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B. Physical Geography and Physical Processes in Canada · Canada's Physical Environment: Landforms, Climate, Hazards and People

Climate Change in Canada: Changing Processes and Their Consequences

B2.4 B1.4 A1.2 A1.3About 75 minutes
Learning goals
  • I can explain how climate change is altering physical processes in Canada (temperature, precipitation, ice, permafrost, sea level).
  • I can analyse environmental, economic, social and political consequences of these changes for Canada.
  • I can explain why relative sea level is rising in some places and falling in others.
  • I can tell evidence from opinion and identify reliable sources about climate change.

Words to know

greenhouse effect
The warming of Earth's surface because gases in the atmosphere (such as carbon dioxide, methane and water vapour) trap heat.
climate change
A long-term change in climate patterns; today, mainly the warming caused by human greenhouse gas emissions.
greenhouse gas
A gas that traps heat in the atmosphere, such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide.
relative sea level
Sea level measured against the land at a particular place; it changes if the sea rises or falls, or if the land rises or sinks.
active layer
The top layer of ground above permafrost that thaws each summer and refreezes in winter.
Arctic sovereignty
Canada's legal authority over its Arctic lands and waters.
Northwest Passage
The sea route through Canada's Arctic islands connecting the Atlantic and Pacific oceans.
food security
Having reliable access to enough affordable, healthy food, including culturally important foods.

A coastline washing away

In Tuktoyaktuk, Northwest Territories, on the Arctic Ocean, the shoreline is eroding as thawing permafrost and stronger waves (with less protective sea ice) eat away at the land; some buildings have had to be moved. In the Prairies, farmers plan for longer growing seasons but worry about drought. In Atlantic Canada, coastal towns face higher storm surges. In Ontario, ski hills and outdoor rinks see shorter seasons.

Expectation B2.4 asks you to analyse environmental, economic, social and political consequences for Canada of changes in some of the Earth's physical processes, including climate change. This lesson covers the consequences; the next lesson covers how communities respond.

What is changing, and why

Burning coal, oil and natural gas, clearing forests and some farming practices add greenhouse gases to the atmosphere. The concentration of carbon dioxide has risen from about 280 parts per million before the Industrial Revolution to more than 420 ppm today. These gases trap more heat, strengthening the natural greenhouse effect.

Changes already measured in Canada (Canada's Changing Climate Report, 2019, and later federal reports):

  • Temperature: Canada's average annual temperature rose about 1.7 °C from 1948 to 2016, about twice the global rate; northern Canada rose about 2.3 °C, roughly three times the global rate. Winters are warming fastest.
  • Precipitation: generally increasing, with more falling as rain rather than snow, and more intense heavy-rain events expected.
  • Snow and ice: shorter snow-cover seasons; less Arctic sea ice, especially in late summer; most glaciers in western and northern Canada are shrinking.
  • Permafrost: warming and thawing in many areas, causing ground to sink and slump.
  • Oceans: warming, losing oxygen and becoming more acidic as they absorb CO₂.
  • Sea level: global sea level is rising as ocean water warms and expands and land ice melts. Relative sea level along Canada's coasts depends on whether the land is rising or sinking (see the diagram).
  • Extremes: more frequent and intense heat waves; longer and more severe fire seasons in many regions.
0.00.51.01.52.02.5about 1.7 °CCanada (whole country)about 2.3 °CNorthern Canadawarming, 1948–2016 (°C)Source: Canada's Changing Climate Report (2019). Canada warmed about twice the global rate;northern Canada about three times.
Canada's warming from 1948 to 2016 (Canada's Changing Climate Report, 2019). The North has warmed faster than the country as a whole, mainly because of feedbacks like the ice-albedo feedback.

Connecting back: relative sea level

Remember isostatic rebound from the glaciers lesson? Around Hudson Bay, the land is still rising faster than the sea, so relative sea level there is actually falling. In much of Atlantic Canada, the land is slowly sinking (part of the long adjustment after the ice sheets), so relative sea level is rising faster than the global average. The same global change has opposite local effects. That is spatial significance in action.

Halifax, N.S.landsealand slowly sinkingsea risingrelative sea level rises fasterChurchill, Man. (Hudson Bay)landsealand rising (rebound)sea risingrelative sea level fallsRelative sea level = sea change + land change. Schematic, not to scale.
Relative sea level depends on what the sea AND the land are doing (schematic, not to scale). Halifax faces faster relative sea-level rise; parts of Hudson Bay see relative sea level falling.

Consequences for Canada

Environmental

  • Species ranges shift north and upslope; southern species arrive, and cold-adapted species (for example, those depending on sea ice, such as polar bears and ringed seals) lose habitat.
  • Longer, more intense wildfire seasons in many regions; insect outbreaks such as the mountain pine beetle spread when winters are too mild to kill them.
  • Permafrost thaw releases carbon and methane, which can add to warming (another feedback), and changes lakes, rivers and land.
  • Warmer rivers stress cold-water fish such as salmon.

Economic

  • Rising costs of disasters: floods, fires, storms and damaged infrastructure.
  • Northern infrastructure: thawing permafrost damages roads, runways, pipelines and buildings; winter (ice) roads that supply mines and communities can be open for shorter periods.
  • Agriculture: a longer growing season could allow new crops farther north, but more drought and heat stress could hurt yields in some places.
  • Shipping: less sea ice could open the Northwest Passage more often, a possible new trade route, but with risks of accidents and spills in a remote area.
  • Tourism and recreation: shorter ski and skating seasons in the south; changes for northern tourism.

Social

  • Health: heat waves are dangerous, especially for older adults and people with health conditions; wildfire smoke affects air quality far from the fires.
  • Inuit and northern communities: less predictable sea ice makes travel for hunting and visiting more dangerous; changes in wildlife affect food security and cultural practices.
  • Displacement: erosion and flooding can force communities or neighbourhoods to move.
  • People can feel anxiety or grief about environmental change, which is why acting together and taking part in solutions matters.

Political

  • Arctic sovereignty: Canada considers the Northwest Passage to be Canadian internal waters; some other countries, including the United States, consider it an international strait. More open water raises the stakes.
  • International agreements: Canada is part of the Paris Agreement (2015) and has a legislated goal of net-zero emissions by 2050.
  • Who decides and who pays? Governments, industries, provinces and Indigenous governments debate policies, costs and responsibilities.
Changes in Earth'sphysical processesEnvironmentalspecies shift northpermafrost thaw, less sea icelonger fire seasonsEconomicdisaster and repair costsnew shipping routesshorter winter-road seasonSocialheat and smoke harm healthunsafe ice for travelfood security in the NorthPoliticalArctic sovereigntyinternational agreementswho pays for adaptation?
A consequences web. One set of physical changes leads to environmental, economic, social and political consequences, and many of them are linked to each other.
Worked example

Modelled example: Classify and connect consequences

For the physical change "Arctic sea ice is shrinking", give one consequence of each type and show one link between them.

  1. Environmental: polar bears and seals that depend on sea ice lose hunting and resting habitat.
  2. Economic: longer ice-free seasons could allow more shipping through the Northwest Passage.
  3. Social: Inuit hunters face less predictable and less safe ice for travel, affecting food security and culture.
  4. Political: more ships increase debate over whether the Northwest Passage is Canadian internal waters or an international strait.
  5. Link: more shipping (economic) → more pressure on Canada to enforce rules in the Arctic (political) → more need to protect wildlife and communities from spills (environmental and social).

One physical change produces consequences of all four types, and they are interconnected.

Worked example

Worked example: Estimating relative sea-level rise

Suppose the sea near a Nova Scotia town is rising 3 mm per year and the land is sinking 1 mm per year. Estimate the relative sea-level rise over 50 years. Then do the same for a Hudson Bay town where the sea rises 3 mm per year but the land rises 9 mm per year.

  1. Nova Scotia: relative change = sea rise + land sinking = 3 + 1 = 4 mm per year.
  2. Over 50 years: 4 × 50 = 200 mm = 20 cm higher.
  3. Hudson Bay: relative change = 3 − 9 = −6 mm per year (the land rises faster than the sea).
  4. Over 50 years: −6 × 50 = −300 mm: relative sea level falls about 30 cm.

The Nova Scotia town sees relative sea level rise about 20 cm; the Hudson Bay town sees it fall about 30 cm. (These are simplified example numbers; real rates vary from place to place and over time.)

🔎 Geographer's toolkit: evidence or opinion? (A1.3)

Climate change is a topic where you will meet strong opinions online. Separate evidence from opinion:

  • Evidence comes from measurements and peer-reviewed science, summarized by bodies such as the Intergovernmental Panel on Climate Change (IPCC), Environment and Climate Change Canada and Natural Resources Canada.
  • Opinion is someone's view of what should be done. Opinions about solutions can reasonably differ; the basic evidence that the climate is warming and that humans are the main cause is supported by an overwhelming body of scientific research.
  • Watch for cherry-picking (one cold day "disproves" warming), outdated sources and sources with a financial interest in one answer.
Hands-on activity

Sea ice vs land ice

You need: two clear cups or jars, water, 6 ice cubes, a small flat stone or an upside-down small plastic container (the "land"), a marker or tape.

  1. Cup A (sea ice): fill halfway with water, add 3 ice cubes, then mark the water level.
  2. Cup B (land ice): put the stone in the cup so it sticks up above the water. Fill with water to the same level as Cup A, then put 3 ice cubes on the stone, above the water. Mark the water level.
  3. Wait until all the ice melts. Mark the new water levels.
  4. Explain: Which cup's water level rose? Why? Which kind of ice (sea ice in the Arctic Ocean, or glaciers and ice sheets on Greenland and in the Canadian Arctic islands) adds to sea-level rise?

What to look for: Cup A's level stays about the same (floating ice already displaces its own weight of water); Cup B's level rises (melting land ice adds new water to the sea). Sea-ice loss matters mainly for albedo, habitat and travel; land-ice loss raises sea level. (Thermal expansion of warming ocean water also raises sea level.)

Just for fun

Funny but true: along parts of Hudson Bay, the land is rising out of the sea so quickly, still bouncing back from the weight of ice-age glaciers, that the local sea level is going down even while global sea level goes up. The land there is basically still stretching after being squashed under a giant ice sheet for thousands of years.

Your turn

1

According to Canada's Changing Climate Report (2019), how much did Canada warm from 1948 to 2016, and how does that compare with the global rate?

2

Name four physical processes that climate change is altering in Canada.

3

Give one environmental, one economic, one social and one political consequence of climate change for Canada.

4

Why is relative sea level falling around parts of Hudson Bay?

5

Why does thawing permafrost matter for buildings and roads?

6

Why can shorter winter-road seasons hurt northern communities and mines?

7

Which melting ice raises sea level: Arctic sea ice or land glaciers? Why?

More practice: warm-up

1

What is a greenhouse gas? Name one.

2

About what was the CO₂ concentration before the Industrial Revolution?

3

What is the Northwest Passage?

4

What year was the Paris Agreement adopted?

5

What is Canada's legislated emissions goal for 2050?

More practice: on your own

1

Explain how climate change could be both good and bad for Prairie agriculture.

2

How does climate change affect food security in Inuit communities?

3

Why do scientists say permafrost thaw can be a feedback?

4

A website argues climate change isn't happening because last winter was very cold where the author lives. Identify the flaw.

5

Explain how shrinking sea ice connects the economic and political consequences of climate change.

Challenge

1

A coastal town's tide gauge shows relative sea level rose 32 cm over 100 years. Scientists estimate the land sank about 15 cm in that time. How much of the rise was due to the sea itself? What does this mean for planning?

2

Rank the four types of consequences (environmental, economic, social, political) for a small Arctic coastal community from most to least serious, and justify your ranking. (There is no single right answer.)

3

Explain why winters warming faster than summers matters for at least three physical processes in Canada.

Check your understanding

Quiz

1.

Compared with the global average, Canada has warmed about:

2.

Why is relative sea level rising faster in parts of Nova Scotia?

3.

Which is a POLITICAL consequence of climate change in Canada?

4.

Which melting ice adds the most to sea-level rise?

5.

Thawing permafrost can speed up climate change because it:

6.

Which is the best evidence for long-term climate change?

For parents and teachers

Big idea: B2.4 asks students to analyse environmental, economic, social and/or political consequences for Canada of changes in the Earth's physical processes, including climate change, and to assess mitigation and adaptation (next lesson). This lesson builds on B1.4 (global systems) and the glaciers lesson (isostatic rebound).

Common difficulties:

  • Weather vs climate. Keep returning to "long-term averages".
  • Sea ice vs land ice. The cup experiment makes this concrete.
  • Feeling overwhelmed. Climate change can cause worry. Balance the consequences with the next lesson's focus on what communities are doing; emphasize that informed people can take part in solutions.

How to help: Read a news story about a climate impact in Canada together and classify its consequences (environmental, economic, social, political). Check the source using the evidence-or-opinion questions.