🏖 Low-lying coasts
Higher seas bring more flooding, coastal erosion and salt water getting into farmland and drinking water. Coastal cities and delta farmland are at risk.
Impacts of Climate Change » Impacts of Climate Change Now and in the Future
What you'll learn this session
Study time: 30 minutes
Cambridge spec: 5.2.1
- The present day and predicted future impacts of climate change
- Rising sea levels, higher temperatures, changing weather patterns and food production
- Impacts on water, ecosystems, health, ice and migration
- How impacts differ by scale, winners and losers, and why LICs are often more vulnerable
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Unlock This CourseClimate change affects every part of the world
The last three lessons showed that the climate is changing and that human activity is the main cause of recent warming. This lesson looks at what that means for people and places. Some impacts are happening now. Others are predicted for the future.
Key terms:
- Impact: an effect on people, the economy or the environment.
- Thermal expansion: water expanding in volume as it gets warmer.
- Heatwave: a period of unusually hot weather lasting several days or more.
- Drought: a long period with much less rainfall than normal.
- Vulnerable: likely to be harmed because there is little ability to cope.
Impacts can be sorted in three ways. Social impacts affect people's lives and health. Economic impacts affect jobs, money and businesses. Environmental impacts affect land, water, plants and animals. Impacts can also be positive or negative, and they happen at different scales: local (a village), regional (part of a continent), national (a country) and global (the whole world).
| Scale | Example impact | Type |
|---|---|---|
| Local | A village is flooded by a more intense storm | Social and economic, negative |
| Regional | A drought across a region cuts crop yields | Economic and social, negative |
| National | A country spends more on coastal defences and cooling | Economic, negative |
| Global | Sea level rises and ice sheets lose ice | Environmental, negative |
| Regional | New Arctic shipping routes open as sea ice shrinks, and cold regions need less winter heating | Economic, positive |
Rising sea levels
Sea level is rising for two reasons:
- The oceans take in heat, so the water gets warmer and expands (thermal expansion).
- Land ice, such as glaciers and ice sheets, melts and the meltwater runs into the sea.
Ice that is already floating, such as sea ice, does not raise sea level much when it melts. Only ice sitting on land adds new water.
The IPCC reports that global sea level rose by about 0.20 m between 1901 and 2018. Its projections for 2100 are given as ranges: about 0.28 to 0.55 m if emissions are very low, and about 0.63 to 1.01 m if emissions are very high (compared with 1995 to 2014). Which end we reach depends on future emissions.
🏝 Low-lying islands
Small islands have little high ground. Homes, airports and fresh water can be lost, and people may have to leave.
Higher temperatures and heatwaves
The world is about 1.1°C warmer than in 1850 to 1900. Heatwaves are becoming more frequent and more intense in many regions. The IPCC projects that global temperature in 2081 to 2100 will very likely be between about 1.0 and 1.8°C higher than in 1850 to 1900 if emissions are very low, and between about 3.3 and 5.7°C higher if emissions are very high.
- Social: heat stress and illness, especially for older people and young children.
- Economic: outdoor workers lose working hours and more energy is spent on cooling buildings.
- Environmental: more wildfires and drying soils.
Changing weather patterns
A warmer atmosphere holds more water vapour and has more energy. This leads to:
- More intense storms and heavy rainfall: more flash flooding and river flooding in some regions.
- More frequent or longer droughts: in other regions, such as parts of the Mediterranean and southern Africa.
- Shifting rainfall: wet seasons start earlier or later, and some places get wetter while others get drier.
Not every place changes in the same way, so impacts are different from region to region.
Food production: winners and losers
Food production is an important example because the impacts are mixed.
| Winners (positive) | Losers (negative) |
|---|---|
| Cooler regions, such as parts of northern Europe, Canada and Russia, may have longer growing seasons and be able to grow new crops. | Hot regions, such as parts of the tropics, may see crop yields fall because of heat stress, drought or flooding. |
| Farmers who can afford irrigation and new crop varieties can adapt. | Subsistence farmers who rely on rain have little protection when a harvest fails. |
Falling yields can push up food prices and cause hunger, which is a social and an economic impact.
Other impacts
💧 Water supply
Droughts and shrinking glaciers reduce river flow. Many people in South Asia and the Andes depend on glacier meltwater.
🐻 Ecosystems and species
Species that cannot move or adapt may be lost. Arctic animals that rely on sea ice, such as polar bears, lose their hunting platform.
🏥 Health
Heat illness rises. Mosquitoes that carry diseases such as malaria may spread to new areas as temperatures rise.
🏔 Glaciers and ice sheets
Most glaciers are shrinking, and the Greenland and Antarctic ice sheets are losing ice. Meltwater first increases river flow, then it falls as the ice runs out.
🚶 Migration
Some people may move because of sea level rise, drought or failed harvests. Views differ. Some people say richer countries should welcome people who have to move. Others say money should go on helping people stay in their homes. Some worry about pressure on housing and services in the places that receive migrants.
Why LICs are often more vulnerable
LICs often have less money for flood defences, early warning systems and healthcare, and more people depend on farming that relies on rain. So the same event can do more harm than in an HIC. HICs are not safe, however: floods, heatwaves and wildfires also cause deaths and large costs there. MICs are in between, with some resources but fast-growing cities and many people at risk.
Common mistakes
Saying all impacts are bad: some regions gain, for example longer growing seasons. Saying melting sea ice raises sea level: the causes are melting land ice and thermal expansion. Writing one fixed number for the future: the IPCC gives a range that depends on emissions.
Exam-style question
Fig. 1.1 is a table of made-up data showing the change in the yield of one crop by 2050 in three regions.
| Region | Change in crop yield by 2050 |
|---|---|
| A (cool northern region) | +12% |
| B (hot tropical region) | -15% |
| C (dry subtropical region) | -6% |
(a) Identify the region with the largest fall in crop yield. [1 mark]
(b) Give two reasons why sea level is rising. [2 marks]
(c) Explain why the impacts of climate change on food production are different in Region A and Region B. [3 marks]
(d) To what extent do LICs suffer more from the impacts of climate change than HICs? [6 marks]
Model answer
(a) Region B, with a fall of 15%. (1)
(b) Water expands as the oceans warm (thermal expansion). (1) Land ice such as glaciers and ice sheets melts and adds water to the sea. (1)
(c) Region A is cooler, so warming may lengthen the growing season. (1) Region B is already hot, so more heat can cause heat stress and drought for crops. (1) This leads to a gain in A (+12%) but a loss in B (-15%). (1)
(d) Level 3 (5 to 6 marks): a balanced, developed answer with a clear judgement. Level 2 (3 to 4 marks): several developed points, little or no judgement. Level 1 (1 to 2 marks): simple, undeveloped points.
A Level 3 answer: LICs often suffer more because they have less money for defences, warning systems and healthcare, so the same flood or drought does more harm. Many people farm for a living using rain, so a failed harvest can mean hunger and lost income, whereas HICs can afford irrigation, flood barriers and insurance. However, HICs are also affected, for example by heatwaves, wildfires and flooding that cost lives and money, and some regions may gain, for example where growing seasons lengthen. Overall, LICs are generally more vulnerable because they cope less well, although no country is free from impacts.
Exam tip
In a "To what extent" question, give points for both sides and end with a judgement that uses words such as "more vulnerable" or "less able to cope".