🌊 Rising sea levels
Warmer seas take up more space, and melting ice on land adds water to the oceans. Low-lying islands such as the Maldives and low coastal land are flooded more often. Salt water can also seep into farmland and drinking water.
Impacts on Fragile Environments » Climate Change Impacts on Places and People
What you'll learn this session
Study time: 30 minutes
Edexcel spec: 7.2 Impacts of desertification, deforestation and climate change on fragile environments (c)
- How rising sea levels and more hazards harm places and people
- How climate change changes ecosystems and jobs
- How it changes where people live and affects health and food supply
- How to read line graphs and bar charts of climate and sea level change
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Unlock This CourseClimate change is already having effects
In The Enhanced Greenhouse Effect you saw how human activity is warming the planet. This lesson looks at the negative effects that climate change is having now, on fragile environments and on the people who live in them. The spec lists six: rising sea levels, more hazards, ecosystem changes, reduced employment opportunities, changing settlement patterns, and health and wellbeing challenges, including food supply.
Fragile environments are the first to feel it. Coral reefs, polar regions, low-lying coasts and dry lands are all easily damaged when conditions change even a little.
Key terms:
- Sea level rise: the increase in the average height of the sea, caused by warm water expanding and by melting land ice.
- Hazard: a natural event that can cause harm to people or property, such as a flood or a drought.
- Ecosystem: a community of living things and the environment they live in.
- Settlement pattern: where people choose or are forced to live.
The six negative effects
⚡ More hazards
A warmer world brings more extreme weather: heatwaves, droughts, floods and stronger storms. Warm sea water gives tropical storms more energy, so coasts can face bigger storm surges.
🐠 Ecosystem changes
Species can only live within a range of temperatures. Warm water makes corals turn white, called coral bleaching, and many die. In the Arctic, sea ice is melting, so animals that hunt on the ice lose their hunting ground. Other species move towards cooler areas.
💼 Reduced employment
Jobs that depend on a steady climate are at risk. Farmers lose crops to drought and floods. Fishers lose fish when reefs die or fish move away. Tourism jobs fall if beaches wash away or reefs bleach.
🏡 Changing settlement patterns
When homes are flooded or farmland fails, people move. Some move inland or to cities. Whole communities on low-lying islands may need to relocate for good.
🏥 Health and wellbeing
Heatwaves cause heat stress. Floods spread disease through dirty water. Warmer conditions can let insects that carry disease, such as mosquitoes, live in new areas. Losing a home or a job also harms mental wellbeing.
Food supply
Food supply is part of health and wellbeing in the spec. Climate change can cut it in three ways. Drought and heat reduce crop yields. Floods and salt water ruin fields. Damaged reefs and warming seas reduce fish catches. Less food means higher food prices, and poorer families may go hungry or become malnourished.
Learn this
The effects link together. Rising seas flood farmland, which cuts food and jobs, which forces people to move. A good answer follows the chain from cause to effect to the effect on people.
Skill: reading climate and sea level graphs
The spec skill is using line graphs and bar charts that show climate and sea level change. Follow these steps.
- Read the title and axes. Check what is measured and the units, for example centimetres or °C.
- Describe the trend. Say whether the line goes up, goes down or stays level, and whether the change speeds up or slows down.
- Use figures. Quote values from the graph, with units, and work out the change.
- On a bar chart, compare the heights of the bars and name the highest and lowest.
Worked example
This is an imaginary graph for an imaginary island. A line graph shows sea level above a starting point of 0 cm: 0 cm in 2000, 4 cm in 2010, 9 cm in 2020 and 15 cm in 2030.
Question: Describe the change in sea level between 2000 and 2030. [3 marks]
Answer: Sea level rises throughout (1) from 0 cm in 2000 to 15 cm in 2030, a rise of 15 cm (1). The rise gets faster, from 4 cm in the first ten years to 6 cm in the last ten (1).
Worked example
An imaginary line graph shows average yearly temperature in a town: 14.0 °C in 2000, 14.4 °C in 2010 and 14.9 °C in 2020.
Question: Describe the change in temperature shown. [2 marks]
Answer: Temperature rises from 14.0 °C in 2000 to 14.9 °C in 2020, a rise of 0.9 °C (1). The rise speeds up, from 0.4 °C in the first ten years to 0.5 °C in the second (1).
Worked example
Another imaginary graph: a bar chart of the number of flood days a year in a coastal town: 2 days in 2000, 5 days in 2010 and 11 days in 2020.
Question: Suggest one effect of this change on people. [2 marks]
Answer: More flood days mean homes and shops are damaged more often (1), so people lose income and may decide to move away (1).
Writing about the effects
Pick an effect, then say who or what it harms and why. Use linking words such as so, which means and therefore.
Common mistakes
- Writing about the causes of climate change when the question asks for effects.
- Saying only "the sea rises". Explain what it does: floods homes, spoils farmland, forces people to move.
- Listing effects without linking them to people. This spec point is about places and people.
- Reading a graph without figures. Always quote values and units, and say if the rate speeds up.
- Writing about how we respond to climate change. That comes in a later lesson.
Exam-style question
An imaginary line graph shows sea level at a coastal town: 0 cm in 2000, 6 cm in 2010 and 14 cm in 2020.
(a) Describe the change in sea level shown on the graph. [2 marks]
(b) State two negative effects of climate change on fragile environments. [2 marks]
(c) Explain how climate change can reduce food supply. [3 marks]
Model answer
(a) Sea level rises by 14 cm, from 0 cm in 2000 to 14 cm in 2020 (1). The rise speeds up, from 6 cm in the first ten years to 8 cm in the second ten (1).
(b) Coral reefs bleach and die as the sea warms (1). Sea ice in the Arctic melts, so animals lose their hunting ground (1).
(c) Drought and heat reduce crop yields (1). Floods and salt water ruin farmland (1). Fish catches fall when reefs are damaged, so less food is available and prices rise (1).
Exam tip
In a "describe" question on a graph, quote at least two figures with units and work out the change. A trend without numbers rarely gets full marks.