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.
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.
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: Paper 2 Q3/Q4 opens with a graph or infographic - a scatter of food spending, a line of middle-class growth, or a sustainable-clothing infographic. You Describe the pattern (with figures) and may Suggest why survey data could be biased. The big finish is a 10-mark 'To what extent' essay judging whether the middle class is the chief threat to resource security.
| 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.