Ontario

Ontario’s diverse landscapes, topography and natural resources help shape social, economic and cultural characteristics across the province (see Figure 3.2). The climate ranges from sub-Arctic in much of the north to hot-summer humid continental in the southern tip of the province near Windsor. Climate change impacts and adaptation capacity will differ across landscapes in Ontario and within the context of regional social, economic, cultural and environmental diversity.

This report characterizes Ontario as having three subregions. The South subregion extends from Point Pelee Island in the south to the Quebec border in east. It contains half of Canada’s most densely populated metropolitan centres, including the Greater Golden Horseshoe Area (which includes the Greater Toronto and Hamilton Area (GTHA) and the Kitchener-Waterloo Region), and the cities of Ottawa and London. Most of Ontario’s projected population growth will continue to be in urban areas, particularly within the Greater Toronto Area and primarily through migration (Ontario Ministry of Finance, 2021a). The region includes the Canadian portions of Lake Huron, Lake Erie and Lake Ontario, which are critical for regional shipping, industry, tourism and agriculture (Woudsma and Towns, 2017).

The Central subregion includes the cities of Sudbury, Thunder Bay, Timmins, Sault Ste. Marie and North Bay, and has a much lower population density compared to southern areas of the province. The communities within this subregion remain largely dependent on natural resource industries, as well as on smaller, emerging sectors such as financial and business services, research and innovation, construction and tourism (Conteh, 2017). The region contains over two-thirds of the province’s highway lines, which along with the rail network, provide important economic and social linkages between communities (Woudsma and Towns, 2017).

The North subregion, whose boundaries are consistent with those of the Far North as defined in the Far North Act (Government of Ontario, 2010), is sparsely populated. Despite covering 42% of the area of Ontario, this subregion contains only 0.17% of the province’s population (Ontario Ministry of Indigenous Relations and Reconciliation, 2017). It is primarily populated by small First Nation communities that rely on subsistence practices and winter road access in order to acquire necessary resources (Ontario Ministry of Indigenous Relations and Reconciliation, 2017). Extending to the coasts of Hudson Bay and James Bay, the subregion includes areas with continuous and discontinuous permafrost and peatlands that sequester large amounts of carbon dioxide (McLaughlin and Webster, 2014). If disturbed, peatlands can release stored carbon into the atmosphere, reversing the carbon sequestration process and enhancing global warming. There are relatively few social, economic or ecosystem similarities between the North subregion and the Central and South subregions of the province.

Ontario has a population of 14.7 million people and its population was the fastest growing amongst Canadian provinces as of July 2020, growing by 1.3% over the preceding year (Ontario Ministry of Finance, 2021b). The rate of population growth varies across the province, with populations in urban centres of the South subregion growing faster than those in the Central and North subregions, which are remaining stable or declining in some areas. These trends are expected to continue to mid-century under a medium-growth scenario, with the provincial population projected to grow by 35.8% (5.3 million people) over the next 25 years, largely resulting from increased net migration (Ontario Ministry of Finance, 2021c). Climate change will amplify existing social and economic stressors in high population urban centres (Wuebbles et al., 2019).

More than 374,000 people in Ontario are registered Indigenous Peoples, including First Nations, Métis and Inuit; of this number, about 116,000 people speak Indigenous languages (Statistics Canada, 2017). The Indigenous population is distributed across the province, with about one-third living in large population centres, such as Thunder Bay, Sudbury, Sault Ste. Marie, Ottawa and Toronto (INAC, 2018; Statistics Canada, 2017). Over one-quarter of Ontario First Nations Peoples live in remote communities of the North subregion that are only accessible by air or winter roads, two modes of travel that are highly dependent on weather and climate conditions (Ontario Ministry of Indigenous Relations and Reconciliation, 2017).

The diversity of economic activity across the province’s subregions contributes greatly to the strength of Ontario’s overall economy (Ontario Chamber of Commerce, 2020). Goods-producing and service sectors are primary contributors to the provincial economy, with the large metropolitan areas of the South subregion experiencing the highest employment growth rate (Government of Ontario, 2021a). Efforts to diversify resource-dependent economies and to build overall resilience include expanding the service and manufacturing sectors and enhancing ecosystem resilience (Government of Ontario, 2011b). For parts of the North subregion, particularly in the chromium-rich “Ring of Fire” area, newly discovered diamond and metallic deposits present unprecedented opportunities for economic development, with associated concerns about impacts on cultural practices and ecosystems (Chong, 2014).

Building on the findings of previous assessments, this chapter identifies climate change impacts and risks specific to Ontario, evaluates adaptation progress across the province, and reports on knowledge gaps and emerging issues. The chapter assesses the knowledge base pertaining to both impacts and adaptation in Ontario, which has grown substantially since completion of the 2008 national assessment report (Chiotti and Lavender, 2008). Ongoing research continues to strengthen the evidence base and, while literature on risks and impacts still dominates, research focused on adaptation and resilience has increased considerably over the past decade (Brinker et al., 2018; Zeuli et al., 2018; AECOM, 2015; Chu, 2015; Lemieux et al., 2013).

Academic and other literature sources have been supplemented by input received through engagement sessions held with key stakeholders and practitioners across the province. The Key Messages reflect the social, economic and ecological diversity of Ontario, as well as the breadth of climate change impacts.

Ontario’s communities vary in size, population, geography and social fabric (see Sections 3.1.1 and 3.1.2). The infrastructure supporting these populations and economies varies in age and performance and will require significant investments in the coming decades (Canadian Infrastructure Report Card, 2019). These investments, encompassing maintenance, repair, reconstruction and new construction, present opportunities for climate change adaptation. Accounting for climate change risks in infrastructure renewal and upgrades yields broad and long-term social, environmental, and economic benefits (Adaptation to Climate Change Team, 2021; Canadian Climate Institute, 2021).

Widespread damage from extreme events in Ontario (see Section 3.2.2), including to human health and safety, has highlighted the vulnerabilities of infrastructure to climate change. This section focuses on flooding in southern Ontario and the impacts of climate change on winter roads in the north. It then discusses how adaptation is advancing across the province, through the application of infrastructure risk assessments and incorporation of climate change into infrastructure asset management. It concludes with a discussion on the importance of considering interdependencies between different types of infrastructure when planning for adaptation.

Climate impacts with the highest documented costs and frequency in Ontario include flooding related to extreme rainfall, rainfall on frozen ground, rapid snow melt and ice jams (Moudrak and Feltmate, 2019; Farghaly et al., 2015; Boyle et al., 2013). Extreme rainfall intensity is increasing in Ontario (Coulibaly et al., 2016; Soulis et al., 2016; Mekis et al., 2015; Shephard et al., 2014; Cheng et al., 2012; Paixao et al., 2011 ), as it is in adjacent regions in the United States (Easterling et al., 2017; Walsh et al., 2014). Non-climatic stressors, such as urban growth and land-use changes, also serve to increase the risks associated with flood events in Ontario (Henstra et al., 2020; Oleson et al., 2015).

Flood-related damage to infrastructure has been a primary driver of the increases in both insured and uninsured losses across Ontario and in many other parts of Canada (Moudrak and Feltmate, 2019; Feltmate et al., 2017; Moghal and Peddle, 2016; IBC, 2015). Flooding events in cities have interrupted business activity and caused hardship and anxiety among residents (Manning and Clayton, 2018; Decent and Feltmate, 2018; Moudrak and Feltmate, 2017). The rising costs associated with flooding in Canada are estimated to be accompanied by significant productivity losses (Insurance Bureau of Canada and Federation of Canadian Municipalities, 2020; Davies, 2016). While reporting on insured losses paints a picture of high costs from urban flood events (see Table 3.1; Robinson and Sandink, 2021), additional uninsured damages increase the magnitude of total losses and are often unknown. However, estimates by the Insurance Bureau of Canada suggest that for every dollar of insured loss, there are three to four dollars of uninsured losses, which are borne by homeowners, business owners and governments (Moudrak et al., 2018).

Given the vulnerability of Ontario’s infrastructure to extreme precipitation and flooding, adaptation approaches frequently involve the use of updated rainfall Intensity-Duration-Frequency (IDF) curves that determine the probability of a given rainfall event occurring (Simonovic et al., 2017; IBI Group, 2016; Soulis et al., 2015; Shephard et al., 2014 ). Methods to adjust IDF curves to account for climate change vary (Schardong et al., 2020; Soulis et al., 2016) and can yield significantly different results. User-friendly Web interfaces (Ontario Ministry of Transportation, 2016; Schardong et al., 2020) and other technical guidance (Canadian Standards Association, 2019) are available for engineers and others to access updated IDF data, helping to facilitate the consideration of changing climate conditions in infrastructure-related decisions (Switzman et al., 2017; Sehgal, 2016; Soulis and Sarhadi, 2016; Solaiman and Simonovic, 2011).

To address extreme rainfall and flood risk, municipalities have traditionally employed end-of-pipe solutions to deal with stormwater. However, in recent years there has been an increase in the use of permeable surfaces and natural infrastructure to help control larger amounts of water (quantity) and to filter the water that recharges sub-surface aquifers (quality) (see Ecosystem Services chapter of the National Issues Report; Eckart et al., 2017; Environmental Commissioner of Ontario, 2017, 2016). Hamilton, Toronto, Thunder Bay, London, Newmarket and many other Ontario municipalities and conservation authorities have been actively promoting climate change adaptation through low-impact development (LID), master planning and watershed adaptation strategies (Henstra et al., 2020). Successful LID pilots include the use of permeable pavement, bioswales, rain gardens, green roofs, infiltration trenches and other forms of stormwater management that can be particularly valuable in limiting the impacts of smaller event storms (see Cities and Towns chapter of the National Issues Report). Natural areas like ponds, wetlands and vegetated areas are increasingly being viewed as tools for flood prevention and have numerous environmental and social benefits (e.g. for biodiversity and water quality), the value of which is highlighted in robust total economic value assessments (Moudrak et al., 2018).

Forty-four Ontario municipalities have combined sewer overflow (CSO) systems that release untreated or partially treated sewage into receiving lakes and rivers, and that are at higher risk of surcharging during flooding due to inadequate design standards at the time of construction, increased impervious surfaces and urban growth (Environmental Commissioner of Ontario, 2018b). As municipalities seek to replace outdated CSO systems and improve stormwater infrastructure, consideration of projected increases in the frequency and magnitude of flooding events will significantly reduce the risk of sewer backup and damage in homes, and the accompanying human health risks (Kovacs et al., 2014).

Compared to more southerly and more densely populated areas of Ontario, infrastructure in the North subregion of Ontario services smaller, more dispersed and less populated communities, which are mostly Indigenous. Transportation infrastructure, which includes winter roads and air strips, is particularly crucial for the movement of goods and services into isolated communities. Warmer winters and temperature variability make winter road construction and maintenance difficult affecting road stability and safety, and ultimately impacting the supply of fuel, food and other staples (Hori et al., 2018a; 2018b).

Winter roads in northern Ontario provide overland connection to provincial highways and railway systems (see Figure 3.3). Winter roads reduce transportation costs of goods, compared to other alternatives, provide more affordable access to services (such as health care), support the self-sufficiency and well-being of people who travel for cultural and community events, and enhance access to remote communities and mineral resources. The roads are partly ice roads, in that portions of them cross rivers and lakes, while other sections traverse land. One metre of good quality ice can support loads of 50,000 kg (NWT, 2015). Over recent years, the operating seasons have been shortening due to early thaw in the spring and warm spells in mid-season, as well as more frequent service disruptions due to variable weather events. These have resulted in softening of the road surface, deteriorating driving conditions requiring slower speeds and smaller loads, increased operations and maintenance costs, and increased risks to health and safety (Barrette, 2018; IBI Group, 2016).

While conditions for more northerly locations may remain suitable for ice road construction in Northern Ontario through the middle of this century, even under high emission scenarios, seasonal warming and variability in weather conditions will affect more southerly locations and may preclude a viable ice road season (Hori et al., 2018b).  Warm spells, such as those reported by winter road operators (Barrette, 2018; Kimesskenemenow Corporation, Ontario National Assessment Engagement Sessions, 2018–2019), and the trend toward fewer days of extreme cold (e.g., average number of days of -25°C or lower decreased from 79 days in the mid-1950s to 57 days in the mid-2010s; IBI, 2015) pose significant challenges for construction and maintenance.

A range of solutions is available to help manage risks to winter/ice roads in the Far North, including the following: 1) using ice-penetrating radar for determining adequate ice thickness; 2) establishing permanent creek and small river crossings at key locations; 3) realigning some sections of road to be on land that is less susceptible to flooding during thaws or winter rain; 4) realigning some sections of road to be in corridors that are suitable for later upgrading to all-season roads; and 5) consistently using the best possible construction and maintenance protocols (Barrette, 2018). Moving from roads to airships or hovercraft for transporting heavy loads continues to be discussed as an option (IBI Group, 2016). In addition to technical solutions, communities have considered other alternatives, including the possibility of having all-weather roads and increasing self-sufficiency with respect to consumables (Reid, 2015). Adaptation responses are ultimately at the discretion of the community and dictated by regional circumstances and capacity.

Climate change risk assessments are key tools for understanding infrastructure vulnerability and options to enhance resilience.  Since 2007, more than 20 engineering-focused climate change risk assessments have been conducted in Ontario as part of a national effort to train engineers on how to consider climate change in infrastructure decisions (see Table 3.2). Most of these assessments were completed using the Public Infrastructure Engineering Vulnerability Committee (PIEVC) protocol, which is a systematic, risk-based approach to reviewing how different weather and climate drivers affect infrastructure performance and life expectancy (Engineers Canada, 2016). The protocol has also been adapted for application in First Nations communities (First Nations Infrastructure Resilience Toolkit (FN-IRT); Félio and Lickers, 2019) and is planned to be released in summer 2022. The resulting assessments reveal the thresholds at which different infrastructure systems will be compromised when exposed to extreme weather and climate variability, and validate the interdependencies between infrastructure systems. They also identify and prioritize locations and populations that are most vulnerable in terms of climate change impacts on infrastructure and related service disruptions (Zeuli et al., 2018). Furthermore, they help raise awareness about climate risks among senior managers (AECOM, 2015) and, more broadly (Chiotti et al., 2017), signal the need for collaboration and coordination regarding adaptation responses, and serve as a catalyst for the creation and implementation of adaptation measures (Chartered Professional Accountants of Canada, 2015a; 2015b). Risk assessments are usually the first step in developing a comprehensive climate change adaptation strategy (see Case Story 3.1).

Municipalities and other infrastructure owners and managers have begun to incorporate adaptation into their asset management practices (see Cities and Towns chapter of the National Issues Report; Kenny et al., 2019; Kenny et al., 2018; Metrolinx, 2018; Federation of Canadian Municipalities, 2017; Félio, 2017; Ontario Chamber of Commerce, 2017; Ernst and Young, 2016; Félio, 2016). New statutory and regulatory requirements have been an important driver of this activity. Of particular importance is the 2015 Jobs and Prosperity Act, with regulation 588/17 requiring municipalities to develop and implement an asset management plan and supporting policies for municipal infrastructure (Ontario e-Laws, 2018). The regulation also requires municipalities to “consider actions that may be required to address vulnerabilities that may be caused by climate change…” (Ontario e-Laws, 2018). Another key driver has been the Federation of Canadian Municipalities Municipal Asset Management Program, which since 2016 has funded 157 projects in Ontario focused on improving asset management practices (Federation of Canadian Municipalities, 2020). Integrating climate change into the planning, maintenance, renewal and rehabilitation cycle of infrastructure assets ensures their longevity and helps to safeguard service levels for communities (see Figure 3.4; Canadian Infrastructure Report Card, 2019; 2016).

Under the Environmental Assessment Act, the Ontario Ministry of Environment, Conservation and Parks (MECP) has issued guidance on how best to consider climate change in the environmental assessment process. Additionally, the Ontario Provincial Policy Statement 2014 states that “planning authorities should promote green infrastructure” (Ontario Ministry of Municipal Affairs and Housing, 2020) that delivers additional benefits in the areas of human health and reduction of greenhouse gas emissions.

Ontario’s water and wastewater, transportation, energy and telecommunications infrastructure, buildings and other forms of infrastructure are highly interconnected. In many cases, interdependencies exist, which means that the safe and consistent operation of one asset contributes to a similarly safe and consistent operation of another. Disruptions, caused by climate events or other factors, can lead to multiple and compounded infrastructure failures, affecting the delivery of critical services and routine business operations (see Sector Impacts and Adaptation chapter of the National Issues Report). Infrastructure interdependencies are not just physical, but also pertain to ownership, responsibility and liability. Businesses are often shared users and owners of infrastructure, and while they can take steps independently to be more climate resilient (through, for example development of business continuity plans, acquiring suitable insurance, etc.), they still remain dependent on the climate resiliency of neighbouring services.  Decision making in such situations requires tools and planning processes that incorporate complex interdependencies (Bondank and Chester, 2020; Farhad et al., 2019; Zeuli et al., 2018; AECOM 2017).

The City of Toronto led a high-level risk assessment to identify interdependencies and adaptation responses that span multiple sectors (hydroelectricity, transportation, water and wastewater, food and agriculture, etc.) (AECOM, 2017). One example highlighted how a natural gas provider and district energy supplier are dependent on Toronto Hydro for electricity, and Toronto Hydro in turn relies on infrastructure like the City’s road network and stormwater system, with the result that flooding associated with extreme rainfall could cascade through all electricity assets and lead to failure (see Figure 3.5; AECOM, 2017).

The Toronto risk assessment exemplifies the collaboration required to mobilize adaptation. It sheds light on the cascading impacts of climate change, as well as efficiencies in planning that can make adaptation more cost-effective. The assessment also highlighted the need for information sharing protocols, detailed engineering-level investigations, enhanced funding and more proactive infrastructure planning and policy development (AECOM, 2017).

Biodiversity is defined as “the variability among living organisms from all sources including inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part: this includes diversity within species, between species and of ecosystems” (United Nations Convention on Biological Diversity, 1992). Biodiversity includes the goods and services that ecosystems provide, including those on which humans depend for our survival, health, safety and/or prosperity (Ontario Biodiversity Council, 2015, 2011). Weather and climate combined with physical site conditions largely determine which species can survive and which cannot (Nituch and Bowman, 2013). Given the climate’s relative stability over the past several millennia, entire ecosystems and their associated species have evolved to cope with prevailing climate and soil conditions (Brinker et al., 2018).

The Ontario Biodiversity Strategy recognizes climate change as one of the greatest threats facing biodiversity (Ontario Biodiversity Council, 2011, 2015). Existing stresses on terrestrial and aquatic ecosystems can be exacerbated by climate impacts, such as changes in the frequency and magnitude of extreme weather, the extent and duration of freshwater ice cover, vegetative phenology, breeding activity and insect emergence, with cascading effects on food webs. A number of other provincial strategies and programs address biodiversity and ecosystem impacts, including the Ontario Ministry of Natural Resources and Forestry (MNRF)’s Climate Change Adaptation Strategy (Ontario Ministry of Natural Resources and Forestry, 2017b), the Wetland Conservation Strategy (Ontario Ministry of Natural Resources and Forestry, 2017c), and the 50 Million Tree Program (Forests Ontario, 2016).

More than 14% of the 15,800 plant and animal species in Ontario that have been assessed by scientists are considered vulnerable, rare or rapidly declining, and their future survival is uncertain (Canadian Endangered Species Conservation Council, 2016). Opportunities to enhance the resilience of species to a changing climate vary depending upon available habitat, species vulnerability and available management tools (see Box 3.1). Integrating species vulnerability assessments into habitat and species management, restoration and species recovery planning can help to enhance resilience, as can judiciously applied assisted migration (see Section 3.5.3) in forest and other habitat restoration activities (Brinker et al., 2018; Douglas et al., 2014; Lemieux et al., 2014; Chu and Fischer, 2012; Gleeson et al., 2011; Ste-Marie et al., 2011).

A number of guidance documents are available to assist ecosystem managers and practitioners to include climate change in planning and management practices (e.g., Environment Canada, 2013; Gleeson et al., 2011). Key approaches for enhancing ecosystem resilience include the following: protecting intact ecosystems; increasing connectivity through the protection and implementation of ecological corridors (see Box 3.2) and regional/urban biodiversity strategies; and strategically using native species suited to new locations and predicted climatic conditions in habitat restoration efforts. Actions that can boost the resiliency of aquatic ecosystems and organisms are as follows (Myers et al., 2017; Chu, 2015; Gleeson et al., 2011):

1. Restricting withdrawals of surface and groundwater from vulnerable lakes, rivers and wetlands;
2. Providing nest boxes or rehabilitating nesting habitats for vulnerable wetland birds;
3. Maintaining natural water levels in lakes and wetlands, and flow rates in rivers;
4. Restoring or enhancing riparian vegetation along stream shorelines;
5. Identifying and protecting refugia; and
6. Limiting human development and industrial activities.

The Great Lakes Basin play a critical role in shaping Ontario’s environmental, social, cultural and economic landscape. As a region, including both Canada and the U.S., the Great Lakes–Saint Lawrence Basin covers more than 765,000 square kilometres, contains 21% of the world’s fresh surface water, and is home to more than 8.5 million Canadians (22% of the population) (Council of the Great Lakes Region, 2017). Surrounding communities rely on the freshwater resource for drinking water, recreation and tourism, manufacturing, fishing, agriculture and shipping industries.

Climate change is considered one of the greatest threats facing the Great Lakes Basin, exacerbating risks associated with land-use changes and other human activities, resulting in changes to the physical, chemical and ecological characteristics of the lakes, and presenting social and economic risks to surrounding communities (Brinker et al., 2018; Government of Ontario, 2016a; McDermid et al., 2015b).

The widespread impacts of climate change have been well documented, as discussed in Section 3.4.2 (Great Lakes Integrated Sciences and Assessments (GLISA) and Environment and Climate Change Canada (ECCC), 2018; International Joint Commission Great Lakes Water Quality Board, 2017; McDermid et al., 2015b) and are projected to worsen over the coming decades (Bonsal et al., 2019; Derksen et al., 2019; Angel et al., 2018; GLISA and ECCC, 2018; McDermid et al., 2015b). The risks associated with climate change are presented in Annexes to both the Great Lakes Water Quality Agreement (Government of Canada and Government of the United States, 2012) and the Canada-Ontario Agreement on Great Lakes Water Quality and Ecosystem Health (Government of Canada and Government of Ontario, 2014). Solutions lie in coordinated and collaborative adaptation planning and management across the Basin.

Climate change presents new threats to the Great Lakes Basin, but opportunities for sustainable development and growth arise with effectively implemented adaptation measures. Adaptation planning and implementation have progressed across Ontario communities within the Basin over the past decade, with many different agencies, groups and partnerships participating (see Box 3.3). The governance of the Great Lakes is highly complex because of its transboundary, multi-jurisdictional nature. Over the years, various binational (e.g., International Joint Commission), national, provincial and state institutions and agencies have developed a number of initiatives and agreements to better protect and sustain the Great Lakes (e.g., the Great Lakes Water Quality Agreement; the Great Lakes and St. Lawrence Cities Initiative; the Great Lakes–St. Lawrence River Basin Sustainable Water Resources Agreement). Despite this, adaptation efforts across the Basin remain relatively piecemeal and fragmented, highlighting the recognized need for more coordinated and collaborative adaptation approaches amongst governing agencies (see Figure 3.12; International Joint Commission Great Lakes Water Quality Board, 2017; McDermid et al., 2015b).

Many conservation authorities, Indigenous communities, property owners, service providers and some regional and municipal governments in Ontario have adopted adaptive management principles in responding to climate impacts in the Great Lakes Basin (Conservation Ontario, 2018; Abdel-Fattah and Krantzberg, 2014a, 2014b; Andrey et al., 2014). Adaptive management involves continuous monitoring, evaluation and improvement of management plans, strategies and programs, and is designed to enhance resiliency in an ongoing fashion (see Water Resources chapter of the National Issues Report; Leger and Read, 2012; Gleeson et al., 2011). Examples of implemented adaptation measures in Ontario communities include the following: flexible fish harvest regulations (e.g., slot size limits, catch limits, season lengths) for species that are vulnerable to, or that benefit from, climate change; restoring banks and shorelines to reduce erosion and flood risks; and modifying municipal zoning and building codes to account for increased coastal flooding (Myers et al., 2017; Lenarduzzi, 2016; Moghal and Peddle, 2016; Abdel-Fattah and Krantzberg, 2014a; Huff and Thomas, 2014; Lemieux et al., 2014).

Many regional and sectoral vulnerability and risk assessments have been, and are being, completed across the basin to identify priority impacts and to begin planning and implementation of adaptive solutions (Perdeaux et al., 2018). While some of this work is driven by statutory and regulatory requirements (see Section 3.2.3), the number of climate change adaptation plans and strategies developed by local governments will increase as more communities experience the direct impacts of the changing climate (see Case Story 3.3). Even with these adaptation planning efforts, examples of adaptation implementation and evaluation remain limited (National Assessment Engagement sessions, 2019).

Ontario’s landscape is 66% forested and accounts for one fifth of Canada’s forest area (Government of Ontario, 2021b). The area includes four broad forested regions: the Hudson Bay Lowlands in the North subregion, the boreal forest in North and Central subregions, the Great Lakes–St. Lawrence forest in the Central and South subregions, and the deciduous forest in the South subregion (see Figure 3.14; Government of Ontario, 2019a).

Ontario’s forests support more than 147,000 direct and indirect jobs (Government of Ontario, 2020) and generated over $18.0 billion in total revenue in 2019 (Government of Ontario, 2020). Social and cultural benefits are harder to quantify, but Ontario’s forests are a source of significant cultural, aesthetic and spiritual importance to Ontarians, especially to Indigenous Peoples (Natural Resources Canada, 2018). Recreational activities such as camping, hiking, berry picking and hunting are also supported by forests (Government of Ontario, 2020).

The unmanaged forests of the Northern subregion sequester significant amounts of carbon. Total carbon storage in this area is projected to increase by between 16.7% to 20.7 % by the end of the century under all Shared Socio-economic Pathway scenarios (see Section 2.22 in Bush et al., 2022 for an explanation of these scenarios), but stands are heavily influenced by wildfire (Ter-Mikaelian et al., 2021). Carbon storage potential in managed forests in the province exceeds that of unmanaged forests, but both are heavily influenced by fire and other stressors (Ter-Mikaelian et al., 2021; Chen et al., 2018).

Warmer winter temperatures have reduced the number of extreme cold days in Ontario, increasing the survival rate of forest pests, such as the emerald ash borer, forest tent caterpillar, spruce budworm and gypsy moth (Natural Resources Canada, 2019; Price et al., 2013; Candau and Fleming, 2011; Regniere et al., 2009). Warmer winters have also reduced resistance to cold and promoted earlier spring bud burst in boreal conifers, making them vulnerable to late spring frosts. For example, in northwestern Ontario in the spring of 2012, warm temperatures in March caused de-hardening, then were followed by freezing temperatures in April, resulting in a massive needle browning event, which affected more than 250,000 hectares of forest (see Figure 3.15; Rossi, 2015; Man et al., 2013). Recovery from browning may take several years, during which time the tree may be more susceptible to other stressors such as insects and disease (Man et al., 2013).

Increasing summer temperatures accompanied by minimal increases in precipitation are projected to lead to drier conditions, more frequent drought and greater fuel loads (e.g., combustible organic matter) across the province, driving an increase in the frequency, intensity, extent, and timing and duration of forest fires (Wotton et al., 2017; Flannigan et al., 2016; Boulanger et al., 2014; Gauthier et al., 2014). The annual area burned from wildfires could double by the 2040s and increase eightfold by 2100, under a high-emissions scenario (Podur and Wotton, 2010). By the end of the century, the area burned by large fires (see Figure 3.16), the number of days where fire is likely to occur, and the number of days where fire intensities exceed suppression resources are all expected to increase significantly, creating challenges for wildfire management (Wotton et al., 2017; Gauthier et al., 2015). Wildfires have cascading impacts, affecting human health and well-being, and causing economic disruptions and losses (see Sector Impacts and Adaptation chapter of the National Issues Report; and the Natural Hazards chapter of the Health of Canadians in a Changing Climate). Fires can affect forestry operations and timber supply, while smoke from fires can taint the taste of agricultural crops such as grapes and berries, disrupt transportation and force evacuation of residents in proximal communities, notably Indigenous communities in the north of the province (see Figure 3.17). Forced evacuations by air from Indigenous communities without road access, such as those that occurred in Pikangikum, Deer Lake and Poplar Hill in 2021, are especially harmful to community members. Residents of Pikangikum were scattered between communities as far away as Cornwall, at a distance of 1,600 km, for almost one month (CBC News, 2021).

More frequent, severe and widespread outbreaks of pests and diseases are expected due to milder winter temperatures, with damage from pests increasing, particularly in the North and Central subregions of the province (Government of Ontario, 2019b; Candau et al., 2018; James et al., 2017; Pureswaran et al., 2015; Huff and Thomas, 2014; Regniere et al., 2009; Williamson et al., 2009). Damage to eastern spruce from budworm results in increased fire risk after defoliation, as breakage of dead tree tops and windthrow (trees uprooted or broken by wind) gradually build up an accumulation of “ladder fuels” that can lead to more forest fire ignitions, and allow the flames to extend higher into the forest canopy (James et al., 2017). Longer periods of moisture deficit driven by increased temperatures, lower seasonal precipitation and other factors, such as wind, will result in periods of decreased water availability, which also increase the risk of fire ignition (Candau et al., 2018; James et al., 2017).

Warming imposes constraints on the growth of several boreal species, including balsam fir and larch, which could restrict their survival by the end of the century under a high greenhouse gas emissions scenario (Yeung et al., 2019; Boulanger et al., 2017). Traits, such as sensitivity to drought-induced mortality and potential for migration failure, affect the vulnerability of tree species and populations to climate change (Aubin et al., 2018). For example, drought events in the southern part of the white spruce’s range during the growing season in Ontario have exceeded the species’ drought tolerance capacity, significantly increasing mortality and reducing growth rates (Sang et al., 2019). Projected temperature increases and the frequency and severity of the growing season drought will likely result in a gradual retraction of white spruce from its current southern range edge (Weng et al., 2019).

Resilient forests provide a range of ecosystem services to society (see Ecosystem Services chapter of the National Issues Report). The influence of climate change on forest disturbance regimes will have negative consequences for the provision of ecosystem services and carbon storage (Thom and Seidl, 2016). However, considering climate change projections and impacts in forest management planning will help to achieve management objectives, including biodiversity, productivity and carbon storage (Ontl et al., 2020).

At longer timescales, shifting climate envelopes will result in a general northward migration of tree species in Ontario, although the pace of climate change is likely to exceed the natural ability of forests to adapt (Brecka et al., 2018; Pedlar and McKenney, 2017; Janowiak et al., 2014; Huff and Thomas, 2014; Colombo, 2008). Some populations of northern conifers respond negatively to temperature increases and are expected to decline at the southern edge of their range, decreasing their dominance in the population by up to 30% (Candau et al., 2018; Pedlar and McKenney, 2017; Janowiak et al., 2014; Thomson et al., 2010).

Initiatives to enhance the climate resilience of forests and forested landscapes are being undertaken at regional and local scales, and involve a wide range of actions. At the provincial level, the 2017 Ontario Ministry of Natural Resources and Forestry climate adaptation strategy includes forest-specific actions such as the following: 1) reviewing tree seed and nursery stock transfer policies to ensure that they are based on the best available science; 2) exploring opportunities to improve provincial monitoring programs to take stock of climate change impacts; and 3) improving knowledge about specific tree species and habitats known to be vulnerable to climate change (Ontario Ministry of Natural Resources and Forestry, 2017b).

In 2018, the Lake Simcoe Region Conservation Authority completed a comprehensive study of the impacts of climate change on tree planting and forest management, and identified ways that local programs might adapt (Lake Simcoe Region Conservation Authority, 2018). Their list of adaptation options included the following examples: 1) increasing the genetic and structural diversity of planted stock; 2) preparing for earlier planting time frames; 3) increasing post-planting tending activities; and 4) selecting climate-appropriate tree species (Lake Simcoe Region Conservation Authority, 2018).

Climate change adaptation to increase forest resilience can also help to achieve carbon storage objectives. A range of options has been documented that can help manage climate change risks on forested landscapes (Edwards et al., 2015). Some forest management measures that support ecosystem services and overall forest health also promote carbon storage (Swanston et al., 2016). The Practitioners Menu of Adaptation Strategies and Approaches for Forest Carbon Management provides a suite of 31 approaches using seven different strategies that provide broad responses to climate change (Ontl et al., 2020).

A key challenge for forest adaptation is addressing the fact that the pace of climate change is likely to exceed the natural ability of forests to adapt (see Section 3.5.2). Many jurisdictions across Canada are examining the potential value of assisted migration, i.e., human interventions to deliberately relocate species to new, more climate-suitable locations (Edwards, 2015; Eskelin et al., 2011). Since 2010, six assisted migration trials have been implemented in Ontario to compare locally sourced and more southern-sourced seeds (Forests Ontario, 2018). The movement of tree seeds beyond their current seed transfer zones requires approval from the Ontario Ministry of Natural Resources and Forestry (Ontario Ministry of Natural Resources and Forestry, 2017a). The Ministry is using SeedWhere to inform updates to the Ontario Tree Seed Transfer Policy (see Box 3.4; McKenney et al., 2009).

A range of actions has been documented to help improve forest resilience in the context of changing climate (see Table 3.4). These adaptive strategies will improve forest health for recovery and enable a transition to new stand structure (Sang et al., 2019).

Knowledge of the rate, magnitude and location of changes in forest composition and distribution remains highly uncertain (Candau et al., 2018). Adaptation in forests is further complicated by the long timelines involved, as forest management decisions made today will have effects far into the future (Lemmen et al., 2014). It is also important that adaptation objectives align with other objectives, such as biodiversity and species-at-risk. Ultimately, a comprehensive and integrated systems approach that accounts for the full range of climate impacts and the interactions between them will best improve understanding of tree vulnerability to climate change and how to support the adaptation of trees (Johnson, 2009). Collaborative initiatives, such as the Forestry Adaptation Community of Practice (see Box 3.5), are helpful in this regard.

Agri-food is a multi-faceted sector that is inextricably linked to other economic sectors and is co-dependent on infrastructure components, such as electricity, transportation and telecommunications (see Sector Impacts and Adaptation chapter of the National Issues Report). According to the 2016 census, Ontario’s agricultural sector employed over 800,000 people (approximately 11.5% of provincial employment) and contributed $39.5 billion to the provincial economy (OMAFRA, 2016). Ontario is also Canada’s top agri-food exporting province (OMAFRA, 2016).

The province’s prime agricultural lands are located mostly in the South subregion and provide current and future opportunities for agriculture. Farm-level agriculture is enshrined in the social fabric of rural communities throughout this subregion. Smaller, but potentially important areas for agriculture are found in the Central subregion, particularly the Great Clay Belt (Cochrane district), Manitoulin Island, Kenora, Rainy River, Dryden and Thunder Bay districts. Further expansion of growing areas in Ontario is possible with ongoing climate change (Robinson et al., 2020; Morand et al., 2017c).

The vulnerability of agricultural systems to climate change depends largely on the characteristics of local farming systems and the specific crops that are grown. Farmers frequently implement adaptive measures and seek new technologies in order to better manage on-site weather and climate risks (Holland and Smit, 2014). These measures often involve the use of crop-specific, commodity-specific and region-specific responses and tools to improve the productivity of farming operations, including cultivar selection, adjusting the timing of cropping operations, fertilizer and pesticide application, crop rotation, tillage practices, tile drainage and irrigation optimization (Ontario Ministry of Agriculture, Food and Rural Affairs, 2021a; Ontario Cover Crops Steering Committee, 2017; Council of Canadian Academies, 2013).

Observed increases in seasonal and annual temperatures in parts of Ontario are reflected by changes in agroclimatic indices, which show increases in average growing season length, the number of growing degree days (GDDs) and rates of average evapotranspiration (Bootsma, 2012; 2011). Continued warming and increases in accumulated crop heat units (CHUs: a temperature-based index used to determine growth potential of corn) will support new crop establishment and/or range expansion into other parts of the province, including in more northerly regions where water availability and soil conditions are suitable (Qian et al., 2012). For example, in the Great Clay Belt region, where just over 18% of the 1.8 million ha of prime agricultural land is currently used in agricultural production, growing season length is projected to increase from 160 days in the 2020s to over 180 days in the 2050s under a high-emissions scenario (Robinson et al., 2020; Morand et al., 2017b). However, such benefits of climate change may be offset, or potentially overwhelmed, by a range of negative impacts, including the increased frequency and intensity of extreme weather events, which can lead to enhanced soil erosion, increased moisture stress, crop damage and an increase in livestock fatalities (Motha and Baier, 2005). The rapid rate of climate change, particularly changes in extreme temperature and precipitation events, may challenge adaptation efforts (Kulshreshtha et al., 2010; Wall et al., 2007).

A wide range of climatic and non-climatic factors influences crop growth and yield. While key factors, including geographic location, soil type, weather patterns and extreme events, are outside the control of producers, responses such as the choice of cultivars, tillage, irrigation and fertilization practices and timing of major operations provide opportunities to improve yield in any given year (Morand et al., 2017c; Brklacich and Woodrow, 2016; Holland and Smit, 2013).

A large number of studies have examined how climate risks to crops and commodities could affect future productivity. These include impacts on maize (Qian et al., 2019; He et al., 2018; Morand et al., 2017a; Zaytseva, 2016; Gaudin et al., 2015), soy (He et al., 2018; Jing et al., 2017; Zaytseva, 2016), wheat (Qian et al., 2019; He et al., 2018), canola (Qian et al., 2019; Qian et al., 2018; Wu et al., 2018), grapes (Hewer and Gough, 2019; Shaw, 2017; Holland and Smit, 2014) and maple syrup (Sugar Maple) (Brown et al., 2015; Richardson, 2015). Dynamic crop models are often used to quantify climate change impacts on crop yields (see Table 3.5), enabling more focused impact assessments (Luo, 2011). Differences and biases in crop models, as well as the climate scenarios and downscaling methods used, create uncertainties in projected crop yield changes (Li et al., 2018). The use of multi-model ensembles reduces biases present in individual models and is recommended in assessments (Qian et al., 2020).

Feed and pasture forage for livestock represents 10% of Ontario’s agricultural production (Ontario Ministry of Agriculture, Food and Rural Affairs, 2016). Forage production, particularly in northern locations, is constrained by growing season length and the resulting number of harvests. Projected increases in forage yield will provide benefits to livestock farming (Payant et al., 2021; Thivierge et al., 2017) along with agricultural expansion opportunities in northern regions (Chapagain, 2017). Livestock are also negatively affected by exposure to extreme or prolonged heat (Smith and Eastwood, 2017; Bishop-Williams et al., 2015), and other weather-related factors including wildfire (Schultz and Lishman 2018), extreme cold (Tarr, 2015; Richardson, 2003) and extreme precipitation (Cheng et al., 2022; Rojas-Downing, 2017).

Climate change will lead to increased movement and establishment of invasive alien species, including pests, disease and competing plants, which will threaten agricultural production (see section 7.4 of the Sector Impacts and Adaptation chapter of the National Issues Report; International Plant Protection Convention Secretariat, 2021). Increased annual temperatures allow pests to expand the northern bounds of their range, while warmer winters allow proliferation of certain pests (Baute, 2020; Taylor et al., 2018). As climate envelopes shift northward to create or expand suitable temperature conditions, the southernmost areas of Ontario stand to be the first to experience new invasive alien species, particularly in areas where their movement may be facilitated by transportation across the international border. Earlier and longer growing seasons may provide a more abundant food source for pests and, in some cases, may warrant additional application of management techniques, such as herbicides or pesticides (Baute, 2020; Taylor et al., 2018).

Aspects of food processing, distribution and retail that complement primary agricultural production and that are dependent on buildings, transportation, electricity, telecommunications and fuel supply also face exposure to climate risks. Disruptions caused by extreme weather events cascade through the broader supply system and highlight the need for adaptation at many levels and by many actors (Toronto Medical Officer of Health, 2018; Zeuli et al., 2018). In many cases, impacts to the food supply chain cascade down to vulnerable populations with pre-existing food security and access challenges (Mbow et al., 2019; C40 Cities, 2018). A systematic review of food system vulnerability was commissioned by Toronto Public Health to identify risks to the food supply chain and impacts on public health, specifically for vulnerable populations. While concluding that Toronto’s food system is relatively resilient to climate change, six main vulnerabilities were identified, along with recommendations to improve climate resilience (see Table 3.6; Zeuli et al., 2018).

Principles for building climate resilience apply to the province broadly, with several province-wide programs serving to enhance climate change education, engagement and capacity support for the agriculture sector as a whole (Morand et al., 2017c). Programs such as the Canadian Agricultural Partnership (Agriculture and Agri-Food Canada, 2021), the Canada-Ontario Environmental Farm Plan (Ontario Ministry of Agriculture, Food and Rural Affairs, 2021b), and business risk management programs, delivered by the provincial agency Agricorp, provide access to clean technology funding, as well as mechanisms for promoting climate change adaptation and increased adoption of best management practices for soil health, water quality and other ecosystem goods and services.

Specific adaptation options are usually dependent on local-scale circumstances, and include actions such as diversifying crops, introducing different crop rotations, managing water on-site, and adjusting the timing of seeding (Qian et al., 2018; Morand et al., 2017a; Gaudin et al., 2015). Tender fruit growers use wind machines or frost fans to protect fruit against early spring frost, and hail nets and hail cannons to protect against hail storms (Ontario Apple Growers, 2018). Tender fruit, grain and oilseed growers are selecting new cultivars better suited to projected climate conditions (Hewer and Gough, 2018; He et al., 2017; Shaw, 2017; Holland and Smit, 2014). Understanding specific vulnerabilities and options to enhance climate resilience can be assisted by decision-support tools (see Case Story 3.4).

The presence of mechanisms to support, enable or encourage adaptation does not necessarily result in uptake. In the absence of increased adaptation, traditional mechanisms such as agri-insurance programs may experience deficits and require additional investment by government to ensure their sustainability over time (Auditor General of Ontario, 2017). Efforts to adapt to climate change are frequently driven by economic opportunities, such as the expansion of grape production for wine, or land-use changes for the expansion of beef farming (Hewer and Gough, 2019; Morand et al., 2017b; Shaw, 2017; Beef Farmers of Ontario, 2014; Holland and Smit, 2014). Recognizing the full potential of these efforts requires investments in areas such as infrastructure and labour, as well as supportive policy in areas of land use, water and agriculture (Chapagain, 2017; Morand et al., 2017b; Barbeau et al., 2015).

Climate change increases existing threats to population health and compounds existing pressures on key factors such as water quality, food security and shelter (see Health of Canadians in a Changing Climate; Decent and Feltmate, 2018; Watts et al., 2018; Zeuli et al., 2018; Gough et al., 2016; Berry et al., 2014b). Vulnerable and marginalized populations, including those with existing social and health inequities, existing or underlying health issues, or economic disparities, face a disproportionally larger burden from the impacts of climate change (see Figure 3.19; Expert Panel on Climate Change Adaptation and Resilience Results, 2018; Berry et al., 2014b).

Extreme weather has significant impacts on human health (Decent and Feltmate, 2018; Rajaram et al., 2016). These include direct impacts to health and safety, for example from heat events (e.g., heat stress), wildfires (e.g., loss of trees, homes, impacts on people), extreme wind (e.g., injuries from flying debris), and from heavy rainfall causing flooding (e.g., drowning) as well as indirect impacts (e.g., illness from poor water quality or exposure to mold, psychosocial trauma) (see Figure 3.20; Council of Canadian Academies, 2019; Gough et al., 2016; Paterson et al., 2012). The impacts of extreme weather events on mental health include incidences of post-traumatic stress disorder, depression, anxiety and grief (see Figure 3.21; Hayes et al., 2019; Hayes et al., 2018). The threat of climate change itself can lead to emotional distress, including “ecoanxiety,” “ecoparalysis” and “solastalgia,” which refers to the distress and isolation resulting from the transformation and degradation of one’s home environment (Galway et al., 2019; Hayes et al., 2018; Albrecht et al., 2007).

Extreme heat

Extreme heat events are projected to continue to increase with climate change (Zhang et al., 2019), leading to increased risk of heat-related illness and excess deaths (Chen et al., 2016; Gough et al., 2016; Margolis, 2013). By 2100, under a high-emissions scenario, Ontario would see 38 (28.1–44.5) more hot days each year, while under a low-emissions scenario there would be 4.7 (2.8–6.8) (Zhang et al., 2019). Extreme high temperatures are associated with increased rates of hospitalization for coronary heart disease and stroke (Bai et al., 2018), diabetes (Bai et al., 2016), increased respiratory related deaths (Chen et al., 2016), and more emergency room visits for mental and behavioural illness in Toronto (Wang et al., 2014). Ontario public health officials ranked extreme heat as their biggest concern among climate change impacts (Paterson et al., 2012). Heat warnings are triggered by regional (northern, southern and extreme southwestern) data on temperature intensity and duration, and also include humidity thresholds (Ontario Ministry of Health and Long Term Care, 2016). During a baseline period from 1971 to 2000, the frequency of a heat event (three consecutive days of maximum temperature greater than 32 °C– Ontario Ministry of Labour) in all Public Health Units (PHUs) was less than one per year. By 2050, the vast majority of PHUs (28 out of 36) will experience at least one heat event annually and, by the 2080s, 33 out of 36 PHUs will see more than one extreme heat event per year (Gough et al., 2016). Windsor-Essex has noted a relationship between extreme temperature-related illnesses and increasing emergency department visits as the number of record heat days increases (Windsor-Essex County Health Unit, 2019).

Heat levels are intensified in urban centres where extensive concrete and paved surfaces produce an Urban Heat Island effect (Mohsin and Gough, 2012; Gough et al., 2001). In the absence of expanded adaptation, increased temperature extremes will lead to greater risk of heat-related illness and mortality, particularly among vulnerable populations, such as the elderly, young children, physically disabled, those living alone and those who work outdoors (Bai et al., 2018; 2016; Guo et al., 2018; McDonald et al., 2016). Projections of extreme heat in Ontario show significant increases in high temperatures over the current century (see Table 3.8; Canadian Centre for Climate Services, 2019).

Vector-borne diseases

Warming temperatures and resulting shifts in bioclimatic envelopes have contributed to the expansion of certain disease vectors, including animals, ticks and insects (Gough et al., 2016; Berry et al., 2014b). Mosquito-borne diseases have increased by approximately 10% in Canada in the last two decades (Ludwig et al., 2019). Some of these diseases, including the Chikungunya virus, which has historically been limited to travel-related cases, could expand to parts of southern Ontario as temperatures increase and conditions become more favourable for transmission (Ng et al., 2017). The observed northward expansion of the blacklegged tick in Ontario, which is responsible for transmitting Lyme disease, is in part due to temperature increases (Cheng et al., 2017; Clow et al., 2017; Werden et al., 2014). The number of confirmed and probable Lyme disease cases observed in Ontario PHUs was three times higher in 2017 than the average from 2012 to 2016, and twice as high in 2018 (Ontario Agency for Health Protection and Promotion, 2019; Nelder et al., 2018). Northward and westward expansion of the distribution of blacklegged ticks and the associated risk of Lyme disease are projected to continue throughout this century in response to changing climate (see Figure 3.22; Gasmi, 2019; Sagurova et al., 2019).

Health impacts in the North subregion

Indigenous communities in Ontario’s North subregion have experienced flooding on several occasions. Whether driven by rapid snow melt, rain on frozen ground or ice jams in the large rivers, flooding in the spring season can bring significant anxiety. Extreme weather and flooding increase the risk of water contamination, water-borne illness and vector-borne disease, and can disrupt critical health care services in hospitals and clinics, as well as in other institutions (Giordano et al., 2017; Clarke, 2009; Brunkard et al., 2008; Cretikos et al., 2007). Anxiety and other mental health conditions are also triggered through evacuations related to wildfire, as well as flooding, and when critical transportation and energy infrastructure is disrupted, highlighting how impacts cascade through an interdependent system (Cunsolo 2018; 2014). These conditions can reverberate over time in the form of post-traumatic stress disorder, emotional fatigue, substance misuse and a lost sense of place (Bourque and Cunsolo Willox, 2014).

Food insecurity is also causing health impacts. Moose, a major source of wild food for many central and northern Ontario First Nations, is in decline in much of the region (Arsenault et al., 2020). Climate change, through later frost onset and earlier spring warming, is increasing exposure to fatal parasites transferred from white-tailed deer (Priadka et al., 2022). Deer are expanding northward in response to shorter winters and decreased snow depth allowing easier movement and access to browse (the leaves, twigs, and buds that deer eat) (Dawe and Boutin, 2016). Alteration of habitat by human and climate influences that reduces the density of the forest canopy is amplifying the impacts on moose by allowing easier access for predators and increasing the accumulation of snow on the ground, making it more difficult for younger animals to negotiate the snow and find browse (Priadka et al., 2022). In Biigtigong Nishnaabeg (Pic River) First Nation, on the north shore of Lake Superior, residents are adapting to the northward shift in the moose population by using a mobile app to pass on information to others about moose sightings, as well as signs of visible parasitic diseases on moose in their Traditional Territory (Popp et al., 2018).

People in thirty-one First Nation communities in the North subregion rely on winter roads to travel south in winter (see Section 3.2.2) for medical services from specialists and in hospitals, as well as to obtain food and other essential supplies (Ontario Ministry of Energy, Northern Development and Mines, 2019). Winter roads transect the traditional territories of most communities in the Nishnawbe Aski Nation and many in Grand Council Treaty #3. Personal snowmobile travel on frozen lakes and rivers supports hunting and fishing, which are not only integral components of subsistence living, but are also fundamental to Indigenous culture (Cunsolo Willox et al., 2014). However, safety is increasingly compromised by thin ice during warmer winter weather, notably in sections that span large water bodies (Hori et al., 2018a; 2018b). Unreliable access for heavy transport vehicles limits commercial food deliveries, making healthier food options such as fresh fruit and vegetables either not available or too expensive. In response, many have begun to develop family and community gardens, taking advantage of a lengthening growing season, and are also building greenhouses (Sioux Lookout First Nations Health Authority, 2019).

Public Health Units (PHUs) across the province are, to varying extents, already assessing and managing the impacts of climate change on human health (Paterson et al., 2012). Addressing public health risks from climate change and extreme weather is mandated through the Ontario Public Health Standards, which references climate change in sections related to population health assessment, healthy environments, and prevention and control of infectious and communicable diseases (Ontario Ministry of Health and Long-Term Care, 2018b; Paterson et al., 2012). Some PHUs (e.g., Peel Region, London Middlesex, Simcoe Muskoka and Grey-Bruce) have undergone comprehensive studies and have published climate change vulnerability assessments and adaptation plans (Grey-Bruce Health Unit, 2017; Levison et al., 2017; Berry et al., 2014a; Region of Peel, 2012). These analyses detail local risks, highlight improvements to monitoring and implementation of adaptation measures, and consider how climate change goals can be aligned with health equity (Buse, 2018).

The Ontario Climate Change and Health Toolkit contains guidelines (Ebi et al., 2016) and a workbook (Paterson et al., 2016) for conducting climate change and health vulnerability and adaptation assessments, as well as a climate modelling study (Gough et al., 2016) that forecasts key health impacts for PHUs. A complementary National Climate Change and Health Workbook and Knowledge Primer to guide adaptation planning for health professionals is currently in development.

Early warning systems and associated response measures are a key feature of health adaptation initiatives in Ontario. The provincial harmonized heat warning, established in 2016, provides a consistent approach and methodology for monitoring weather forecasts, identifying signals of a potential localized heat event and notifying PHUs that, in turn, can provide targeted, heat-related warnings and messages (Ontario Ministry of Health and Long-Term Care, 2016). The standardized messaging provided by these alert systems include details about the event itself (onset, intensity, duration), as well as response messaging, for example about who is at risk and potential symptoms of heat stress or stroke (Ontario Ministry of Health and Long-Term Care, 2018b). PHUs can escalate heat warnings and, alongside emergency management and municipal stakeholders, implement additional measures to protect vulnerable populations from extreme heat. Implementation of these heat alert systems in Hamilton, Toronto, Sudbury, Kingston and Windsor provides valuable lessons learned (see Case Story 3.5; Guilbault et al., 2016).

Warning systems are also in place to identify mosquito-borne disease outbreaks like West Nile virus. Such systems can be adapted and improved to incorporate weather forecasting to supplement conventional public health surveillance techniques, similar to those piloted by the Peel Region Public Health Unit (Ogden et al., 2019; Wang et al. 2011).

The strong linkages between a population’s social and economic circumstances and its health (Keon and Pépin, 2009) are recognized as key factors in determining vulnerability to climate health impacts (City of Toronto, 2016; Toronto Public Health, 2015; Berry et al., 2014b; Toronto Public Health, 2008). Programs that target the underlying causes of inequity will lessen climate risks and improve overall quality of life (Buse, 2018). Institutional capacity to protect vulnerable populations through the provision of emergency services, access to hospitals, cooling and warming centres, and other actions contributes significantly to reducing health-related impacts of climate change. The presence of green spaces is also associated with improved health outcomes, including improved air quality and provision of shade for cooling (Kingsley and EcoHealth Ontario, 2019; Mitchell and Popham, 2008).

Implementation of adaptive measures and the mainstreaming of adaptation into existing decision-making processes initially require efforts to methodically build knowledge and assess risks (see Figure 3.24; Ministry of Environment and Climate Change Strategy, 2019; ICLEI, 2016; Canadian Council of Ministers of the Environment, 2015; Douglas et al., 2011; Gleeson et al., 2011; Black et al., 2010). The core elements of a risk-based approach for climate resilience are consistent with international standards such as ISO 31000 (2018), ISO 14090 (2019) and ISO 14091 (2019). These processes, supported by appropriate expertise and resources, provide a backdrop for planning and implementation to occur (see Case Story 3.6).

Adaptation planning in Ontario varies in scale and scope. Multi-themed assessments (e.g., Lalonde et al., 2012; Douglas et al., 2011) identify risks across broad landscapes, while more technical and in-depth analyses (e.g., Tu et al., 2017), often employing geographic information systems and climate change information, delineate risks at finer scales.

The institutional arrangement of Conservation Authorities (CAs) in Ontario has proven successful at advancing adaptation planning at watershed scales, particularly as it relates to flood risk. As watershed and ecological stewards with jurisdictions stretching across many municipal boundaries, CAs participate in municipal and regional climate change initiatives in addition to having their own climate change plans (e.g., Lake Simcoe Region Conservation Authority). CAs have undertaken research to advance the climate change knowledge base, established best practices for managing climate change risk, and developed tools to assist adaptation decision making (e.g., the Risk and Return on Investment Tool (Credit Valley Conservation, 2020) and the Source Water Protection Tool (Milner et al., 2018b)). CAs are also key partners in the development and implementation of municipal or regional adaptation plans, including those in Kingston (City of Kingston, 2014), Thunder Bay (City of Thunder Bay, 2015), Windsor (City of Windsor, 2020; 2012) and Durham Region (Durham Region, 2016). All of these plans reflect the collective input of many partners contributing expertise or experience to mobilize adaptation across multiple themes and sectors.

Despite significant progress with respect to adaptation planning, the level of implementation of adaptation actions in Ontario remains low. Climate resilience planning has not kept pace with the rate of climate change, and the adaptation deficit in Ontario (Environmental Commissioner of Ontario, 2018a) continues to grow.

Many provincial government policies have the potential to support adaptation and climate resilience. The Provincial Policy Statement (Ontario Ministry of Municipal Affairs and Housing, 2020), environmental assessment guidelines (Ontario Ministry of Environment, Conservation and Parks, 2014), asset management planning guidelines (Ontario Ministry of Infrastructure and Ministry of Transportation, 2012), the Northern Ontario Growth Plan (Ontario Ministry of Infrastructure and Ministry of Northern Development, Mines and Forestry, 2011) and other policy instruments signal recognition of climate change impacts and the need for adaptation.

Barriers that impede progress on the planning, implementation and evaluation of adaptation in Ontario include financial constraints, lack of expertise and access to data, limited political will, support and mandate for action, and uncertainty associated with roles and responsibilities (see Box 3.6; Abdel-Fattah and Krantzberg, 2014a; Gregg et al., 2011). Addressing these barriers would help mainstream adaptation into policy and planning processes.

The inherent complexity and diversity of climate change impacts, the multiple scales and cross-cutting nature of some adaptation actions, and other factors make tracking the success of adaptation challenging (Expert Panel on Climate Change Adaptation and Resilience Results, 2018). Indicators for province-wide monitoring and evaluation of adaptation implementation would help define pockets of inaction, create examples of success and inspire further action.

While progress has been made on adaptation planning in Ontario, action is fragmented and has not been conducted in a systematic way. This is not necessarily a negative, as a variety of approaches are required to determine best practices. Planning to date has primarily been undertaken in larger regions or cities where there is greater capacity and resources, disadvantaging smaller communities. Stronger coordination and governance among those implementing adaptation planning processes can improve information sharing and expedite climate resilience.

Governance of climate change issues is complex due to the range of authorities, including national, provincial and local governments, Indigenous communities, the private sector, civil society and other actors who work in this space. Coordination among all these parties on aspects of climate change adaptation can be challenging. A centralized information-sharing platform that includes climate science, climate change data, impacts, risk levels and adaptation would help facilitate access to information and increase coordination between actors, while also defining research opportunities related to cumulative impacts and interdependencies within the region (Angel et al., 2018; Milner et al., 2018a).

The issue is compounded in the Great Lakes Basin by the international dimension involving two countries and multiple provinces and states. Within the Basin, and under mandate from the Government of Canada and the United States Government, the International Joint Commission has engaged with local, state and provincial governments to coordinate action on climate change (International Joint Commission Water Quality Board, 2019; 2017) and will seek to advance elements of a binational climate change adaptation and resilience strategy in 2022 (International Joint Commission, 2020).

While climate data has become more accessible over the last few years, particularly with the launch of the Ontario Climate Data Portal (Zhu et al., 2018) and the Canadian Centre for Climate Service’s Climate Data platform (Environment and Climate Change Canada et al., 2019), actionable climate information continues to be identified as a barrier for communities and others who undertake assessment or adaptation planning processes. Even when practitioners have access to local climate information, there is often a lack of understanding of the data, including which datasets are most useful for specific decisions (Milner et al., 2018a). The utility of climate datasets could be improved by including interpretation summaries that highlight general data trends (Milner et al., 2018a). The development of climate science communication pathways (e.g., data-sharing platforms and forums) would allow for information to be effectively communicated among various sectors and stakeholders, and would contribute to improving the use of climate science information for informing adaptation decisions (Milner et al., 2018a; International Joint Commission Great Lakes Water Quality Board, 2017).

Climate change affects the quantity of water in lakes and rivers, primarily through changes in temperature, precipitation and evaporation. The balance of these influences is difficult to assess, and this becomes even more challenging in the context of climate change. In the case of the Great Lakes, there are divergent views on future water-level trends (Bonsal et al., 2019; GLAM Committee, 2018; Angel and Kunkel, 2010). Recent experience with both high lake levels (Lake Ontario and Lake Erie in 2017 and 2019) and low lake levels (Lake Huron and Lake Michigan in 2013) indicate that extremes in water levels can vary considerably within relatively short periods (Gronewold and Rood, 2019), which reveals the need for resilience measures that can accommodate both high water and low water scenarios over time.

Climate change impacts elsewhere in North America, and elsewhere in the world, could stimulate migration to seemingly water-abundant areas like the Great Lakes Basin (American Society of Adaptation Professionals, 2021; Great Lakes Now, 2021). Research concerning transboundary climate change impacts and the migration of people into the area remains limited. Research into the impacts of climate change on other domestic and international regions, and into subsequent effects on the Great Lakes Basin, is warranted.

Long-term climate change can have magnified impacts on Indigenous culture, particularly in northern Indigenous communities. As climate change affects all aspects of the biosphere, cultural aspects that are intimately tied to the environment are also affected. Knowledge about the impacts of climate change on the mental health of Indigenous Peoples in Canada (Cunsolo and Ellis, 2018) continues to evolve, but with few examples coming from Ontario. Short-term displacements, like community evacuation in the event of a flood or wildfire, can compound levels of stress among displaced people, further increasing vulnerability within communities. Given the significant social and economic challenges that exist within northern Indigenous communities, programs to monitor and address impacts to mental health are important.

The impacts of extreme weather events, combined with infrastructure and adaptation deficits, have led to increases in insured and uninsured losses in Ontario. Large asset holders, including investment firms, property holding companies and pension funds, have yet to mobilize on climate change adaptation in a significant way. These sectors are increasingly reporting on climate risk for their own portfolios, but also have a role to play in mobilizing or unlocking financing for adaptation investment (see Climate Disclosure, Litigation and Finance chapter of the National Issues Report). There is a need to further mobilize the investment community and researchers to use innovative financial mechanisms that promote adaptation action and can assist in disaster recovery.