Ministry of the
Solicitor General

Hazard Identification Report 2019 - Section B - Environmental Hazards

HAZARD IDENTIFICATION REPORT 2019 - SECTION B - ENVIRONMENTAL HAZARDS

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Hazard Identification and Risk Assessment Program

Hazard Identification Report 2019
Section B: Environmental Hazards

Office of the Fire Marshal & Emergency Management

Introduction

The Hazard Report contains information profiles for hazards, including a high-level overview of possible consequences. It is divided into 10 parts; an introduction and 9 sub-sections labelled A-I as follows:

  1. Agriculture and Food
  2. Environmental
  3. Extraterrestrial
  4. Hazardous Materials
  5. Health
  6. Public Safety
  7. Structural
  8. Supply and Distribution
  9. Transportation

Avalanche

Go to next hazard: Drought or Low Water

Definition

A snow avalanche ensues when a pent up snow mass loses its hold and is discharged from a slope.

Description

Snow can fracture when the strength of the bonds that hold it together are overcome by stress that overloads the bonds. If enough bonds fracture at once, an avalanche occurs. The sources of stress that can overload a snowpack and cause fracture are called triggers.

Natural triggers occur independently of human activity. Some common natural triggers are:

  • Loading from new snow, wind driven snow or rain.
  • Temperature changes and thawing caused by warm air and solar radiation.

Even if the right snowpack conditions and triggers are available, avalanches will only occur on terrain with certain features and characteristics. Avalanches are most likely to occur on slopes between 30-45 degrees, and in areas where wind causes snow to accumulate, and where sun exposure has resulted in weak snow due to rapid warming and melting.

The three main types of avalanche are:

  • Sluffs/Sloughs: Small slides of dry powdery snow that move as a formless mass
  • Slab: Slabs of snow break loose from a mountainside and shatter like broken glass as they race downhill. These moving masses can reach speeds of 80 miles (130 kilometers) per hour within about five seconds.
  • Wet: Low velocity suspension of snow and water, with the flow confined to the track surface. Can be initiated from either loose snow releases, or slab releases, and only occur in snow packs that are water saturated

Every modern ski resort will issue notices (bulletins) indicating the level of Avalanche Risk for each day. These risk levels range from Low to Very high (extreme).

Spatial Scale, Timing and Warning period

Spatial Scale: The spatial scale of avalanche in Ontario would be small, and usually away from settlements.

Timing: Avalanche could occur during the winter and into the spring, and are most common in the 24 hours following heavy snowfall.

Warning Period: The warning period would vary from 24 hours to seasonal in scale.

Potential Impact

A strong Avalanche may result in:

  • The need for debris management
  • Reports of missing individuals. The need for search and rescue, family reunification operations
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • The need for damage assessment.
  • The need for evacuation or shelter in place.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • The need for site or area access restrictions.

Secondary Hazards

Potential secondary hazards may include:

  • Building or Structure Failure
  • Erosion
  • Rail, Light Rail, Subway
  • Road and Highway

Past Incidents

There have been two incidents of avalanche recorded for Ontario in the Canadian Disaster Database:

  • Scarborough, 1972: An avalanche in highland creek killed 2 people.
  • Chelmsford, 1978: An avalanche killed 1 individual that was hiking in Chelmsford area.

Both avalanches were small and isolated.

Provincial Risk Statement

Avalanches are exceedingly rare in Ontario. While snow is common, the terrain is generally not steep enough to create significant avalanche risk.

Educating the general public about avalanche risk, as well as sign-posting and cordoning off areas at risk for such hazards are the most utilized and effective means of prevention. There are also safety courses and other further education opportunities available for those spending a lot of time in the backcountry.

Given that the risk of avalanche is so low in Ontario, further mitigation measures are seldom needed.

Human Impacts

Avalanche rarely results in fatalities or injuries.

Social Impacts

Avalanche would not lead to impacts on community support mechanisms.

Property Damage

Property can be vulnerable to avalanche, though the occurrence is extremely unlikely in Ontario.

Critical Infrastructure Disruptions

Critical Infrastructure can be vulnerable to avalanche, though the occurrence is extremely unlikely in Ontario.

Environmental Damage

Avalanche would not result in environmental damage, except when it damages forests and trees.

Economic

Avalanche could result in very limited economic impacts, though this is unlikely in Ontario.

Drought or Low Water

Go to Previous Hazard: Avalanche

Go to next hazard: Earthquake

Definition

Drought (also referred to as a period of low water) is an extended period, with one or more of the following: [1]

  • Three months or greater with below average precipitation which may be combined with high rates of evaporation.
  • Conditions in which the water levels in streams are at the minimum required for the survival of aquatic life. Water must be rationed only for high priority uses since many wells are becoming dry.
  • Conditions that have socioeconomic impacts that are felt over a much larger area than the individual properties that the drought/low water conditions have been reported at.

Description

Drought conditions are naturally occurring phenomenon that can also be triggered or exacerbated by human activities, such as the altering of ecosystems. They are characterized by decrease in the normal amount of precipitation that the area receives. High air temperatures leading to higher rates of evaporation may increase the severity of the drought. The amount and type of vegetation in the affected area may also contribute to the severity through evapotranspiration losses.

Natural factors that influence the levels of Lake Ontario include inflow from Lake Erie and weather patterns (precipitation, wind, and temperatures). Of particular concern are lack of precipitation and warm weather, which have the greatest effect on water levels, along with reduced levels of ice during the winter, which increases evaporation. Changes to weather and climate patterns could therefore have a more serious impact on the water levels, including Lakes Ontario and Huron, in future.

The first signs of a drought conditions are a decrease in surface and underground water levels and soil moisture. Plants may begin to grow slower, wither, or even die. This can lead to challenges for wild animals that rely on them for food, as well as food supply issues or losses for the agricultural industry.

Low water conditions can affect the adequate provision of potable water as well as the distribution of goods via marine transportation. Over 50% of the population of Ontario use Lake Ontario as their main source of potable water, followed by 28.5% who use groundwater sources. The remainder is sourced from the Ottawa River, Lake Erie, Lake Huron and other rivers and lakes across the province.

The Lake Ontario Regulation plan, implemented primarily to help regulate outflow used in operation of the Moses-Saunders power dam, is described as follows by the International Lake Ontario - St. Lawrence River Board:"[the Lake Ontario regulation plan] helps protect various interests in the St. Lawrence River that may be affected by extreme flows or levels. These include adequate flows for hydropower production, minimum depths for navigation, and protection against flooding. Short-term adjustments to the outflows of Lake Ontario have little impact on the water level of that lake in comparison to … natural factors."

There are several characteristics that increase the system’s vulnerability to drought. These include:

  • Groundwater and river water sources
  • Rapid population growth
  • Aging water system components
  • Poorly maintained water system components
  • Limited storage capacity relative to demand
  • Lack of demand management measures
  • Industrial growth

Spatial Scale, Timing and Warning Period

Spatial Scale: Drought is a large scale hazard and may even affect several provinces at one time.

Timing: Drought is more common during the summer months.

Warning Period: Drought conditions build gradually from months to years.

Potential Impacts or Emergency Response Needs

Drought/Low Water emergencies may result in

  • The need for distribution of potable water
  • Delays with suppression of structural fires
  • Increases of water-borne illnesses
  • Decreases in hydro-electric power generation
  • Economic loss for water-intensive manufacturers and farmers
  • Water use restrictions
  • Animal welfare concerns
  • Disruption of shipping channels and/or docks

Potential Impacts

  • The need for emergency provision of essential needs, including food.
  • The need for increased public safety or policing measures.
  • The need for water use restrictions.
  • Economic, social, economic or political instability
  • Ecosystem damage or disruption. Need for assurance monitoring of the environment.
  • Disruption or closure of government, business or financial institutions.
  • Strain on emergency services and response resources.

Secondary Hazards

Potential secondary hazards may include:

  • Civil Disorder
  • Erosion
  • Geopolitical Pressures
  • Land Subsidence
  • Plant Disease or Infestation
  • Water or Wastewater Disruption
  • Water Quality
  • Wildland Fire

Water supply issues can occur as a secondary impact of low water and drought events, as the direct impact of Critical infrastructure failure (such as sanitary trunk sewer collapse), or as the result of any other of the previously defined direct threats. Information about water supply issues is found in the ‘Water or Wastewater Disruption’ hazard profile.

Past Incidents

Ontario has experienced drought/low water conditions in the past and will continue to do so in the future. According to the Canadian Disaster Database, the following past droughts have affected Ontario:

  • Across Canada, 2001
  • Ontario, 1983
  • Central Ontario, 1978
  • Ontario, 1973
  • Ontario, Quebec and New Brunswick, 1965
  • Ontario and Quebec, 1964
  • Ontario, 1963

From 1918-2015 the lowest level recorded for Lake Ontario was 73.75m in 1935, closely followed by 73.8 in 1965[2]. On these occasions, and in 2013 when water levels dipped below average levels, the main negative impacts experienced were economic, linked to environmental impacts to the fishery, as well as cargo supply, fishing and tourism industry losses.

Provincial Risk Statement

From 2001–2010 many exceptional droughts were observed across Canada, and this trend seems to have continued since then. Scientists expect drought to affect new areas across the country and to become even more frequent and severe[3]. The Canadian Drought Monitor records and monitors drought conditions for Canada. It has recorded increasing trends in the frequency of unusually dry conditions in Far Northern Ontario, as well as an increase in the average precipitation levels for Southern Ontario and great lakes regions.[4],[5]

Such conditions could have secondary impacts on ice jams, flood conditions, water supply and Fire season length across the province. For example, Fire season length is projected to be up to 30 days longer in some areas of the province, based on worst-case scenario (under RCP 8.5) data from Environment and Climate Change Canada.

Human Impacts

People in Ontario are not particularly vulnerable to drought/low water emergencies. It is extremely rare in Canada for people to experience health effects from drought, given the abundance of naturally occurring and alternative water supply options, though it is possible.

Social Impacts

Psychosocial impacts are not common among the general population during a drought but are certainly possible. Droughts that have a severe impact on agriculture may trigger psychosocial impacts and effect social bonds, particularly among those who work for the agricultural industry.

Property Damage

In general, property is not especially vulnerable to drought/low water; however, a sudden decrease in groundwater does have the potential to increase the occurrence of land subsidence (sinkholes) in some areas. Crops however, are very vulnerable to drought and significant losses may occur depending on the duration and intensity of the drought/low water event. Irrigation practices have lessened the impact of drought on agriculture and livestock.

Critical Infrastructure Disruptions

The result of low water could result in widespread negative impacts to residents, businesses and other infrastructure. Hydroelectric production is dependent on the water supply and output may decline during a drought/low water event.

Environmental Damage

A shortage of water, especially if combined with high air temperatures can cause vegetation to be stunted or die. if the drought is particularly long or severe, then wildlife may suffer as well. The loss of soil moisture and plant life can led to soil erosion causing further damage. Low water conditions can also impact aquatic life.

Economic

Industries which rely on large volumes of water for production, such as manufacturing, may also suffer during periods of drought/low water. They may be forced to decrease their production or find other methods of production that are less dependent on water. This could have significant economic repercussions for a company.

Earthquake

Go to Previous Hazard: Drought or Low Water

Go to next hazard: Erosion

Definition

An earthquake occurs when rocks break and slip along a fault in the earth. Energy is released during an earthquake in several forms, including as movement along the fault, as heat, and as seismic waves that radiate out from the "source" in all directions and cause the ground to shake, sometimes hundreds of kilometers away.[6]

Description

Earthquakes are caused by the movement and deformation of the tectonic plates caused by the heating and cooling of rock underneath them. Earthquakes can occur anywhere but are most common on active fault lines found at tectonic plate boundaries.

Movement is usually an extremely slow process with the rates of plate movements between 2 to 12 centimetres per year at tectonic plate boundaries and even slower in some areas.[7] This makes their frequency and potential consequence difficult to estimate.

Ontario is divided into three areas for the purposes of earthquake monitoring and study by Natural Resources Canada, which straddle jurisdictional boundaries.[8] These zones are:

  • Western Quebec (includes Eastern Ontario)
  • Southern Great Lakes Ontario
  • Northeastern Ontario

Although most earthquakes are naturally occurring, human activities have caused small earthquakes. These activities include mining activities (including underground collapses and rockbursts), fluid injection for oil recovery and wastewater disposal, and the filling of reservoirs behind large dams.

Earthquakes are measured by the amount of energy released. There are several different magnitude scales, of which the most universal today is the moment magnitude scale, though the Richter scale is still very commonly used. The Modified Mercalli intensity scale is a measurement scale used to describe an earthquake’s impact on natural features, buildings and people. This scale ranges from one (the earthquake is recorded by instruments but is not felt by people) to twelve (total destruction of buildings)[9].

The amount and type of damage depends on the magnitude of the earthquake, the distance from the earthquake epicenter (the origin point of the earthquake), the depth of the earthquake, the frequency of the ground motion, the kind of faulting and the soil and rock type of an area[10].

Building codes are designed to help reduce risk of collapse or damage. The National Building Code of Canada was revised in 2005 to include standards designed to withstand an extremely low-likelihood event and with updated modelling (which are now available online).[11] Such updates have further reduced the risk of damage to new structures, but do not address risk for existing structures. Even with modern building practices, those with high, unsupported roofs, unanchored structures or contents, or buildings not built to code, carry a higher risk.

Existing mitigation measures in place to prevent or limit ground failure, building collapse, damage to building from storms and severe weather will also help militate against the secondary impacts of earthquake. Therefore, the risk of earthquake remains low for Ontario.

Spatial Scale, Timing and Warning Period

Spatial Scale: A strong earthquake can be felt by bordering communities, provinces or even countries. Ontario could experience significant shaking from a large earthquake, particularly in the St. Lawrence Valley seismic zone.

Timing: Earthquakes can occur at any time of the year.

Warning Period: There is currently no warning for earthquakes.

Potential Impacts

A strong earthquake may result in:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Illness, injury or death. May strain the health system and response resources.
  • The need for debris management
  • Reports of missing individuals. The need for search and rescue, family reunification operations
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • Overloaded communications networks.
  • The need for damage assessment.
  • The need for financial assistance.
  • May strain response resources, including emergency services.
  • The need for emergency shelter services.
  • Illness, injury or death of domestic or livestock animals.
  • The need to evacuate or shelter in place.
  • The need for emergency provision of essential needs, including food.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Disruption or closure of government, business or financial institutions.
  • Worsening of existing systemic social issues.
  • Worker shortages and business continuity issues.
  • Strain on emergency services and response resources.
  • Spoilage of food and medicine due to a lack of refrigeration.
  • Psychosocial effects including stress disorders
  • Disruption of navigation and other satellite services.
  • Loss of emergency services connectivity.

Secondary Hazards

Potential secondary hazards may include:

  • Avalanche
  • Civil Disorder
  • Flood
  • Geopolitical Pressures
  • Landslide

As well as all hazards within the following groups:

  • Hazardous Materials (Fixed site or in transport)
  • Supply & Distribution
  • Structural
  • Transportation

Past Incidents

Three of the largest recorded earthquakes in Ontario occurred within 350 km of Ottawa:

  • 1732: M5.8 Montreal earthquake
  • 1935: M6.2 Temiskaming earthquake
  • 1944: M5.8 Cornwall-Massena earthquake

According to Natural Resources Canada, the majority of Ontario’s earthquake activity occurs in the East of the Province. Metropolitan areas of Ontario that have earthquake risk include Ottawa, the GTA, Niagara Falls, and Windsor.[12]

Provincial Risk Statement

Earthquake risk is not uniform throughout the country or province. Ontario exists in a zone known for intraplate earthquakes. In general, earthquakes in eastern Canada (including Ontario) are not significant. There are approximately 300 earthquakes recorded a year in eastern Canada but on average only one every two years has reached or exceeded a magnitude of four on the Richter scale.[13].

The simplified seismic hazard map for Ontario shows that the probability of strong shaking is very low (less than 1% chance of it occurring in 50 years) for the northern and western part of Ontario. The probability of strong shaking in southern Ontario is slightly higher, but the highest probability is in eastern Ontario where it is estimated that there is a 5-15% chance that significant damage would occur to a fraction of one to two-story buildings in a town during a 50 year time-period[14].

Human Impacts

A severe earthquake that damages buildings may result in people being trapped, or injuries from falling debris such as glass, chimneys, book cases and roof tiles. Further fatalities and injuries may occur during aftershocks or other secondary hazards such as landslide or fires.

Shelter-in place orders are effective to protect the general public from shaking during an earthquake.

Social Impacts

Critical infrastructure service disruption can lead to significant interruptions to formal and informal support systems, as well as individual and community wellbeing. Even in cases where such damage is limited, increased instances of homelessness, reduced access to community resources, and reduced income are common in the aftermath of severe earthquakes.

Property Damage

The type of soil and rock building are located on influences the amount of shaking, and therefore damage. Shaking beyond the parameters of building code requirements result in more damaging scenarios.

Buildings on a thick layer of loose sand, silty clays, soft and saturated granular soils, or sand and gravel may experience more damage than a building built on deep, unbroken bedrock and stiff soils. In saturated sand and silt, liquefaction (where saturated soil behaves like a liquid) may result in the cracking, sinking or collapse of a building.

Critical Infrastructure Disruptions

In extreme cases, damage from earthquakes can include the complete or partial destruction of transportation routes and any other critical infrastructure in the affected area. Secondary hazards such as falling debris, flooding from burst pipes or communications outages would also be of concern.

Disruptions could also be caused by damage/rupture of gas/oil pipelines, chemical storage and fuel tanks.

Environmental

Environmental damage is usually noticeable only after a particularly strong earthquake. Powerful earthquakes have caused landslides, altered waterways, caused land subsidence, and created ruptures or fissures. Spills of hazardous materials/substances to air, ground and water may also result.

Economic

A powerful earthquake can disrupt business and financial activities in the affected area, or cause supply issues if the affected area has significant production, warehousing or distribution capacity. Buildings may need to be inspected to ensure that they are safe before customers and workers can enter. Critical infrastructure issues would also hinder business activities.

Erosion

Go to Previous Hazard: Earthquake

Go to next hazard: Extreme Cold

Definition

The gradual wearing away and removal of soil or rock particles by water, ice, snow, air, plants, animals, or humans. Eroded sediment or dissolved material may be transported just a few millimetres, or thousands of kilometres.[15]

Description

Erosion occurs naturally and affects all landforms.[16] It can also be caused or exacerbated by natural or human processes. Locations with little vegetation are more susceptible to erosion by wind, water and other processes. Erosion can result in instability of structures built on eroding soil, soil and nutrient loss, decreased crop yields, damage to aquatic ecosystems and dust storms.

The areas of Ontario that are at greatest risk of erosion are:

  • River and valley slopes: these areas have a higher risk due to fluvial processes (rivers, streams, precipitation etc.).
  • Shorelines: shoreline property and natural features such as dunes are at risk from erosion by waves, currents, ice, and fluctuations in water levels. Erosion is a natural occurrence that has been altering the shorelines of the Great Lakes since they were formed 12,000 years ago.
  • The dynamic beach hazard limit: the combined flooding hazard limit, plus, the dynamic beach allowance of 30 m on the Great Lakes - St. Lawrence River system (or 15 m on large inland lakes).
  • Deforested areas: the loss of vegetation affects the amount of surface water run-off. Vegetation not only slows erosion by taking up water, but it also anchors the soil in place.
  • Agricultural lands: the exposure of the topsoil, the building of ditches, livestock grazing, tilling and land management practices all directly impact the rate of soil erosion.

Natural Causes of Erosion:

  • Heavy and/or prolonged rainfall
  • The effect of gravity on soils that rest on steep slopes
  • Wind
  • Flooding, wave action and/or currents.
  • Movement of glaciers
  • Droughts, dry spells and/or high temperature

Human Causes of Erosion

  • Removal of vegetation
  • Construction
  • Poor land use planning or practices

The rate and magnitude of soil erosion by water is controlled by the following factors[17]:

  • Rainfall and Runoff
  • Soil Erodibility
  • Slope Gradient and Length
  • Cropping and Vegetation
  • Tillage Practices

Wind erosion occurs in susceptible areas of Ontario but represents a small percentage of land – mainly sandy and organic or muck soils. The rate and magnitude of soil erosion by wind is controlled by the following factors:

  • Soil Erodibility
  • Soil Surface Roughness
  • Climate
  • Unsheltered distance
  • Vegetative cover

Tillage erosion is the redistribution of soil through the action of tillage and gravity. Erosion of soil is of particular concern for agricultural and beach properties in Ontario, as well as those near waterway. However, this rarely occurs at a scale or during a time period that would result in emergency management concerns.

The Provincial Policy Statement 2014 sets out policy direction for municipal and other land use decision-makers to restrict development and site alteration in areas prone to natural or human-made hazards, including areas prone to erosion and flooding hazards.  As required by section 3 of the Planning Act, land use decisions need to be consistent with the policies.[18]

The Conservation Authorities Act gives Conservation Authorities the power to establish and undertake initiatives on private and public land to help achieve its objectives and can include monitoring and remediation of areas affected by flooding, erosion, and or slope instability [19]:

Such policy makes a significant difference for new development, and also obligates decision makers to restrict development in areas that are prone to this hazard, closely regulates Industrial and agricultural activities, and protects groundwater[20]

Spatial Scale, Timing, and Warning Period

Spatial Scale: Erosion is in most cases, a small scale hazard. It naturally occurs in all landscapes, but only in isolated instances does it become a hazard.

Timing: Erosion can occur throughout the year, although faster rates are more common during the warmer months.

Warning Period: Erosion events can occur across multiple timescales from minutes to years.

Potential Impacts

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • Injury or death. May strain the health system and response resources.
  • Production losses for agricultural products. May result in a lack of available products.
  • Possible financial and economic effects.

Secondary Hazards

Secondary hazards could include:

  • Land Subsidence
  • Landslide
  • Building or Structure Failure

Past Incidents

It is extremely difficult to quantify the number of events that have been influenced by erosion. For this reason, while erosion is a hazard, erosion emergencies are not considered in available databases.

Provincial Risk Statement

Erosion is an indirect cause of damage and loss of life. However, it is rarely the direct cause of an emergency. It is also usually a slow process, so it is unlikely to cause injuries or fatalities.

Human Impacts

Vulnerability of the human population of Ontario to the erosion hazard is nominal. Embankments and slopes may be weakened through erosion and may be more likely to fail which may present a hazard to anyone walking on them at the time.

Social Impacts

Psychosocial and community impacts are not likely.

Property Damage

The Provincial Policy Statement minimizes the number of occurrences of damage due to erosion; however, it still poses an isolated threat to property and infrastructure in at risk areas, such as along shorelines and in deforested areas.

Critical Infrastructure Disruptions

Erosion is unlikely to result in critical infrastructure disruptions, although localized disruptions may be possible if the critical infrastructure equipment itself is directly affected (i.e. erosion of ground supporting a road causes damage to the road).

Environmental Damage

The increased sediment in rivers, streams or lakes can negatively affect aquatic ecosystems by effecting the oxygen and nutrient levels, and the visibility. Ground instability often occurs as a result of erosion.

Economic

The loss of soil from farmland may be reflected in reduced crop production potential, lower surface water quality and damaged drainage networks.

Extreme Cold

Go to Previous Hazard: Erosion

Go to next hazard: Extreme Heat

Definition

Extreme cold events occur when winter temperatures drop significantly below average for that time of the year.[21]

Description

Exposure to cold temperatures, whether indoors or outside, can cause other serious or life-threatening health problems.

Human vulnerability is determined by a range of factors, including exposure. When core body temperature drops by 1 or 2ºC (1.8 or 3.6ºF), or when an individual is exposed to severe cold, it increases the risk of harmful effects. While anyone who isn't dressed warmly is at risk in cold weather conditions, some are at greater risk than others for frost bite and hypothermia:

  • homeless people
  • outdoor workers
  • people living in homes that are poorly insulated or with no heat or no power
  • people with certain medical conditions such as diabetes, peripheral neuropathy, and diseases affecting the blood vessels
  • people taking certain medications including beta-blockers
  • winter sport enthusiasts
  • infants (under 1 year)
  • seniors (65 years or older)

The impacts of Extreme Cold can be increased with the presence of a high wind chill value. Wind chill worsens the health impacts of a cold wave by increasing the rate of heat loss.

Extreme Cold can also affect the province by placing a far greater load on the energy sector. Such conditions can cause widespread and dangerous situations, particularly in combination with winter weather hazards. A combination of cold and lack of electrical power can lead to severe conditions for those affected. In addition, extreme cold can cause secondary issues for other infrastructure such as pipes, which can burst when water freezes.[22] The official Government of Canada criteria for Extreme Cold varies for each region of Ontario:[23]

  • Far Northern Ontario
    Issued when the temperature or wind chill is expected to reach minus 45 for at least two hours.
  • South-central and Southwestern Ontario (roughly southwest of a line from Midland to Kingston)
    Issued when the temperature or wind chill is expected to reach minus 30 for at least two hours.
  • Southeastern Ontario
    Issued when the temperature or wind chill is expected to reach minus 35 for at least two hours.
  • Northern Ontario
    Issued when the temperature or wind chill is expected to reach minus 40 for at least two hours.

The terms listed below may sometimes be used during extreme cold events:

Cold wave

The term ‘cold wave’ is sometimes used to describe sustained cold weather, just like the term ‘heat wave’ is for a sustained heat event. There is no official definition for cold wave.

However, there are also many types of winter weather than can occur in such conditions. These are covered within their own hazard profiles, below.

Polar vortex

Polar vortex is a persistent, large area of low pressure and cold air that rotates counter-clockwise at the North Pole, and clockwise at the South Pole. It is not a feature that exists at the Earth’s surface, but rather, high up in the sky, at least 5 km above sea level. The vortices weaken in the summer and strengthen in the winter. When the polar vortex expands, it sends cold polar air and the jet stream towards the equator.

Cryoseisms

Cryoseisms or "frost quakes" occur when the water in saturated ground. It is the sudden freezing and expansion of the water that can result in cyroseisms. Toronto experienced them during the 2013-2014 winter season. Damage can occur to structures but this appears to be rare and minor. Cryoseisms are generally more surprising than dangerous.[24]

Winter Weather

Winter weather can occur concurrently with extreme cold conditions. See the ‘Winter Weather’ hazard profile.

Spatial Scale, Timing and Warning Period

Spatial scale: Extreme temperatures can affect large geographic regions.

Timing: Extreme cold events that occur at a level of severity to trigger an emergency are limited to the winter months. Provincial Risk Statement

Warning Period: Extreme temperature events are often forecasted days to a week in advance.

Potential Impacts

  • Illness, injury or death. May strain the health system and response resources.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • The need for site or area access restrictions.
  • The need for emergency provision of essential needs, including food.
  • The need for emergency shelter services.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.

Secondary Hazards

Secondary hazards could include:

  • Electrical Energy Failure
  • Water or Wastewater Disruption

As well as all transportation hazards.

Secondary hazards can also develop from the usage of fireplaces and generators during an extreme cold event.

Past Incidents

Extreme Cold events occur regularly in Ontario. Three significant events from recent history are the cold waves of 2014, 2016 and 2018.[25] Frigid weather has caused record levels of power consumption for heating in the last five years. Extreme weather events have also occurred during the winter season. They both affected parts of Canada and parts of the north-central and upper eastern United States, and were caused by a southward shift of the Jetstream, allowing cold arctic air mass to invade southward.

Provincial Risk Statement

Extreme Cold events are common across the Province, though the number of extreme cold days in Canada is projected to decline by 2050.[26]

A 2015 international study found that cold weather kills as much as nine times as many people as hot weather in Canada, but that most weather-related deaths were not associated with times of temperature extremes, but to moderately cold days. This highlights the need for public information and alerting to consider the incremental risk of temperatures just outside of normal seasonal conditions, not just for extreme events.[27]

Human Impacts

Human effects due to extreme cold can be widespread and serious if the conditions are prolonged, or if there is limited relief from the conditions. However, the capacity to manage such effects is high in Ontario.

Social Impacts

Extreme cold events have the capacity to interfere with the healthy functioning of communities, in that people’s mobility and ability to go outside can be severely restricted. This can affect the capacity for community members to prepare and respond to emergency conditions effectively.

Property Damage

Extreme cold generally does not result in as much property damage as many of the other identified hazards. Fires may occur as a secondary hazard as people may resort to unsafe heating methods.

Critical infrastructure

Damage to critical infrastructure due to the direct impact of cold conditions or increased demands on a utility and power services are possible. During these events, hospitals are often pushed to handle more cases of frostbite, hypothermia and falls from icy sidewalks and streets, and experience a sharp decline in blood donation numbers.

There are also a variety of transportation impacts due to cold, including disruptions to shipping due to frozen rivers or lakes or cancellation of flights due to accumulation of frost or ice on planes.

Environmental

The general negative effects of cold waves on animals include decreased animal activity, nutritional uptake, reproduction, and increased mortality.

Economic

Agriculture may be negatively affected depending on the time of year in which the cold wave occurs. Damage to crops caused by freezing temperatures result in crop yield losses in Ontario every year.

Marine and other supply chains can also be interrupted, and costs related to the extreme weather, including from employees having difficulty doing their jobs and increased heating needs, can lead to severe losses for businesses, particularly if conditions persist.

Extreme Heat

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Go to next hazard: Flood

Definition

Extreme heat is when:

  1. the temperature for a region is significantly above the average high for an extended period
  2. the average daytime high and nighttime minimums are expected to be above a certain temperature; or
  3. there is a high humidex.

Description

Adverse heat impacts are most likely during heat wave events and during periods of high summer temperatures. The effects of extreme heat go well beyond the potential impact on people and communities; heat can also destroy crops and effect agricultural, forestry, industrial and many other significant economic activities across the province. A range of effects, from crop failure to buckling roads, may continue long after the extreme heat has passed.

Humidity can make the temperature feel hotter than it actually is. It decreases the ability for the human body to cool itself, and can lead to an increase in related human health problems, including:

  • Heat illness (humans or animals)
  • Increased heat stress on crops
  • Increased power demand for air conditioning

Nightly minimum temperatures during a heat wave can change the impact since temperatures often cool overnight and provide relief. However, if temperatures remain high, this can result in a greater impact.

Adverse effects can occur in moderate or short duration heat events not formally classified as ‘Extreme Heat’ or unseasonal heat conditions. Risk factors in such cases include:[28]

  • Air Conditioning is activated only during certain times of the year in some buildings, and may not be available during unseasonal events.
  • People have not had time to acclimatize to the conditions
  • Public information campaigns are seasonal, and may be less visible during unseasonal heat events. This may result in lower public awareness of the risk.

Scientific evidence suggests that extreme heat events are associated with sudden short-term increases in mortality, particularly among seniors, the chronically ill and the socially disadvantaged.[29] The following groups are thought to be particularly vulnerable:

  • People with chronic and pre-existing illnesses
  • Infants and young children
  • People on certain medications
  • Those who are marginally housed or homeless
  • Outdoor workers
  • People who exercise outdoors

A recent study found that each 5°C change in daily temperature was associated with approximately four more non-accidental deaths per day in summer on average in Ontario. The same study found that heat was most strongly associated with in-hospital deaths, whereas extreme cold appeared to be associated with cardiovascular related deaths and especially affected mostly those younger than 65 years.[30]

Urban centres have been found to have higher temperatures due to the ‘heat island effect’ in which the concrete and buildings retain heat and release it slower than surrounding areas. However, this does not preclude the possibility of extreme heat elsewhere in the province.

In Ontario, the Harmonized Heat Warning Information System (HWIS) released by Ministry of Health and Long-Term Care (MOHLTC) triggers heat warnings*[31] and public messaging according to set criteria for three regions based on seasonal averages.[32] High levels of air pollution also frequently occur during hot weather conditions, due to the chemical reaction between the sun’s intense ultraviolet light and particles in the air. Current data and forecasts are issued by Air Quality Ontario, to help residents understand their level of risk to these effects.[33]

The risk of power outages also increases during periods of extreme heat as the demand for electricity can exceed the capacity of the electrical system.

Spatial Scale, Timing and Warning Period

Spatial: Extreme temperatures can affect large geographic regions.

Timing: Extreme heat events that occur at a level of severity to trigger an emergency are more common during the summer months.

Warning Period: Extreme temperature events are often forecasted days to a week in advance.

Potential Impacts

  • Illness or death. May strain the health system and response resources.
  • The need for water use restrictions.
  • The need for emergency shelter services.
  • Need for assurance monitoring of systems.
  • Population health monitoring.
  • Poor air quality.

Secondary Hazards

Secondary hazards could include:

  • Drought or Low Water
  • Plant Disease or Infestation
  • Wildland Fire

Past Incidents

Comparing heat-related deaths across Canada is challenging, as each province records and investigates heat deaths differently. In Ontario, heat-related deaths are only those classified as Hyperthermia (elevated body temperature due to failed regulation of heat).[34]

The maximum number of annual deaths from Hyperthermia in Ontario is 5. There have been only two extreme heat events recorded in the Canadian Disaster Database for Ontario:

  • Ontario and Manitoba, 1988: Resulted in 14 deaths.
  • Toronto, 1953: Resulted in 1 death. 186 others experienced adverse health effects.

Extreme heat and humidity have caused significant adverse effects in many countries, most notably the following:

  • France 2003: 14,800+ excess deaths
  • Moscow 2010: 11,000+ excess deaths
  • Chicago 1995: 600+ heat-related deaths over 5 days
  • United States, 1999-2009: Extreme heat exposure caused or contributed to 7,800+ deaths in the US[35]

Provincial Risk Statement

Heat waves are projected to become more intense and more frequent, therefore increasing the risk over time for this hazard.[36]

Human Impacts

Human effects due to extreme temperatures are mostly limited to adverse health impacts due to heat, humidity and pollution. These can be widespread and serious if the heat wave is prolonged, or if there is limited relief from the conditions. Studies have recorded an increase in the number of fatalities associated with heat waves, particularly in Southern Ontario.

Social Impacts

The health and vitality of the social fabric is generally not limited by extreme heat events.

Property Damage

Damage can be caused by the thermal expansion of materials but is a fairly rare occurrence in Ontario. Buildings and other structures such as bridges can experience moisture loss in concrete during a heat wave, particularly when it occurs along with low relative humidity which can result in cracking.

Critical Infrastructure Disruptions

Extreme heat can also alter road surface conditions and railway infrastructure. Heat can result in the expansion or buckling of roads or tracks, which can cause accidents or delays.

Utilities are susceptible to damage from extreme heat events. The demand for electricity and water increases during periods with high temperatures and may exceed the supply. Rolling blackouts and restrictions on water usage may be implemented. The efficiency of transmission lines decreases due to high air temperatures and power lines may expand which can make them more susceptible to damage.

Environmental Damage

The majority of native plants and animals in Ontario have adapted to occasional heat waves and the environmental damage caused by a heat wave is often minimal. However, prolonged, higher than usual temperatures, especially when coupled with high humidity may result in heat stress in animals and plants, especially those that have been introduced to Ontario, including many agricultural plants.

For some crops, a heat wave during the growing season may result in a decrease in the crop yield and grain quality. Low oxygen levels and higher water temperatures can also trigger increased nutrient pollution resulting in algal blooms.

Economic

Any business/financial interruption is likely to be minimal, or related to secondary hazards rather than directly to the heat wave. Agriculture and tourism are the industries that are most likely to be negatively impacted by a heat wave.

Flood

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Definition

An overflow or inundation of water from a river or other body of water, or over land, which causes or threatens damage[37].

Description

Flooding is common in Ontario, and essential to a healthy environment. However, it is also the most costly type of natural disaster in Canada in terms of property damage.[38]

Floods have affected hundreds of thousands of Canadians and can cause human hardship, property damage, and economic loss. Floods are usually caused by extreme meteorological and hydrological conditions, though human activities can contribute to flooding, in part by altering drainage patterns. The severity of damage caused by a flood depends on the depth, flow velocity, duration, contamination, sediment load, and the density and vulnerability of population, property and infrastructure.

The majority of floods in Ontario are caused by extreme precipitation events, snowmelt, and ice break up. Flooding caused by extreme precipitation is more common in Southern Ontario due to this region experiencing the highest number of heavy rainfall events. Northern communities along the Hudson Bay and James Bay coasts are particularly at risk due to the annual ice break up and their remote locations, which can make evacuations difficult.

After floodwaters subside, exposure to objects contaminated by substances (e.g. sewage or chemicals) carried by the water and mould can lead to health complications[39].

There are distinct types of flooding:

  • Riverine (Fluvial): A flood due to the increase of the water level beyond the channel capacity of a natural or somewhat natural watercourse.
  • Urban (Pluvial): Occurs when rainfall or snowmelt overwhelms the capacity of the urban drainage system, or when there isn’t a sufficient overland flow route to move the water away
  • Flash Flooding: Rapid on-set flooding, where water rises rapidly in a short amount of time, with little or no advanced warning. Such flooding can be Fluvial or Pluvial, and often features fast-moving waters that carry large amounts of debris.
  • Storm Surge: Storm surge is defined as an abnormal, sudden rise of sea (or lake) level associated with a storm event.
  • Seiche: A period of oscillation of an enclosed body of water that may result in large waves.
  • Coastal Flooding: (from Lake Ontario) historically has caused less severe instances of flooding Ontario, however there is potential for this type.

Flooding can be caused by:

  • Extreme precipitation
  • Snow melt
  • Ice break-up
  • Soil moisture conditions
  • Ice jams
  • Frazil ice
  • Natural dams
  • Structural failure of dams

These conditions, combined with insufficient overland flow capacity or saturated soil, can exacerbate the hazard conditions[40].

When land is converted from natural cover to infrastructure or for human use, this introduces people and property to flood-prone areas such a flood plains, and reduces the natural ability of the environment to absorb rainfall.[41] In addition, the built environment (rural or urban) can interrupt natural drainage channels or routes, causing flooding in areas not previously prone to this effect.

Changing climate is likely to lead to more extreme weather, which may result in more frequent flooding, erosion, shoreline damage, infrastructure failures, and decreased water quality due to increased runoff and debris. Milder, shorter winters could also lead to:

  • earlier snowmelt
  • less ice cover on lakes
  • changing rainfall patterns
  • changes in water’s movement between air, soil, plants and bodies of water 

The Ministry of Natural Resources and Forestry, Conservation Authorities, and municipalities all have legislated responsibilities to manage and respond to flooding.[42] Agencies such as conservation authorities and other government agencies monitor conditions and support in the preparation of adequate response and recovery actions. While this has not always significantly reduced the damage to property, it has allowed for some mitigation of human impact and a reduction in the potential effects to property.

A general lack of understanding of insurance coverage can also drastically affect the risk to property owners. Overland flood insurance is a relatively new addition to the available policies, and insurance companies can differentiate between overland, sewage and other causes of flooding.[43]. The Ministry of Municipal Affairs and Housing (MMAH) coordinates disaster financial assistance programs for some uninsurable losses for eligible groups, and liaises with the Government of Canada for federal funding when appropriate.

Capacity to produce high-quality maps and models of to analyze and evaluate specific risk factors is limited and inconsistent. Such analyses, alongside traditional knowledge sharing and community engagement, create a foundation for well-informed risk management. Such approaches are necessary for Ontario jurisdictions to continue to anticipate and understand flood risk, particularly around built structures and in urban environments, where currently overland flood risk is not well understood.

Improvements in flood prevention, mitigation, warning, and response systems and procedures have greatly decreased the potential loss of life from flooding in developed countries. Such measures can be extremely costly, and may be outpaced by the growing risk. Development of structural flood control, along with floodplain development restrictions and other ‘soft’ measures also help to address the risk of flooding in Ontario. In spite of this, floods are the leading cause of municipal declared emergencies in Ontario and the most costly type of natural disaster in Canada in terms of property damage.[44]

The Provincial Policy Statement 2014 sets out policy direction for municipal and other land use decision-makers to restrict development and site alteration in areas prone to natural or human-made hazards, including areas prone to erosion and flooding hazards. 

In 2014 $200 million over five years was earmarked to establish the National Disaster Mitigation Program (NDMP), designed to address rising flood risks and costs, through local small scale structural and non-structural mitigation efforts[45].

Spatial Scale, Timing and Warning Period

Spatial Scale: The spatial scale of flooding can vary significantly from a small area (i.e. a neighbourhood) to large area (i.e. entire watershed).

Timing: Floods can occur at any time during the year. Certain types of flood, however, are more common during particular seasons. For example, flooding may be caused by the ice break up during spring or extreme rainfall which is more common during summer thunderstorms.

Warning Period: The warning period varies significantly from several weeks (especially in the case of flooding caused by spring ice break up) to almost none (in the case of severe rainfall).

Potential Impacts

Potential impacts of flood may include:

  • Illness, injury or death. May strain the health system and response resources.
  • Illness, injury or death of domestic or livestock animals.
  • The need for debris management
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Reports of missing individuals. The need for search and rescue, family reunification operations
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • The need for emergency shelter services.
  • The need for emergency provision of essential needs, including food.
  • The need for financial assistance.
  • The need for damage assessment.

Many of these impacts would need formal damage assessment, either through government emergency programs, engineering assessment, insurance appraisal or other types.

Secondary Hazards

Secondary hazards associated with flooding may include:

  • Aviation
  • Electrical Energy Failure
  • Erosion
  • Food Shortage
  • Landslide
  • Land Subsidence
  • Public Transit Systems
  • Rail, Light Rail, Subway
  • Road and Highway
  • Water Quality
  • Water or Wastewater Disruption

Past Incidents

Hurricane Hazel, 1954: The worst flood in the recorded history of Ontario was a secondary effect of Hurricane Hazel.

The Canadian Disaster Database contains 61 other records for significant floods in Ontario since 1920. The most costly of these is the urban flooding of July 8th, 2013 which resulted in a total of $940 million. This compares to the dollar-adjusted estimated amount of $1.2 billion for Hurricane Hazel[46].

The historical context of the 1954 hurricane Hazel is significant to the story of flooding, flood regulation and floodplain management in Ontario. It spurred large amendments to the Conservation Authorities Act, including the empowerment of Conservation Authorities to create regulations to prohibit filling in floodplains, and has since been even further expanded.

In 1960, the Lands Acquisition Program was implemented, to transfer the liability of floodplain land from private hands to Conservation Authorities, who now operate in watersheds in which 90 per cent of the provincial population reside. These organizations are responsible for management of their respective watershed areas and for local flood messaging. The Ontario Ministry of Natural Resources and Forestry also issues flood watches or flood warnings for the province, to further support communication of flood risk to the public.[47]

Significant flood events occurring in the last 5 years include:

  • Windsor and Tecumseh, 2016
  • Kenora, 2016
  • Kashechewan First Nation, 2016
  • Fort Albany and Kashcewan First Nation, 2015
  • Toronto ON July 8, 2013
  • Kasabonika Lake First Nation, 2013
  • Thunder Bay, 2012
  • Fort Albany and Kashechewan First Nations, 2012
  • Flood Kashechewan and Fort Albany, 2012

Provincial Risk Statement

In the majority of historical cases, flood conditions have been anticipated by the communities at risk, either because of specific warning signs or because of general preparedness activities.

Environment and Climate Change Canada, conservation authorities and other government agencies monitor conditions and support in the preparation of adequate response and recovery actions. Studies including those from Natural Resources Canada and Intergovernmental Panel on Climate Change (IPCC), predict that this flooding is likely to get worse as the climate heats up and introduces more moisture into the atmosphere.[48] Such trends are likely to amplify the risk of flooding significantly, and push the limits of flood prevention infrastructure.

Human Impacts

Flooding can result in loss of life due to drowning or, if the floodwaters are carrying a significant amount of debris or ice, crushing. Health problems may arise after the flood due to contamination of standing water, the backup of sewers, and the growth of mould in buildings that suffered water damage.

Social Impacts

Psychosocial effects from floods are possible, along with disruptions to the network of community supports .Floods have resulted in many partial or full evacuations of communities in Ontario.

Property Damage

Floodwaters can wash away and destroy property and infrastructure. Flooding is the leading cause of Water damage and mould growth may add to the damage. Flooding is most costly type of natural disaster in Canada in terms of property damage

Critical Infrastructure Disruption

Flooding can also negatively affect utilities and critical infrastructure. Utilities such as wastewater treatment, electricity, and gas may be disrupted in the event of a flood. Emergency response ground vehicles may be unable to respond if roads and bridges are flooded, washed out, or covered by debris. The transportation of both people and goods may be halted if roads are flooded. Sewage systems may be overwhelmed and damaged by the excess water. This may result in raw sewage backing up into buildings. Electricity may be halted to the affected areas in order to prevent accidental electrocution. Water quality may diminish due to bacteria, sewage, or chemicals being introduced into the water supply by the flood.

Environmental Damage

Floods that are part of a natural cycle can be beneficial to the environment and provide nutrients to the soil. These floods result in little environmental damage. However, human-caused changes to the environment have altered the runoff patterns in some areas resulting in changes in flood frequency and severity. These floods have the potential to cause more harm to the environment since they may occur in areas which did not previously experience floods.

Another possible cause of environmental damage is that the floodwater may be contaminated with raw sewage, chemicals, or other contaminants. Wells and certain types of drinking water systems use water that normally filters down through the soil.  Contaminated flood water can enter the system in this way, impacting drinking water.

Economic

A flood can result in a large business/financial interruption for a community. The degree of the interruption depends on the size of the affected area. Water damage and mould growth may slow business from reopening.

Fog

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Definition

A cloud at the earth's surface, consisting of tiny water droplets, or under very cold conditions, ice crystals or ice fog. It is generally found in calm or low wind conditions. Under foggy conditions, visibility is reduced to less than 1 kilometre.[49]

Description

There are many types of fog. The two most common types in Ontario are advection and radiation fogs. Advection fog is generated when moist air travels over a cool surface, such as snowpack or cold bodies of water. This type of fog can be widespread. Radiation fog is more localized and is generated by surface cooling in calm weather conditions.  It often occurs close to open fields or streams in slight depressions. It often forms late at night and may persist through to the morning resulting in reduced visibility during rush hour traffic. Smoke can contribute to fog formation by providing condensation nuclei for water droplets to adhere to, which then becomes fog.

Fog is a naturally occurring hazard in Ontario. The weather patterns, geography and the presence of the Great Lakes all contribute to fog Ontario. Fog is more likely to result in an emergency if it restricts visibility, and where lack of visibility affects human activities. For example, areas with high traffic volume may result in major road or highway incidents.

Fog advisories are issued by the Ontario Storm Prediction Centre of the Meteorological Service of Canada for Ontario when visibility falls below 0.5 km and this reduction of visibility lasts for more than six hours. However, they can also issued at forecasters’ discretion when fog is widespread even though it does not last more than six hours.  

Spatial Scale, Timing, Warning Period

Spatial Scale: Fog occurs from time to time, particularly around the Great Lakes. Fog can be localized and only affects a part of a municipality. Widespread fog such as advection fog would affect more than a couple of municipalities.

Timing: Fog can occur at any time of year but is more common during spring and fall.

Warning Period: Forecasting fog can be difficult depending on the conditions in which it develops.

Potential Impacts

Potential impacts of fog may include:

  • Poor visibility.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.

Secondary Hazards

Secondary hazards associated with fog are mainly limited to transportation emergencies, though cascading hazards could include hazmat incidents.

Past Incidents

In September 3, 1999 a dense fog led to a massive car accident on Highway 401 near Windsor. Reports state that over 85 vehicles were involved in the collision, including transport trucks, vans and cars, resulting in eight deaths and over 60 injured. The intensity of the fire, which caused the road's asphalt to melt, and the fire damage, which destroyed many of the vehicles, made it impossible to fully understand how the collisions occurred.

A coroner's inquest into the crash led to 25 recommendations for safety improvements. The recommendations led to installation of fully paved shoulders and a concrete median barrier, rumble strips, and reflective markers in curved sections, which were completed in 2010. The inquest also led to a review of safety standards for highway construction.

Provincial Risk Statement

Fog is a naturally occurring hazard in Ontario, and it can be localized or widespread. The weather patterns, geography and the presence of the Great Lakes all contribute to the of the formation of fog.

The population, property/infrastructure, environment and business/finances of Ontario are not particularly vulnerable to fog.

Human Impacts

Fog is not likely to result in direct human impact, though secondary and cascading impacts may lead to this. Traffic accidents due to a lack of visibility are a common secondary impact.

Social impacts

Fog may temporarily restrict community activities and support systems. However, it is not likely to result in direct social impact.

Property Damage

Fog is unlikely to cause property damage with the exception of damages caused by transportation accidents.

Critical Infrastructure Disruptions

Fog is not likely to directly result in critical infrastructure disruptions, although there is an increased likelihood of transportation and associated cascading impacts. Fog also drastically reduces visibility, increasing the risk associated with outdoor activities, including response activities connected to other types of emergencies.

Environmental Damage

Fog is not likely to result in environmental damage.

Economic

Fog is not likely to result in significant business/financial impacts, though interruptions to transportation either resulting from compromised visibility (e.g. air traffic control, road traffic) or through damage to infrastructure as a cascading impact.

High Wind

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Definition

High wind events can be defined as strong, non-tornadic winds that have the potential to cause damage in Ontario.

Description

A high wind event can produced by strong, and sometimes rapidly intensifying low pressure systems or severe thunderstorms. Note, that strong winds are also a secondary hazard of events such as thunderstorms, hurricanes and tornadoes.

Intense low pressure systems can produce widespread damaging winds that last for hours. 

Straight-line wind is a term used to define any thunderstorm winds that is not associated with rotation, and is used mainly to differentiate from tornadic winds. They move horizontally along the ground away from severe thunderstorms[50], and are caused by the thunderstorms’ downdrafts. This family of winds includes derechos and downbursts. A derecho is one type; a widespread, long-lived wind storm that is usually associated with a curved band of rapidly moving showers or thunderstorms. In order to be classified as a derecho, the system by the United States National Weather Service, the swath of wind damage must span about 400 km (~ 250 miles) in length and have wind gusts of greater than 93 km/h (~ 58 mph) along most of its length. The winds within a derecho can vary greatly from below 93 km/h (58 mph) to greater than 93 – 161 km/h (~100 mph).

A downburst is another type. This is a descending column of air which spreads out in all directions after reaching the surface. Dry downbursts are associated with thunderstorms with very little rain, while wet downbursts are created by thunderstorms with high amounts of rainfall. Downbursts are divided into two categories; those that occur over areas greater than 4 km are called macrobursts while those that occur over areas of less than 4 km are called microbursts. Damage from downbursts can easily be confused by the public as tornado damage.

In Ontario, Environment and Climate Change Canada can issue two types of wind-related warnings:[51]

  • Wind Warning is issued when sustained winds of 70 km/h or more and/or any wind gusts of 90 km/h or more are forecast[52].
  • A Severe Thunderstorm Warning may be issued since gusts of 90 km/h or greater are one of the criteria for a thunderstorm to be classified as severe.

It is also possible for high winds to occur during a storm event, tornado, hurricane or as part of winter weather, though wind can occur independently of other hazards.

Spatial Scale, Timing and Warning Period

Spatial Scale: Some wind events can be a large scale hazard affecting a large part of the province depending on the strength and location of the pressure system causing the wind. Others may be fairly localized.

Timing: High wind events can occur at any time of the year. From fall to spring, high wind events are usually associated with strong low pressure systems. From spring to fall, high wind events are usually caused by thunderstorms..

Warning Period: The amount of warning depends on the cause of the high winds and can range from a couple of days to no warning.

Potential Impacts

Potential impacts of windstorms may include:

  • Injury or death. May strain the health system and response resources.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • The need for damage assessment.
  • The need for debris management
  • The need for financial assistance.
  • The need for site or area access restrictions.

Secondary Hazards

High wind events frequently occur in conjunction with severe thunderstorms or other weather hazards, or as a secondary effect of these hazards.

  • Building or Structure Failure
  • Communications Failure
  • Electrical Energy Failure
  • Erosion
  • Storm Surge

As well as all transportation hazards.

Past Events

Southern Ontario, 2018: The windstorm was the most expensive weather event the province has seen in the previous 5 years. The Insurance Bureau of Canada indicated that the event cost insurers in Ontario $380 million dollars.

Provincial Risk Statement

Almost all areas of Ontario have experienced recorded wind speeds greater than 100 km/h. Vulnerability to high wind events has decreased due to revisions to the Building Code improvements. However, extensive property damage remains a possibility. Ontario has a great number of structures, of varying ages and construction types, which could be vulnerable to high wind exposure.

Human Impacts

Although fatalities are possible due to high winds, they are uncommon. The majority of fatalities and injuries are caused by crushing injuries from objects moved by wind. Mobile homes can be destroyed and are not a safe shelter.

Social Impacts

As with any serious event, mental distress and effects on support networks can linger long after severe weather events. Such impacts from high wind are uncommon.

Property Damage

The National Building Code of Canada provides standards that account for high winds. However, property damage is the most likely cause of damage in a high wind event.

Critical Infrastructure Disruptions

Common damage also includes downed power lines, sewage backup, downed trees, and damage to roofs. In addition, secondary impacts to transportation such as debris blocking roads and railways, as well as cascading effects on the local economy, emergency or government services, are also a concern.

Power lines and poles may be damaged resulting in a loss of electricity. Air and marine transportation may be cancelled or delayed.

Environmental Damage

Strong winds can create debris containing waste/contaminated materials that could enter the environment.  Winds also contribute to the spread wildfires causing additional damage.

Economic

High wind events normally do not cause a significant business or financial interruption. The greatest economic impact could come from the travel sector since aircraft may not be able take off and land in cross-winds and concurrent precipitation, for safety purposes.

Hurricane

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Definitions

Hurricanes are tropical cyclones that occur in the Atlantic Ocean and northeastern Pacific Ocean, with maximum sustained surface winds of at least 118 km/h. Tropical cyclone is a generic term for the family of tropical low pressure systems, including tropical depressions, tropical storms, and hurricanes.

Hurricanes are known as typhoons in the western Pacific, very severe cyclonic storms in the North Indian Ocean, and severe tropical cyclones in Australia.

Description

In order to understand hurricanes, one must start with understanding all tropical cyclones, which refers to the whole family of tropical low-pressure systems.

Tropical cyclones are non-frontal weather systems that originate over tropical or subtropical waters, and are identified by organized showers, thundershowers, and a cyclonic surface wind circulation. The temperature, rain, and wind patterns are generally uniform across these systems, while most other systems have conditions that are more variable.

The criteria used to differentiate between different types of tropical cyclones are:

  • Tropical Depression: Maximum sustained surface wind speed of ≤ 62 km/h.
  • Tropical Storm: Maximum sustained surface wind speed of 63 to 118 km/h.
  • Hurricane: Maximum sustained surface wind speed of at least 119 km/h.

Because hurricanes have huge impacts, they are further divided into five categories according to the Saffir–Simpson Hurricane Wind Scale (SSHWS), based on the intensities of their sustained winds.

This scale is used only to describe hurricanes forming in the Atlantic Ocean and northern Pacific Ocean, east of the International Date Line. Other areas use different scales to label these storms. The SSHWS classifications are as follows[53]:

  • Category 1 maximum sustained winds 119 - 153 km/h
  • Category 2 maximum sustained wind 154 - 177 km/h
  • Category 3 maximum sustained winds 178 - 208 km/h
  • Category 4 maximum sustained winds 209 - 251 km/h
  • Category 5 maximum sustained winds 252 km/h or higher

Hurricanes are of Category 3 or above are labelled as major hurricanes.

For Ontarians, tropical cyclones, or their remnants that affect the province all originate from the Atlantic basin; its hurricane season runs from June 1 to November 30, with the peak from August to October. While tropical cyclones cannot originate in Canada or in Canadian waters (as these waters are too cold), they can span a few hundred to a few thousand kilometres, and while at sea, possess lifetimes of a few to several days, or weeks. Heavy rains, thundershowers, and high winds are common to tropical cyclones.

After they make landfall, their winds weaken. By the time they reach Ontario, they generally lose a lot (but not all) of their tropical characteristics, as they lack access to open and warm water. They often transition to post-tropical storms (storm systems that used to be tropical but have since lost most of their tropical characteristics). It is important to note that they can still bring intense rainfalls and damaging wind gusts.

Sometimes post-tropical storms will gradually lose tropical characteristics and gain the characteristics of extratropical cyclones that gain energy results from temperature contrast between warm and cold air masses. Other times, post-tropical storms may merge with existing extratropical cyclones (the type of systems that Ontarians experience from fall to spring).

There are three types of organized systems of strong storms, with a defined surface circulation and maximum sustained surface winds:

  • at least 118 kilometers per hour - Hurricane
  • 63–118 km/h – Tropical Storm
  • ≤ 62 km/h – Tropical depression

The Canadian Hurricane Centre (CHC) was established in 1987 after it became clear that Canadians needed an expert source for information that was focused specifically on how tropical cyclones affect Canada. The CHC also coordinates with the United States National Hurricane Center, supplementing their forecasts through detailed forecasts and warnings tailored specially for Canada. It prepares and issues Canadian tropical cyclone information statements, and hurricane and tropical storm watches and warnings for all coastal and inland regions. Since often times, only remnants of tropical cyclones affect Ontario and no hurricane or tropical cyclone warnings and watches are issued for the province, warnings and statements for any weather hazards associated with them, such as heavy rains and strong winds, becomes the responsibility of the Ontario Storm Prediction Centre of the Meteorological Service of Canada. 

Spatial Scale, Timing and Warning Period

Spatial Scale: Since hurricanes are not small-scale events, their effects can extend for hundreds of kilometres inland. They may impact a large portion of the province.

Timing: Hurricanes are most common during hurricane season, which runs from June 1 to November 30, though those that affect Ontario are more common in late summer and the early fall.

Warning Period: Hurricanes and post tropical storms tend to provide sufficient warning, although there is often uncertainty about the exact track.

Potential Impacts

Due to Ontario’s geographic location, the impacts are weaker than what could be experienced further south and along coastal areas. However, potential impacts include:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Injury or death. May strain the health system and response resources.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Reports of missing individuals. The need for search and rescue, family reunification operations
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • Worker shortages and business continuity issues.
  • The need for site or area access restrictions.
  • The need for emergency provision of essential needs, including food.
  • The need for damage assessment.
  • The need for debris management
  • The need for financial assistance.
  • The need for evacuation or shelter in place.
  • The need for emergency shelter services.

Secondary Hazards

Secondary hazards include:

  • Building or Structure Failure
  • Erosion
  • High Wind
  • Lightning
  • Storm Surge
  • Thunderstorm
  • Tornado
  • Water Quality

As well as all hazards within the following groups:

  • Hazardous Materials (Fixed site or in transport)
  • Transportation
  • Supply & Distribution

Past Incidents

The only ‘landfalling’ hurricane recorded by Environment Canada is hurricane Hazel. There have also been none recorded by the government of Canada since 2014.[54]

Toronto, 1954: Hurricane Hazel caused 81 fatalities, and the evacuation of almost 1500 people. The total cost of the destruction has been estimated at $100 million (about $1 billion today). There was widespread and severe damage, with thousands left homeless. The entry for 1954 is perhaps the most famous hurricane in Canadian history – Hurricane Hazel. The storm intensified unexpectedly and rapidly, with winds that reached 110 kilometres per hour and 285 millimetres of rain in 48 hours.

Southern Ontario, 2012: Post-Tropical Storm Sandy affected the southern part of the province on October 29 and 30 with strong winds. Gusts reached above 90 km/h in Toronto; a woman in the city was struck by a falling sign. Sarnia reported gusts of 120 km/h in Sarnia; sustained winds of 70 to 80 km/h were reported a number of times at the airport. 50,000 hydro customers were without power including about 45,000 in Toronto. There were localized roof damage; toppled trees, trees limbs and other debris littered streets and roadways. Impressive wave heights of at least 7 m were also observed over southern Lake Huron during the storm.

Provincial Risk Statement

Southern Ontario experiences the greatest risk of hurricanes, tropical storms, and post tropical storms due to its location. However, their occurrence is extremely rare in the province. When this class of hazard affect Ontario, they most likely will come as post tropical storms in late summer and early fall, when trees are in full leaf and susceptible to damage from strong winds. Falling trees and branches may disrupt transportation, damage property or disrupt critical infrastructure.

On occasion, a weakened hurricane will collide with another storm system or weather front resulting in a strengthened storm. This happened in 1954 with Hurricane Hazel. Even a weakened storm can still result in extreme precipitation, storm surges, flooding and strong winds.

Human Impacts

The potential consequences to human life and health are connected mainly to the secondary effects of hurricanes, including flying debris, flood conditions or other factors.

Social Impacts

Social impacts are possible, particularly following a severe and widespread event. Harsh conditions can cause disconnectedness, and interrupt social bonds that may have otherwise supported response and recovery. Once conditions subside, damage and debris from the storm can continue to impede community recovery. In the aftermath of devastating events such as hurricane Katrina, it has been found that forms of anxiety and stress disorders including Post-traumatic stress disorder (PTSD) are prevalent in the affected population.

Property Damage

Vulnerability to hurricanes, tropical storms, and post tropical storms has decreased greatly due to revisions to the National Building Code of Canada and improvements in floodplain management practices since Hurricane Hazel in 1954.

However, extensive property damage is still possible. Common damage includes downed power lines, sewage backup, downed trees, damage to roofs and other forms of wind damage.

Critical Infrastructure Disruption

Critical infrastructure may be damaged hurricanes, tropical storms, and post tropical storms. Common disruptions include downed power lines, sewage backup, blocked transportation corridors, and cancelled flights. Commonly, roads and rail lines may be impassable due to debris.

Environmental Damage

The environment of Ontario is not especially vulnerable to hurricanes, tropical storms, and post tropical storms. Environmental damage is usually more severe with a salt water storm surge, rather than the fresh water of the Great Lakes. Contaminated flood waters may result in some environmental contamination.

Economic

The majority of hurricanes, tropical storms, and post tropical storms that have affected Ontario in the past have caused little to no business/financial interruption with the exception of Hurricane Hazel.

Landslide

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Go to next hazard: Land Subsidence

Definition

A landslide is any type of slope failure or downward movement of rock and/or sediment.[55]

The flow of soil (earth or debris) or rock down a slope can range from a few cubic meters to more than 10 km3.

Description

In a landslide, geological material (rock, soil or debris) moves down-slope under the influence of gravity. The specific causes, speed and type of movement of a landslide depend on the specific geology and topography of the region.

The rates of landslide movement can range from virtually imperceptible to greater than 100 km/hour landslides can be induced, accelerated or prevented by human actions such as grading, vibrations, and changing drainage patterns:[56]

Landslides can move in a variety of ways, ranging from free-fall, end-over-end toppling, and/or liquid-like flow of completely disintegrated materials. Some landslides move only short distances, while others can travel several kilometres from their point of origin.

The term ‘landslide’ includes:

  • Rock-fall: Quantities of rock falling freely from a cliff face.
  • Debris flow: A moving mass of loose mud, sand, soil, rock, water and air that travels down a slope.
  • Earth flow: Movement of saturated earth in a liquid state.
  • Slump: loosely consolidated materials or rock layers moves a short distance down a slope.
  • Earth spread: Very rapid spread of a soil mass, resulting from liquefaction or plastic flow of underlying materials, and dominated by sideways movement. This type of landslide occurs in areas with postglacial marine clay (Leda Clay) deposits, such as those near Ottawa.

More than a third of landslides are triggered by heavy precipitation or snowmelt events. Landslides are also a secondary impact of flooding and storm. Jurisdictions consider ground stability in municipal planning, and some issue slope stability guidelines for Development, which help support developers in their adherence to the Ontario Building Code section 4.1.8.17.

The Provincial Policy Statement 2014 sets out policy direction for municipal and other land use decision-makers to restrict development and site alteration in areas prone to natural hazards, including areas of unstable soils (e.g., areas of leda clay. unstable organic soils and unstable bedrock which can trigger landslides, sink holes and soil collapses).  As required by section 3 of the Planning Act, land use decisions need to be consistent with the policies.

Additional regulations, such as the 162/06: ‘Development, Interference with Wetlands and Alterations to Shorelines and Watercourses’ further increase measures to protect the environment, and mitigate slope instability issues.

Spatial Scale, Timing, Warning Period

Spatial Scale: Landslides are usually a small-scale hazard affecting an area of a few meters. However, much larger landslides are possible depending on the geology and human activities of the area.

Timing: Landslides can occur at any time of year, but are more likely with heavy precipitation or snowmelt events.

Warning Period: Landslides frequently occur with little warning.

Potential Impacts

Some of the potential impacts of landslides include:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Reports of missing individuals. The need for search and rescue, family reunification operations
  • Injury or death. May strain the health system and response resources.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • The need for site or area access restrictions.
  • The need for debris management
  • The need for damage assessment.
  • The need for evacuation or shelter in place.
  • The need for emergency provision of essential needs, including food.

Secondary Hazards

  • Flooding
  • Erosion
  • Building/Structural collapse
  • Transportation disruption

Past Incidents

Terrestrial landslides represent a constant and ubiquitous threat to the well-being of Canadians. However, from 1900 to 2015, there were only two instances of landslides causing fatalities in Ontario, both occurring in Capreol in June 1930 as the result of the same railway embankment collapse and subsequent train derailment.

The vast majority of landslides are un-reported due to their limited impact to people and property.

Provincial Risk Statement

Landslides account for an estimated $200 to $400 million in direct and indirect costs annually in Canada. However, Ontario has relatively few major landslides when compared to provinces with steeper topography[57].

Landslides are more frequent in areas of Ontario with unstable, steep slopes, postglacial marine clay deposits and those with karst topography. It can be hard to predict ground failures within the built environment, as the addition of man-made structures and materials can drastically change susceptibility to the causes of ground instability (erosion, steepness, saturation of soils etc) [58].

Human Impacts

The only recorded landslides in Ontario that resulted in fatalities occurred at Capreol (4 fatalities) and Crerar (8 fatalities) in 1930. These fatalities did not occur as a direct result of the landslides, but as a result of the subsequent train derailment. However, in other provinces landslides have directly resulted in fatalities and injuries so the possibility cannot be ruled out for Ontario.

Social Impacts

Psychosocial impacts due to severe landslides are possible, though would be generally limited to those affected by the incident. Landslides occurring in populated areas or affecting vital services are likely to have a far greater psychosocial  impact on the community and individuals affected.

Property Damage

Depending on the severity and type of the landslide, property damage can be severe, with buildings being completely removed from their foundations or crushed. However, the damage is normally fairly localized.

Critical Infrastructure Disruptions

Landslides can also destroy rail lines and roads potentially resulting in train derailments, traffic accidents and may prevent emergency vehicles from quickly reaching the affected site. Both above and below ground utilities may be affected including electricity, gas, sewage and water.

Environmental Damage

Landslides alter the landscape of the affected area. Land is destroyed or altered both above and below the slope. If the debris from a landslide crossed a river, it may dam the river and either alter its course or create a lake or pond. Potential collapse of the debris dam presents another hazard. Underwater landslides may generate large waves that can cause damage on shore. Vegetation may be uprooted or crushed.

Economic

Since landslides tend to be a localized event in Ontario, they are unlikely to cause a business/financial interruption in most cases. If the landslide damages or destroys an important rail line or transportation artery, the effects of the landslide may be felt at a greater scale.

Land Subsidence

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Go to next hazard: Lightning

Definition

Land subsidence is a gradual settling or sudden sinking of the Earth’s surface owing to subsurface movement of earth materials.[59]

Description

Subsidence is the removal of material from below the surface causes the land to settle downward creating a depression or hole and is one of the most diverse forms of ground failure.

Sinkholes are just one of many forms of ground collapse, or subsidence. A sinkhole is a depression in the ground that has no natural external surface drainage. This hazard occurs when rock below the land surface can be dissolved by groundwater circulating through them. This dissolving of rock creates spaces underground, which can be small or become so large that large holes are created because there the rock below cannot support the land above[60].

Causes of subsidence include the dissolving of bedrock, compaction of layers of clay or soil, or even deformation of the earth’s crust. Groundwater extraction in connection with urbanisation and population growth is the main cause of severe land subsidence worldwide. Similarly, ‘overdrafting’ is a common cause of this hazard, where groundwater is extracted beyond the safe yield of an aquifer.

Sinkholes can be divided into three main types[61]:

  • Dissolution soluble, exposed, bedrock dissolves in water.
  • Cover-Subsidence sinkholes that occur where sand covers bedrock. Sand filters down through gaps in the bedrock, gradually causing the surface to sink.
  • Cover-Collapse occurs when a layer of clay covers bedrock. As bedrock erodes over time by water, it creates a cavern underneath. When the remaining thin layer of clay collapses it creates a sinkhole.

In addition, land subsidence can be induced by human activities such as drilling activities which can cause changes in the ground structure, and unanticipated shifting of subsurface layers.

Land subsidence can occur after a heavy precipitation event or during a rapid snowmelt. A positive feedback cycle may occur with the removal of the underlying, supporting rock creating further subsurface weakness and triggering other collapses[62].

Aquifer and groundwater management, as well as the Environmental Protection Act (1990) Safe Drinking Water Act (2002) Conservation Authorities Act (1990) and others, severely restrict and protect human use of aquifers, water courses, as well as hazard lands. Such policy protections help to ensure that the interaction of people with potentially unstable or sensitive land is restricted, and therefore severe effects of land subsidence are limited.

Spatial Scale, Timing, Warning Period

Spatial Scale: Land subsidence is a small scale hazard. The affected area can range from being barely detectable on the surface to being hundreds of feet in diameter.

Timing: Land subsidence can occur at any time during the year.

Warning Period: While land subsidence can be gradual, it often goes unnoticed until it becomes visible on the surface leading it to appear to occur with little to no warning.

Potential Impacts

Potential impacts of land subsidence may include:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Injury or death possible.
  • The need for site or area access restrictions.
  • The need for damage assessment.
  • The need for evacuation or shelter in place.

Secondary Hazards

  • Flooding
  • Erosion
  • Building/structural collapse
  • Transportation disruption

Past Incidents

Sinkholes have occurred frequently in Ontario, but none have involved fatalities. Some of the most severe include:[63]

Location

Event Date

Comment

Toronto

Sept 28 2011

Water main break under Woodbine Ave and John St created 10m fissure

Toronto

Nov 4 2011

Broken water main under Bayview Ave and Steeles Ave caused sinkhole 30m long, 1.5m deep

Wawa

Oct 26 2012

Heavy flooding leads to sinkhole underneath motel.

Ottawa

Jun 08 2016

Van swallowed by a large sinkhole that formed next to a construction trench on Rideau St. Evacuation of the Rideau Centre and businesses.

Ottawa

Mar 27 2015

A sinkhole 26 feet wide and 39 feet deep near the University of Ottawa

Provincial Risk Statement

Past instances of sinkholes demonstrate the interaction of ground instability with urban, industrial, or transportation infrastructure is most likely to result in serious damage to property and injury to people. Instances of sinkholes near or under structures where people reside is in many cases unpredictable and can be fatal.

Human Impacts

Land subsidence rarely results in fatalities or injuries. Fatalities and injuries have generally occurred when a person stepped on a sinkhole, or in cases where roadways have collapsed into a sinkhole. However, deaths are unlikely due to the relatively small scale of these events.

Social Impacts

Social impacts due to land subsidence are not likely, though could occur as a secondary consequence of infrastructure failure.

Property Damage

Property can be vulnerable to damage caused by land subsidence. Large past events have caused localized damage to buildings. If the sinkhole is large enough, it may undercut a building enough that the building collapses into the sinkhole.

Critical Infrastructure Disruptions

Land subsidence has damaged critical infrastructure in the past. Sinkholes may cause damage to underground water, internet or other service lines or pipes, or buildings at ground level. Large events have caused damage on the surface of roads, rail or other transportation infrastructure.

Environmental Damage

Environmental damage is not common but could occur if a sinkhole affected hazardous material storage facilities or means of transportation.

Economic

Financial damage is not normally associated with land subsidence, except the immediate and direct effect on property or infrastructure. Although an event that is large enough to damage subsurface infrastructure, such as water pipes, may impact some of the local businesses.

Lightning

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Go to next hazard: Storm Surge

Definition

Lightning is an electrical discharge caused by a build-up of static electricity between thunderclouds, or between thunderclouds and the ground. It can deliver as much as 100 million volts of electricity and strike a target up to 16 kilometres away, making it an extremely dangerous form of severe weather.[64]

Description

In Ontario, lightning occurs most commonly in rainstorms, and much less frequently in snow squalls. Moreover, Lightning can start forest fires.

Lightning occurs between opposite charges within a thunderstorm cloud (intra-cloud lightning) or between opposite charges in the cloud and on the ground (cloud-to-ground lightning). Lightning tends to strike higher elevations and tall structures since it is drawn to the shortest path to the ground. It also has a tendency to strike objects made out of materials that are good conductors of electricity, such as metals.

There are several ways in which lightning can injure or kill a person:[65]

  • Direct Strike
  • Contact (with an object struck by lightning): The electrical current from the lightning strike travels from the struck object to the person touching or holding the object.
  • Side flash: lightning travels down an object and then jump to a person nearby.
  • Ground Current: Lightning enters the earth, travels through it and voltages are set up in the ground. One part of the victim’s body contacts one voltage, and another part contacts a different voltage. The difference in voltage drives the current through the victim’s body.
  • Upward Leaders: During a lightning storm, the atmosphere around and below the storm clouds is electrified. Upward leaders happen when currents of positive charge start growing upward from the ground from elevated objects. If a downward moving charge (known as a stepped leader) and an upward leader meet, a conductive path will be formed and a lightning stroke will occur. Other upward leaders in the area of the main stroke still carry a charge. This charge is much smaller than the main stroke, but it is still large enough to cause injury or death.
  • Blunt Trauma: It occurs when a shock wave on the ground throws a person up to three metres away, causing injuries. It can also occur from injuries related to fire, explosions, or falling objects that are caused by the lightning strike. When a tree is hit by lightning, branches can explode and hit a person standing underneath.

Survivors of lightning strikes may be left with chronic injuries such as neurological damage, loss of hearing, chronic pain, cataracts, and psychological problems including memory problems.

Records show that the two-year average for emergency department visits due to lightning-related injuries in Ontario is 2.5 times greater than all reported admissions in the rest of Canada. More than 60% of the fatalities and 65% of the injuries reported in Canada occur in Ontario[66].

Every year, lightning flashes occur about 2.34 million times in Canada. Lightning strikes kill up to 10 people and injure up to 164 others in Canada each year.[67] Windsor is the lightning capital of Canada but the CN Tower in Toronto is the object that gets struck by lightning the most in Canada.[68]

Spatial Scale, Timing and Warning Period

Spatial Scale: Lightning is a localized, small scale hazard.

Timing: Over southern Ontario, the average lightning season extends from mid-March to early November.[69] In the North, the average season runs from mid-to-late May until mid-September.

Warning Period: The potential for thunderstorms causing lightning may be forecast a couple of days in advance.

Potential Impacts

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Injury or death possible.
  • The need for debris management.

Secondary Hazards

Secondary hazards of lightning include:

  • Electrical Energy Failure
  • Wildland Fire
  • Explosion/fire
  • Transportation emergency

Provincial Risk Statement

More than 50 percent of lightning fatalities occur after a thunderstorm has passed over the area. While the risk of a lightning strike lessens after the last sounds of thunder, the risk may still persist for more than 30 minutes afterwards[70].

Human Impacts

Due to the small scale nature of this hazard, Ontario’s population is only slightly vulnerable to lightning. Historically, the greatest risk posed by lightning is the secondary hazard of wildland fires.

Fatalities caused by lightning are possible, though have decreased over the past century due to improvements in weather forecasting technology and changes in social behavior, such as fewer people working in exposed areas outdoors. However, on average, lightning claims fifteen lives a year in Canada with an additional sixty to seventy serious injuries[71].

Social Impacts

Psychosocial impacts due to lightning are rare and are likely to be very small in number.

Property Damage

Lightning may result in fires, that could lead to property damage. At the same time, some buildings, particularly those at risk of lightning strikes are grounded to avoid damage.

Critical Infrastructure Disruptions

Lightning may result in localized damage to infrastructure, particularly for electrical systems.

Environmental Damage

Environmental damage can range from localized to vast. Trees may be split or suffer bark damage. Lightning is one of the main causes of wildfires which impacts the environment, ecosystems and wildlife.

Economic

Economic damage, including interruption to financial institutions or businesses due to lightning is usually localized.

Storm Surge

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Go to next hazard: Thunderstorm

Definition

An abnormal, sudden rise of sea or lake level associated with a storm event.[72]

Description

These events can be caused by wind and air pressure causing very high waves and high water levels. Such events often result in coastal flooding and can occur along all coastal areas and in large lakes, such as the Great Lakes.

Storm surge is commonly associated with hurricanes and winter storms. Since inundation of water is a defining characteristic of storm surge, flooding and erosion of shoreline areas are also connected hazards.

Residents, particularly those living in low-lying areas near the coastline, are at risk. Storm surge generally occurs in tandem with storm hazards.

Spatial Scale, timing and warning

Spatial: Areas around the great lakes are at risk.

Timing: Storm surges can occur at any time of the year and can be particularly damaging in icy waters of winter.

Warning Period: Flooding or shoreline flooding in Ontario has become the responsibility of local conservation authorities, or the ministry of natural Resources and Forestry if a conservation authority does not exist for the area.

Potential Impacts

Potential impacts of storm surge may include:

  • Injury or death possible.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Reports of missing individuals. The need for search and rescue, family reunification operations.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • The need for debris management.
  • The need for site or area access restrictions.
  • The need for emergency provision of essential needs, including food.

Secondary Hazards

Secondary hazards associated with flooding may include:

  • Hazardous Materials Incident
  • Erosion
  • Landslide or land subsidence (due to soil and bedrock instability)
  • Drinking Water Emergency

Past Incidents

There are routinely flood watches and warnings issued in Ontario because of storm surge. These are common along Lakes Erie, Ontario and St Clair coastlines in vulnerable areas.

2017 saw the highest water levels ever recorded for Lake Ontario, and areas including Hamilton, St. Catherine’s and Toronto Islands experienced localized flooding. Storm surge and wave action led to further flooding and erosion of shoreline areas, including Lake Ontario and Lake Erie. The combination of high water, wind and storm surge in 2017 led to expected costs of $7.38 million for repair and shoreline remediation work in the City of Toronto[73], and emergency declarations in a number of jurisdictions.[74]

Provincial Risk Statement

While storm surge has historically been a frequent but low-risk hazard in Ontario, changes to climate are predicted to result in stronger and more frequent storms. This means that storm surge will likely play a much larger and more significant role in future storms, in particular when water levels are already seasonally high.

The interface between severe storms, flooding, storm surge and ecological system disruption (such as removal of wetlands in Lake Ontario) are likely to create increasingly complex and frequent hazards.

Human Impacts

There is a possibility for storm surge to result in injury or fatalities, if individuals are caught in wave action and pulled into the water. However, this is not a frequent occurrence.

Social impacts

Storm surge may temporarily restrict community activities and support systems. However, it is not likely to result in direct social impact.

Property Damage

Storm surge can cause property damage to waterfront property through wave action.

Critical Infrastructure Disruptions

Storm surge can affect lakefront infrastructure, and has had an influence on other connected infrastructure such as Stormwater management assets. Capacity improvements and upgrades for such infrastructure are generally outpaced by the increasing risk of urban flooding and storm surge. This could create water backflow issues and affect storm drain capacity, which can each drastically increase the risk or urban flooding.

Environmental Damage

Storm surge is not likely to result in extensive environmental damage, though waterfront areas can be affected.

Economic

Storm surge is not likely to result in significant business/financial impacts, though interruptions to waterfront businesses and system can occur as a secondary impact of damage to infrastructure or property, or resulting from disruptions to access to waterfront property.

Thunderstorm

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Go to next hazard: Tornado

Definition

Thunderstorms are local storms, usually produced by a cumulonimbus cloud and accompanied by thunder and lightning.[75] They can bring lightning, heavy rain, hail, strong winds and tornadoes.

Description

Thunderstorms can produce some of nature’s most destructive and deadly weather. They are accompanied by lightning and may produce damaging weather such as tornadoes, hail, high winds and heavy rain.

Environment and Climate Change Canada issues Severe Thunderstorm Warnings , and have specific criteria to do so.[76]

The three key elements for thunderstorm formation are moisture, rising unstable air, and a lifting mechanism.

Other hazards that may occur during a thunderstorm include:

  • Lightning: Lightning is an electrical discharge caused by a build-up of static electricity between thunderclouds, or between thunderclouds and the ground[77]. (See ‘Lightning’ hazard profile).
  • Tornado: A tornado is a narrow, violently rotating column of air that can form from the base of a thunderstorm to the ground. Tornadoes can form as part of a storm system, or independent of them. (See ‘Tornado’ profile).
  • Rainfall and Floods: Thunderstorms can also cause flash flooding because of significant rainfall. (See ‘Flood’ profile)
  • High Wind: See the ‘high wind’ hazard profile.
  • Hail: Hail is a form of precipitation that occurs when updrafts in thunderstorms carry raindrops upward into extremely cold areas of the atmosphere where they freeze into balls of ice. If the resulting storm has strong updrafts, then raindrops may be carried high into the storm where the air temperature is below freezing, forming hail. Eventually, when the hail is too heavy for the updraft to lift, it falls to the ground at speeds of 100 km/h or greater.

Past Incidents

According to the Canadian Disaster Database, the following are significant storms that occurred in Ontario. Every year there are many thunderstorms, so this list is not exhaustive:

  • Southern Ontario, 2016: Severe thunderstorms in Southern Ontario, including Orillia, Markdale and Bradford, produced winds of up to 100 km/hr, intense lightning, heavy rain and hail. The Insurance Bureau of Canada reported that large hail coupled with strong winds damaged crops, roofs, siding and windows on homes, dented cars and broke windshields. Catastrophe Indices and Quantification Inc. (CatIQ) reported that the incident resulted in more than $30 million in insured damage.
  • South Dumfries, 1996 (Estimated total cost of $99,870)
  • Ontario and Quebec, 1992
  • Central Ontario, 1991 (Estimated total cost of $5,982,309)
  • Chesley, 1984 (Estimated total cost of $39,066,000)
  • Lake Superior, 1953

Spatial Scale, Timing and Warning Period

Spatial Scale: On average, -thunderstorms have a short duration. However, multiple thunderstorms can train over the same area, prolonging the duration.

Timing: Severe thunderstorms are most likely in the spring and summer months. If conditions are humid and/or warm enough, they can also happen in winter. The peak time for thunderstorm development is the afternoon and evening hours, but they can occur at all hours.

Warning Period: Severe thunderstorm watches and warnings are issued by the Meteorological Service of Canada of Environment and Climate Change of Canada. - Weather prediction models allow meteorologists to locate areas favourable for the development of thunderstorms, sometimes over days in advance of occurrence. Nonetheless, severe thunderstorm watches are only issued a few hours in advance as confidence level of thunderstorm development is not usually high enough before then. For issuance of severe thunderstorm warnings, lead time can be nil since thunderstorms develop rapidly.

Potential Impacts

Some of the potential impacts of severe storms may include:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Injury or death possible.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • Worker shortages and business continuity issues.
  • The need for site or area access restrictions.
  • The need for emergency provision of essential needs, including food.
  • The need for damage assessment.
  • The need for debris management
  • The need for financial assistance.
  • The need for evacuation or shelter in place.
  • The need for emergency shelter services.

Secondary Hazards

  • Lightning
  • Flooding
  • High wind
  • Tornado

Provincial Risk Statement

Extensive property damage remains a possibility even with strict regulations around building materials and construction practices. Damage, injuries or fatalities are more likely to occur as a cascading effect of wind and precipitation, which can cause significant amounts of debris, flooding and other risks. Public warnings and alerts are effective in enhancing public awareness of the risks, and how to mitigate them.

Human Impacts

Severe storms are routine in Ontario, and rarely cause significant numbers of injuries, though this is possible.

Social Impacts

Psychosocial impacts and effects on wellbeing, social cohesion or community activities from hail are not likely.

Property Damage

Vulnerability to storm events has decreased greatly over time due to revisions to the Building Code. However, Ontario has a great number of buildings of varying ages and construction types. Hail, wind, flooding and other secondary hazards can cause property damage, mostly in the form of broken windows, dented automobiles, and destroyed crops. The extensive agriculture in southern Ontario is vulnerable to damage, particularly early in the growing season and then right before the crop is picked.

Critical Infrastructure Disruptions

Critical infrastructure disruptions are unlikely due to hail, though mostly superficial damage is certainly possible.

Environmental Damage

Plants and crops may be damaged or destroyed by hail. Wildlife is usually not severely affected as most animals are able to take shelter.

Economic

Agricultural businesses may experience losses due to damaged crops.

Tornado

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Go to next hazard: Wildland Fire

Definition

A violently rotating column of air that results in the formation of a funnel cloud that extends fully or partially from the cumuliform cloud to the surface.

Description

Tornadoes are violently rotating columns of air that extends from a cumuliform cloud to the surface. They are typically made visible by a funnel cloud, and rotating debris near the ground or a spray ring near the water surface. Tornadoes are one of the least extensive but most severe of all weather phenomena.

Although about 12 tornadoes, on average, are verified each year in Ontario, this number is misleading; a considerable number of tornadoes are believed to escape detection each year, particularly in areas with low population density, are not included in the count.

From the extreme southwest of the province to the farthest northern tip, a tornado can strike anywhere. However, they are most frequently observed in a corridor between Lakes Erie, Huron and Ontario from Windsor and Sarnia in the southwest to Hamilton and Barrie in the northeast.

Tornadoes usually occur between May and September, when the frequency of thunderstorms is highest. They usually hit in the afternoon or early evening, but they have been known to strike at night too. Given the right conditions, they are capable of moving at speeds of more than 70 km/hour and leaving a long path of destruction. Such tornadoes are powerful enough to uproot trees, toss cars and demolish houses. At other times, the tornado may be small and brief, and do only minor damage.

Tornadoes that occur over water are referred to as waterspouts. They have the same characteristics as tornadoes over land. They are sometimes associated with severe thunderstorms accompanied by high winds and seas, large hail, and frequent dangerous lightning.[78] The powerful and deadly Goderich tornado began as a waterspout over Lake Huron. In the fall, when colder air begins to move over the still warm Great Lakes, waterspouts can form even in the absence of thunderstorms, though they tend to be weak.

Tornadoes can be classified into two categories, depending on the type of storm that generates them:

  • Supercell tornadoes: A supercell storm can last for longer than one hour due to its extremely intense, rotating updraft and high degree of internal organization. Though only about 30% of supercells produce tornadoes[79], nearly all ‘violent’ tornadoes are generated by supercells. Doppler radar can be used to determine if a storm is a supercell having the potential to produce a tornado.
  • Non-supercell tornadoes: These tornadoes form with storms that do not have the updraft strength of a supercell storm and are therefore generally weaker, shorter lived and less destructive. Detection of tornado potential using radar is often difficult.

Powerful storms can generate multiple tornadoes, or even a ‘multi-vortex’ tornado (a single tornado with a number of smaller vortices within it). The high wind speeds and debris carried by the tornado are responsible for damage[80].

Up to 2012, the intensity of a tornado in Canada was assessed using the Fujita Scale, a six-point scale that uses damage to estimate tornado intensity. In 2013, Environment and Climate Change Canada’s Weather Service began to use the Enhanced Fujita Scale (EF-Scale) to measure the intensity of wind damage (See table below)[81]. One of the main enhancements was a better correlation between observed damage and estimated wind speeds, resulting in much lower wind speeds at the top end of the scale.

Table 1: The Enhanced Fujita Scale

EF Scale Rating

EF Scale Wind Speed Rounded to 5km/h

0

90 - 130

1

135 - 175

2

180 - 220

3

225 - 265

4

270 - 310

5

315 or more

Table 1: The Enhanced Fujita Scale (Environment and Climate Change Canada, 2013).

Environment and Climate Change Canada is responsible for warning the public when storms exist that may produce tornadoes. Tornado warnings are considered broadcast intrusive alerts; that means they are mandated by the Canadian Radio-television and Telecommunications Commission (CRTC) to be disseminated through television and radio by having programming signals interrupted, and through the mobile phone network on the Alert Ready system. .

Past events have highlighted the importance of developing tornado forecasting tools and risk information systems for engineering and financial loss models that will improve our capacity to cope with damage control and minimize the societal risk of tornadoes.

Spatial Scale, Timing and Warning Period

Spatial Scale:  Tornadoes are typically a small to medium scale hazard with the majority of tornadoes being only a few hundred metres wide and about 10 km in length. However, the width and length of the track may vary significantly.

Timing: Tornadoes can occur at any time of the year and at any time of day. They are most common in Ontario from May to September, with a peak in occurrence in June and early July. The majority of tornadoes occur in the afternoon and evening.

Warning time: Conditions favourable for tornado development may be forecast in advance, often leading to the issuance of a Tornado Watch. But since tornadoes themselves often develop very quickly, the lead time for Tornado Warnings is often only minutes, and sometimes nil.

Potential Impacts

Potential impacts caused by a tornado may include:

  • Injury or death. May strain the health system and response resources.
  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure including electricity and telecommunications.
  • Reports of missing individuals. The need for search and rescue, family reunification operations.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • Disruption or closure of government, business or financial institutions.
  • The need for damage assessment.
  • The need for debris management.
  • The need for financial assistance.
  • The need for evacuation or shelter in place.
  • The need for site or area access restrictions.
  • The need for emergency shelter services.

Secondary Hazards

Secondary hazards associated with Tornadoes are:

  • Building/Structural failure (or damage)
  • Transportation Emergency
  • Supply or Distribution emergencies
  • Hazardous materials incidents

Past Incidents

There have been a number of significant tornadoes recorded in Ontario over the last 72 years. Each year about 60 tornadoes are verified in Canada, causing an average of 2 fatalities, 30 injuries, and nearly $20M in property damage.

An Environment and Climate Change Canada assessment showed that the Ontario Storm Prediction Centre was successful in issuing both a severe thunderstorm watch and a tornado warning before the Goderich Tornado made landfall on the shore of Lake Huron. However the tornado and its parent supercell developed and intensified over the Lake and well behind a cold front, both of which are very rarely seen in the Great Lakes area. The Insurance Bureau of Canada estimates that the Goderich incident cost $75 million in insured damage, but the bulk of the costs  were insured.

Table 2: Tornado hazard historic data

Place

Event
Start Date

Fatalities

Injured

Evacuated

Estimated Total Cost

SW Ontario

Aug 2, 2015

0

0

Unknown

$60,000

Goderich ON

Aug 21, 2011

1

37

Unknown

$150,000,000

Midland ON

Jun 23, 2010

0

15

0

$15,000,000

Leamington ON

Jun 6, 2010

0

0

0

$24,000,000

Toronto, Windsor, Vaughan and Newmarket ON

Aug 20, 2009

1

0

0

$2,500,000

Southern Ontario

Aug 19, 2005

0

6

0

$1,500,000

Grey County, Wellington and Dufferin County ON

Apr 20, 1996

0

9

0

$8,000,000

Frome / Komoka

Aug 28, 1990

0

5

0

$20,000,000

Grand Valley / Barrie ON

May 31, 1985

12

224

800

$155,000,000

London ON

Sept 2, 1984

0

33

0

$5,000,000

Reeces Corners ON

May 2, 1983

0

13

0

$20,000,000

Stratford / Woodstock ON

Aug 7, 1979

3

141

0

$100,000,000

Windsor ON

Apr 3, 1974

9

30

0

$1,800,000

Sudbury, Lively, Coppercliff and Field ON

Aug 20, 1970

6

200

0

$17,000,000

Huron and Perth counties ON

Apr 17, 1967

1

1

0

$1,000,000

Sarnia ON

May 21, 1953

5

49

500

$9,000,000

Windsor to Tecumseh ON

Jun 17, 1946

17

100

0

$1,500,000

Table 2: Tornado hazard historic data. Source: Canadian Disaster Database, 2018. Environment Canada, 2019.

Provincial Risk Statement

Canada is second only to the United States in tornado frequency. According to Environment and Climate Change Canada, Ontario confirms an average of about twelve tornadoes per year. However, this number can be deceiving as some tornadoes cause no damage to property, occur in unpopulated areas or simply go unreported.

Southern Ontario experiences one of the highest tornado occurrence rates in all of Canada. The vast majority of tornadoes in Ontario are weak (ranking as F0 or F1 on the Fujita scale for tornado intensity) (Figures 14 & 15). There have been no confirmed F5 tornadoes (the highest ranking on the Fujita scale) in Ontario. However, there is no evidence that suggests that an F5 cannot occur in the province – F5 tornadoes have occurred in neighbouring Michigan, Ohio and Pennsylvania. Ontario is also not immune to tornado outbreaks, in which multiple tornadoes are reported.

Human impacts

On average, tornadoes in Canada result in two deaths and 30 injuries per year.[82] However, the number of deaths and injuries can deviate significantly from the average if a strong tornado occurs in a populated area. The majority of deaths and injuries are caused by flying debris.[83]

Social Impacts

Tornadoes may result in psycho-social impacts. Harsh conditions can cause disconnectedness, and interrupt social bonds that may have otherwise supported response and recovery. Once conditions subside, damage and debris from the storm can continue to impede community recovery.

Property Damage

Tornadoes can cause a wide variety of property damage including broken windows, uprooted trees, or the complete destruction of buildings. Especially vulnerable to damage are houses, mobile homes and other buildings that are not anchored; structures without properly attached roofs. Additional damage from downbursts, hail, lightning and flooding may come from the same storm that produced the tornado.

Critical Infrastructure Disruptions

A tornado may result in power outages due to downed poles and power lines. In order to minimize the risk of an explosion, damaged properties often have their natural gas shut off. Roads may be blocked by debris preventing emergency vehicles from reaching the impacted area.

Environmental Damage

Tornadoes have been known to topple swaths of forest and destroy orchards and field crops. Hazardous material spills may occur if a tornado destroys a fixed site facility or results in a transportation accident involving hazardous materials. Additionally, debris, including hazardous material, can be carried a significant distance by the winds, impacting both land and water.

Economic

A tornado is a localized phenomenon; the largest are usually less than 2 km wide, so the economic impacts are usually restricted. However, there have been instances in which significant portions of towns have been destroyed, such as in Sarnia in 1953 and Goderich in 2011. Since tornadoes can cause significant damage to buildings, recovery and restoration of a business to an acceptable level of activity may take quite a bit of time. Power or communications outages caused by the storm increase the chances of business interruption.

Wildland Fire

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Go to next hazard: Winter Weather

Definition

Any fire in forests, shrub lands and grasslands.

Some are uncontrolled wildfires are started by lightning or humans. A small number are prescribed fires set by authorized forest managers to mimic natural fire processes that renew and maintain healthy forests.[84]

Description

Wildland fires present a challenge for forest management because they have the potential to be both harmful and beneficial. They can threaten communities and destroy vast amounts of timber resources, resulting in costly losses. However, wildland fire is an important natural disturbance in Ontario’s forests and grasslands. Fire renews the forest, creates healthy natural habitat, and provides diverse landscapes.

Ontario’s 10-year average is 791 fires, though the total number of hectares burned varies considerably from year to year. Only 3% of all wildland fires that start each year in Canada grow to more than 200 hectares in area. However, these large fires account for 97% of the total area burned across the country. On average 55% wildland fires in Canada are human caused.[85]

There are three types of wildland fires which are classified based on the level at which they occur; Ground fires, Surface Fires and Crown Fires[86] [87]

There are two main threats associated with this hazard: smoke and fire. In past wildland fire emergencies in Ontario, communities have declared emergencies or evacuated more often a result of smoke effects than fire activity.[88] Wildland fire smoke is made up of a mixture of gases and very small particles that are produced when wood and other organic matter burn. These small particles and gases can be harmful when inhaled.[89]

Those who are most at risk from forest fire smoke are:

  • Children, seniors and pregnant women.
  • People who have chronic heart or lung problems. These individuals may feel the effects of smoke earlier and worse than others.
  • People who are very active doing work or sports outside.

A fire requires dry, organic matter such as surface litter to continue and spread. The moisture content of the fuel has an important influence on the duration and spread of the fire. The temperature of a wildland fire is also dependant on the type and moisture content of the fuel.[90]

Wet weather conditions decrease the quality of the fuel and can suppress fire. Prolonged, dry weather, especially drought conditions, can increase the amount and quality of the organic matter available as fuel. Changing climate may result in hotter and drier conditions, leading to a significant increase in forest fire activity over the next 20 to 50 years.[91]

Fire needs oxygen to burn. Wind can provide large quantities of oxygen, and rapidly spread the fire. Such conditions create a very challenging fire suppression environment that is more dangerous than in calm weather conditions.

Many factors contribute to the frequency and severity of fires; this includes the activities of insect species, infestation or plant disease, which in some cases increase the amount of dry, dead organic matter that can provide fuel for a fire.

The Provincial Policy Statement 2014 sets out policy direction for municipal and other land use decision-makers to direct development away from area of wildland fire risk (areas with a high risk due to the presence of hazardous forest types for wildland fire), where the risk cannot be appropriately mitigated. As required by section 3 of the Planning Act, land use decisions need to be consistent with the policies.

Spatial Scale, Timing, Warning Period

Spatial Scale: The size of forest fires can vary significantly. The size, location, spread direction, and fire intensity all have an effect on the potential for threats to public safety or social disruption. Smoke further increases the size of the impacted area.

Timing: The wildland fire season is April 1 to October 31. Fires are more common during the spring (before canopy cover is renewed and while there this still a large amount of dry vegetation on the forest floor) and summer (when lightning is more frequent). Both of these seasons tend to have periods of hot, dry and windy weather, which can further spread fire.

Warning Period: The amount of warning varies for each situation, although several days is average.

Potential Impacts

Potential impacts of wildland fires may include:

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Poor air quality.
  • Illness, injury or death. May strain the health system and response resources.
  • Reports of missing individuals. The need for search and rescue, family reunification operations.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • Disruption or closure of government, business or financial institutions.
  • Ecosystem damage or disruption. Need for assurance monitoring of the environment.
  • Psychosocial effects including stress disorders
  • Strain on emergency services and response resources.
  • The need for evacuation or shelter in place.
  • The need for debris management.
  • The need for financial assistance.
  • The need for emergency shelter services.
  • The need for emergency provision of essential needs, including food.
  • The need for site or area access restrictions.

Secondary Hazards

  • Water Quality Emergency
  • Supply and Distribution issues
  • Transportation Emergencies
  • Building/Structural failures
  • Explosion or Fire (secondary)

Past Incidents

Based on data in the National Forestry Database, over 8000 fires occur each year, and burn an average of over 2.1 million hectares. Also, lightning causes about 50% of all fires but accounts for about 85% of the annual area burned, although these areas are less likely to be populated.[92]

Those which led to the evacuation of more than 1000 people include:

  • Timmins, 2012
  • Northern Ontario, 2011
  • East of Lake Winnipeg MB (In ontario), 1999
  • Northern Ontario, 1998
  • Red Lake, 1980
  • Haileybury, 1922
  • Cochrane and Matheson, 1916

Only one recorded fire led to more than $1 million in damages; the 1955 fires in Quebec and Ontario.

Provincial Risk Statement

Fires that occur in storm-damaged forests are generally more intense and make firefighting efforts more difficult.

Of particular concern are fires that occur within or close to areas where homes, cottages and subdivisions are built into the forest landscape (the urban interface).[93]  .

Organized forest fire protection has been active in Ontario since 1885. To support the protection of public safety and other values, the Ministry of Natural Resources and Forestry maintains a system of firefighting resources to allow appropriate response to wildland fire. The goals of the wildland fire management program are to:

  • prevent loss of human life and injury
  • prevent and mitigate losses alongside economic and social disruption
  • promote understanding of the ecological role of fire
  • use fire to benefit resource management

Human Impacts

Wildland fires can endanger lives when they approach populated areas. However, due to improvements in fire prediction and forest fire management, deaths due to forest fires remain uncommon in Ontario. Injuries due to wildland fires are also uncommon, although there are often health concerns about air quality and smoke.

Social Impacts

Evacuations may occur due to smoke even if the community is not directly threatened by the fire itself. This can cause serious disruptions in social networks and support systems.

Property Damage

Property is vulnerable to wildland fires and can result in substantial property damage. Buildings and structures within the path of the fire may be completely burned. Buildings that remain structurally intact after a fire has ended may have had their contents damaged due to smoke.

Critical Infrastructure Disruptions

Wildland fires and can result in substantial infrastructure damage. Structures within the path of the fire may be completely burned. Roads, electrical lines, and other above-ground assets can be burned, as well as below-ground cable and communications infrastructure. Large networks of assets such as these are challenging to defend from fire; the strategy often employed to defend them is for wildfire services to prioritize ‘values protection’ on key hubs or nodes in the areas at risk.

Environmental Damage

Wildland fires are a natural feature of the forest ecosystem. While a forest fire may have what appears to be negative effects, these often turn out to be beneficial for the ecosystem in the long-term. Many species are adapted to fire, and some (such as jack pine) use fire to release seeds. Fire also benefits vegetation by enriching the soil with ash, and allowing more sunlight and precipitation to reach the forest floor. Fire can help control invasive species (including insects, plants and diseases) that have not evolved in areas in which fire is a natural part of the maintenance of the landscape, and reducing the competition for some species.

Excessive fire over large areas may adversely impact ecosystems, wildlife and species at risk.

Erosion and changes in water temperature caused by the loss of vegetation due to a fire can negatively impact water quality affecting cold water fish habitats.

Economic

Wildland fires can have a negative economic impact if they occur near communities and necessitate the evacuation of large numbers of people. Resources needed for suppression may be costly. The forestry sector is the industry most likely to be negatively impacted by wildland fires, although tourism can also be severely affected.

Perceived impacts of fire can lead to similar negative effects, even if there are no direct or immediate hazards. In July 2018 the community of Parry Sound reported a decline in tourism and cottage-related industry as a result of a significant fire. While the fire was more than 100km away from the community, the fire was widely covered in the media, and its official designation ‘Parry Sound 033’ led to concern about the settlement.

Winter Weather

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Definition

Winter weather is a severe weather event with varieties of precipitation that can form only at low temperatures, such as a snow, freezing rain and ice.

Description

Severe winter weather is a fact of life in Canada. Snow storms, ice storms, snow squalls, blowing snow, and more rarely flash freeze and blizzards visit Ontario every year. Lightning, high wind and fog can occur in winter storms, but are covered in their own hazard profiles as they can also occur at other times of the year. Extreme Cold events in the province do not usually happen with other winter severe weather; it is also covered separately.

Generally, winter weather can include the following:

  • Snowstorm: A period of rapid accumulation of snow, often accompanied by high winds, cold temperatures, and low visibilities. Snowfall warnings are issued by Environment and Climate Change Canada. when there is an expected accumulation of 15 cm or more during a period of 12 hours or less.
  • Blizzard: A severe weather condition characterized by winds of 40 km/h or greater causing widespread reductions in visibility to 400 m or less due to blowing snow, or blowing snow in combination with falling snow for at least four hours. Blizzard warnings are issued by Environment and Climate Change Canada when the above conditions are expected.
  • Snow Squall: Sudden heavy snow showers with strong, gusty winds causing blowing snow conditions that reduce visibility. Sometimes, snow squalls bring zero visibility, which is referred to as a whiteout and is similar to a blizzard but is localized .
  • Freezing Rain: Rain or drizzle, which falls in liquid form and then freezes upon contact with the ground or a cold object forming a coating of ice. Freezing rain occurs when upper air temperatures are warm enough for rain to develop, but temperatures near the surface are cold enough that the rain cools and forms ice on contact. A long-lived freezing rain event is often referred to as an ‘ice storm’.
  • Flash Freeze: A flash freeze warning is issued by Environment and Climate Change Canada when significant ice is expected to form on roads, sidewalks or other surfaces over much of a region because of the freezing of residual water from either melted snow, or falling/fallen rain due to a rapid drop in temperatures.

It is possible for some of those conditions follow one another. For example, heavy snowfall may be followed by freezing rain as temperatures warm. Another hazard, extreme cold, may follow a storm system as cold arctic air pushes a warmer air mass southeast.

A comprehensive list of alert bulletins of winter weather hazards (blizzard, blowing snow, flash freeze, freezing drizzle, freezing rain, snowfall, snow squall, winter storm) issued by Environment and Climate Change Canada is listed on the following website:

https://www.canada.ca/en/environment-climate-change/services/types-weather-forecasts-use/public/criteria-alerts.html#winterStorm

There are also some weather systems with unique characteristics and consequently, names have been developed for them, including:[94] [95]

Nor’easter

A winter storm that impacts the East Coast of North America, particularly Atlantic Canada. Nor’easters usually develop in the latitudes between Georgia and New Jersey, within 100 miles east or west of the East Coast. They gain their name from winds over coastal areas, which are typically from the northeast. They are usually most intense during winter and can result in more severe winter weather conditions in parts of southern Ontario.

Alberta Clipper

A fast moving low pressure system that moves southeast out of Alberta through the rest of the Prairies, and Great Lakes region usually during the winter. This low pressure area is usually accompanied by light snow, strong winds, and colder temperatures. Areas on the lee of lakes may get more snow. Another variation of the same system is called a "Saskatchewan Screamer".

Colorado Low

A low pressure storm system that forms in winter in southeastern Colorado or northeastern New Mexico and tracks northeastward across the plains of the U.S. over a period of several days and eventually into Ontario. Storms of this type usually brings a combination of snow, freezing rain, and rain to the province.

Winter weather can have a variety of impacts as it involves sub-zero temperatures. Impacts can include frozen pipes, resulting in water supply issues and burst pipes, downed power lines caused by freezing rain and high winds, and power outages from downed or damaged lines. Prolonged power outages may result in residents having to vacate homes and discard spoiled food. Those who are particularly vulnerable to winter weather conditions include those who:

  • are socially isolated
  • require power for medical or special equipment such as breathing apparatus
  • are dependent on a caregiver
  • have mobility challenges or issues

by environment Canada The effects of winter weather on physical infrastructure and the continued operation of critical services can be severe and varied. For example, low visibility can impede travel routes and create unsafe outdoor conditions. Snow accumulation can create slippery conditions or even cause collapse of weak structures. Icy conditions further increase the potential for slips and falls, and present challenges for the transportation sector. Ice can also accumulate on objects causing them to topple or break, power lines and trees are particularly susceptible to this form of damage. Severe power outages can accompany this type of weather event.

Such conditions can also limit mobility and the ability for people to remain independent. Individuals with special needs may experience more severe limitations and require greater assistance. In the case of power outages, those dependent on life-sustaining equipment such as dialysis machines are particularly at risk.

Snow or blowing snow can lead to poor visibility; it can wreak havoc on road conditions for drivers and pedestrians. 

Heavy snowfalls may present a flood risk later in the season. Large accumulations of snow and ice can swell waterways, especially if there is a rapid thaw.

Areas downwind of the Great Lakes are prone to lake-effect snow between November and February. Lake-effect snow refers to heavy, usually localized snow squalls which are generated by the difference in temperature between the cold air and the warmer water of the lakes.[96]

Spatial Scale, Timing and Warning Period

Spatial Scale: While summer severe weather tends to be localized, winter severe weather can sometimes affect large parts of the province or region. Snowstorms and blizzards may differ greatly in size. Some are fairly localized (e.g. lake effect snow) while others may span a significant portion of the Province.

Timing: In Ontario, the winter weather events usually occur from November to April. In general, these events have lasted between 12 hours and 1-2 days. Snow squalls are more frequent earlier in the fall/winter season before ice covers the Great Lakes.

Warning Period: Unlike summer severe weather, of which lead-time can be nil, winter severe weather has longer lead time and can be forecast days ahead. Winter weather alerts issued more than twelve hours before impact are not uncommon.

Potential Impacts

  • Property and structural damage, the need for repair. Possible impact on Critical Infrastructure.
  • Illness, injury or death. May strain the health system and response resources.
  • Reports of missing individuals. The need for search and rescue, family reunification operations.
  • Multi-modal transport disruptions, the need for detours or re-routing. May strain transportation management resources and cause transportation delays.
  • The need for damage assessment.
  • The need for debris management.
  • The need for emergency shelter services.
  • The need for evacuation or shelter in place.
  • The need for site or area access restrictions.

Secondary Hazards

Secondary hazards that may be associated with snowstorms/blizzards may include:

  • Transportation emergency
  • Flooding
  • Building/Structural Collapse
  • Fire/Explosion (due to unsafe use of heating/cooking equipment)

Indirect effects include:

  • roof collapse due to the weight of the snow (usually due to the accumulation of snow from more than one storm)
  • major traffic accidents
  • fire or carbon monoxide poisoning from alternate and/or unsafe heating sources

Past Incidents

By far the costliest winter event was the North American Ice Storm of 1998 at a cost of $4,635,720,433 and 25 deaths (primarily from hypothermia). between Ontario, Quebec and New Brunswick. A weather system stalled over the St. Lawrence region dumping a steady stream of freezing rain for 80 hours. Hundreds of hydro towers toppled under the weight and millions of people in Eastern Canada and the North-Eastern United States were plunged into darkness. The event prompted the largest military mobilization in Canadian history since the Korean War.

The following additional significant incidents are recorded in the Canadian Disaster Database:

  • Mar 23, 2016: Southern Ontario
  • Feb 24, 2016: Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland. 200 injured
  • Dec 21, 2013: Southern Ontario. 2 fatalities. 25 injured. $262,781,642 estimated total cost.
  • Dec 12, 2010: Lambton County ON. 1 fatality. 1 injury. 625 evacuated
  • Dec 01, 2006: Russell ON
  • Feb 13, 1999: Barrie ON. 30 injured.
  • Jan 13, 1999: Toronto ON. 2 fatalities. $122,000,000 estimated cost
  • Jan 03, 1999: Southern Ontario. 11 fatalities. 7 injured.
  • Jan 04, 1998: Ontario, Quebec and New Brunswick. 35 fatalities. 945 injured. 17800 evacuated. $4,635,720,433 estimated cost.
  • Dec 10, 1995: Southern Ontario. 1 fatality. 50 evacuated
  • Nov 01, 1993: Quebec and Ontario
  • Dec 23, 1986: Eastern Ontario and Southwestern Quebec
  • Jan 26, 1978: Southwestern Ontario. 8 fatalities. 400 injured
  • Jan 28, 1977: Niagara Peninsula ON.
  • May 18, 1973: Barrie ON. 12 fatalities. 43 injured
  • Jan 13, 1968: Southern Ontario
  • Dec 11, 1944: Toronto ON. 21 fatalities

Provincial Risk Statement

In Ontario, winter weather is a fact of life and severe winter weather will continue to bring hazards to Ontarians. These hazards changes in frequency and severity from year to year; jurisdictional ability to reinforce structures against adverse conditions and to reach vulnerable members of the community, will remain a significant challenge.

The potential consequence and likelihood of power outage has been historically high, but so have prevention and mitigation efforts. Efforts to counteract or protect against such effects are often unfeasible, either resulting in trade-offs of one risk for another, or requiring an immense investment for disproportionately minor enhancements. For example, burying wires can protect them from wind and ice, but this is also costly and makes failures harder to identify, more difficult to access and costly to repair. They are also more susceptible to flooding.

Secondary effects accretion caused by freezing rain. While these hazards can directly affect overhead wires and power infrastructure, secondary impacts from falling tree limbs or cascading failures felt as a result from effects in other regions (such as in the 2003 Eastern blackout) should also be considered in risk assessments and planning efforts.

The long term costs of winter storms can be particularly significant, given the high level of complexity and likelihood for secondary and cascading failures.

Human impacts

The number of traffic accidents skyrockets during winter storms, causing injuries and (some) fatalities. In addition, people trapped outside, in their vehicles or in isolated residences without adequate heating may suffer from hypothermia. While hypothermia can directly result in fatalities and injuries, indirect causes of fatalities and injuries are more common during snowstorms and blizzards.

Social Impacts

People in Ontario can be vulnerable to winter storms. Familiarity with this hazard, as well as advanced forecasting has helped to decrease the population’s vulnerability. Of particular concern are socially isolated individuals, those with mobility challenges, and those with a dependence on support services.

Property Damage

The Ontario Building Code has reduced the vulnerability of property. Buildings that have not followed this code risk the collapse of roofs under the weight of the snow. Flat roofs are more vulnerable than sloped ones.

Buildings may be damaged by ice accumulation, falling branches, or water seepage. 

Critical Infrastructure Disruptions

Without power, many buildings will not have a source of heat. Heavy snowfall may also make unplowed roads and rail lines impassable. Poor visibility may further hamper transportation conditions. Transportation and electrical infrastructure are particularly sensitive to freezing rain.

Health care facilities may experience higher than normal volumes, and experience capacity issues as a result of power disruption.

Environmental Damage

Snowstorms and blizzards are a naturally reoccurring hazard in Ontario. As a result, the majority of the native flora and fauna are well adapted to survive the impacts of such a storm. Plants, in particular deciduous trees, are especially sensitive to the effects of freezing rain.

Economic

A large and prolonged snowstorm or blizzard or freezing rain, in particular ice storms with a long duration and that result in a large ice accumulation, can significantly disrupt business and financial transactions. Disruptions to air, road, and rail travel could lead to financial loss, especially if it occurs for several days.

An impactful snowstorm or blizzard or a prolonged episode of snow squalls can cause significant business and financial interruption. Snowstorms can be expansive; a large portion of the province can be affected simultaneously. Heavy snowfall and poor visibility may prevent people from coming to or leaving from work. The power outages that are frequently associated with these storms can result in further disruption.

Agriculture, particularly maple syrup production and orchards, may suffer substantial losses. Gardens and ornamental plants can also be damaged.

End Notes

[1] Ministry of Natural Resources and Forestry (MNRF), 2018.

[2] http://www.lre.usace.army.mil/Portals/69/docs/GreatLakesInfo/docs/WaterLevels/LTA-GLWL-Graph_2015.pdf

[3] Environment Canada, 2016

[4] http://www.agr.gc.ca/atlas/agclimate

[5] https://open.canada.ca/data/en/dataset/7b817d93-f34d-4aa8-8658-d9abe9d84a8f

[6] Natural Resources Canada, 2016. http://www.earthquakescanada.nrcan.gc.ca/info-gen/faq-en.php#What_is_an_earthquake Accessed January 2019. Natural Resources Canada, 2016

[7] http://www.earthquakescanada.nrcan.gc.ca/info-gen/faq-en.php#What_is_an_earthquake Accessed January 2019. Natural Resources Canada, 2017, Stein and Mazzotti, 2007

[8] Natural Resources Canada, 2018 http://www.seismescanada.rncan.gc.ca/zones/eastcan-en.php Accessed October 2018.

[9] United States Geological Survey, 2018

[10] Natural Resources Canada, 2017

[11] Natural Resources Canada. Earthquake Hazard Maps and Calculations, 2018. http://www.earthquakescanada.nrcan.gc.ca/hazard-alea

[12] Simplified seismic hazard map for Canada, the provinces and territories: http://www.seismescanada.rncan.gc.ca/hazard-alea/simphaz-en.php

[13] USGS, 2017; Natural Resources Canada, 2017

[14] Halchuck and Adams, 2010

[15] Natural Resources Canada, 2018. Ministry of Municipal Affairs, 2015.

[16] Ministry of Agriculture, Food & Rural Affairs, 2009 (http://www.omafra.gov.on.ca/IPM/english/soil-diagnostics/erosion.html )

[17] Ministry of Agriculture, Food & Rural Affairs, 2016

[18] http://www.mah.gov.on.ca/AssetFactory.aspx?did=10463  Order in Council No. 107/2014

[19] Toronto and Region Conservation Authority, 2018. https://trca.ca/conservation/erosion-risk-management/

[20] Natural Resources Canada, 2017; Ministry of Natural Resources and Forestry, 2015

[21] Ministry of health and long Term Care, Ministry Programs, 2015. http://www.health.gov.on.ca/en/public/programs/emu/emerg_prep/et_cold.aspx

[22] Government of Canada, Extreme Cold, 2017. https://www.canada.ca/en/health-canada/services/healthy-living/your-health/environment/extreme-cold.html

[23] Government of Canada, Criteria for Public Weather Alerts, 2017.  https://www.canada.ca/en/environment-climate-change/services/types-weather-forecasts-use/public/criteria-alerts.html

[24] Natural Resources Canada, Frequently asked Questions about Earthquakes, 2016. http://www.earthquakescanada.ca/info-gen/faq-en.php

[25] The Weather Network, Record low temperatures in Ontario amid deep freeze, 2016. https://www.theweathernetwork.com/news/articles/record-low-temperatures-in-ontario-amid-deep-freeze-/63649

[26] Natural Resources Canada, Overview of Climate Change in Canada, 2015. https://www.nrcan.gc.ca/environment/resources/publications/impacts-adaptation/reports/assessments/2008/ch2/10321

[27] Gasparrini, Antonio et al. Mortality risk attributable to high and low ambient temperature: a multicountry observational study. The Lancet , Volume 386 , Issue 9991 , 369 - 375

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