Reducing carbon footprints

A carbon footprint is the amount of greenhouse gas emissions associated with a person, activity or product. It can be reduced by lowering emissions of greenhouse gases, especially carbon dioxide ($$\ce{CO2}$$) and methane ($$\ce{CH4}$$).

Reducing carbon dioxide emissions

Burning fossil fuels releases carbon dioxide, so using less fossil fuel can reduce emissions. One way to do this is to improve energy efficiency: providing the same service while using less energy. For example, better insulation reduces the energy needed to keep a building warm.

Another approach is to switch to energy sources that release less or no carbon dioxide during use. For example, electricity generated by wind turbines does not release carbon dioxide while the turbines operate. This does not necessarily mean that there are no emissions from making and installing them.

Carbon dioxide can also be captured before it enters the atmosphere and stored, for example deep underground. This can reduce emissions from sources that continue to produce carbon dioxide.

Reducing methane emissions

Methane can escape during the production and transport of natural gas. Finding and repairing leaks reduces the amount released. Methane from landfill and other waste can also be collected rather than allowed to escape.

Some agricultural activities release methane. Changes to farming practices, such as managing animal manure differently or changing livestock feed, can reduce these emissions.

Practical constraints on reducing carbon footprints

A method can reduce emissions in principle but be difficult to use in practice. It may be expensive or require new technology and infrastructure. It may also depend on consumers changing their behaviour or farmers changing their methods.

Changes can affect jobs and industries, and a method that works in one place may be difficult to apply elsewhere. Reducing a carbon footprint therefore involves weighing scientific possibilities against these practical constraints.

Carbon footprint

A product, service or event can cause greenhouse gases to be released at many different stages, not just when it is being used. Its carbon footprint is the total amount of carbon dioxide and other greenhouse gases released because of it.

To judge a carbon footprint, the whole life cycle must be considered. For a product, this includes obtaining raw materials, manufacturing, transport, use and disposal. Each stage can contribute emissions, so looking at only one stage gives an incomplete picture.

For example, a product may release no greenhouse gases while it is being used, but still have a carbon footprint because gases were released when its materials were obtained, it was manufactured and transported, and when it was disposed of. Its footprint reflects the contribution from all these stages together.