The impacts of climate change along the East Coast may be less severe than in most other regions. Atlantic Canada is actually experiencing a cooling trend. However, the region is particularly vulnerable to rising sea levels.
- Increased coastal erosion, sedimentation, flooding of low-lying habitats, shrinking of tidal flats and nesting beaches needed by shorebirds, and submersion of barrier islands vital to breeding raptors and colonial birds are among the effects of sea-level rise.
- Most at risk are salt-marshes. These coastal wetlands have adapted to a unique mix of fresh and salt water. Too much salinity could throw them off balance and harm the habitat of a wide range of species, particularly fish and waterfowl.
- Heavier rainfall would increase the volume of run-off polluting bays and estuaries that provide key stopovers for migratory birds and nourish and feed countless species of molluscs, crustaceans, and fish.
- Changes in sea temperature would affect the range, distribution, and food supplies of sea-bird and marine-mammal populations.
- Heightened storm intensity, frequent fires, and other ecological pressures would increase the die back of coniferous trees and promote a transition from boreal to mixed and temperate forests.
Great Lakes-St. Lawrence Region
Climate change models predict major impacts on this region's lands and waters:
- Average temperatures could rise by 2 to 5°C while precipitation could increase by up to 25 percent by the end of this century.
- More days when heat stress and air pollution threaten the health of wildlife and humans, changes in forest composition due to shifting vegetation zones, increases in the frequency and severity of forest fires, the northward extension of agriculture, and a longer growing season are among the changes expected on land. Significant declines in the populations of neotropical migratory birds, including many wood-warbler species, could result.
- As the region warms up, the temperatures of lakes, streams, and rivers will rise and much more water will evaporate. The levels of the Great Lakes and St. Lawrence River could fall by a metre in 30 years, reducing the volume of water that flows through the system and circulates oxygen to biologically productive zones.
- These changes will benefit some aquatic species and spell disaster for others. Cold-water fish, like salmon and trout, could suffer substantial loss of both habitats and populations. Such species at risk as the spotted turtle and swamp rose-mallow could see their habitats dry up while the nesting sites of waterfowl become more accessible to predators in Great Lakes marshes.
Climate change could impact dramatically on British Columbia and the Yukon:
- Higher air temperatures could result in droughts in southern coastal and interior zones; cause landslides by melting glaciers and permafrost in northern and mountainous areas; reduce the flow of rivers and streams; make forests drier and more defenceless against pests, diseases, and fire; and imperil wildlife on land and in water.
- Warmer ocean temperatures could result in shifts in the ranges, spawning times, and food supplies of marine species, like Pacific salmon, thereby depriving terrestrial species, like bears and bald eagles, of nourishment.
- Rising sea levels could threaten such coastal zones as the Fraser River delta with floods and erosion.
- Increasing rain and snow could cause flooding throughout the interior.
The consequences of climate change in Canada's Prairies could be severe:
- Rising temperatures, decreasing rainfall, greater rates of evaporation, and drier soils will mean habitat loss both on land and in water.
- Warmer weather may prolong the growing season and expand agriculture further north. It could also cause longer, more frequent droughts, diminished crop yields, and the spread of desert-like conditions over part of the southern Prairies.
- Widespread fires in the boreal forest region may cause the northward expansion of grasslands and shrink the habitat of the woodland caribou and many other species.
- More than 50 percent of Prairie potholes could disappear. These ephemeral wetlands are key breeding habitats and migratory stopovers for Canadian ducks, including mallards, widgeons, and pintails, and their loss would come as a brutal blow not only to waterfowl but also to reptiles, amphibians, and mammals.
Western Mountain Region
The Rockies' extremes of climate and altitude make them particularly prone to the effects of climate change:
- As temperatures rise, low-elevation glaciers are rapidly melting and may disappear or cause landslides that put wildlife habitat at risk; plant and animal species are shifting upward, for example, sagebrush is replacing glacial meadows, and life forms restricted to the highest peaks are being displaced by others moving up from below.
- Increasing precipitation means deeper snow, which could make it more difficult for animals like deer and elk to forage for food and drive them into valleys where they are more vulnerable to car and train collisions and predator attacks.
Boreal Forest Region
Scientists predict that this northern region — comprising one-third of the planet's forests — will be one of the areas most affected by climate change:
- Dry, warm weather could alter the ecosystem, making the forest fire season weeks longer, sparking more frequent and severe "monster blazes," and doubling the area burned each year. Rising temperatures could also result in more frequent and deadly attacks by forest pests, including spruce budworm and bark beetle.
- The species composition of the forest could change as conditions suitable for the growth and regeneration of pine, spruce, fir, and other temperature-sensitive trees continue to shift.
- The timberline could move hundreds of kilometres further north, pushing the tundra back to the Arctic Islands and reducing it to one- to two-thirds its current size.
- As evergreen trees lose ground to hardwoods in the region's lower latitudes, losses from the southern margin of the forest will likely exceed the gains in the north.
- More than half of the boreal forest could vanish in the next hundred years due to climate change, imperilling boreal chickadees, pine martens, spruce grouse, and countless other species whose survival depends on this vast ecosystem.
Arctic Ocean Region
The far-reaching impacts of climate change will be felt nowhere greater than in Canada's Arctic, one of the fastest-warming regions on Earth:
- As temperatures rise, climatologists anticipate not only the shrinking of the Arctic tundra but also the shrinking of the Arctic sea ice. This frozen platform is integral to the lives of a huge array of species, such as walruses, seals, and polar bears, that feed, travel, and breed on its vast expanses. Algae living under the sea ice are the foundation of an ocean food chain that supports plankton, copepods, fish, sea birds, and mammals. The average thickness of the sea ice has shrunk by 40 percent in the past three decades, jeopardizing the future of this web of life.
- Among the species affected most is the black guillemot, a sea bird whose populations have been plummeting since 1990 as the melting of sea ice increases the distances it must fly to forage for food.
- Likewise, the polar bear faces the loss of the frozen habitat it requires to hunt for ringed seals, its principal prey. As the climate gets warmer, the sea ice could break up several weeks earlier than normal in spring, reducing the time in which bears can fatten up prior to summer, when they usually fast. Unseasonable warmth could also cause the snow dens of ringed seals to collapse, reducing their pup's chances of survival and depriving polar bears of food. With lower body weight, mother bears will have more difficulty nursing their cubs. Biologists have already noticed a sharp decline in the birth rates of some populations and suspect that the physical condition of animals is worsening.
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