave and we make the hours of opening longer to make sure that everybody has the occasion to go there if they wanted. We also have jeux d’eau, water games, in some parts and we make them open a lot longer to make sure that it’s open in the evening when people need to refresh after their day and need to be able to sleep after. It’s good to have such infrastructure for the families and everybody.”

— Valérie Patreau

Valérie Patreau is a borough councilor for Outremont, District Joseph-Beaubien, since 2017. She is also the chair of the Standing Committee on Water, Environment, Sustainable Development and Great Parks. Councilor Patreau used to work in a research centre in environmental impact evaluation with the life cycle assessment approach.

“We work with ‘table de concertation des aînés‘, or consultations, with people, representatives of the people, and older people to make sure that we understand the situation and we act on their demands. And also for kids, we work with the CPE (Centre de la petite enfance / Early childhood centre). And as I mentioned, we will make sure that we maintain in good condition the parks and the areas where people can benefit from climatised (air-conditioned) spaces to make sure that people can have places to go, it is important.”

— Valérie Patreau

 

“So this is an issue too, and it’s difficult to work on this alone because usually air climatization (air-conditioning) is done as the standard. However, we are following the situation with our different partners. We want to see how we can have regulations for climatization. Also for climatization, we want to review the regulation to make sure that it’s used when there is no other choice. But we also would like new construction to be able to use less climatization and more natural ways of climatization. So it’s a work in progress with the architecture sector and the urban planners also. And for cars we tried to propose different solutions for transportation to reduce the need for cars and to make sure that we have less cars in our borough to have more spaces that we can make greener. We can plant trees if we need less parking places in some areas, and more parks so it will help in this situation.”

— Valérie Patreau

Borough-specific Statistics

Montréal is comprised of 19 boroughs currently. These statistics are from what could be found on the Ville de Montréal website. They do not include policies or information that can be found outside of the official city portal.

%

Percentage of boroughs in Montréal with borough-specific sustainable development policies

%

Percentage of boroughs in Montréal with local greening policies

%

Percentage of boroughs in Montréal with a page on the urban heat island effect on their borough portal

%

Percentage of boroughs in Montréal with borough-specific emergency heat wave plans

Policy Gaps

Gaps in the policies were identified independently through desk research and interviews with experts, then collaboratively through the Urban Heat in Montréal workshop on 03 August 2019. Overall, Montréal has constructive policies in place currently. However, there is room for improvement. This section will explore how climate policy in Montréal can be improved by, for example, shifting to an interdisciplinary perspective.

Community Resilience and Social Connectedness

Addressing climate change requires building community strength because tight connections underpin community resilience and enable residents to coordinate community action.31Hayes, K., Berry, P., & Ebi, K. L. (2019). Factors Influencing the Mental Health Consequences of Climate Change in Canada. International journal of environmental research and public health, 16(9), 1583. Community resilience is a community’s ability to withstand and recover from adverse situations.32 Isc. “What Is Community Resilience, and Why Does It Matter?” Institute for Sustainable Communities, February 20, 2019. https://sustain.org/what-is-community-resilience-and-why-does-it-matter/. Building a tight-knit community is especially important for the most vulnerable populations. We should be taking care to include the older population and those suffering from mental illnesses, chronic ailments, and homelessness. Additionally, there is not enough community input in the policies being made. Consultations are available to residents but there is low attendance and a lack of diversity in the people who attend.

“If you look at something like social identity, it turns out that people can feel like they belong to their local community, they can also feel like they belong to their city of province or country. Now, those are very different things. And you might think that we have some kind of a limited amount of loneliness that we can feel, it turns out not… So the people who are happiest are the ones who feel they belong to every single layer and, you know, belonging to other groups, we actually are able to do that in parallel.. and it seems like those bonds just add up in their benefit to us.”

— Dr. Christopher Barrington-Leigh

Dr. Christopher Barrington-Leigh is an associate professor at McGill University. He is jointly appointed at the Institute for Health and Social Policy and the School of Environment. He is an economist by training and also an associate member of the Economics Department.

 “I think there’s obviously as always, kind of the short term and the long term. The long term, we’re going to have to stop pollution and stop global warming. We have to change to clean energy and all these other things. But I think in the short term, there has to be this official recognition by cities that this is a social issue. We need to start talking about it and phrasing it and legally enshrining it as a social, human rights issue. It’s not about just plants and trees, it’s about people. I’m hoping that that could already kind of switch the way we talked about it.”

Alienor Rougeot

Alienor Rougeot is a climate justice activist based in Toronto, Canada. She works as the Greater Toronto Area liaison for Climate Strike Canada. She also organizes the local Fridays for Future chapter in the Greater Toronto Area.

Urban Planning and the Environment

“I always say that the tree planted today will be your air in 20 years.” — Mélanie Beaudoin

The greening efforts that are taking place in Montréal should do more to account for the inequities that exist in the city.  The low-income population and visible minorities have disproportionately less access to green spaces than more affluent population, which is concerning since they are more in need of the benefits provided by green spaces.33Apparicio, P., Séguin, A. M., Landry, S., & Gagnon, M. (2012). Spatial distribution of vegetation in Montréal: an uneven distribution or environmental inequity?. Landscape and urban planning, 107(3), 214-224. The Grande parc de l’Ouest sounds impressive but it is located on the west end of the island which has a higher average income and more green space than the east end.34Hsu et al.

 

“Green spaces are quite an important measure in addressing the issue of urban heat islands. We did have a program and some projects that were conducted since 2006, to address the urban heat island effect. So a lot of those projects were indeed having vegetation, increasing the canopy, these kinds of measures. So the effects of green spaces are quite important. It’s also good for air quality and water quality. So the impacts of the green spaces are various and they touch a lot of the diverse sectors as in environment when I talked about air and water quality. In addition, the population can have access to better places to play sports or exercise. So one of the effects of green spaces is as well to have better health of the population by having availability to these kinds of spaces.”

— Mélanie Beaudoin

There is also a limit to the benefits of expanding green spaces to mitigate the urban heat island effect. Trees take up large swathes of area and their roots impact building foundations. Therefore we need more urban planning regulations that balance green space expansion with reducing urban sprawl. There are also not enough regulations for new buildings. New buildings are often built to rely on air-conditioning instead of using passive cooling or considering air flow.

“A tree is equivalent to 5 air conditioner units that work 20 hours a day.”

— Mélanie Beaudoin

Efficiency and Collaboration

The existing policies mentioned above are generally silo-ed into different departments, ignoring the crucial benefits that result from collaboration. Additionally, with policies like Sustainable Montréal 2016-2020, there is no transparent progress tracking that ensures the city is reaching its goals.

“People who are pro-social are also used to the idea that we can solve our problems by coming together collectively. There is an expectation, understanding, experience that we can actually make ourselves better off by coming together, thinking better about problems collaboratively and implementing collective solutions.”

— Dr. Christopher Barrington-Leigh

Policy Recommendations

These recommendations heavily drawn from the Urban Heat in Montréal workshop (03 August 2019). Through desk research and discussions from the workshop, three key policy gaps emerged: community participation and resilience, urban planning and the environment, and efficiency and collaboration.

Community Resilience and Participation

“I think it’s important that youth get involved for several reasons. First of all, I think we’re such a good voice and a legitimate voice. It’s really important that we’re able to be a non-political, non-partisan voice that says, listen, this is our concern, because we’re going to be more affected than all of you. So I think we have this legitimacy, this candid voice. At the same time, our voice has a lot of power, because we are organized, and we are capable.”

— Alienor Rougeot

Borough councils and community organizations should work to increase participation and engage new demographics in consultations by being more proactive in their promotion. For example, they could:

  • Set up a tent at neighborhood events.
  • Advertise information about consultations in several streams of media.
  • Incentivize going to consultations with low cost benefits.
  • City councilors should also be made more accessible through weekly ‘office hours’ that occur after work hours in order to address resident concerns outside of formal consultations.
  • Create an easy to use app that can field questions and concerns from residents.

Borough councils and community organizations should focus on increasing community resilience. The following are examples of how to accomplish this: 

  • Retrofit existing community centres in order to make them multi-use, intergenerational, and accessible.
  • Urban planners and sociologists should be involved in community centre design to maximize their efficiency and to make them eco-friendly.
  • Community events could be held by community organizations like weekly neighborhood potlucks. 
  • A sharing economy could be established by creating toy libraries, shared tool sheds, etc. This would decrease the necessity of consumerism and foster community bonds. 
  • Intergenerational programs should be created by both actors such as a buddy system where a young adult is paired with an older adult.

Urban Planning and the Environment

Montréal requires better urban planning in conjunction with green spaces to combat the urban heat island effect and climate change. The existing initiatives to expand green spaces must protect against gentrification– for instance, by freezing rent prices for current residents. 

“Sometimes what happens is, when you take a neighborhood that people have less money and you put in a park, you green the place, what happens is the rent increases. And then the population that was there cannot afford to rent anymore, so you just transfer the problem elsewhere. So you need to be careful when you green places in cities to make sure that the municipality has policies against gentrification. Not every municipality does, but we hope that they will in the future have policies to protect low income rents or low income buildings to prevent populations from moving to other places that are still urban heat islands.”

— Mélanie Beaudoin

Furthermore, funding should be allocated to creating more equitable green spaces in underserved areas in lieu of, or in addition to, building an enormous park in the west end.

“When you do a park that is linear, so you follow, for instance, a river and you green all of the side of the river, while you will cross many neighborhoods, and then you will lessen the effect of green gentrification because all kinds of population will have access to this long park instead of one big spots like Mont-Royal in Montréal.”

— Mélanie Beaudoin

Additionally,

  • All ongoing and future construction projects must consider climate sensitive design and materials.35Interview with Federal Government Employee. July 15th, 2019. 
  • Developers should be required to incorporate passive cooling and good airflow in new construction. 
  • In the same vein, all new city designs should be required to consider the valley cooling effect which allows currents from lakes and oceans to cool the city.36Ibid
  • The design of cities will have environment, health and social implications for years to come so interdisciplinary collaboration is key. For example, boroughs could require having residents who are trained in health and sustainability on urban planning advisory committees.

Efficiency and Collaboration

Increasing accessibility to information provided by a policy increases its efficacy exponentially. Community organizations can: 

  • Inform local community leaders of relevant policies in order to increase the communities’ understanding of the initiatives and services that are available.

 

The municipal government and borough councils can:

  • Translate policies into different languages in order to inform and empower populations who don’t speak English or French (e.g. immigrants, refugees, asylum seekers).
  • Incorporate information into signboards and events around the city to increase awareness.
  • Perform more frequent evaluations of policies to determine their performance that lead to modifications if necessary.
  • Keep the progress of these policies transparent and open to the general public on the city website to keep the government accountable and to keep the public informed. The policy evaluations could be outsourced to community organizations for cost-effectiveness, to reduce bias, and in order to increase collaboration between stakeholders.

 

Climate change needs to be addressed collaboratively through different perspectives in order to address the root causes of environmental, social and health issues rather than reacting individually to the fallout. Interdisciplinary communication during the planning process of policies has economic benefits as collaborating on preventive measures is cheaper than scrambling to create reactive policies.

Certain outcomes of and causes of vulnerability to the urban heat island effect are social in nature. The urban heat island effect and climate change as a whole need to be addressed through a social lens in order to tackle these societal matters.

  • Community organizations should run campaigns expressing the right to have cool communities, especially during heat waves. 

 

Addressing climate change from a health perspective increases its sense of importance and urgency.

  • In order to bring stakeholders together, the municipal government and community organizations could work together to have a three tier collaboration where each government hospital or healthcare centre is tied with a climate organization and a human rights organization. 
  • Climate policies should include health impact assessments in the process. 
  • Moving forward, there should be more collaboration between researchers, community organizations, and the government to create joint recommendations.

The urban heat island effect is inextricably tied with climate change as a whole, with health, and with social equity. Montréal has several policies in place to adapt to and to mitigate the urban heat island effect. However none reflect this interconnection, rendering them much less effective. The next crucial step is to bring together overlapping disciplines in order to optimize existing and future solutions. Policies should be preventive instead of reactive and should have a focus on social connectedness. In the future there should be more research into concrete methods that ensure interdisciplinary collaboration. In addition, there should be research into how to include the private sector as an important stakeholder in interdisciplinary collaboration. Finally, there should be more investigation into how to extend what has been learned in this analysis to other cities.

Photos from Unsplash

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