ONTARIO REGION EXECUTIVE SUMMARY
As the likelihood of climate change resulting from human activities increases,
there is a growing need to estimate the magnitude of these changes,
determine their impacts on the environment, our society and our
economy, and identify the most effective strategies for adapting
to the anticipated changes. This report summarizes the most recent
literature describing the impacts of current climate and the potential
effects of anticipated climate change on the environment and on
those social and economic sectors in Ontario most likely to undergo
Current Climate of Ontario
Ontario's climate varies widely from season to season and from one part of the province
to another. In Northern Ontario, the climate is primarily continental,
with cold winters and mild summers. Most precipitation falls
in the form of summer showers and thunderstorms; winter snowfall
amounts can be impressive, but usually contain less water. Precipitation
amounts increase as one moves from northwest to southeast - a
reflection of the increasing influence of moisture transported
from the Great Lakes and the Gulf of Mexico. In Southern Ontario,
the climate is highly modified by the influence of the Great Lakes.
The addition of moisture from the Great Lakes in autumn and winter
increases precipitation amounts, while the heat of the Great Lakes
protects the region from the worst of winter's cold. In the spring
and summer, the cooler waters of the Great Lakes act to moderate
the oppressive heat of tropical air, which regularly approaches
the area. The combination of uniform precipitation amounts year-round,
delayed spring and autumn, and moderated temperatures in winter
and summer makes Southern Ontario's climate one of the most suitable
in Canada for both agriculture and human settlement.
Ontario experiences a variety of extreme weather events. In winter, Northern Ontario
can have prolonged periods of extreme cold. Farther south, very
heavy snow is a regular feature in the snowbelts to the lee of
Lakes Superior and Huron, and Georgian Bay; major storms lash
most parts of Ontario at least once or twice per year, with high
winds and a mix of rain, freezing rain and snow. In spring, rapid
snowmelt or ice jamming can lead to flooding of Ontario's rivers.
Spring also marks the beginning of the tornado season in Southern
Ontario, which has the highest frequency of tornadoes in Canada.
In summer, thunderstorms can produce heavy downpours, hail, damaging
winds and occasional tornadoes. Stagnant tropical air masses can
bring poor air quality, heat waves and drought. In autumn, an
early frost can damage crops, and remnants of hurricanes occasionally
produce high winds and excessive rainfalls.
Impacts of Climate
Ontario's environment, society and economy are all affected by climate.
The environment is well adapted to the current climate. Our economy
and society have also adjusted, but as our knowledge of climate
expands and our awareness of its impacts increases, further improvement
is possible. The social and economic sectors most affected by
climate include water resources, human health, the built environment,
energy, transportation, tourism and recreation, forestry, agriculture,
construction and finance. Some of the most significant impacts
are listed below.
- The major climate-dependent regional air issues
are: smog, fine particulates, acid rain, and hazardous air pollutants
(HAPs). Local pollutant concentrations depend on: weather patterns,
local and regional emission rates, and weather-dependent air chemistry.
Concentrations of smog and particulates continue to exceed ambient
air quality objectives on some days. Interannual climate variability
affects the frequency of such weather-related extremes.
- Climate affects health directly, especially in summer through heat stress.
Severe weather poses a hazard in all seasons. In addition, climate
affects health indirectly by interacting with other atmospheric
- Variability in temperature and precipit-ation causes
variations in lake levels and river flows, which affect hydroelectric
power generation. Thunderstorms, freezing rain, high winds, freeze-thaw
cycles and frozen ground affect the infrastructure of the energy
distribution system. Wind patterns and cloud cover play a significant
role in determining the feasibility of wind and solar energy.
Daily and year-to-year fluctuations in energy demand are driven
largely by temperature.
- The composition of terrestrial ecosystems
is generally determined by temperature, water availability and
soils. Aquatic ecosystems are affected by water temperature,
the distribution of freshwater, and the hydrologic cycle. Past
temp-erature changes of one degree have caused sub-stantial changes
in the home ranges of species.
- The boreal forest covers 82 percent
of the total forested area in Ontario. Climate has direct (fire
conditions and strong winds) and indirect (insects and disease)
impacts on the health of existing stands and on restocking efforts.
The forest industry is vulnerable to changes beyond the adaptive
capability of trees, which are able to withstand most natural
- Mean climate conditions and soils determine
which agricultural products will be viable in a particular area.
Year-to-year changes in productivity are governed largely by the
interannual variability of climate.
- Up to four percent of building
costs in Toronto are attributed to adaptation to current climate.
Snow loading is a key determinant of structural strength. Temperature
determines heating and cooling requirements. Precipitation amounts
affect the design of dams, sewers, and other water management
infrastructure. Freeze-thaw cycles, ultraviolet (UV) radiation
and acid rain weather exterior surfaces. Severe weather events
can damage or destroy structures. Snow and excessive rainfall
affect operations on construction sites. Variations in temperature
can cause building materials to expand and contract.
- The estimated total cost of damages (in 1989 dollars) for the major flood events
recorded in Ontario between 1837 and 1989 is between $566 million
and $1.5 billion.
- Extreme low lake levels can restrict the maximum
cargo capacity of vessels, and can increase operating costs of
ports and shipping channels. Temperatures and wind patterns affect
ice conditions, which determine the operating season of the St.
Lawrence Seaway. Colder winter temperatures require changes in
fuels and lubricants and increase maintenance costs for aircraft
and airports. Traction can be impaired by rain, snow and freezing
precipitation. Snow removal and anti-icing costs comprise a large
portion of road and airport operating budgets; some of the chemicals
that are used damage vehicles, structures and ecosystems. Weather
conditions have a major impact on flight operations, with consequences
for profitability. Road and railway infrastructure can be damaged
or rendered impassable by major winter storms, flooding and objects
felled by wind. High winds are hazardous to shipping, and can
prevent stacking of containers on trains.
- Each outdoor recreational activity has a set of climatic requirements and a level of sensitivity
to fluctuations in climatic conditions; key climate variables
are temperature, precipitation, sunshine and wind.
Future Climate of Ontario
For Ontario, results from some of the latest Global
Circulation Model (GCM) simulations of climate, with an atmosphere
containing twice the current amount of greenhouse gases, suggest
an average annual warming of some 2° to 5°C by the latter
part of the 21st century. Even if greenhouse gas amounts stabilize
at that point, temperatures would continue to increase thereafter,
with overall warming of 3° to 8°C possible. Increases
will probably be greater in the winter than in the summer. These
changes would significantly decrease the duration of the annual
snow season and lengthen the growing season. They could increase
the frequency and severity of extreme heat events in summer.
It must be remembered, however, that even the most sophisticated
GCMs do not incorporate the effects of important local climate
controls, such as the Great Lakes. For this and other reasons,
considerable uncertainty still exists about the application of
GCM results on a regional scale.
Anticipated Impacts of Future Climate
While the greatest confidence is attached to projections
of changes in temperatures, the most significant impacts are expected
to result from the changes in other climatic conditions. These
include changes in precipitation patterns, in soil moisture, and
possibly in the frequency and intensity of severe weather events.
Some of the key impacts of a changing climate are listed here.
- Changes in weather patterns may affect the frequency and intensity
of pollution episodes. Air-water partitioning of HAPs may be
affected by increased temperatures, and reduced frequency of lake
turnover. Increased summertime temperatures could increase the
volatilization of organic compounds, and the rates of chemical
reactions, which could enhance the formation of ground-level ozone.
However, these increases might be modulated by changes in cloud
cover and precipitation frequency.
- Increased heat stress, and
possible increases in the number or severity of episodes of poor
air quality and extreme weather events could all have a negative
effect on human health. A warmer climate may facilitate migration
of disease-carrying organisms from other regions.
- Average water levels of the Great Lakes could decline to record low levels during
the latter part of the 21st century. Water supply from both surface
and groundwater sources is expected to decrease in Southern Ontario;
the effect on water supply in Northern Ontario is unknown. Water
demand is expected to increase during the summer months.
- Changes in the hydrologic cycle may result in more variability in water
supply for hydroelectric power production. Energy demand is expected
to increase in the summer and decrease in the winter.
- In the Great Lakes, the warming of waters in the summer is expected to
cause fish species to shift northward. Many of the nearshore
parts of the Great Lakes and stream waters will become too warm
for salmonids in the summer, but will become optimal earlier in
the spring and later in the autumn. Changes in wetlands and littoral
areas may alter their efficacy as spawning and nursery areas.
Some wetlands could shrink or disappear, others could move or
expand, and new wetlands could be created. Increases in water
temperature in the Great Lakes could reduce the frequency of overturning,
which would seriously affect aquatic ecosystems.
- The cool temperate, moderate temperate and grassland regions are expected to expand
northwards as the boreal forest retreats. Additional damage to
forest ecosystems by pests and diseases, and increased frequency
and intensity of fires may occur. Some moose and caribou habitat
could be destroyed, leading to a decrease in the numbers of these
animals. Species currently threatened with extinction face the
greatest risk of extinction in a changing climate, while opportunities
for successful establishment of exotic species will be enhanced.
Forest industry operating costs may increase because of a shorter
winter harvesting season.
- Warmer temperatures and a longer growing
season may increase opportunities for crop selection. Productivity
in some areas may be limited by moisture rather than by temperature.
Should climate variability increase, it would increase variability
in productivity. Increased concentrations of carbon dioxide (CO2)
may improve yields and water utilization for some crop types.
- Decreased snow load may result in reduced cost of buildings and
infrastructure. More frequent freeze-thaw cycles could increase
weathering. The need for heating will be reduced, while demand
for cooling will increase. Warmer winters will lengthen the construction
season. In far Northern Ontario, degradation of permafrost may
affect the stability of existing structures and the conditions
for future construction.
- Changes in the frequency or intensity
of extreme events would have consequences for the property insurance
industry and possibly for disaster-relief agencies. Changes in
human health could affect the health and life insurance and pension
- Reduced ice on the Great Lakes is expected to increase
the length of the shipping season. Dramatically lower lake levels
would reduce the maximum capacity of vessels and could increase
operating costs for ports and shipping channels. Changes in shipping
conditions on the Great Lakes could affect demand for bulk shipment
by rail. Changes in production of climate-sensitive commodities,
such as agricultural products, could affect demand for rail and
marine transport. The need for snow removal and aircraft de-icing
could be reduced in Southern Ontario. Shorter seasons are anticipated
for winter maintenance in Northern Ontario.
- Snow conditions are expected to be less reliable for outdoor winter recreation. Increased
use of beaches and parks is possible as the annual period of favourable
temperatures lengthens; this may be limited by beach aesthetics
and water quality.
Adaptation to Climate Variability and Change
As we have seen, many aspects of Ontario's environment, economy and
society are sensitive to climate variability and anticipated changes
in climate conditions. One way Ontario could lessen the impacts
of a changing climate is to reduce known vulnerabilities to current
climate variability. In some cases, a changing climate could
necessitate additional adaptive actions. Some adaptive strategies
for climate sensitive sectors are suggested here.
- Increased use of energy-efficient cooling technologies and practices would reduce
heat stress on humans. Adjustments in the health care system
may be necessary to cope with new diseases.
- Water demand can be reduced through increased efficiencies of its delivery and
utilization. Adjustment of shoreline ecosystems and facilities
may be necessary to compensate for lower water levels.
- Energy conservation and efficiency measures should be encouraged. Water
storage could be increased to reduce the variability of water
supply for electricity production.
- Efforts to restore degraded habitats and preserve existing ecosystems should allow for expected
changes in climate and their effects on optimum ranges of species.
Where the estab-lishment of exotic species is inevitable, it may
be possible to select species that would be most beneficial to
other components of the ecosystem.
- Preservation of existing tree
stocks could be enhanced by increased public education and fire
suppression, and improved pest and disease management. When replanting,
new strains or species more tolerant of expected conditions could
be introduced. Practices may have to be tuned to optimize use
of these resources.
- Crop types could be adjusted and new agricultural
areas developed as climate changes. Crop insurance programs could
be adjusted to encourage adaptation.
- Water control structures may need to be redesigned to handle greater variability of precipitation,
including a possible increase in the intensity of extreme events.
Building codes and land-use planning regulations may need to
- Improved knowledge regarding spatial patterns of,
and trends in extreme weather events is necessary to improve estimates
of future risk. The insurance industry could have more input
into land-use planning to reduce exposure to future risks.
- Road weather information systems could be used more widely to optimize
winter maintenance operations. Cleaner energy tech-nologies would
reduce emissions of pollutants. Increased use of communications
technology could reduce the need for travel. More convenient public
transit could encourage reductions in automobile usage. Shipping
channels and ports may require increased dredging when lake levels
- Operations at recreational facilities could be diversified
to improve resilience to climate variability.
- Reducing emissions remains the best way to address air issues.
Areas Requiring Further Research
Information regarding climate change impacts, especially
on regional scales, is still somewhat inexact. Although much
more is known about the impacts of current climate variability,
there remain gaps in our knowledge in this area, too. In order
to better assess the relative magnitudes of climate impacts, and
devise effective adaptation strategies, more research is required
in all areas. Some of the key areas for future study are:
- climate and impacts modelling-increasingly accurate simulations of climate
on regional and smaller scales, and better simulations of the
hydrologic cycle, to improve our ability to quantify impacts of
- integrated air issues-the interaction of the
various air issues with climate and with each other, as well as
our understanding of their synergistic impacts on human and ecosystem
health, and on economic sectors sensitive to atmospheric stresses;
- the impact of climate on water resources-on groundwater across
Ontario, and also on surface waters in Northern Ontario;
- the climatology of severe weather and climate events-this should continue
to be refined as more data becomes available, so that sectors
sensitive to extreme events are better able to quantify risks;
- response strategy development-continued development will be possible
as the scientific foundation continues to improve.
Accessible, high-quality environmental and socio-economic data is a requisite
in order to detect climate change, to understand climate impacts,
and to formulate and execute effective adaptation strategies.
Adapting most effectively to a changing climate requires
a knowledge of how climate will change and how the changes will
affect the environment, society and the economy. However, changes
in other key variables, such as technology, personal preferences
and social values, will probably influence both the rate of climate
change and our ability to adapt to it. For this reason, the unforeseeable
future, the most prudent strategies to adopt today are so-called
"no regrets" strategies. That is, regardless of what
changes occur, these strategies will provide a net benefit to
the environment, society and the economy. Examples of no-regrets
strategies include more efficient use of energy and materials,
and improving adaptation to current climate.
For Ontario, a changing climate will present challenges for some sectors, and opportunities
for others. The present technology of climate prediction and
our knowledge of climate impacts do not allow us to make confident
estimates of losses and benefits. However, most expert opinion
suggests that climate will continue to change, and that the costs
of the impacts are likely to exceed the benefits from a warmer
climate. Therefore, a sensible approach would be to: minimize
anthropogenic forcing of climate change to the extent possible,
without unduly disrupting the very environmental, social and economic
systems we seek to preserve; and to improve our adaptation to
current climate conditions in ways that will increase our ability
to adjust to future changes.
The responsibility for action is broadly
based: the scientific community must provide advice and information;
governments must identify and eliminate barriers and disincentives
to adaptation; and those in affected sectors must educate themselves
about the risks and opportunities of a changing climate and act
Ontario Green Lane Home |
||By: Teresa Gamble, December 22, 1997
Copyright © 1997, Environment Canada. All rights reserved.