Climate Sensitivities, Impacts and Vulnerability: Subregional Perspectives
The south subregion (Figure 1, Box 1) includes southwestern Ontario, extends east to the Quebec border and includes the Great Lakes (Box 2). The majority of research examining climate change impacts and adaptation in Ontario is focused on this subregion. Changes in Great Lakes water levels (Case Study 1) are projected to be one of most significant impacts of changing climate in this subregion, with implications for water management, hydroelectricity generation, transportation, tourism and recreation and ecosystem sustainability. Other key issues include the impacts of climate change and extreme weather events on water quality and quantity (Case Study 2), critical infrastructure (Case Study 3), human health (Case Study 4) and agriculture.
Regional warming is strongly reflected in the physical attributes of aquatic ecosystems. For example, there is a strong regional trend toward later freeze-up and earlier break-up of ice on lakes. On Lake Simcoe, average freeze-up occurs 13 days later and average break-up occurs 4 days earlier than 140 years ago (Canadian Council of Ministers of the Environment, 2003). On the Great Lakes, the season of ice cover has been shortened by about 1 to 2 months during the last 100 to 150 years (Kling et al., 2003). The ice-cover period for Lake Ontario's Bay of Quinte has also decreased substantially, particularly since the late 1970s, with the fall and winter of 2005–2006 showing the least ice cover in the last 50 years or more (J.M. Casselman, pers. comm., 2006). Projected warming, particularly in winter months, will lead to further changes in the duration and extent of ice cover on the lakes. For example, Lofgren et al. (2002) determined that the ice-in period over selected parts of the Lake Superior and Lake Erie basins could be further reduced by 16 to 52 days by 2050, from a current average of 11 to 16 weeks. Less ice cover results in greater loss of water through evaporation and enhanced shoreline erosion during winter storms, and may affect lake-effect snowfall (Mortsch et al., 2006).
Increases in nearshore temperature have been recorded at several locations around the Great Lakes since the 1920s. They are most pronounced in the spring and fall, and are positively correlated with trends in global mean air temperature (King et al., 1997, 1999; McCormack and Fahnenstiel, 1999; Shuter et al., 2002; Kling et al., 2003). This warming has likely contributed to major ecosystem impacts on the Great Lakes associated with extensive algae (green and blue-green) blooms and invasions of non-native invertebrates (e.g. spiny water flea, zebra mussels and quagga mussels) and vertebrates (e.g. round goby and various carp species; Schindler, 2001; Kling et al., 2003; MacIssac et al., 2004). These impacts have required that many coastal communities make modifications to infrastructure, such as water treatment plants, and implement other remedial measures, such as removing mussels from encrusted water intake pipes (Sarrouh and Ramadan, 1994; Aldridge et al., 2006). Projected warming will further exacerbate these problems, as these and other species that were inadvertently introduced from warmer habitats will find it easier to establish themselves in a warmer climate (Schindler, 2001; MacIsaac et al., 2004). Average annual surface-water temperatures for all of the Great Lakes are projected to increase in the future; for Lake Superior, the deepest and coldest lake, they have been projected to increase by between 3.5 and 5 °C by 2050 (Lehman, 2002).
The Great Lakes
The Great Lakes cover an area of 244 160 km2, and have a total shoreline length of 17 000 km and a volume of 22 684 km3 (Figure 14; Environment Canada, 1991). They are connected to the Atlantic Ocean by the St. Lawrence River and contain almost 20% of the Earth's unfrozen surface fresh water. The area surrounding the Great Lakes region is home to more than 90 million people, and supports the generation of more than 30% of the continent's gross national product and the production of more than 60% of Canada's industrial output (Sousounis and Bisanz, 2000).
Climate and Great Lakes Water Levels
Although water levels within the Great Lakes are regulated to a certain degree at the outflows of Lake Superior and Lake Ontario, and several diversions exist throughout the basin, climate is the dominant factor affecting lake levels (Changnon, 2004). Lake levels reconstructed from tree ring studies show that low water levels occurred more frequently prior to the twentieth century, indicating that natural variability is greater than that of recent experience (Quinn and Sellinger, 2006). In the past 150 years, annual average water levels in the Great Lakes have varied, with the range between minimum and maximum levels being around 180 cm (Mortsch et al., 2006). Water levels were 50 to 80 cm higher than average in 1973 to 1975, 1985 to 1986 and 1997, and 50 to 80 cm lower than average in 1934 to 1935, 1964 to 1965 and 1999 to 2002 (Changnon, 2004; Mortsch et al., 2006). In 2001, Lake Superior was at its lowest level since 1925 and lakes Michigan-Huron were at their lowest levels since 1965. Low water levels reflect substantial loss of water volume in the Great Lakes system. For example, between April 1998 and May 1999, reductions in Great Lakes water levels resulted in a loss of about 120 km3 from the system — the equivalent of almost 2 years of flow over Niagara Falls (Moulton and Cuthbert, 2000).
While it is clear that temperature and precipitation greatly influence lake levels, the exact relationship is not well understood, in part because neither precipitation nor evaporation are measured over the lakes. Analysis of long-term regional climate data suggests that precipitation accounts for 55% of the variability in lake levels, with temperature accounting for 30% (Changnon, 2004). However, there is also evidence that increased temperatures can be the primary cause of low water levels, at least over the short term, as found in a study of the 1997 to 2000 period (Assel et al., 2004).
Although most scenarios of future climate project increases in regional precipitation, the increase in evaporation caused by higher temperatures is expected to lead to an overall decrease in Great Lakes water levels (Mortsch et al., 2000, 2006; Cohen and Miller, 2001; Lofgren et al., 2002; Kling et al., 2003). Increased evaporation is expected in all seasons, and particularly in winter as a result of decreased ice cover on the lakes. Results from studies that have modelled future changes in the water levels of lakes Ontario, Erie, St. Clair and Michigan- Huron are presented in Figure 15. In the majority of experiments, lake levels are projected to decrease (Mortsch et al., 2000, 2006; Cohen and Miller, 2001; Lofgren et al., 2002; Kling et al., 2003). For all but Lake Ontario, projected water levels under warm and wet, and warm and dry scenarios fall below the lower bounds of variability observed during the last 50 years. Under scenarios of lower temperature increases and wetter conditions, increases of 0.02 m annually and 0.07 m in the winter are projected for Lake Ontario. Reductions are projected to be most pronounced in the lakes Michigan-Huron basin, at 0.73 to 1.18 m by the 2050s (Mortsch et al., 2006). It is also expected that low levels will occur more frequently, especially in Lake Erie, and that seasonal variation will increase (Mortsch et al., 2000; Lofgren et al., 2002; Croley, 2003). The impacts of lower water levels will be most pronounced in parts of the system that are already shallow, specifically western Lake Erie, Lake St. Clair, and the St. Clair and Detroit rivers (de Loë and Kreutzwiser, 2000).
The projections of water level changes described above consider only changes in climate. Moulton and Cuthbert (2000) evaluated the cumulative impact of change in climate, consumptive uses, and diversions and bulk water transfers within the watershed on lake levels. Additional water removals of up to 200 m3/s were assumed, a value consistent with current consumptive use (Moulton and Cuthbert, 2000). The study concluded that the cumulative impacts on Great Lakes water levels from these multiple stresses may necessitate that changes be made to the transborder Niagara Treaty and to the Lake Superior and St. Lawrence River orders of approval, administered by the International Joint Commission. The study further noted that the control structures on the St. Mary's and St. Lawrence rivers may require significant modification to accommodate water level changes, and that the increased dredging required to maintain navigation routes under low water conditions would involve excavation and subsequent management of contaminated materials. Finally, the study concluded that the existing Lake Superior and Lake Ontario water level regulation plans are inadequate to deal with future low water levels, as maintaining minimum outflows would draw down the level of the lakes by several metres.
Increasing water temperatures also impact the composition of fish communities, affecting both commercial and recreational fisheries. Fish communities in the Great Lakes basin are highly diverse, and include species with preferences for cold water (<15°C), cool water (15—25°C), and warm water (>25°C). Acceleration of this warming trend will enhance production of warm-water fish and negatively affect production of cool-water and cold-water species, as has been documented in Lake Ontario's Bay of Quinte (J.M. Casselman, pers. comm., 2006). It is expected that the disappearance of cool- and cold-water species, particularly lake trout, will be most pronounced in Lakes Ontario and Erie (Casselman, 2002; Casselman et al., 2002; Kling et al., 2003; Shuter and Lester, 2003; Casselman and Scott, 2003). Many warm-water species, such as bigmouth buffalo and flathead catfish, are already being seen more frequently in the Great Lakes basin.
Coastal wetlands function as important staging, breeding and wintering habitat for waterfowl, and breeding and nursery areas for many fish. Reduced water levels as a result of changing climate (see Case Study 1) will modify or eliminate wetlands that help maintain shoreline integrity, reduce erosion, filter contaminants, absorb excess storm water and provide fish and wildlife habitat (Mortsch, 1998; Branfireum et al., 1999; Devito et al., 1999; Mortsch et al., 2000; Lemmen and Warren, 2004). Many coastal wetlands in the Great Lakes basin are already under significant stress from non-climatic factors, such as land-use change and nutrient loading, and may be unable to maintain their function and integrity in response to the additional pressures of a changing climate (Easterling et al., 2004). Protecting areas for new wetlands to develop has been identified as an ecosystem management issue for the coming decades (Whillans, 1990; Inkley et al., 2004).
Climate change also represents an important additional stressor on terrestrial ecosystems in the south subregion. The loss of natural habitat associated with agricultural development and urbanization has been a major factor resulting in biodiversity loss. The remaining remnants of Carolinian forests contain rare and endangered species, such as the tulip tree, black gum, sycamore, Kentucky coffee tree and papaw. The southwestern part of this subregion features the most extensive remaining remnants of tall-grass prairie vegetation in the province. There are few studies on the impacts of observed climate change on plants and animals of these ecosystems (e.g. Hussell, 2003).
Water resources management in the south subregion is complex and balances the demands of many different users, rapidly increasing urbanization and economic growth, and in-stream flow needs. Most communities in this subregion rely on surface water, although 90% of rural inhabitants rely solely on groundwater for their potable water supply (Ontario Ministry of the Environment, 2001, 2006b). Although total annual runoff is projected to decrease as a result of future climate change, this will consist of increased flows during the winter months and significantly decreased flows during the summer months when demand is the highest (Mortsch et al., 2000; Cunderlink and Simonovic, 2005).
Despite the general abundance of freshwater supplies, seasonal water shortages have been documented (de Lo ë et al., 2001; Ivey, 2001) in the Region of Waterloo (Cambridge, Kitchener and Waterloo), Wellington County (Guelph), Dufferin County (Orangeville) and Peel County (Caledon). Many shallow wells in the subregion are sensitive to low water or drought conditions, and some areas may be susceptible to wells going dry (Ontario Ministry of Natural Resources, 2006c). Many of the areas identified as most vulnerable to water shortages have been included within the Greenbelt Area of the Growth Plan for the Greater Golden Horseshoe Region, which places limits on, among other things, urbanization (Ontario Ministry of Public Infrastructure Renewal, 2006).
Several studies have investigated the impacts of climate change on water resources in areas surrounding the Great Lakes basin (e.g. Mortsch et al., 2000, 2003; Bruce et al., 2003; Kling et al., 2003). Projected changes in regional hydrology that have implications for water quality and quantity are identified in Table 2. Of particular concern are areas already under stress from non-climatic factors (Box 3). Communities accessing water from the Great Lakes via shallow water intakes or pipelines designed for relatively high historical water levels may experience problems in future, resulting from more frequent low water levels. In conjunction with increased algal growth, low water levels will likely cause problems for water supply, odour and taste (Mortsch et al., 2000; Bruce et al., 2003; Kling et al., 2003).
In general, communities dependent on surface water systems other than the Great Lakes will also become increasingly susceptible to more frequent water shortages (Kreutzwiser et al., 2003). The impacts of climate change projected for 2020 are likely to be more significant than changes arising from projected urban development, in terms of both magnitude of peak flows and total loads of nitrogen and phosphorous (Booty et al., 2005). The same study concluded that subwatersheds have unique sensitivities and responses to similar stressors. As a result, communities within these subwatersheds may require different adaptation responses (Booty et al., 2005).
In addition to projected decreases in seasonal water supply, forecast population increases will increase the demand for potable water. Eighty per cent of Ontario's population growth by 2031 is expected to occur within the Greater Golden Horseshoe region (which includes the GTA). Some of the largest percentage increases in population growth are forecast to occur in the Region of Waterloo and the counties of Wellington, Dufferin and Simcoe, where periodic water shortages already occur (Ontario Ministry of Public Infrastructure Renewal, 2006).
Reducing vulnerability to more frequent water shortages can be accomplished by understanding source waters and demands within a watershed and addressing possible threats. For example, in response to past water shortages, the Grand River Conservation Authority conducted a comprehensive assessment of water use within the watershed (Bellamy and Boyd, 2005). This analysis found that irrigation, the eighth largest water user over the course of a year, is the second largest water user in July, the time of lowest surface water availability (Bellamy and Boyd, 2005). Combining this information with climate and population projections will help determine problem areas during the next 20 to 50 years.
The vulnerability of water supply to drought in the south subregion is reduced by the ability to access water of the Great Lakes through deepwater intakes, and by the interconnected water treatment and distribution systems, which allows sharing between plants during shortages (Kreutzwiser et al., 2003). In areas reliant on groundwater, deeper sources are more protected from climate variability, and are often exploited as shallow sources become compromised (Environment Canada, 2004). Protection of source water is a critical adaptation measure to reduce the risks to safe and reliable groundwater supplies resulting from a changing climate (Case Study 2).
|Hydrological parameter||Expected changes in the 21st century, Great Lakes basin|
Since the south subregion is the most intensely urbanized area of the province, the magnitude and economic cost of infrastructure impacts and disruption of services caused by extreme weather events is significantly higher than elsewhere in the province. The majority of the flood emergencies reported between 1992 and 2003 in this subregion occurred between the months of January and May, and were the result of rain-on-snow conditions. Increasing winter temperatures will mean that the spring freshet will likely occur earlier and, because of more frequent winter thaws, it will likely be lower (Kling et al., 2003). This, in turn, will likely decrease the risk of spring flooding (Hengeveld and Whitewood, 2005).
Climate change and water quality in systems under stress
The Great Lakes Remedial Action Plan Program was created in 1987 by the International Joint Commission (IJC) as part of the Great Lakes Water Quality Agreement (International Joint Commission, 1989) between Canada and the United States. Under this process, areas that have experienced environmental degradation in the Great Lakes basin are identified as Areas of Concern (AOCs), and Remedial Action Plans (RAPs) are developed and implemented. Currently there are 10 AOCs in Canada, 26 in the United States and 5 shared by both countries. The IJC monitors progress in all of the AOCs. Of the 43 AOCs initially identified, two have been de-listed: Collingwood Harbour and Severn Sound in Ontario (Environment Canada, 2006b).
The success of RAP efforts will be affected by the hydrological impacts of climate change. For example, Walker (1996) stated that periodic reduction in seasonal flow, along with increased winter rainfall and erosion, already make it difficult for water managers to meet the Quinte RAP phosphorus loading targets in somecatchments. Projected changes in climate will put additional stresses on investments in effluent treatment, agricultural conservation practices and urban stormwater management. The RAPs and Lake-Wide Management Plans (LaMPs) will need to account for the impacts of climate change when establishing and reviewing water quality objectives, and it is likely that further investments will be required to meet their objectives (Bruce et al., 2000).
Flooding damage also occurs from heavy rainfall events. Between 1979 and 2004, the southwestern part of this subregion received the greatest number of heavy rainfall events in the province (Figure 16). An exceptionally heavy event occurred on August 19, 2005 and led to considerable damage in Toronto (see Case Study 3). There have been seven other heavy rainfall events resulting in severe flooding in Toronto in the past 20 years, all of which were considered to have return periods of greater than 25 years (D'Andrea, 2005).
The Region of York and City of Niagara have reported an increase in basement and localized flooding (Brûlé and McCormick, 2005), and several municipalities are looking into the need to retrofit their storm-water infrastructure in order to accommodate heavier rainfall events (Ormond, 2004; Brûlé and McCormick, 2005; D'Andrea, 2005). In 2001 and 2002, the City of Stratford experienced heavy rain events that caused widespread flooding. As a result, the city has adopted a 250-year design storm standard (see Case Study 3) and is investing $70 million in retrofitting their storm-water infrastructure (Rickett et al., 2006).
(adapted from de Loë and Berg, 2006)
Between May 8 and 12, 2000, extraordinary rainfall facilitated the transport of microbiological pathogens (E. coli 0157:H7 and Campylobacter) into the municipal water system in Walkerton, Ontario, through a shallow well. The source of the pathogen was manure that had been spread on a field using accepted best practices. Seven people died and 2300 became ill because of improper water disinfection treatment (O'Connor, 2002; Richards, 2005). In response to this tragic event and the subsequent public inquiry, provincial water policy has shifted towards a multi-barrier approach to ensuring drinking water safety. Although the inquiry report does not address climate change in any great detail, it does recognize that increasing frequency of extreme rainfall events as a result of climate change may have long-term impacts on the quality and quantity of drinking water sources in Ontario (O'Connor, 2002).
The Ontario Clean Water Act (CWA), passed in October 2006, requires that source-water protection plans be developed and reported based on assessments of water quantity and quality in each watershed of the province. These plans, among other things, must include a water budget for each watershed and identify existing and future threats to drinking water in vulnerable areas. The process also provides an opportunity for assessing vulnerability to climate change. Although the focus in the guidance document related to watershed characterization is on past and current trends, teams preparing these characterizations are also expected to consult appropriate climate change models. Therefore, the requirement to consider future climate change explicitly, in concert with other projected changes for the watershed (such as population growth and land-use or -intensification change) will allow comprehensive identification of vulnerable areas.
Projected increases in the frequency, and possibly the intensity, of extreme rainfall events will result in increased summer flood risk (Hengeveld andWhitewood, 2005), with implications for large urban drainage systems (Table 3). The Toronto and Region Conservation Authority (TRCA) has recognized climate change as one of the key challenges facing its water management and conservation mandate (Toronto and Region Conservation Authority, 2006a). In 2005, the TRCA initiated work to enhance flood protection on the lower Don River. Following sensitivity testing to determine the potential impact of an increase in extreme rainfall on storm flows and flood levels, the TRCA designed the flood protection berm to be able to withstand a 15 to 20% increase in the regulatory flood to address future uncertainties, including climate change. Further, they designed the berm so that it could be raised 1 to 2 m in the future if required (Toronto and Region Conservation Authority, 2006b).
There is a substantial body of literature dealing with the impacts of climate on human health in the south subregion of Ontario (e.g. Smoyer et al., 2000; Last and Chiotti, 2001; Chiotti et al., 2002; Cheng et al., 2005). The most significant impacts are likely to relate to temperature stress; air pollution; extreme weather events; vector-, rodent- and water-borne diseases; and exposure to ultraviolet (UV) radiation.
Extreme Rainfall and Storm-Water Infrastructure
Flood management planning relies on historical rainfall data to develop infrastructure design standards. These standards are generally based on the larger of the following two calculations: 1) the maximum peak flow in a basin that results from a storm with a return frequency of once every 100 years; or 2) the maximum peak flow that results from applying a 'design storm' (a historical storm that exceeds the once every 100 years storm) to the basin. Changes in basin characteristics, such as the proportion of impermeable surfaces, are also considered. The impacts associated with the following three examples highlight the vulnerability of critical infrastructure. Adaptation strategies that address infrastructure maintenance, upgrading and design will need to consider uncertainties in the changing frequency and magnitude of extreme climate events, existing infrastructure and land-use vulnerability, and the costs of proactive action relative to those of reactive recovery and repair.
South Subregion: North Toronto Flood, August 19, 2005
An intense storm system moving across southwestern Ontario on August 19, 2005 caused extensive flooding and infrastructure damage, and more than $500 million in insured losses (Klaassen and MacIver, 2006). Rain gauges at the northern end of the city recorded 103 mm of rainfall in one hour, and City of Toronto rain gauges recorded total rainfall of up to 153 mm during the roughly 4 hours of the rainfall event. Both measurements are two to more than three times the rainfall intensities of the 1954 Hurricane Hazel design storm (Environment Canada, 2005a). The 2005 storm highlighted the interconnectivity of different kinds of infrastructure in large urban areas, and the resulting vulnerabilities. For example, the storm resulted in the collapse of a section of Finch Avenue, a major arterial street, which resulted in damage to two high-pressure gas mains, a potable water main, and telephone, hydro and cable service lines that were buried beneath the road (Figure 17).
South Subregion: Peterborough Flood, July 15, 2004
In July 2004, an intense one-hour storm hit the City of Peterborough (Figure 18) with almost as much rain as would be expected to fall in 24 hours from a 100-year design storm. A number of factors compounded the effect of the intense rainfall. First, rainfall was concentrated in downtown Peterborough, which consists of largely impervious paved surfaces, including streets that were not well designed to convey floodwater, thereby producing large overland flows. Second, it has been estimated that 82% of the pipes in the city's storm-water system did not meet current design standards, resulting in bottlenecks in the conveyance of floodwaters. Finally, excess water in the sanitary system from groundwater seepage into cracked or misaligned sanitary sewer pipes led to system back-ups and basement flooding. It has been estimated that the cost of actions to rectify the infrastructure deficiencies could reach $200M (Klaassen and Seifert, 2006).
The Peterborough flood resulted in $95 million in insured loses (Insurance Bureau of Canada, 2005) and illustrates the importance of non-climatic factors in determining vulnerability to flood risk.
Central Subregion: Northwestern Ontario Storm, June 8 to 11, 2002
Between June 8 and 11, 2002 a series of very intense thunderstorms dropped between 220 and 401 mm of rain in the central subregion of Ontario, far exceeding previous records (Klaassen, 2005). Rail and road networks were disrupted, and estimated damages directly related to flooding totalled $31 million in Ontario, more than $7 million in Manitoba and an estimated US$70 million in Minnesota and North Dakota (Figure 19; Cummine et al., 2004; Klaassen, 2005; Groeneveld, 2006).
The Longbow Dam basin (49 km2), which received 187 mm of rain and a peak flow of 30.1 m3/s in the 1961 Timmins design storm, received 361 mm of rain and a peak flow of 57 m 3/s during the 2002 event (Groeneveld, 2006). Based on the historical record, this one event has been calculated to have a return period of 1486 years. Water managers and engineers need to consider whether the 2002 event should now serve as the design storm for planning purposes.
|Anticipated climate change||Expected system sensitivity|
|Combined systems||Partially separated systems||Fully separated systems|
|Increased rainfall intensities, similar event type and similar annual volume||Increased risk of basement flooding. Lower level of service.||Minor impact on peak flows and available capacity.||Minimal impact on peak flows and available capacity.|
|Increased frequency of large volume—high intensity events, similar annual volume||Increased risk of basement flooding. Lower level of service. Potential increase in combined sewer overflow (CSO) volume but reduced frequency.||Increased risk of surcharge and basement flooding. Lower level of service.||Potential impact on available capacity for growth. Increased risk of sewer surcharge and risk of flooding.|
|Increased rainfall event frequency and annual volume, minimal increase in peak intensities or frequency of large volume events||Minimal impact on system capacity. Increase in CSO volume and frequency.||Potential increase in risk of system flooding. Potential impact on wastewater treatment costs as a result of volume and degraded quality.||Potential impact on wastewater treatment as a result of volume and degraded quality.|
The south subregion experiences warmer temperatures and higher humidity, relative to other regions of the province, due to many factors, including urban heat-island effects that can produce temperatures as much as 3 °C warmer than in surrounding rural areas (Gough and Rozanov, 2002). Environment Canada issues a Humidex Advisory when the temperature is forecast to reach 30 °C or when the humidex reading (considering both temperature and relative humidity) reaches 40 °C (Smoyer et al., 1999, 2000). The estimated average number of excess deaths during periods of hot weather in 1999 amounted to 120, 41 and 37 for Toronto, Ottawa and Windsor, respectively (Cheng et al., 2005). Ambulance calls and hospital admissions in cities in the south subregion generally increase during hot weather (Thompson et al., 2001; Dolney and Sheridan, 2006).
Climate change projections of milder winters and warmer summers will have both positive and negative consequences for temperature-related morbidity and mortality. The annual average number of 'hot days' (1961—2000) with temperatures of 30°C or above was 8 in Toronto, 8 in Ottawa and 15 in Windsor (Cheng et al., 2005). According to Cheng and Campbell (2005), these numbers could more than double in these cities by 2050, and more than triple in Windsor and nearly quadruple in Toronto and Ottawa by the 2080s. In the absence of effective adaptation measures, this could lead to a proportionate increase in the number of heat-related deaths. In contrast, cold-related mortality could decrease by about 45% for Ottawa and 60% for Windsor and Toronto by 2050, and by 60 to 70% in all three cities by 2080 (Cheng et al., 2005; Pengelly et al., 2005). However, this positive health impact may be counterbalanced by the increased risk of winter mortality associated with air pollution, if climate change is associated with increased incursions of maritime tropical air masses into the subregion during winter (Rainham et al., 2005).
Concern over the potential for more frequent heat waves has prompted seven municipalities in the south subregion to develop heat-alert plans, most of them based on humidex advisories. The City of Toronto's Hot Weather Response Plan (Case Study 4), which was part of a World Health Organization —World Meteorological Organization showcase project, uses a spatial synoptic classification system based on local climate conditions, and incorporates information on the impacts of, and responses to, past heat waves (Rainham et al., 2005). Other communities across the GTA are considering adopting their own synoptic classification systems based on the Toronto model.
Air Pollution and Related Diseases
Thousands of Canadians die prematurely each year from short- and long-term exposure to air pollution (Judek et al., 2004). The Ontario Medical Association (2005) has estimated that the annual illness costs of air pollution in Ontario include 5 800 premature deaths, more than 16 000 hospital admissions, almost 60 000 emergency room visits and 29 million minor illness days. Estimates are also provided for 2015 and 2026, assuming no improvements in regional air pollution levels and taking into account an aging population. Under such conditions, the number of premature deaths is expected to rise to about 7 500 by 2015, and may exceed 10 000 by 2026. The total number of minor illness days is projected to increase to more than 38 million annually by 2026, with most of this increase associated with persons 65 years and older (Ontario Medical Association, 2005).
Toronto's Hot Weather Response Plan
The City of Toronto's Hot Weather Response Plan is an example of municipal adaptation to changing climate, and highlights how frequent review, assessment and refinement of adaptation measures can reduce vulnerability. The response plan is designed to alert those most at risk to heat-related illness and death due to hot weather conditions that either exist or are expected, and of the need to take precautionary action. High-risk groups include socially isolated seniors, persons with chronic and pre-existing illnesses (including mental illness), children and persons who have low incomes or are homeless.
The process of developing Toronto's plan began in 1998, when the Seniors Task Force and Advisory Committee on Homelessness and Socially Isolated Persons asked Toronto Public Health to develop a comprehensive hot weather emergency response plan. This was the result of the increasingly hot summers in Toronto, and the devastating effects of heat waves in the United States, including that in Chicago in 1995. Toronto Public Health was tasked with identifying weather conditions that would establish the threshold for calling a heat alert, and the development of a co-ordinated response plan involving all key partners. An initial heat alert system introduced in 1999 was based on forecast humidex readings over 40 °C. However, rapid changes in humidex levels made this threshold of limited value. Furthermore, studies found that heat-related deaths were occurring in the south subregion when the humidex was less than 40 ºC, again suggesting the need for a more appropriate threshold measure.
The summer of 2001 saw the launch of an improved alert system developed specifically for Toronto. The system utilizes calculations of the probability of excess morbidity or mortality, based on local climate conditions (e.g. temperature and dew point, wind speed and direction, and cloud cover), and incorporates information on the impacts of, and responses to, past heat waves (Rainham et al., 2005). The system utilizes historical meteorological and mortality data, classifies weather according to air masses and then determines the most ‘oppressive' weather types and conditions that affect the city's population. An alert is issued when an oppressive air mass is forecast for the area. A heat alert is issued when the likelihood of excess mortality is between 65 and 90%; when this likelihood exceeds 90%, a heat emergency is issued. A heat emergency will always be preceded by at least a one-day heat alert, in order to ensure that everything is in place to provide the appropriate emergency response.
When a heat alert is issued, Toronto Public Health officials notify the media and community stakeholders likely to be affected by extreme temperatures, such as child care centres, long-term care facilities and hospitals, local shelters and community agencies. Other measures include distributing bottled water where the vulnerable are likely to gather, asking shelters to ease their curfew rules and providing a Heat Information Hotline to answer heat-related questions. If a heat emergency is called, additional actions taken include the opening and staffing by Community and Neighbourhood Services of four cooling centres located in city-owned buildings throughout the city. If needed, one of the centres would be open 24 hours, and bottled water, cots and an air-conditioned space would be available to anyone needing them.
Three times a year, a Hot Weather Response Committee meets to monitor, evaluate and update the Hot Weather Response Plan. Early changes included having the Red Cross operate the Heat Information Hotline on all days when an alert is called, including weekends, and co-ordinate the distribution of bottled water. In 2001, additional partners were recruited and outreach efforts were enhanced. Steps were taken to ensure that 1) drinking water fountains in city parks were functioning properly; 2) the hours of operation for city pools would be extended during heat alerts; and 3) street patrol teams would provide free transit tokens to those found to be in need of a cooling centre.
A record number of heat alert–heat emergency days was issued in Toronto in 2005. Despite full implementation of the Hot Weather Response Plan, a number of heat-related deaths prompted a coroners inquiry and calls for improvements to cooling centres, including their opening in the event of a heat alert, not just a heat emergency. Of particular concern was that many vulnerable groups do not have access to a TV, radio or telephone, and may therefore be unaware that a heat alert or emergency had been announced. In response, Toronto Public Health embarked on a targeted, city-wide education campaign of landlords and tenants regarding the health risks of heat stress, especially for persons taking psychiatric drugs and other medications.
A Hot Weather Response Plan based on the Toronto system is being developed for Peel Region, while the Region of Waterloo, the Regional Municipality of Halton, the City of Kingston and the City of Ottawa have introduced advisory systems based on Environment Canada's humidex advisories, with the latter two municipalities also incorporating air-quality conditions into their heat advisories.
Higher temperatures associated with climate change will increase the potential for photochemical oxidant (smog) formation (Pellegrini et al., 2007), and also increase ambient air concentrations of pollen (Breton et al., 2006). Increased energy use, and especially increased demand for air conditioning in summer, could also have a significant impact on air quality, depending upon how electricity is generated. Cheng et al. (2005) provided projections for air quality in theWindsor, Toronto and Ottawa regions, and concluded that premature death associated with air pollution could increase 15 to 25% by 2050 and 20 to 40% by 2080.
The Ontario Ministry of the Environment currently calculates and publishes an air-quality index for 37 urban and rural sites across the province, and provides air-quality forecasts year round. These initiatives are important means of minimizing exposure of vulnerable people during poor air-quality days. Many municipalities in the south subregion have developed their own smog response plans, based on provincial guidelines (Ontario Ministry of the Environment, 2005). These plans tend to focus on emission reduction measures that address the immediate local contribution to pollution levels, but also recommend measures that individuals can adopt, such as reducing outdoor physical activity, to lower their risk of exposure to air pollutants.
Extreme Weather Events
Extreme weather and associated natural hazards can have significant direct and indirect impacts on human health. In the last 55 years, the south subregion has experienced a number of notable extreme weather events, including Hurricane Hazel in 1954, the Barrie tornado in 1985, the ice storm of 1998 and the Toronto snowstorm in 1999, among others (Mills et al., 2001; Chiotti et al., 2002). The 1998 ice storm, which in Canada impacted eastern Ontario, southern Quebec and parts of the Atlantic provinces, resulted in 28 deaths, an estimated 60 000 physical injuries and tens of thousands of individuals potentially affected by post –traumatic stress disorder (Edwards et al., 1999; Kerry et al., 1999; Chiotti et al., 2002).
Climate models project that certain kinds of extreme weather are expected to become more frequent in a warmer world (e.g. Intergovernmental Panel on Climate Change, 2007; see Chapter 2). Based on historical experience, the associated health impacts could be considerable (Chiotti et al., 2002). In addition to death and injuries directly attributable to natural hazards, examples of indirect impacts include injuries associated with serious traffic accidents that are often caused by extreme weather (Andrey and Mills, 2003), and illness associated with the spread of toxic moulds and compromised indoor air quality that may follow flooding of residential and institutional buildings.
Vector- and Rodent-Borne Diseases
Future changes in climate could lead to more favourable conditions for the establishment and re-emergence of vector- and rodent-borne diseases, as evidenced by the recent spread of Lyme disease (Ogden et al., 2004, 2005, 2006a –c). The range of the tick vector, Ixodes scapularis, is thought to be constrained by temperature, spring migratory bird densities and woodland habitats (Ogden et al., 2004). Although this tick has historically been isolated along the north shores of Lake Erie and Lake Ontario, it has recently been discovered that birds migrating northward in spring are carrying I. scapularis long distances north and west, beyond the boundaries of Ontario and into neighbouring provinces (Ogden et al., 2006a). Projected temperature increases could lead to the northward expansion of the potential range for Lyme disease by up to 1000 km, while greatly increasing the survival rate of ticks in the south subregion (Ogden et al., 2005a, 2006b). The current health risks related to infected ticks are well recognized by public health officials in the south subregion (Charron and Sockett, 2005).
The first death in Ontario from hantavirus pulmonary syndrome (HPS), a rare but very serious lung disease transmitted to humans through the urine, saliva and droppings of rodents, was recorded in Owen Sound in 1997 (Egan, 1997; see Section 3.2.6). Since outbreaks of HPS in the United States have been greatly influenced by weather (Glass et al., 2000; Hjelle and Glass, 2000; Charron et al., 2003), changing climate may alter the health risk in Ontario, especially in the urban-rural fringe where people and mice are likely to come into contact (Chiotti et al., 2002). However, there are a number of measures that can be taken to reduce human exposure to the virus, such as preventing access of rodents to buildings and precautionary measures for handling of dead rodents.
Examples of mosquito-borne diseases that may become more prevalent as a result of climate change include West Nile virus and malaria (cf. Duncan et al., 1997; Chiotti et al., 2002). West Nile virus arrived in Ontario in 2001, and its rapid spread throughout the province has been related to weather conditions favourable to the host vector (Chiotti et al., 2002). Domestically contracted malaria is not currently a health concern, although the climate is capable of supporting the mosquito vector species. Of more immediate concern for the health care system is the importation of the disease as the result of increased travel and immigration, and the disease's increased resistance to drugs (Chiotti et al., 2002; Riedel, 2004).
The young, the elderly and people with impaired immune systems are particularly sensitive to water-borne gastrointestinal diseases. The incidence of enteric infections, such as Salmonella and Escherichia coli (E. coli), is sensitive to weather conditions, particularly heavy rainfall and high temperatures, and climate change could lead to an increased risk of such infections (Schuster et al., 2005; Waltner-Toews, 2005). Non-climatic factors, such as close proximity to animal populations, treatment system malfunctions, poor maintenance of infrastructure and treatment practices have all been associated with past disease outbreaks from drinking water supplies (Schuster et al., 2005). Historical experience, including the Walkerton outbreak described previously, indicates that Ontario's water supply is vulnerable to weather-induced water-borne disease outbreaks (Richards, 2005). Source-water protection represents an important first step in reducing the risks of water-borne diseases (see Case Study 2). Auld et al. (2004) proposed using weather monitoring and forecast information as the basis for a ‘wellhead alert system', in order to alert managers of water supply systems to weather conditions that could increase the risk of system contamination.
If projected warming leads to an increase in outdoor activities, there is an associated risk of greater exposure to ultraviolet (UV) radiation (Craig, 1999; Chiotti et al., 2002; Riedel, 2004). Related health impacts would include temporary skin damage (sunburn), eye damage (e.g. cataracts) and increased rates of skin cancer (Martens, 1998; Walter et al., 1999). Toronto is already experiencing an increase in the number of days with high or extreme UV readings (Perrotta, 1999). A UV index is issued daily across Canada, as part of a broader adaptive response by public health departments to educate the public about health risks associated with UV exposure.
Studies examining the impacts of climate and climate change on agriculture in the south subregion include discussion of technological, institutional and behavioural adaptations that reduce the vulnerability of crop production, farming systems and agriculture-dependent communities to climate-related risks (Bryant et al., 2000; Wall et al., 2007). Agriculture has a long history of adaptation based on management of risk. For example, agricultural support programs have proven to be an important mechanism for dealing with the short-term impacts of recent drought, with crop insurance payments from 2000 to 2004 exceeding $600 million (Figure 20).
The relationship between climate and agriculture is complex, with a wide range of climate parameters influencing crop and livestock production. These include maximum and minimum temperatures, growing degree days, length of growing season, amount and timing of rainfall, extreme weather events, drought, snow cover and frost periods. Climate change also indirectly impacts agricultural productivity by affecting the viability of pests, invasive species, weeds and disease, and through interactions with other air issues, such as acid rain and smog. Projected changes in agri-climate conditions could be beneficial for production of many crops, including corn, sorghum, soybeans, maize and some forage crops, and could lead to a northward extension of crop production (e.g. Singh et al., 1998; Andresen et al., 2000). Fruit production could also benefit from a longer growing season and seasonal heat accumulation (Winkler et al., 2002).
However, most impact studies do not include potential effects of pest infestations or other disturbances, the impacts from extreme weather events, or the cumulative impacts of climate change and other air issues, such as acid deposition and air pollution (Drohan et al., 2002). Projections based on average temperatures and precipitation also do not always consider important spatial and inter-annual variability in agri-climate (Kling et al., 2003). When factors such as the frequency and timing of threshold events (e.g. fall and spring freeze dates) are considered, it appears that farming in the south region of Ontario will remain vulnerable to springtime cold injury (Winkler et al., 2002). In the case of the grape and wine industry, warmer winter temperatures and less snow cover could also have adverse impacts on icewine production, depending on the timing and frequency of the cold spells that are required for harvesting (Chiotti and Bain, 2000).
Climate change is expected to produce conditions that favour agricultural pests and diseases, which could negatively impact crop production. Increased migration, reproduction, feeding activity and population dynamics of insects, pests and mites are expected to lead to greater crop losses (Lipa, 1999). Similarly, changing climate is projected to alter the geographic distribution of plant diseases and challenge existing plant disease management practices (Chakraborty et al., 2000). Climate change may also impact the survival of pathogens, the rate of disease progress during a growing season and the duration of the annual epidemic in relation to the host plant (Boland et al., 2003). Invasive weed species are expected to show a strong growth response to increased atmospheric CO 2 levels, which may possibly be combined with a weakened efficacy of herbicides (e.g. Archambault et al., 2001; Ziska, 2004). While it is widely recognized that too much or too little precipitation has more pronounced effects on plant disease than temperature, there is comparatively little research on plant disease management (cf. Boland et al., 2003; Coakley, 2004; Guiterrez, 2004).
Changing climate may also have direct impacts on livestock production. For example, increases in heat stress are expected to result in lower weight gains in beef cattle, lower milk production in dairy cattle, and lower conception rates and substantial losses in poultry production (e.g. Owensby et al., 1996; Kling et al., 2003). Climate change also affects animal diseases, and therefore livestock production, by altering the chances for survival and enhancement of insect vectors (ticks, mosquitoes) and associated diseases that are presently considered exotic or rare (Charron et al., 2003). Milder winters may reduce some current problems, such as pneumonia in adult cattle, but will also increase parasite survival in and on animals. Water supplies for livestock can be contaminated by run-off in watersheds where heavy rainfalls flush bacteria and parasites into water systems. In extreme drought conditions, the potential for water to become toxic from sulphur and Cyanobacteria (blue-green algae) creates serious problems for cattle production (Prairie Farm Rehabilitation Administration, 2003).
Producers' perceptions of climate risk appear to vary by commodity (Harwood et al., 1999). In the south subregion, cash crop producers voiced more concern about impacts from climate change than livestock operators during focus group discussions (Reid, 2003). Generally speaking, Canadian producers think the agricultural industry will continue to furnish adequate technological solutions to meet a variety of risks, including stresses from changing climate and weather conditions (Holloway and Ilbery, 1996; Brklacich et al., 1997; Bryant et al., 2000; Smit et al., 2000).
Producers inevitably face risks associated with year-to-year climate variability (Kling et al., 2003), with the greatest fluctuations in farm profits resulting from variability in precipitation and extended frost-free seasons (Brklacich and Smit, 1992). The capacity of individual producers to manage risk and undertake adaptation depends on many factors, including the size and diversity of their operations. Livestock operators, whose farms tend to be relatively large, are likely to adopt a wider range of actions than farmers who presently have diversified operations (Brklacich et al., 1997). Small- to medium-size operations will be relatively more disadvantaged in higher risk circumstances (Kling et al., 2003).
The impacts of the 1998 ice storm, where dairy farmers in Ontario were impacted more severely than their Quebec counterparts, demonstrate how experience can significantly affect vulnerability. Ontario operators had not generally been exposed to frequent losses of electricity prior to this major storm; as a result, only about 20% of them had backup generators in place (Kerry et al., 1999). Since the ice storm, there has been a substantial increase in the installation of backup generators in rural areas, reflecting responsive adaptation.
Ontario producers perceive that climate conditions have changed noticeably in the past five years, and their responsive actions have included growing different crops and/or crop varieties, altering tile drainage, employing conservation tillage, changing the timing of planting and installing irrigation systems (Canadian Climate Impacts and Adaptation Research Network –Agriculture, 2002; Wall et al., 2007). Soybean producers have adapted to recent climate stresses by planting new or improved crop varieties, adopting crop rotation and altering the timing of planting (Smithers and Blay-Palmer, 2001). Tomato producers in the southwestern part of the south subregion have adopted measures to reduce the impact of extended droughts, including the use of improved irrigation systems adapted from Australia. In 2002, one of the driest years in history, Ontario tomato growers who were using the new system had their second highest yield ever (Agriculture and Agri-Food Canada, 2003). Given recent drought, decreases in streamflows and increased irrigation demands, producers at the community level in the south subregion have worked with local water managers to develop a framework for participatory irrigation advisory committees to ensure both the fair sharing principle and the maintenance of flows for ecosystem services (Shortt et al., 2004).
Changes in Great Lakes water levels and temperatures directly impact hydroelectricity generation in the south subregion. Historical water level changes (see Case Study 1) have reduced hydroelectricity output by up to 26% at some stations and required that additional supplies of electricity be secured from other domestic or American sources during periods of peak demand (Mercier, 1997; Smith et al., 1998). In 1998, low water levels, in combination with hot summer temperatures that resulted in increased demand for air conditioning, placed considerable stress on the electricity generation and transmission system (Ligeti et al., 2006). In recent years, rising water temperatures in the Great Lakes have impacted electricity generation from nuclear and coal-fired plants by reducing the efficiency of their cooling systems, and could potentially force cutbacks in production in order to meet limits on the temperature of discharged water (Spears, 2003).
The transmission and distribution grid is also sensitive to extreme weather events. The impacts of the 1998 ice storm on the south subregion were most severe in the Ottawa to Kingston area, affecting 600 000 electricity consumers, damaging more than 100 high-voltage transmission towers and requiring at least 10 500 new poles (Kerry et al., 1999; Chiotti, 2004; see also Chapter 5). A number of storms, generally associated with strong winds, disrupted service to hundreds of thousands of customers in a 12-month period beginning September 2005 (McMillan and Munroe, 2006; Table 4). Extreme summer warmth results in greater losses along the transmission and distribution lines. In 2002, these losses amounted to 11.5 kW •h, or 7.5%, of the province's total generation supply (Ontario Energy Board, 2004; Gibbons and Fracassi, 2005).
|Severe storm dates||Customers affected (loss of service)|
|September 29, 2005||93 000|
|November 6, 2005||120 000|
|November 16, 2005||50 000|
|February 4, 2006||100 000|
|July 17, 2006||170 000|
|August 2, 2006||150 000|
|September 24 and 27, 2006||93 000|
The 2003 summer blackout in southeastern Canada and the northeastern United States, although not directly caused by hot weather, demonstrated the vulnerability of the electricity transmission system and illustrated the types of impact that Ontario could experience as a result of future large-scale power interruptions. Although the shutdown and restart of hydro, coal-fired and nuclear electricity generating facilities were done in an orderly fashion, full power was not restored until 11 days after the blackout began (Ontario Ministry of Energy, 2004; United States –Canada Power System Outage Task Force, 2004). Although the exact costs of the blackout are unknown, gross domestic product in Canada was down 0.7% in August, there was a net loss of 18.9 million work hours and manufacturing shipments in Ontario were down $2.3 billion (United States –Canada Power System Outage Task Force, 2004). The blackout also put at risk vulnerable persons, such as the elderly, mothers and children in shelters, and persons in palliative care units (Ligeti et al., 2006).
Changing climate, with a trend towards warmer winters and hotter summers, has contributed to the peak energy demand in Ontario now occurring in summer (Independent Electricity System Operator, 2006). Electricity demand decreases as mean daily temperatures rise until roughly 18 °C, the threshold at which electricity demand begins to climb (Cheng et al., 2001; Figure 21). Annual heating degree days have decreased in Toronto during the past century (Figure 22), with the lowest number of heating degree days occurring in the warmest year on record (1998), due largely to unusually mild winter temperatures (Klaassen, 2003; Chiotti, 2004). Recently, this ongoing decrease has lowered demand for heating fuels, including natural gas (Klaassen, 2003).
Projected impacts of Great Lakes water level changes (Case Study 1) on hydroelectricity facilities on the Niagara and St. Lawrence rivers for 2050 range from small increases in production to a 50% decline in hydroelectricity output, the latter representing a loss of more than 1100 MW annually (Buttle et al., 2004; note that this analysis does not consider the potential contributions of any new hydroelectric developments). The decline could be even more significant during extremely low water years (Buttle et al., 2004). Lower water levels in the Great Lakes will also impact the cost of shipping coal to supply coal-fired electricity generating plants (Quinn, 2002; Millerd, 2005). If these plants are still operating in 2050, the average annual cost of shipping coal from American Lake Erie ports and Lake Superior ports could be 13 to 34% higher than in 2001 (Millerd, 2005). Continued warming of Great Lakes water will further reduce cooling efficiency in nuclear and coal-fired generating plants. Output has been reduced from 1 to 3% during past hot summers (Chiotti, 2004).
Future changes in the frequency and magnitude of extreme weather events, particularly ice storms, heavy snow storms and wind storms, are likely to increase the risk of interrupted electricity supply and distribution. For example, the frequency and duration of freezing rain events are projected to increase throughout the subregion, with greater increases in the eastern portion (e.g. Ottawa) and smaller increases in the south-central portion (e.g. Toronto; Klaasen et al., 2003; Cheng et al., 2007). In the event of future catastrophic failures of the electricity transmission system, large urban areas are at higher risk of extended blackouts because local electricity generation, as a percentage of local electricity consumption, is very low in Toronto (1.2 per cent), London (4.4 per cent) and Hamilton (0.8 per cent; Gibbons and Fracassi, 2005).
Demand for electricity in the south subregion will continue to reflect changing climate, with summer demand projected to increase significantly (Figure 23), although average monthly demand may still be highest in winter, particularly in unusually cold years (Klaassen, 2003). Changes in electricity demand are significantly higher for changes in cooling degree days than for changes in heating degree days, depending on the cooling source (Canadian Council of Ministers of the Environment, 2003), with a 1 °C increase in summer temperature having four to five times the impact on energy demand of a 1 °C drop in temperature in winter (Cheng et al., 2001).
Further changes in Ontario's energy mix will be necessitated by decreased hydroelecric capacity of existing Great Lakes facilities and increased energy demand for summer cooling. Some options, such as the greater use of coal, will not likely be considered viable in the future (Mirza, 2004), thus placing more emphasis on nuclear, combined-cycle natural gas, untapped hydroelectric sources and other renewable sources. For example, there is considerable wind power potential in the south subregion, much of it located along the shores of the Great Lakes. The potential for wind, solar, biomass and new river-run hydro has been estimated to be considerably greater than the province's proposed green power target of 10% of its total energy capaciy by 2010 (Pollution Probe and the Summerhill Group, 2004). However, none of these renewable sources can address short-term increases in peak demand as effectively as large-scale hydroelectric developments (Pollution Probe and the Summerhill Group, 2004).
Increased energy efficiency, as well as behavioural changes on the part of consumers, should play a significant role in reducing total demand. Extreme estimates for more energy efficiency are in the 50% range (ICF Consulting, 2005), and adaptation measures such as developing green roofs and expanding urban forests could lead to even more energy savings by reducing the urban heat-island effect (Banting et al., 2005). Peters et al. (2006) have argued that aggressive energy efficiency measures could be implemented in Ontario relatively quickly and cost effectively.
The Great Lakes—St. Lawrence River system provides a convenient, low-cost and relatively environmentally friendly means of commercial transportation (Millerd, 2005). Handling approximately 200 million tonnes of cargo each year, the seaway provides access to the industrial heart of North America. Almost 50% of seaway traffic travels to and from ports in Europe, the Middle East and Africa (Statistics Canada, 2005; Great Lakes —St. Lawrence Seaway System, 2006; Transport Canada, 2006).
Most vessels used are designed specifically for the seaway, and are operated to take advantage of maximum water depths in connecting channels and ports. As such, their usable capacity diminishes with decreases in water levels (Millerd, 2005; see Case Study 1). Depending on the size of the ship, each 2.5 cm loss in draft translates into between 100 and 270 tonnes of lost carrying capacity (Lindberg and Albercook, 2000). During 2000, lake cargo carriers were forced to reduce their loads by 5 to 8% and, in 2001 a proportion of the slow-down in navigation (causing a $11.25 million decrease in business volume) could be attributed to low water levels (AMEC Earth and Environmental, 2006; International Lake Ontario –St. Lawrence River Study Board, 2006). In October 2001, sustained high winds on Lake Erie resulted in already low water levels falling another 1.5 m at the lake's western end, making the link between lakes Erie and Huron impassable for large vessels for two days (Canadian Council of Ministers of the Environment, 2003).
Adaptive measures to address future decreases in Great Lakes water levels include reducing the weight carried per ship and dredging connecting channels and ports, both of which have significant environmental and economic costs. Projected increases in shipping costs by 2050 range from 8 to 29%, depending on commodity, with higher increases for coal, aggregates and salt, and lower increases for petroleum products and grain (Millerd, 2005). Some of these costs could be offset by a longer shipping season because of warmer winter temperatures and reduced winter stockpiling and ice-breaking costs, but this has not been assessed (Millerd, 2005). Increased costs will reduce the competitive advantage of shipping by water, and shifts in modes of transport may occur. In some cases, operations established specifically to access the low-cost water transportation, such as some gravel, sand and stone quarries, may no longer be economically viable (Millerd, 2005).
Extensive dredging could be employed to deepen channels and harbours and keep connecting rivers navigable for commercial shipping. Estimated costs have been as high as US$31 million per harbour on the American Great Lakes, not including the costs associated with physical infrastructure (Changnon et al., 1989; AMEC Earth and Environmental, 2006). For the 101 km Illinois shoreline of Lake Michigan including the Port of Chicago, it was estimated that $138 to $312 million would be needed over a 50-year period for dredging harbours to compensate for a 1.25 to 2.5 m decline in lake level. Another study estimated dredging costs as high as $6.84 million for Goderich harbour on Lake Huron if water levels were to drop 1 m below February 2001 levels (Schwartz et al., 2004). These cost estimates do not include treatment costs or other environmental risks related to contaminated materials brought up during the dredging (Moulton and Cuthbert, 2000; see Case Study 1).
Road and Rail
The most significant impacts of changing climate on land transportation in the south subregion are expected to be temperature-related damage to paved roads and rail systems, snow and ice control, and infrastructure damage related to heavy rainfalls and other extreme weather events.
Climate variability exacerbates rutting, thermal cracking and frost heaving of paved surfaces. Increases in the number and severity of hot days in southern Ontario will result in an increase in rutting and flushing or bleeding of asphalt from older pavement, which in turn affects functional performance of the pavement (ride quality) and has implications for safety and maintenance costs (Mills and Andrey, 2002). Currently, however, cold winter temperatures are a much greater concern for paved surfaces in Canada than summer heat. Freeze-thaw cycles accelerate road deterioration, particularly in wet areas with a subgrade composed of fine-grained sediments (Haas et al., 1999). Freeze-thaw cycles have increased in recent years in the south subregion, except in the City of Toronto, where they have decreased (Canadian Council of Ministers of the Environment, 2003). As a result of an increase in freeze-thaw cycles, the County of Haldimand is accelerating its conversion of granular roads to tar and chip roads (Br ûlé and McCormick, 2005). Although some studies suggest that freeze-thaw cycles will decrease significantly in the south subregion by 2050 (e.g. Andrey and Mills, 2003), detailed analysis for Toronto suggests that projected warming is unlikely to significantly change the number of freeze-thaw cycles experienced this century (Ho and Gough, 2006).
Railway track can experience buckling in extreme summer heat. While buckling is likely to become more frequent in future, cold temperatures and winter conditions are currently responsible for a much greater proportion of the damage to tracks, switches and railcars. Based on limited analysis, a warmer climate is expected to have a net benefit for rail infrastructure in Ontario (Andrey and Mills, 2003).
The Province of Ontario allocates approximately $120 million per year to de-ice and plough provincially designated roads (Andrey et al., 1999). Snow and ice removal is also a significant component of municipal budgets. For example, the City of Ottawa spent $53.9 million in winter maintenance of roads, rights-of-ways and sidewalks in 2004 (City of Ottawa, 2005). Assessment of total costs for 1998 winter road maintenance incurred by the provincial government and municipalities representing 51.4% of the population calculated these costs at $273.5 million (Jones, 2003). Projected increases in freezing rain (Klaassen et al., 2003; Cheng et al., 2007) could increase de-icing costs in most areas of the province during the next 50 years, but overall snow removal costs are expected to decrease (Jones, 2003).
The south subregion contains most of the downhill ski areas in Ontario, located primarily along the southern shore of Georgian Bay. Projections of decreases in the length of the ski season range from to 0 to 16% for the 2020s and 7 to 32% for the 2050s, with continually increasing dependence on machine-made snow (Scott et al., 2003, 2006). Future challenges to the ski industry may have been foreshadowed in January 2007, when the delayed start of winter, warm night-time temperatures and a lack of snow resulted in the first closure in the history of Intrawest Blue Mountain, Ontario's largest ski resort (Teotonio et al., 2007; Rush, 2006).
Vulnerability of ski-facility operators to these projected impacts is variable. Large corporate ski entities are generally less vulnerable to climate change impacts than are smaller ski operations. This is because large operations tend to have more diversified business operations involving real estate and four-season activities, and generally have greater capacity to make substantial investments in state-of-the-art snowmaking systems. Most importantly, however, corporate operations tend to be regionally diversified, reducing their overall business risk to poor snow conditions in one location (Scott et al., 2006).
The longstanding tradition of ice fishing in the subregion is diminishing as a result of reduced lake-ice cover and less safe ice conditions. During 1997 –1998, the Lake Simcoe ice fishing season was 52% shorter than the near-normal winter of 2000 –2001 (Scott et al., 2002). In 2002, the lack of ice on Lake Simcoe resulted in the cancellation of the Canadian Ice Fishing Championship. Winter festivals may also need to adapt to changing climate. For example, the renowned Rideau Canal Skateway in Ottawa is a key recreation resource and primary attraction for the city's Winterlude Festival. The average skating season between 2001 and 2006 was 50 days (Blackman, 2006). The 2002 skating season was one of the shortest on record (at 34 days), and the 2006 season was plagued by a delayed opening and sporadic closures. Organizers have adjusted by moving more activities on land and by making snow for slides and storing ice blocks (for sculptures) in large freezers (Blackman, 2006). The average skating season is projected to start later and last 43 to 52 days in the 2020s and 20 to 49 days in the 2050s (Scott et al., 2005; Jones et al., 2006).
Although the recreational boating season is expected to increase as a result of longer ice-free seasons, the Great Lakes recreational boating and fishing industry is negatively impacted by extremely low water levels (Thorp and Stone, 2000; American Sportfishing Association, 2001). A 2001 survey of marinas on Lake Ontario and the upper St. Lawrence River found that fluctuating water levels had a ‘major' or ‘devastating' impact on the majority of respondents during the previous five years (McCullough Associates and Diane Mackie Associates, 2002). In response to low water levels on Lake Huron, the federal government created a $15 million Great Lakes Water-Level Emergency Response Program to aid marina owners and operators with emergency dredging costs (Scott and Jones, 2006a). Given that the frequency of low water levels is projected to increase in future, there is a high likelihood that marinas and recreational boaters will experience similar conditions to those experienced during 1999 to 2002 on a regular basis (Jones et al., 2005). Projected declines in water levels will also reduce navigability in some channels as a result of newly exposed sandbars and accelerated plant growth, necessitating changes in the location of launch points for boats and possibly requiring restrictions on the size and weight of boats allowed to operate in certain water bodies (Jones et al., 2005).
The recreational fishery in Ontario is the largest in Canada, valued at more than $1.5 billion annually (Ontario Ministry of Natural Resources, 2005a). Ecosystem changes described previously may force fishers seeking cold-water species to travel outside the south subregion (Minns and Moore, 1992). However, smallmouth bass, a popular warm-water sport fish species, is projected to increase substantially in eastern Lake Ontario and adjacent areas (Casselman et al., 2002). The sustainability of recreational fisheries may depend largely upon fishers being made aware of such changes, and their willingness to adjust their preferences to reflect new opportunities. The overall impact of climate change on recreational fisheries in Ontario remains uncertain, and any analysis would have to consider a range of potential adaptation responses, including changes in lake stocking strategies (Ontario Ministry of Natural Resources, 2005a).
Other important warm-weather recreation industries in Ontario are generally expected to benefit from the longer seasons that will result from changing climate, but adaptations will be needed to realize these benefits. The golf season in the Greater Toronto Area is projected to increase by up to 7 weeks in the 2020s and up to 12 weeks in the 2050s, with golf courses experiencing a 23 to 37% increase in annual rounds played in the 2020s, and a 27 to 61% increase in the 2050s (Scott and Jones, 2006b). Aspects of golf operations, including turf grass selection, irrigation and pest management, would need to be adapted for these increases to be realized. Higher temperatures will also extend the shoulder seasons for beach recreation, and increase demand during summer months. Analysis of beach use and lake swimming at several sites in the subregion projected a 2 to 4 week increase in season length by the 2020s, and an increase of as much as 8 weeks in the 2050s (Scott et al., 2005).
The central subregion (Figure 1, Box 1) is characterized by huge areas with low population densities, vast expanses of forested land and a rich endowment of mineral resources. Most of the research on the impacts of climate variability and change in this subregion has focused on ecosystem impacts, particularly aquatic ecosystems and forest disturbance (Case Study 5). Climate change adaptation issues of greatest concern include the sustainability of resource-dependent communities, particularly those related to forestry and tourism, and the vulnerability of critical transportation infrastructure to extreme weather events.
The entire central subregion lies within the Boreal Shield ecosystem. Changing climate will result in ecosystem shifts, including changes in the distribution of individual species. Paleoecological evidence demonstrates that, during past warm intervals (7000 –3000 BP), thermal habitats were suitable for deciduous forest as far north as Timmins (Liu, 1990). Nonetheless, wholesale ecosystem changes will be limited by species-specific migration rates, as well as a host of environmental factors including soil types, migratory pathways and presence of pollinator species (e.g. Cherry, 1998; Thompson et al., 1998; Loehle, 2000). Hence, more southerly tree species (e.g. those in the oak-hickory forests of southwestern Ontario, south-central Minnesota and Michigan) would require hundreds of years to migrate naturally into the central subregion, even if suitable climate habitats are established in coming decades (Davis, 1989; Roberts, 1989). The lag between changes in regional climate and species response could result in reduced local biodiversity (Malcolm et al., 2002).
The net impact of climate change on forest productivity will be influenced by increases in the frost-free period, growing season temperatures and atmospheric CO 2 concentrations, as well as changes in moisture supply and disturbance regimes. Longer and warmer growing seasons, as well as enhanced CO 2 fertilization, will have a positive effect on tree growth (e.g. Colombo, 1998; Chen et al., 2006). At sites where moisture and soil nutrient supply are presently the limiting factors for tree growth, the positive effects of temperature and CO 2 increases may be minimal (e.g. Jarvis and Linder, 2000). In addition, elevated CO 2 will increase the growth of grasses and other understorey species, potentially delaying forest regeneration after disturbance (e.g. Gloser, 1996; Wagner, 2005).
The primary sources of natural disturbance in the boreal forest are insect outbreaks, disease, fire and wind, all of which will be impacted by climate change. Fire is an integral part of the Boreal Shield ecosystem. In more southerly portions of the boreal forest, where fire suppression is practiced, the area burned is limited to about 0.11% of the total forest per year (Ward et al., 2001). The length of the fire season has increased by up to 8 days in many Ontario boreal forest ecosystems since 1963 (R.S. McAlpine, unpublished data, 2005). Drought and high temperatures sometimes create conditions that make present fire suppression techniques ineffective. There is a strong interrelationship between forest fire risk and the impacts of forest pests and diseases, since dead trees increase the fuel load (Fleming et al., 2002; see Case Study 5). Weber and Flannigan (1997) concluded that changes in fire regimes may be more important in determining changes in boreal forest ecosystems in the twenty-first century than changes in productivity and species composition. Future increases in forest fires will remove standing forests at a greater rate (Flannigan et al., 2005), leading to an increase in the number of early successional ecosystems dominated by fire-adapted species, such as jack pine, black spruce, white birch and trembling aspen. Similarly, extreme climate events such as drought will affect forest composition, with recurrent moisture deficits favouring drought-tolerant species (Grime, 1993; Bazzaz, 1996; Hogg and Bernier, 2005), including jack pine, white spruce and trembling aspen at the expense of species such as black spruce and balsam fir.
Spruce budworm is currently the most damaging forest insect in Ontario (Candau and Fleming, 2005; see Case Study 5). Since the late 1980s, Ontario has experienced repeated infestations of the spruce budworm, resulting in the die-off of large tracts of forested area (Ontario Ministry of Natural Resources, 2004). Susceptibility to disease is enhanced by host tree stress, particularly related to moisture (e.g. McDonald et al., 1987; Greifenhagen, 1998). The limited water retention capacity of the shallow soils that are common in this subregion makes them particularly susceptible to drought (Greifenhagen, 1998).
Among the projected impacts of climate change on boreal forests in the subregion is the potential arrival of the mountain pine beetle, which is presently limited to British Columbia and northeastern Alberta (see Chapters 7 and 8). Projected warming may allow this pest to reach Ontario by mid-century (Logan and Powell 2001; Logan et al., 2003), where it could cause great damage to extensive forests of jack pine, white pine and red pine (Parker et al., 2000). Other projected impacts include increases in the severity of forest fires throughout the subregion (McAlpine, 1998) and an increase in average area burned (Flannigan et al., 2005). The combined impact of higher temperatures and increased drought may create a 'tipping point' beyond which fire suppression is no longer feasible (Flannigan et al., 2005).
Comparatively little attention has been given to the impacts of climate change on Boreal Shield fauna. Nonetheless, environmental monitoring has provided insights into the climate sensitivity of some boreal species (e.g. Bowman et al., 2005). Thompson et al. (1998) concluded that larger wildlife will be most affected by changes in landscape structure, and they projected significant decreases in the moose population and increasing numbers of white-tailed deer. The impacts on moose reflect the northward expansion of white-tailed deer, increased mortality from the brain worm carried by white-tailed deer, and elevated predation by grey wolves (Thompson et al., 1998), illustrating the complex interactions that will influence the distributions of a single species.
The abundant rivers and lakes of this subregion support a wide range of fish species, including: 1) those with cold-water requirements (<15°C); 2) those with cool-water requirements (15—25°); and 3) those with warm-water requirements (>25°C). As in the south subregion, projected climate change is expected to favour expansion of fish species with warm-water requirements, such as largemouth bass, smallmouth bass, pumpkinseed, rock bass and bluegill, and place stress on cool- and cold-water species. Historical data demonstrate that warm-water species recruitment is much enhanced in an increasing temperature regime (Casselman, 2002). Temperature increases of 1, 2 and 3 °C at spawning time resulted in 2.0-fold, 3.9-fold and 7.7-fold increases, respectively, in rock bass (a warm-water species) recruitment (Casselman, 2005). Cool- and cold-water species were negatively affected, with the same temperature increases at spawning time resulting in 1.5-fold, 2.4-fold and 20.1-fold decreases, respectively, in lake trout emergence the following spring. Warm-water species can negatively affect growth and production of cold-water species by out-competing them for available prey fish (Vander Zanden et al., 2004; Casselman, 2005).
In 2005, the value of exports from Ontario's forestry and forestry-related industries was $8.4 billion, with 84 500 persons employed in this sector (Natural Resources Canada, 2006). The vast majority of the forestry-reliant communities in Ontario are located in the central subregion, and the forestry sector accounts for more than 50% of employment income in more than half of these communities (Natural Resources Canada, 2006). In addition to international market forces affecting the industry across the country (see Chapter 9), the forestry sector in Ontario currently faces a range of other non-climatic stresses. The forest supply near established major mills is dwindling, forcing the industry to move farther north into areas that are more costly to harvest. Energy costs in Ontario, which have risen by as much as 30%, have also affected logging, road building and transportation; in some cases, they have been cited as the main reason for recent mill closures (Natural Resources Canada, 2006).
Spruce Bud Worm and Forest Fires
A forest insect native to North America, the spruce budworm has caused more damage than any other insect in North America's boreal forest (Figure 24a, b). Spruce budworm larvae feed on the flowers, cones and youngest available foliage of its preferred hosts, balsam fir and white spruce (Candau and Fleming, 2005). Damage caused by defoliation interferes with forest stand development and causes tree mortalities in dense, mature stands of forest over a wide area, with outbreaks occurring in cycles of approximately 35 years (Candau et al., 1998). The most recent outbreak ran from 1967 to 1999, with a peak year in 1980 that caused 18.85 million hectares of severe defoliation (Ontario Ministry of Natural Resources, 2002). Outbreaks occur more frequently in the warmer margins of the host tree's range and seem to be associated with drought, which is projected to become increasingly frequent in the future. Late spring frosts also play a key role in terminating outbreaks in the north, and these are projected to become less frequent in the future (Volney and Fleming, 2000).
Areas devastated by spruce budworm increase the fire fuel load and can burn more readily than non-affected forests (Flannigan et al., 2005). Although the forest industry has successfully salvaged and renewed significant portions of areas infested in the most recent outbreak (Ontario Ministry of Natural Resources, 2004b), there are still large tracts of dead or dying forest, killed by budworm, that pose a substantial fire hazard. Forest managers confronted with damaged forest areas recognize the value of fire in renewing these stands. Forest health depends on fire as the vehicle for converting insect- and disease-infested or wind-damaged stands to fire succession species (Canada Interagency Forest Fire Centre, 2005).
Four broad components have been defined for adaptation strategies to deal with disturbances in forests that can reduce vulnerability and enhance recovery (Dale et al., 2001). These include:
- managing the system before the disturbance (e.g. planting or maintaining tree species that are less vulnerable to fire and insects will reduce vulnerability to those disturbances);
- managing the disturbance through preventive measures or manipulations, such as fire control;
- managing the recovery either immediately after the disturbance (e.g., through salvage logging), or during the process of recovery (e.g., through reseeding); and
- monitoring for adaptive management, to determine how disturbances affect forests and to continually upgrade understanding of how limate change can influence the disturbance regimes.
Current forestry operations at some sites in the central subregion rely on the presence of frozen ground and winter roads for harvesting and hauling activities.These operations are shut down during periods of winter thaw to avoid road damage through rutting and compaction by harvesting equipment and skidders. Periods of winter thaw and extended spring conditions also require that hauling be shut down on some all-season forest roads that would be damaged by heavy loads. It is anticipated that the incidence of such shutdowns on forestry activities will increase as winters become shorter and milder. An adaptation to these conditions would be to construct more all-weather roads, although this would involve significant cost.
Current forestry operations at some sites in the central subregion rely on the presence of frozen ground and winter roads for harvesting and hauling activities.These operations are shut down during periods of winter thaw to avoid road damage through rutting and compaction by harvesting equipment and skidders. Periods of winter thaw and extended spring conditions also require that hauling be shut down on some all-season forest roads that would be damaged by heavy loads. It is anticipated that the incidence of such shutdowns on forestry activities will increase as winters become shorter and milder. An adaptation to these conditions would be to construct more all-weather roads, although this would involve significant cost.
As noted in the preceding discussion of ecosystems in the central subregion, fire, insect and pathogen outbreaks and wind are important climate-sensitive stresses affecting forests in this subregion (see Case Study 5). A recent assessment (Munoz- Marquez Trujillo, 2005) of the impacts of climate change by 2060 in the Dog River—Matawin River forest west of?under Bay concluded that the combined impact of climate change and harvesting could reduce timber availability by 35% over a 1961 to 1990 baseline.?e primary factor in this reduction was projected increases in forest fire activity, resulting in a younger forest. Although changes in tree species composition would not be noticed in the short term, there would be a shi? in dominance from hardwood to so?wood by 2060 (Munoz-Marquez Trujillo, 2005).
If the growth rates of economically important species decrease due to increased moisture stress, pest outbreaks or other factors resulting from changing climate, logging prior to stand deterioration can be used to speed the replacement of forest types. Stands in which trees are too small for commercial harvest may be thinned to promote stand productivity and health; to remove suppressed, damaged or poor-quality individuals; and to increase the vigour of the remaining trees (Wargo and Harrington, 1991). During periods of severe insect infestation, insecticides may used to protect young stands and reduce losses of timber volume.
Where it is preferable to regenerate with species or genetic sources not in the existing stand, planting would be required. For example, sites being affected by increasing moisture stress could be regenerated with drought-tolerant tree species. Planting also provides an opportunity to move species from current to future ranges (Davis, 1989; Mackey and Sims, 1993). According to Mackey and Sims (1993), tree migration can be facilitated in the near term by limited experimental planting of selected species to appropriate sites as much as 100 km north of their current range limit. Given the uncertainty regarding the timing and magnitude of future climate change, the use of planting stock representing widely adapted populations and diverse seed source mixtures is a low-risk adaptation strategy to increase the likelihood of regeneration success of forests adapted to future climate.
Some non-commercial tree species, shrubs and herbaceous species respond more positively to elevated CO 2 concentrations than do commercial tree species. This may require increased use of mechanical or chemical site preparation and site tending, to assist the regeneration of commercial tree species (Dale et al., 2001).
The central subregion is characterized by large numbers of lakes and rivers. Historical trends indicate that the smaller lakes in the Boreal Shield ecosystem are more sensitive to climate variability and change than are larger water bodies (Environment Canada, 2004). Between the 1970s and 1990s, stream flow in the northwestern part of the subregion (Experimental Lakes Area) declined significantly in response to decreased precipitation and increased evaporation. Associated changes to lakes included longer water renewal times, increasing water temperatures, longer ice-free seasons and changes in lake-water chemistry (Schindler et al., 1996). Much less is known about the climatic sensitivity of water resources in the rest of this subregion. Although quantity of source water is not a present concern in this part of the province and population growth is not projected to add additional stress, decreased water quality associated with changing climate could increase treatment costs and may compromise already stressed water treatment systems in some First Nations communities (see Section 3.3.3).
Half of the 46 flood emergencies declared by Ontario municipalities between 1992 and 2003 occurred in the central subregion (Wianecki and Gazendam, 2004). There appears to have been a recent shift in the causes and timing of flood events. Although the overwhelming majority of flooding has historically been associated with spring snowmelt runoff, only 34% of floods between 1990 and 2003 occurred in the spring (March and April), with the remainder occurring throughout the year as a result of heavy rainfall, rain-on-snow conditions and ice jamming. The most damaging of these resulted from a series of very intense thunderstorms between June 8 and 11, 2002 that dropped up to 400 mm of rain (see Case Study 3).
More than $32 billion in minerals, wood, paper and other products are produced and shipped on highways of the central subregion each year (Ontario Ministry Transportation, 2005), which include major segments of two trans-Canada highways (highways 11 and 17). Highway transportation is especially important in this subregion because the sparse population and long distances reduce the viability of other modes of passenger transportation. Many small communities rely on highways to access essential services provided in urban centres. The road system provides physical links between eastern and western Canada, and serves as a gateway to the United States (Ontario Ministry of Northern Development and Mines, 2006b). When these transportation routes are damaged or cut off, shipping delays are costly and alternative access to many communities is difficult.
Climate-related disruptions to the road network in this subregion are most likely to result from extreme precipitation (rainfall or snow). As a result of a June 2002 storm that brought unprecedented rainfall (see Case Study 3), major and secondary highways were closed for a week or more, and bridges, culverts, railways, private residences, commercial properties and agricultural operations were damaged by associated flooding (Cummine et al., 2004). A temporary bridge had to be installed to restore traffic on the Trans-Canada Highway between Kenora and Thunder Bay. The CN Rail line between Winnipeg and Thunder Bay was washed out in more than thirty places, with one of the washouts measuring almost a kilometre in length. Projected increases in extreme precipitation events, a trend supported by the limited data available for this area (Wianecki and Gazendam, 2004), therefore pose a significant risk to transportation infrastructure in this subregion.
Ontario's most northerly downhill ski area is located near Thunder Bay. Analysis of the impact of climate change on the downhill ski industry in this area suggests that the length of ski seasons would decrease by up to 17% in the 2020s and up to 36% in the 2050s (Scott and Jones, 2006a). To maintain viable operations, snowmaking will need to increase. This would add significant costs for ski resort operators and would be dependent upon the availability of adequate water supplies.
Unlike the downhill skiing industry, snowmobiling relies on natural snowfall and is highly vulnerable to climatic change. In seven snowmobiling areas across the central subregion, the average projected reduction in season length may be between 30 and 50% by the 2020s and between 50 and 90% by the 2050s (Scott et al., 2002). Recent market trends showing decreases in sales of new snowmobiles and increases in sales of all-terrain vehicles (ATVs) may already reflect adaptation by recreationists to these climate trends (Suthey Holler Associates, 2003). It is noteworthy that climate change was not considered in the development of Canada's recent (2001) National Snowmobiling Tourism Plan (Scott et al., 2002).
Currently, less than 300 premature deaths a year are attributed to air pollution in the central and north subregions of Ontario (Ontario Medical Association, 2005), indicating it is much less of an issue there than in the more populous south subregion. Neither has heat stress associated with extreme hot days historically been a significant problem. Increases in either factor as a result of changing climate could lead to disproportionate health impacts, as studies have shown that mortality caused by air pollution and high temperatures is often greater in communities that are not accustomed to such conditions, relative to those that experience more frequent smog episodes and heat waves (cf. Cheng et al., 2005).
The central subregion contains woodland habitats that could support populations of Ixodes scapularis ticks, with Lyme disease projected to spread across most of the subregion by 2050 (Ogden et al., 2006c). The virus responsible for hantavirus pulmonary syndrome (see Section 3.1.3), has been found in deer mice collected in Algonquin Provincial Park near the southeastern limit of the central subregion (Drebot and Artsob, 2000).
Coal-fired electricity generating stations in Atikoken and Thunder Bay provide much of the electricity to communities in this subregion through the provincial energy grid. Electricity is also produced from co-generation facilities that burn natural gas or forest-based biomass, especially from pulp-and-paper operations. Both coal-fired electricity generating stations have been targeted for shutdown by 2014. Electricity demand is presently falling in the subregion. While projected increases in temperature could increase summer electricity demand in the future, there are significant opportunities for enhanced energy efficiency, especially in the pulp-and-paper and mining sectors (ICF Consulting, 2005).
Future electricity needs could also be provided by alternative sources. The subregion has extensive river-run hydro facilities in operation (Figure 7), but many dams are aging and changing precipitation patterns could cause reservoirs to exceed their capacity, suggesting a potential need for upgrading of this infrastructure. There is also considerable potential for wind power, particularly along the north shores of Lake Superior (Figure 7). Biomass could be an additional option for many industrial sites, especially in the pulp-and-paper industry, where facilities have a ready-made source of electricity and heat as a by-product of their manufacturing activities.
Increases in the frequency and duration of ice storms are projected for both the central and north subregions (Cheng et al., 2007), thus presenting an increasing climate risk to the power transmission and distribution grid.
Most of the mining-reliant communities in Ontario are located within the central subregion (Natural Resources Canada, 2001). There are more than 25 mines operating in the area, including gold, base metal, and platinum group metal mines, as well as major industrial mineral operations (Ontario Prospectors Association, 2007).
Both drought and extreme precipitation impact mining infrastructure. Tailings ponds currently capped with water to prevent oxidation and acid mine drainage are at risk of overflowing and releasing contaminants when heavy rainfall events occur (Mining Watch Canada, 2001; NorthWatch, 2001). Slope stability and integrity of engineered berms are also vulnerable to extreme precipitation. Increased temperatures will lead to increased evaporation from tailings ponds, potentially exposing raw tailings to subaerial weathering. Wind erosion of any exposed fine-grained tailings could contribute to the acidification of the watershed (Nriagu et al., 1998). Nonetheless, all of these potential impacts are manageable with application of appropriate adaptation measures already practiced elsewhere in the mining sector.
Of greater long-term consequence may be projected reductions in water levels of lakes and rivers. Warm dry conditions in 2005 reduced water levels throughout the watershed near the Williams, David Bell and Golden Giant mines. In response, efforts were made to reduce water intake, and recycling of process water was increased. Infrastructure was also established to move water from tailings ponds, pits and quarries for underground use (Brown et al., 2006).
Agriculture is presently of only limited significance in the economy of the central subregion. Although a longer growing season and increased growing degree days could present opportunities for northward expansion of some crops, constraints presented by soil quality and other factors are likely to preclude development of extensive new areas of agriculture (Bootsma et al., 2001, 2004). Impacts of changing climate on livestock are expected to parallel those for the south subregion (see Section 3.1.4).
The north subregion (Figure 1, Box 1) remains the least studied part of Ontario with respect to climate change impacts (cf. Smith et al., 1998), and very little of the available research considers adaptation. There is also limited knowledge of current vulnerabilities that may be climate related. Because of its northern latitude, the key issues in the subregion are, in some cases, similar to those of the northern parts of the adjacent provinces (see Chapters 5 and 7) and the Northwest Territories (see Chapter 3). In a recent risk assessment workshop on the impacts of climate change on Aboriginal and northern communities (Indian and Northern Affairs Canada, 2007), potential issues of particular concern included impacts on traditional food supplies, increased risk of forest fires and impacts on infrastructure, including reduced winter road access and declining water quality. Traditional knowledge represents a valuable source of information on climate variability and ecosystem impacts in this subregion (e.g. McDonald et al., 1997).
Changes observed in both marine and terrestrial ecosystems of the north subregion primarily reflect recent changes in climate. For example, decreases in the proportion of Arctic cod in the diet of thick-billed murre chicks near Coats Island, NT and associated increases in warmer water species, such as capelin and sandlace, suggest that the marine fish community in northern Hudson Bay changed from Arctic to subarctic around 1997 (Gaston et al., 2003, 2005). These changes were associated with a 50% reduction of the mid-July ice cover in Evans Strait from 1981 to 1999, likely reflecting a general warming of Hudson Bay waters.
Ringed seals and bearded seals depend on sea ice in Hudson and James bays to provide a safe and predictable birthing platform, while polar bears depend on the ice to mate and to hunt seals. The ice platform that forms each year in eastern Hudson Bay and James Bay is melting about 2 to 3 weeks earlier than 20 to 30 years ago (Gagnon and Gough, 2005), with similar trends reported for southwestern Hudson Bay (Stirling et al., 1999; Gough et al., 2004). An earlier melt reduces the amount of time available for the polar bears to forage on seals and accumulate the body fat needed to get them through the ice-free season when they are on land and have limited access to high-protein foods. The trend toward decreasing sea-ice cover has led to long-term declines in the body condition of polar bears in the western and southern Hudson Bay populations (e.g. Stirling et al., 1999). Although the southern Hudson Bay population has remained steady at about 1000 individuals, the western Hudson Bay population has declined from about 1200 in 1987 to less than 950 animals in 2004 (Obbard, 2006).
While the observed declines in sea-ice cover have not yet had a demonstrable impact on ringed or bearded seal reproduction, projections of reduced snowfall and increased spring rain events are expected to negatively impact ringed seal reproductive success by weakening or destroying birthing lairs (Stirling and Smith, 2004). In the short term, such events may have a positive effect on the polar bear population by increasing the vulnerability of ringed seals and their pups to predation, but a decline in this important prey species will negatively impact polar bear populations in the long term (Stirling and Smith, 2004). Polar bears in Ontario often construct maternity dens in permafrost features such as palsen (Obbard and Walton, 2004). Projected changes in permafrost extent resulting from increasing air and ground temperatures (Gough and Leung, 2002) are likely to lead to palsa collapse, negatively affecting the reproductive success of polar bears.
Arctic char and brook trout are two anadromous fish species that use salt and fresh water in the Hudson Bay basin. Both of these are cold-water species that will be affected by changes in water temperature, with the Arctic char being near the southern limit of its range and the brook trout near its northern limit. With anticipated increases in water temperature, the range of the Arctic char would be expected to be restricted, while the range of the brook trout is expected to expand (Chu et al., 2005).
The impacts of changing climate on forest disturbances are a concern to many communities in the Boreal Shield ecosystem (see Section 3.2.1). Climate change could result in annual burn areas increasing 1.5- to 5-fold by the end of this century (see also Ward et al., 2001; Flannigan et al., 2005). Changes in forest insect disturbance are more difficult to predict, since their occurrence is affected by complex climatic interactions with biochemistry and phenology of the host plant, and by the life cycles of the insects themselves and their parasites (Scarr, 1998; Logan et al., 2003). Warmer temperatures will tend to expand ranges northward and enhance insect growth rates (Logan et al., 2003). Spruce budworm is historically the most damaging forest insect in Ontario (see Section 3.2.1, Case Study 5) and is predicted to become even more damaging in the northern parts of the boreal forest (Fleming and Candau, 1998).
None of the communities in the north subregion have access to all-weather roads and, except for the winter months, are accessible only by air or water. During the summer months, the port of Moosonee provides barge services to neighbouring communities, supplying bulk materials and essential supplies that are transported to Moosonee by train. However, the key to supplying most communities in this subregion is a winter road system that operates between late January and late March (Figure 25). Annual construction of the 3000 km road network provides cheaper transport of heavy equipment and materials, allowing the communities to lower their cost of living and reduce the cost of capital construction projects (Ontario Ministry of Northern Development and Mines, 2005). The new Victor diamond mine, 90 km west of Attawapiskat, will also rely on ice and winter roads for transportation of equipment and supplies. In addition to direct economic benefits, these roads also facilitate social interaction between isolated communities (Ontario Ministry of Northern Development and Mines, 2006a; see also Chapter 7).
Delays of up to 10 days in opening several sections of the winter road network, particularly routes that cross lakes and rivers, occurred in 2005 and 2006 (Wawatay News, 2005a, b). Projected increases in winter temperatures of 4 to 6 °C by 2050 will undoubtedly affect the viability of this seasonal transportation network. A study of the Berens River area of Manitoba, on the northeast shore of Lake Winnipeg, concluded that the winter road season would be 5 days shorter by the 2020s and 10 days shorter by the 2050s (Blair and Babb, 2002). As discussed in Chapter 3, modifications in ice road construction may be able to compensate for decreased winter cold in the short to medium term; however, longer term adaptation measures may involve construction of all-season water crossings, and ultimately construction of all-season roads.
Air transportation plays a crucial role in delivering essential goods and services to many remote northern communities year-round. Where landing strips have been built on permafrost, increased seasonal thaw or disappearance of permafrost as a result of climate change will necessitate increased maintenance and likely the reconstruction of some facilities.
Although no assessment of the impacts of climate change on water quality has been undertaken in the north subregion, decreases in river flows have been documented for the Severn, Winisk, Ekwan, Attawapiskat, Albany and Moose rivers between 1964 and 2000 (D éry et al., 2005). Reduced flows and increased temperatures further stress water treatment systems that are already approaching, or have surpassed, their capacity to provide safe drinking water.
Communities located on floodplains in this subregion are susceptible to infrastructure damage from spring flooding and ice jams. Because northern communities are small and remote, they depend greatly on emergency access and the ability to evacuate the residents if needed. Spring flooding in 1986, when, precipitation was nearly three times the historic normal, resulted in two deaths and the evacuation of 129 people from the community ofWinisk (Public Safety Canada, 2006). The community of Attawapiskat was evacuated in 1989, 1992, 2002 and 2004, each time because of spring floods (Environment Canada, 2005b; Public Safety Canada, 2006). In 2005 and 2006, spring floods forced the evacuation of 200 people from Kashechewan. The impact of projected changes in climate on flood hazards has not been assessed specifically in this subregion; however, projections of increased winter precipitation and earlier springs will affect the timing and intensity of spring flooding. Adaptation will likely involve evaluation of existing emergency management activities, including relocation of buildings or even entire communities as the result of detailed assessment of flood risk potential at the local scale.
The remote location of communities in the north subregion presents a number of challenges to human health in addition to limited access to health care services. For example, the impact of climate change on traditional ways of life, particularly regarding access to country foods, is a significant health concern (see Chapters 3 and 5). Although there is access to expensive southern foods, traditional foods constitute a significant proportion of the local diet with important nutritional value. In a survey conducted in Fort Severn in 2002, 40% of the households that reported food insecurity over the previous year indicated that they rely on hunting and fishing to supplement their food supply (Lawn and Harvey, 2004). Changing climate impacts ecosystems directly, and also affects access to traditional territories (see Chapters 3 and 7), with implications for both food security and availability of traditional medicines.
The potential for outbreaks of waterborne disease represents a primary health risk in the north subregion that is likely to be exacerbated by changing climate, especially extreme climate events. Several First Nation communities have been identified as having vulnerable water treatment systems (O'Connor, 2002; Commissioner for the Environment and Sustainable Development, 2005). Two communities (Kingfisher and Muskrat Dam Lake) were included in the March 2006 priority list of 21 First Nation communities across the country identified as having high-risk water systems (Indian and Northern Affairs Canada, 2006).
Woodland habitats in the southern part of the north subregion have potential to support populations of Ixodes scapularis ticks (vectors of Lyme disease), as their range expands northwards in response to warmer temperatures. Modelling by Ogden et al. (2006c) indicated that Lyme disease could encroach upon communities in this region by 2080.
Space heating accounts for the largest portion of energy use in the north subregion, roughly 70% of community energy needs. As of 2000, 31 First Nation communities in this subregion were off-grid, of which 13 used diesel generators. The electricity provided by these systems serviced approximately 18 000 residents living in over 4000 homes (Zulak et al., 2000). Supply of diesel fuel is dependent on a viable winter road network, which will be difficult to maintain in the face of projected climate change, for the reasons given in Section 3.3.2.
In recent years, there have been efforts by federal departments and Aboriginal organizations to promote energy efficiency, energy conservation and energy from renewable sources to First Nations communities as part of a broader national effort to reduce greenhouse gas emissions (Neegan Burnside Ltd., 2004; Fox, 2006). Renewable options being promoted include electricity generation from river-run hydro and wind power, and there is considerable potential for the development of new generation from these sources (Figures 6 and 7). Developing community-based renewable energy sources is also viewed as an economic development tool, creating jobs in the local community (Venema and Cisse, 2004; Chiotti et al., 2005). These initiatives also enhance adaptive capacity by reducing community vulnerability to interruptions in the supply of diesel fuel via the winter road network.
There is currently extensive exploration for mineral resources in the north subregion, particularly for diamonds. The Victor diamond mine is currently under construction in the Hudson Plains west of Attawapiskat, while the Boreal Shield hosts active gold mining and past production of a wide range of minerals. Extrapolation from other regions of Canada suggests the potential for climate-related issues, including access via winter roads and the impact of permafrost degradation on containment structures and other physical infrastructure (e.g. Arctic Climate Impact Assessment, 2005; Mining Environment Working Group, 2004; see Chapter 3). Impacts of climate change on mining in the Boreal Shield are discussed in Section 3.2.8.
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