Global trends in consumption practice questions.

A line graph shows a country's annual coal output rising from 1990 to a peak in 2005 and then falling steeply to 2020 (hypothetical data). Which response would gain full marks for the instruction 'Describe the trend shown'?

• Output changes considerably across the thirty-year period shown
• New mines opened in the 1990s and cheap gas later replaced coal in power stations
• The highest annual output in the whole period occurs in the year 2005
• Output rises to a peak in 2005 and then falls steeply to 2020

Answer: Output rises to a peak in 2005 and then falls steeply to 2020

Describe asks for the shape of the trend together with the turning point and its dates. Giving reasons is explanation rather than description, and quoting one value describes a single point instead of the trend.

The Democratic Republic of the Congo holds more renewable freshwater than any other African country, yet in 2020 fewer than half of its people had access to at least a basic drinking-water service. Which type of water scarcity does this illustrate?

• Physical water scarcity
• Seasonal water scarcity
• Economic water scarcity
• Absolute water scarcity

Answer: Economic water scarcity

The DRC's problem is not the amount of water available but the lack of investment in the pumps, pipes and treatment plants needed to deliver it — the definition of economic water scarcity. The typical error is assuming scarcity always means a dry climate, which describes physical scarcity.

Which energy source is non-renewable, yet emits almost no carbon dioxide at the point of electricity generation?

• Nuclear power
• Natural gas
• Onshore wind
• Hydroelectric power

Answer: Nuclear power

Uranium is a finite mineral resource, so nuclear power is non-renewable, yet fission releases no carbon dioxide during generation. The typical error is treating 'low-carbon' and 'renewable' as the same property — natural gas is neither, while wind and hydropower are both.

Households around a communal woodland cut fuelwood faster than the trees regrow, so the standing stock of timber falls year on year. Which description of this resource use is correct?

• It is a non-renewable resource, because the standing stock is falling
• It is a sustainable use of a resource that is not renewable
• It is a renewable resource that is not being used sustainably
• It is renewable, and for that reason it is also sustainable

Answer: It is a renewable resource that is not being used sustainably

Renewable describes the source - the trees regrow - while sustainable describes the rate of use. Harvesting faster than the regrowth rate runs the stock down, so a renewable resource can be used unsustainably; the two words are not interchangeable.

A student writes: 'India's total ecological footprint is much larger than Norway's, so the average person in India consumes more resources than the average person in Norway.' Which single error does this reasoning make?

• It confuses the ecological footprint with the country's biocapacity
• It assumes the two footprints are measured in different units
• It treats the carbon component as if it were the whole footprint
• It compares a national total with a figure that must be per person

Answer: It compares a national total with a figure that must be per person

A national total scales with population, so a country of well over a billion people can have a large total while each person's footprint is small; Norway's footprint per person is several times India's. Totals answer 'how much does the country use', per capita figures answer 'how much does a person use'.

In a high-income country, population and average income both stay unchanged for a decade. Which change over that decade would raise the country's ecological footprint per person?

• Raising the share of journeys made by bicycle instead of by car
• Replacing hydropower with coal-fired stations for electricity generation
• Increasing the share of aluminium drinks packaging that is recycled
• Shortening the distance that fresh vegetables travel from farm to shop

Answer: Replacing hydropower with coal-fired stations for electricity generation

The carbon component dominates most national footprints, so moving generation to a fuel with high emissions per unit of electricity raises the footprint even when income and population are constant. The other three changes all cut energy or material throughput per person.