The big idea: As emerging economies grow, hundreds of millions of people are joining the global middle class — households with enough disposable income to spend beyond bare survival.
This matters in geography because rising incomes change what people consume. The clearest change is diet: people eat more meat, dairy, processed food and out-of-season produce, which puts pressure on water, land and energy.
Key terms
- Global middle class — households with enough income for discretionary spending (often roughly $11-110 a day).
- Disposable income — money left after paying for essentials, which can be spent or saved.
- Dietary shift (nutrition transition) — the move from a starch-based diet to one richer in meat, dairy, sugar and processed food as incomes rise.
- Resource footprint — the water, land and energy needed to produce what a person consumes.
Why examiners care: Paper 2 repeatedly asks you to explain how a growing middle class changes diets and raises water use, and to judge (To what extent) whether this is the chief threat to resource security. The chain you must master is: more income -> richer diet -> bigger resource footprint.
The main reasons diets change
- Affordability — with more income, families can afford meat, dairy and fresh produce, not just cheap staples like rice or maize.
- Urbanisation — city living brings supermarkets, fridges and fast food, so processed and packaged foods become normal.
- Globalisation & advertising — exposure to global brands and Western diets shifts tastes toward meat, snacks and soft drinks.
- Time and lifestyle — busier, dual-income urban households buy more convenience and ready-made food.
Explain two reasons why diets are shifting in middle-income countries.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Develop the point: Explain needs a mechanism, not a label. Don't write 'incomes rise' - write incomes rise, so families can afford meat and dairy, so diets become richer.
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The resource link: A richer diet has a much bigger resource footprint. Producing meat and dairy uses far more water, land and energy than producing grains.
For example, producing 1 kg of beef needs roughly 15,000 litres of water (for the crops the cattle eat, drinking water and processing) - many times more than 1 kg of wheat (about 1,500 litres). So as the middle class eats more meat, water demand soars.
How a richer diet raises resource use
- Water — meat and dairy are very water-intensive, so a meatier diet sharply raises a country's water footprint.
- Land — grazing and growing animal feed needs huge areas, driving deforestation and competition for farmland.
- Energy & emissions — refrigeration, processing, transport and livestock methane raise energy use and greenhouse gases.
Explain why the expanding global middle class tends to drive up water consumption.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Real example - China: As China's middle class expanded after 2000, meat consumption per person roughly doubled. China now eats about a quarter of the world's meat, hugely increasing demand for animal feed (soy), grazing land and water - a textbook case of diet-driven resource pressure.
How this is tested: An infographic or graph is the stimulus here - often a trend in ethical-clothing sales, a food-spending scatter, or a middle-class-growth line. The data tasks are short: Describe or Outline the pattern with figures [2], and Suggest why a survey behind it might be biased [2]. The bigger marks come from an 'Explain' chain and a 10-mark 'To what extent' essay on resource security.
Read the axes first. By how much does revenue rise across the period, and is the trend steady?
Interactive diagram
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Describe the trend in sustainable clothing sales revenue shown on the graph.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
| Country (income group) | Food spend per person ($/year) | Share of income on food (%) |
|---|---|---|
| High income | 3,200 | 9 |
| Upper-middle income | 1,800 | 18 |
| Lower-middle income | 900 | 32 |
| Low income | 450 | 48 |
IB-style question - read the table
Using the table above: (a) identify the income group that spends the most per person on food [1]; (b) describe the relationship between income and the share of income spent on food [2].
How to answer each part
- (a) Identify. Scan the food-spend column - high-income spends the most, about $3,200 per person per year.
- (b) Describe with figures. It is a negative relationship: as income rises, the share of income spent on food falls - from 48% in low-income to just 9% in high-income countries (Engel's law). Richer people spend more in total but a smaller fraction of income.
Final answer
(a) High income (about $3,200/person); (b) a negative relationship - richer groups spend a smaller share of income on food (48% down to 9%).
Spotting survey bias: If a question gives a survey (e.g. 'city populations supporting sustainable fashion'), think about who was asked: only city dwellers, only people who answered, or a self-selecting online sample - so the result may not represent everyone and can be biased toward wealthier, younger or greener views.
To what extent is the rising global middle class the chief threat to the resource security of places?
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.