Life Cycle Assessments (LCAs) are tools used to evaluate the environmental impact of products and services throughout their entire lifespan. By assessing each stage of a product's life, LCAs help societies understand how to live more sustainably and make informed choices, such as opting for paper bags over plastic ones. However, LCAs are not without their challenges, including subjective judgements on the scale of a product's impact.

An LCA examines the environmental effects of a product from the extraction of raw materials to its disposal. The stages considered in an LCA include:

1. Materials Extraction:

• To produce a product, the raw materials must first be extracted. This process often involves mining operations, which can destroy natural environments and generate significant carbon emissions.

2. Materials Processing and Manufacturing:

• The raw materials are processed in factories to create the final product. Manufacturing can produce large volumes of carbon emissions and other waste, which must be managed to prevent harm to people and the environment.

3. Distribution of Products:

• After production, products are distributed to consumers. This stage primarily produces carbon emissions due to transportation, whether by lorries, ships, or planes.

4. Use and Operation:

• Some products, like motor vehicles, generate emissions during use. Electrical goods indirectly contribute to emissions by increasing the demand for fossil fuel-based power generation. Other products, such as food, cleaning supplies, and cosmetics, may produce waste in the form of packaging and chemical residues.

5. Disposal:

• Once a product reaches the end of its useful life, it must be disposed of. Disposal methods include recycling, incineration, and landfilling, each with its own environmental impact. For example, recycling and incineration can produce carbon emissions, while landfills can release toxic pollutants into the environment, particularly into groundwater. Specific LCAs can be incredibly comprehensive, taking into account factors like the renewability and biodegradability of materials used in both the extraction and disposal stages.

While plastic and paper bags have similar impacts during manufacturing, distribution, and use their environmental effects differ significantly during raw material extraction and disposal. Paper bags have the advantage of being renewable and biodegradable, whereas plastic bags contribute to long-term waste.