Climate Resiliency Strategy

The City of Ottawa in partnership with Ottawa Public Health created two urban heat island maps using satellite imagery from July 18, 2019, a hot day a day where temperatures reached 27.3 degrees Celsius and the humidex reached 31:

• Map showing temperature differences for Ottawa
• Map showing temperature differences within Ottawa’s Greenbelt

The colour codes show how surface temperatures ranged from 15 to 38 degrees Celsius across the City. The map shows cool areas include the Ottawa and Rideau Rivers and their tributaries; the Greenbelt; greenspaces, parks, natural spaces; and light-coloured surfaces including buildings with white roofs. Buildings with dark roofs, such as those found on large commercial and institutional buildings, parking lots and artificial turf show up as hot areas that absorb and retain heat.

These maps highlight areas of potential risk created by the urban heat island effect. Additional factors that influence an individual’s risk include access to air conditioning at work, school, home and during commutes, if they work or exercise outdoors, their age, and pre-existing health conditions.

How are these Urban Heat Island Maps being used?

Heat island maps show us how land use choices affect surface temperature. With temperatures expected to rise by 3.2 degrees Celsius by the 2050s and the number of days above 30 degrees Celsius expected to rise fourfold to 43 days, heat islands worsen the impact of extreme heat events. Extreme heat affects everyone, but certain people are more vulnerable to heat stress, including the very young and old, people who are pregnant, people with existing health conditions, people who work outside, athletes, people who are homeless or precariously housed, and those that don’t have good access to air conditioning.

Heat island maps can be used to guide policies and planning of the built environment. Strategies to reduce surface temperatures include tree protection and plantings. the use of vegetation on and around buildings and parking lots, and the inclusion of parks and greenspace and reflective surfaces such as light-coloured roofs.

Find out more about urban heat islands:

• Health and the Built Environment - Ottawa Public Health
• Reducing urban heat islands to protect health in Canada
• How Health Canada is collaborating with Canadian communities to reduce the urban heat island effect
• Does urban vegetation reduce temperature and air pollution concentrations? Findings from an environmental monitoring study of the Central Experimental Farm in Ottawa, Canada

Thanks to everyone who has provided input into the Climate Resiliency Strategy. We have received over 350 responses to the Ottawa resident survey so far. A summary of theses responses can be found in the Interim What We Heard Report. The key findings are also summarized below.

Key findings from Ottawa residents

• 93% of respondents are very concerned or concerned about climate change.
• The top three concerns about climate change are:
  • the increase in the number of heat waves and the number of hot days over 30 degrees Celsius (78%)
  • changes in the natural environment (73%)
  • and increased risk of flooding (71%)

• The most common impacts experienced by respondents are heatwaves (77%), changes in the natural environment (51%) and high winds/tornadoes (49%).
• When asked to describe how they’ve been affected respondents told stories of their property, health or lifestyles being impacted by extreme weather events (heatwaves, drought, flooding, tornadoes, ice storms), Lyme disease and increased in winter temperatures.
• Just over half (56%) of respondents say they are very prepared or somewhat prepared for the impacts of climate change. 30% say they are not prepared.
• Taking steps to keep safe in the sun and keep homes cool were the most common actions that respondents are already taking followed by protecting against ticks and mosquitoes. Developing an emergency preparedness plan, checking in on neighbours during extreme events and protecting against ticks and mosquitoes were the most common actions that respondents are planning to do.

The survey for residents is still open so if you haven’t already, please take a few minutes to share your thoughts. We will be updating the Interim What We Heard Report in the fall.

We also want to hear from local business owners, organizations and institutions. Has climate change impacted your operations? How are you preparing. Take the survey to tell us about your experiences.

Ottawa’s climate is already getting warmer. Between the mid-1940s and the mid-2010s the average temperature in Ottawa increased by 1.3 degrees Celsius.

This trend will continue in the future. Ottawa will be warmer year round, there will be more heatwaves and less extreme cold days.

What we are expecting

By the 2050s, under a high-emission scenario, temperature in the National Capital Region is projected to change in the following ways.

Increase in average temperatures in all seasons
The average temperature will increase by 3.2 degrees Celsius. No single season is projected to warm significantly faster than the others.

Less cold extremes
The number of days below -10 degrees Celsius will decrease by 35 per cent. That’s a decrease to 46 days per year from the current 71 days.

More warm extremes
There will be four times as many very hot days over 30 degrees Celsius. That’s an increase to 43 days per year from the current 11 days.

Increase in humidex
The number of days with high humidex levels will increase.

Shorter winters
Seasons will shift. Winter will be five weeks shorter, fall will start three weeks later and spring will start two weeks earlier.

More freeze-thaw
There will be 33 per cent more free-thaw events in winter.

You can find out more details of what to expect in the 2030s and 2080s in the Summary of the Future Climate in Canada’s Capital Region.

What are the potential impacts?

We can expect changes in temperature to have the following impacts in Ottawa:

Increase in heat related illnesses
More extreme heat means more heat related illnesses. Extreme heat can cause dehydration, heat exhaustion, heat stroke and even death. High temperatures can put everyone at risk, especially people without good access to air conditioning. Health risks are greatest for:

• infants
• older adults
• those who work or exercise outdoors
• those with pre-existing health conditions
• people experiencing homelessness
  
  

Increase in cases of Lyme disease, West Nile virus and possibly other diseases
Extended, warmer seasons means tick populations can grow, spread and be active longer. Ticks can carry Lyme Disease. Other vector borne illnesses such as West Nile virus which is spread by mosquitoes could also increase as the weather warms as well as other diseases that are not currently prevalent in our region.

Reduced winter recreation opportunities
Warmer winter temperatures mean thinner ice. Ottawa is also expected to get less snow and more winter rain. This means less opportunities for winter activities like cross-country skiing or skating. These winter activities provide immense value for locals, tourists and the economy.

Longer growing season
Longer warmer seasons could benefit agriculture, although variable precipitation and the risk of drought may cause additional challenges.

Changes in the natural environment
Warmer temperatures combined with more variable rainfall can impact the growth of trees and vegetation. Conditions may be more favourable for invasive species and other species may be at risk due to changing habitat.

Changing energy demands
The demand for energy is expected to shift seasonally as we require more cooling in the summer and less heating in the winter. In addition to reducing overall energy use in the winter, this could reduce the amount of wood burned for heat in some areas which would result in improved air quality.

Increased damage to roads and other infrastructure
More extreme heat and increased freeze-thaw cycles caused by warmer winters can cause damage to our roads and other infrastructure.

The impacts of climate change will be looked at in further detail as part of the climate vulnerability assessment.

Find out how the built environment affects surface temperature

Find out what the City is already doing to adapt to climate change.

Have your say

How will warmer temperatures affect you and your community? How can we prepare for these changes? Let us know by completing the survey.

Your input will help us assess how Ottawa is vulnerable to climate change and inform the development of the climate resiliency strategy.

Ottawa has seen increased rainfall over the past decades, especially in spring and fall. As our climate warms, these trends will continue. There will be an increase in the amount and intensity of rain and a decrease in snow.

What we are expecting

By the 2050s, under a high-emission scenario, precipitation in the National Capital Region is projected to change in the following ways.

Increase in total precipitation (except in summer)
The total amount of precipitation (rain and/or snow) will increase in spring, winter and fall by eight per cent. Rainfall in summer (June – September) will not increase.

Wet days will be wetter
Although the total annual precipitation will increase, this precipitation will be concentrated within the same number of ‘wet days’. The maximum amount of precipitation that falls in one day will increase by 15 per cent.

Decrease in total snowfall
The annual total snowfall will decrease by 20 per cent.

Shorter snow season
The first snowfall will be later in the year, and the last snowfall will be earlier. As a result, the number of days with snow cover is projected to decrease from the current 115 days to 72.

Increase in freezing rain and ice storms in winter
The colder months will likely see more freezing rain due to the increase of days around zero degrees Celsius. Freezing rain in spring and fall will likely decrease.

You can find out more details of what to expect in the 2030s and 2080s in the Summary of the Future Climate in Canada’s Capital Region.

What are the potential impacts?

We can expect changes in rain and snowfall to have the following impacts in Ottawa:

Increased risk of flooding
More intense rainfall, including rain in winter, can overwhelm sewer systems and increase the risk of flooding in our streets and homes.

More rainfall in the spring combined with rapid melting of snow can increase the risk of flooding along rivers and creeks.

Public health
Flooding and other extreme events negatively affect the mental and physical health of those directly affected and put an added strain on emergency services. Risk of injuries due to icy sidewalks may increase. Reduced snow could mean we see increases in active ways of getting around the city such as by biking, walking or rollerblading with associated public health benefits.

Reduced crop yields
More variable rainfall, including the risk of both droughts or flooding, can reduce crop yields.

Changes in the natural environment
More variable rainfall combined with warmer temperatures can impact the growth of trees and vegetation. Conditions may be more favourable for invasive species and other species may be at risk due to changing habitat.

Reduced winter recreation opportunities
Reduced amount of snow combined with warmer weather will negatively affect winter recreation activities such as cross-country skiing and snowshoeing. These winter activities provide immense value for locals, tourists and the economy.

The impacts of climate change will be looked at in further detail as part of the climate vulnerability assessment.

Find out what the City is already doing to adapt to climate change.

Have your say

How will changes in rain and snow affect you and your community? How can we prepare for these changes? Let us know by completing the survey.

Your input will help us assess how Ottawa is vulnerable to climate change and inform the development of the climate resiliency strategy.

Ottawa’s weather is becoming more variable and unpredictable. In recent years we have experienced more extreme heat, wind, rain and snow. Climate science tells us that these trends will continue in the next decades.

Some examples of extreme weather events in Ottawa include:

• Five successive ice storms in January 1998, which caused massive damage to trees and electrical infrastructure causing widespread power outages and a shutdown of activities across Ottawa and the region for several weeks
• Over 50 cm of snow in February 2016, which caused closures throughout the city and set a new record for the biggest snowfall in a single day
• Significant flooding along the Ottawa River in the spring of 2017 and 2019 resulted in extensive property damage and health concerns
• Tornadoes in 2018 and 2019 caused extensive damage to property and power outages.
• A prolonged extreme heat event that latest six days in July 2018. On Canada Day, at the hottest time of the day, humidex levels made it feel like 47 degrees Celsius.

What we are expecting

By the 2050s, under a high-emission scenario, we can expect:

• More freezing rain, particularly in the winter
• Favourable conditions for ice storms or severe snow storms, tornadoes and high wind gusts, droughts and wildfires

What are the potential impacts?

Public health and safety
Extreme events such as ice storms, tornadoes, floods and wildfires greatly affect the mental and physical health of those directly impacted and can have significant financial costs. They can cause extended power outages and put added strain on emergency services and costs to the City.

Damage to property and other infrastructure
Extreme events damage property and other infrastructure such as roads, pathways and communication and power lines. This is expensive to repair and can disrupt lives, local businesses and City services.

The impacts of climate change will be looked at in further detail as part of the climate vulnerability assessment.

Find out what the City is already doing to adapt to climate change.

Have your say

How will increased extreme weather events affect you and your community? How can we prepare for these changes? Share your ideas by completing the survey.

Your input will help us assess how Ottawa is vulnerable to climate change and inform the development of the climate resiliency strategy.

The Climate Resiliency Strategy will review the impacts of climate change, assess where the City is vulnerable and prioritize solutions. The City has been addressing climate change risks for many years, including the following initiatives:

• An Emergency Management Plan to prepare and respond to the needs of the community during a major emergency such as flooding, while still ensuring continuation of essential services
• Environmental health education, awareness and response plans to reduce climate related illnesses and deaths associated with ultra violet radiation, extreme heat and humidity, cold weather, poor air quality (including wildfire smoke), flooding, Lyme disease and West Nile virus.
• Applying a climate and health lens to the new Official Plan (policies that guide the building of the city) and its supporting documents to build energy and climate resiliency into future growth and development. The new Official Plan integrates climate change mitigation and adaption policies throughout. For example, it includes revised policies to reduce the impacts of the urban heat island effect, reduce risks in areas vulnerable to flooding and protect our natural and agricultural areas.
• Raising awareness of the link between health and the built environment and highlighting how residents can get involved to make changes in their communities to become more resilient to climate change.
• Using urban heat island maps to better understand what areas are impacted by hot weather, and to inform policies that will reduce the urban heat island effects to better protect public health.
• Supporting community gardens to encourage local production of food
• Building our infrastructure to be resilient in future climate conditions such as extreme weather, greater rainfall and higher temperatures. For example:
  1. new City sewers are designed to handle larger rainfall events to reduce the risks of flooding.
  2. the City’s wastewater treatment plant is being upgraded to permit the plant to operate independent of the utility grid, using power produced on site to so it can remain operational in the event of a sustained power failure.
  3. using asphalt that is more resistant to temperature fluctuations for roads, pavement and parking lots
  4. the new Combined Sewage Storage Tunnel will greatly reduce the frequency of sewage overflows during storms from entering the Ottawa River and reduce the risk of basement flooding in downtown neighbourhoods.
  5. flood response plans are in place at the City’s two water purification plants to protect this critical infrastructure during a flooding event along the Ottawa River, in order to ensure continued drinking water supply
• Growing Ottawa’s urban forest and making it healthier, more diverse and resilient through the Urban Forest Management Plan.
• Supporting homeowners with grants for backwater valves through the Residential Protective Plumbing Program
• Supporting farmers to adopt new technologies that protect soils and enable them to manage variable rainfall events through the Rural Clean Water Program
• Promoting sustainability and building resiliency in the agriculture and agri-food industry through innovation and knowledge transfer at the Ottawa Smart Farm, which focuses on leveraging technology to help producers optimize their efforts and overcome challenges such as changes in growing seasons and extreme weather events.