What this lesson teaches
I can trace how climate change affects oceans, the atmosphere and living things.
Syllabus K335, Topic 3.2, Key Question 3. How might climate change affect natural systems?
Make a guess
As the climate warms, a plant that lives near a mountain top needs cooler conditions. What is its biggest problem?
- It can easily move to the poles instead.
- There is no higher ground to move up to.
- Warming helps plants grow faster, so it will do well.
- Nothing, because mountain tops stay cold enough.
Show the answer
There is no higher ground to move up to.
Warming shifts suitable conditions uphill. On a mountain top, the habitat runs out, so the species has nowhere to go.
Warming changes heat, rain and the timing of seasons, and some plants and animals cannot move or adapt fast enough.
Warming increases evaporation. At higher temperatures, more water vapour can be present before the air is saturated. So where moisture is available, heavy rain can become heavier. Elsewhere, more evaporation and less reliable rain make droughts worse. A stronger water cycle can make some places wetter and others drier.
Each species needs the right conditions to survive and breed. Warming shifts those conditions towards the poles or uphill, and changing rain alters water supply. But plants and animals may not be able to follow. Roads and broken-up habitats can block movement. On a mountaintop, there is no higher ground to reach.
Seasonal timing can go wrong. Flowers, insects and breeding birds may respond to warming at different speeds. A species can then miss its food source when it needs it most, such as birds hatching after their insect food has peaked. The effects spread to predators, pollination and other links in the ecosystem.
Drought slows plant growth, dries soil and stresses animals. Hot, dry weather helps wildfires spread where there is fuel and a spark. Too much rain waterlogs and erodes soil, floods habitats and can trigger landslides. Some species in cold regions may gain longer growing seasons at first, but water, nutrients and heat extremes still limit growth.
- Water cycle
- Some places get heavier rain, others worse drought.
- Species shift
- Suitable conditions move towards the poles or uphill.
- Timing mismatch
- Food may peak before animals need it.
Step by step
Conditions change
Heat, rain and extremes change.
Species respond
Habitats shift, but movement and adaptation have limits.
Links break
Food, breeding and pollination fall out of step.
Worked example: Why rainfall totals are not enough
Two years can have the same total rain. In one, long dry spells are broken by violent downpours. Plants suffer between storms, and fast runoff means little water soaks in. So timing and intensity matter too.
Watch out for this
Every species can simply move towards the poles as it warms.
Barriers, lack of land and the speed of change can stop them. Their food and partners may not move with them.
Check your understanding
Why can the same yearly rainfall total have different effects on plants?
- Yearly totals are measured badly, so they mislead us.
- Plants respond to the yearly total, so the effects are the same.
- Timing and intensity change how much water soaks in.
Show the answer
Timing and intensity change how much water soaks in.
Yes. Long dry spells and sudden downpours stress plants.