B. Diversity of Living Things · Diversity of Living Things

Climate Change and the Diversity of Living Things

B1.2 A1.3 A1.8About 75 minutes

Learning goals

I can analyse how climate change affects biodiversity through range shifts, habitat loss, timing mismatches and extreme water conditions.
I can identify the traits that make species more or less vulnerable to climate change, with Canadian examples.
I can calculate and interpret the rate of a range shift from data.
I can evaluate strategies that help biodiversity adapt, including the role of Indigenous knowledge.

Words to know

range shift
A change in the geographic area where a species lives, often northward or uphill as climates warm.

phenology
The timing of seasonal biological events, such as leaf-out, flowering, egg-laying and migration.

phenological mismatch
When the timing of two linked events (e.g. food supply and the needs of young) drifts apart.

climate refugium (plural: refugia)
An area where conditions stay suitable for a species even as the surrounding climate changes.

habitat connectivity
How well patches of habitat are linked so that species can move between them.

specialist / generalist
A species with narrow needs (food, habitat, temperature) / a species that can use many foods and habitats.

assisted migration
Deliberately moving a species to a new area where the future climate is expected to suit it.

A warmer Ontario

In Grade 9 and Grade 10 you learned how burning fossil fuels and clearing forests strengthen the greenhouse effect, and you used indicators (temperature records, sea ice, ice cover on lakes, earlier springs) to show that the climate is changing. Canada is warming about twice as fast as the global average, and northern Canada even faster.

The curriculum asks you to analyse the impact climate change might have on the diversity of living things, including habitat change and extreme water conditions such as drought and flooding. This lesson connects climate science to everything you have learned in this unit.

1. Range shifts

Each species has a range of temperatures and conditions it can tolerate. As climate warms, suitable conditions move north (and uphill). Species that can move follow them:

The Virginia opossum and the southern flying squirrel have spread north in Ontario in recent decades.
Southern flying squirrels moving north now overlap with northern flying squirrels, and researchers have documented hybrids between the two species in Ontario.
Blacklegged ticks, which carry Lyme disease bacteria, have expanded across much of southern and eastern Ontario.

But the southern edge of a range can shrink as it becomes too warm, and species that live at the edge of the continent or on mountaintops have nowhere to go. Arctic species are especially at risk because there is no "further north" to move to.

A schematic range shift. As the climate warms, a species gains new habitat at its northern edge and loses habitat at its southern edge. The new range may also overlap with other species, creating new competition or even hybridization.

Worked example

Let's calculate the speed of a range shift

The northern edge of a bird species' breeding range was at 45.0° N in 1980 and at 46.2° N in 2020. One degree of latitude is about 111 km. How fast did the edge move?

Change in latitude = 46.2° − 45.0° = 1.2°.
Distance = 1.2 × 111 km ≈ 133 km.
Time = 2020 − 1980 = 40 years.
Rate = 133 km ÷ 40 years ≈ 3.3 km per year.
Precision: the edge position is uncertain by tens of kilometres, so "about 3 km per year" is a fair summary (A1.13).

About 3.3 km per year northward (roughly 130 km in 40 years).

2. Habitat loss and change

Sea ice: polar bears hunt seals from sea ice. In western Hudson Bay, near Churchill, Manitoba, the ice now breaks up earlier in spring and forms later in fall, so bears spend longer on land without hunting. This population has declined since the 1980s.
Cold water: brook trout and lake trout need cold, oxygen-rich water. Warmer summers make the warm surface layer of lakes thicker, while the cold bottom layer shrinks and can run short of oxygen, squeezing these fish into less habitat.
Permafrost and peatlands: thawing ground changes northern wetlands and forests.
Pests and disease: cold winters once killed most mountain pine beetle larvae in British Columbia. A run of mild winters helped an outbreak that killed pine forests over millions of hectares. Shorter, milder winters also help winter ticks, which can heavily infest moose.

3. Timing (phenology) mismatches

Many species time their life cycles using cues. Plants and insects often respond to temperature, while many migratory birds respond to day length, which climate change does not alter. When springs warm, leaves and caterpillars may peak earlier, but birds arrive and raise chicks at their usual time. Nestlings then hatch after the food peak and may go hungry. Studies of insect-eating songbirds in Europe have shown this kind of mismatch.

A model of phenological mismatch. In the past, the peak of caterpillars matched the time when nestlings needed the most food. With warmer springs, caterpillars peak earlier, but the birds, timing nesting by day length, do not shift as much, leaving a gap.

4. Extreme water conditions

Climate change is making droughts and heavy rainfall more frequent or intense in many regions.

Drought dries out vernal pools and small wetlands that frogs and salamanders use to breed, lowers stream flows, and warms the remaining water. It also raises the risk of wildfire: Canada's 2023 wildfire season burned more than 15 million hectares, the most on record.
Flooding washes out nests of shoreline and ground-nesting birds and turtles, erodes stream banks, and carries sediment and fertilizer into lakes, which can trigger algal blooms that reduce oxygen.
Changing lake levels expose or drown shoreline wetlands.
In the oceans, warming and acidification (CO₂ dissolving in seawater) harm shell-building animals and coral reefs.

Trait	More vulnerable	Less vulnerable
Diet and habitat	specialist (e.g. needs sea ice, cold water)	generalist (eats many foods, uses many habitats)
Range	small or at a geographic limit (Arctic, mountaintops)	large, with room to move
Dispersal	slow-moving, poor disperser (salamanders, many plants)	mobile (many birds, flying insects)
Reproduction	slow (few young, long generations)	fast (many young, short generations)
Temperature tolerance	narrow	broad
Current status	already rare or at risk	abundant

Traits that make species more or less vulnerable to climate change. Climate change tends to favour generalists, including many invasive species.

Worked example

Let's assess a species' vulnerability

Use the table to assess two Ontario species: (a) the brook trout, which needs cold, clean streams, cannot cross warm stretches of river, and is popular with anglers; (b) the raccoon, which eats almost anything and lives in forests, farms and cities.

(a) Brook trout: specialist for cold water, limited dispersal (warm water and dams block movement), narrow temperature tolerance. → High vulnerability, especially at the southern edge of its range.
(b) Raccoon: generalist diet and habitat, mobile, broad tolerance, abundant. → Low vulnerability; its range may even expand north.
General pattern: climate change can reduce overall biodiversity while some generalists increase, making ecosystems more alike and less diverse.

Brook trout: highly vulnerable. Raccoon: low vulnerability, and possibly a climate "winner."

5. Helping biodiversity adapt

Cut emissions to slow warming (the most important long-term action).
Protect and connect habitat: wildlife corridors, protected areas and riparian (streamside) buffers let species move to new ranges. Shade from streamside trees keeps trout streams cooler.
Protect climate refugia, such as deep cold lakes and cool north-facing valleys.
Reduce other stresses (pollution, invasive species, habitat loss) so populations are stronger.
Assisted migration is debated: moving tree seed sources north may help forests, but moving animals risks creating new invasive species.
Monitoring and knowledge: Inuit hunters and Elders have observed changes in sea ice, weather and wildlife for generations, and many research programs in the North now work with Inuit communities and include this knowledge alongside scientific monitoring. Citizen-science programs (bird counts, iNaturalist, frog call surveys) also track changes across large areas.

Just for fun

A funny-but-true fact: as southern flying squirrels moved north into Ontario's warming forests, they met northern flying squirrels, and researchers found hybrids. Climate change is literally rearranging who meets whom in the treetops.

Hands-on activity

Climate vulnerability scorecard

You need: internet access (with a grown-up's help), a notebook or spreadsheet.

Choose three species found in Ontario or your province, ideally one fish, one bird or mammal, and one plant or amphibian (for example: lake trout, common loon, moose, wood frog, Blanding's turtle, sugar maple, monarch butterfly).
For each, find reliable sources (A1.3): government wildlife pages, conservation organizations, university or museum sites. Record the source, author and date.
Score each species from 1 (low) to 3 (high) on the six traits in the vulnerability table. Add the scores (6 to 18).
For your most vulnerable species, describe two specific climate impacts (range shift, habitat loss, mismatch, drought, flooding, pests) and suggest two actions that would help it.
Note any trait where your sources disagreed or the evidence was weak, and explain how that affects your confidence (A1.8).

What to look for: scores supported by evidence from sources (not guesses); specific impacts linked to each species' biology; realistic actions; honest discussion of uncertainty.

Your turn

Name four ways climate change can affect biodiversity.

Why are Arctic species especially vulnerable to warming?

Explain a phenological mismatch with an example.

How can drought reduce amphibian diversity?

Why did mild winters help the mountain pine beetle?

Which is more vulnerable, a generalist or a specialist? Why?

Give two actions that help species adapt to climate change.

More practice: warm-up

What is phenology?

Which direction do most range shifts move in the Northern Hemisphere?

Name one species that has expanded north in Ontario.

What do polar bears need sea ice for?

What is a climate refugium?

More practice: on your own

A plant's southern range edge moved from 43.5° N to 44.3° N over 50 years. Calculate the rate in km per year (1° ≈ 111 km).

Why might an expanding range be bad news for other species?

Explain how planting trees along a stream can help brook trout adapt.

Explain why climate change could make ecosystems in different places more alike.

Give one argument for and one against assisted migration of a tree species.

Challenge

A frog species breeds when ponds reach 10 °C. Its main predator (a dragonfly larva) develops faster in warmer water. Predict two ways warmer springs might affect the frog population, and how you could test one prediction.

Explain how climate change and habitat fragmentation together are more harmful than either alone.

Evaluate this claim: "Canada is cold, so a few degrees of warming will only increase biodiversity here."

Check your understanding

Quiz

As the climate warms, many species' ranges in Canada are moving:

A phenological mismatch is:

Which species is likely MOST vulnerable to climate change?

Why did the mountain pine beetle outbreak in BC grow so large?

A range edge moves 2° north in 40 years (1° ≈ 111 km). The rate is about:

Which action helps species track a changing climate?

Which extreme water condition dries out breeding ponds of frogs?

For parents and teachers

Big idea (B1.2): climate change affects biodiversity through range shifts, habitat loss (sea ice, cold water), timing mismatches, extreme water conditions (drought, flooding), pests and wildfire. Specialists and Arctic species are most vulnerable. Students calculate range-shift rates, research with reliable sources (A1.3) and judge uncertainty (A1.8).

How to help: Help your teen find reliable sources for the scorecard (government, conservation, university sites). Share observations: Do you remember winters or springs differently from when you were young? (Personal memories are interesting but are not the same as data.)

Common difficulties:

Thinking warming only causes heat problems. Drought, flooding, pests and timing all matter.
Assuming all species lose. Some generalists gain, but overall diversity and unique species decline.
Latitude conversion: multiply degrees by about 111 km.

Sources: Canada warming about twice the global rate (Canada's Changing Climate Report, 2019); western Hudson Bay polar bears (Environment and Climate Change Canada); flying squirrel hybridization (Garroway et al., 2010, Global Change Biology); 2023 wildfire area (Canadian Interagency Forest Fire Centre); mountain pine beetle (Natural Resources Canada); range-shift and mismatch figures in this lesson are models or practice data.