Earth's Resources and Sustainable DevelopmentAQA GCSE Chemistry: Revision notes
Section 1
What Are Earth's Resources, and What Is Sustainable Development?
Humans use the Earth's natural resources, supplemented by agriculture, to provide warmth, shelter, food and transport. Resources can be classed as:
- Finite — will eventually run out (e.g. fossil fuels, metal ores)
- Renewable — can be replenished at a similar rate to their use (e.g. timber, wind energy)
Many natural products are supplemented or replaced by agricultural and synthetic products, such as synthetic fibres replacing natural ones.
Sustainable development means meeting the needs of current generations without compromising the ability of future generations to meet their own needs.
When asked to classify a resource as finite or renewable, think about whether nature can replace it as fast as humans use it.
Section 2
What Is a Life Cycle Assessment?
A life cycle assessment (LCA) is carried out to assess the environmental impact of a product across four stages:
- Extracting and processing raw materials
- Manufacturing and packaging
- Use and operation during the product's lifetime
- Disposal at the end of its useful life, including transport and distribution at each stage
LCAs help compare the true environmental cost of different products, not just the impact of using them.
Section 3
Are Life Cycle Assessments Fully Objective?
Some parts of an LCA — such as the use of water, resources and energy, and the amount of some wastes produced — can be fairly easily quantified with numbers.
However, allocating numerical values to the effects of pollutants requires value judgements, so an LCA is not a purely objective process.
Because of this, selective or abbreviated LCAs can be devised to fairly evaluate a product, but they can also be misused to reach a predetermined conclusion — for example, in comparative LCAs for plastic versus paper shopping bags, the stages included can change which option looks 'better'.
Don't assume LCAs always give a clear, unbiased answer — the choice of what to include or leave out can change the outcome.
Section 4
How Can We Reduce the Use of Resources?
Ways of reducing the use of Earth's limited resources include:
- Reduction in use
- Reuse of materials
- Recycling of materials
Metals, for example, can be recycled by melting and recasting them into new products, saving both the raw material and the energy that would be needed to extract new metal.
Aluminium drink cans are melted down and recast into new cans, using far less energy than extracting new aluminium from ore.
Must Know
- Resources are finite (will run out) or renewable (replenished at a similar rate to use)
- Sustainable development meets current needs without compromising future generations' ability to meet theirs
- A life cycle assessment (LCA) covers four stages: extraction/processing, manufacture, use, and disposal
- LCAs are not fully objective — pollutant effects require value judgements, so LCAs can be selective, abbreviated or misused
- Reduction, reuse and recycling (e.g. melting and recasting metals) all help reduce the use of limited resources
That's the notes covered.
Carry on to the next subtopic.