Our Action Plan
Appendix 5: Glossary of Terms
Units of measurement
A carbon footprint is measured in tonnes of carbon dioxide equivalent (tCO2e). The carbon dioxide equivalent (CO2e) allows the different greenhouse gases to be compared on a like-for-like basis relative to one unit of CO2. CO2e is calculated by multiplying the emissions of each of the six greenhouse gases by its 100-year global-warming potential.
A carbon footprint considers all six of the Kyoto Protocol (opens in a new tab) greenhouse gases: Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs) and Sulphur hexafluoride (SF6).
Source - Carbon Trust (opens in a new tab)
Kilowatt
(kW) is simply 1,000 watts, which is a measure of power. So, for example, a 10,000 watt electric shower could also be called a 10 kilowatt shower.
Megawatt
(MW) is simply 1,000 kilowatts, which is a measure of power. A gigawatt (GW) is 1,000 megawatts, and a terawatt (TW) is 1,000 gigawatts.
Kilowatt hour
(kWh) is a measure of energy – specifically, a measure of how much energy is being used. It doesn’t mean the number of kilowatts used per hour. It is simply a unit of measurement that equals the amount of energy you would use to keep a 1,000 watt appliance running for an hour – for example:
- One 100 watt light bulb would take ten hours to rack up 1 kWh of energy.
- One 2,000 watt appliance would use 1 kWh in just half an hour.
- One 50 watt item could stay on for 20 hours before it used 1 kWh.
Source - Ovo Energy (opens in a new tab)
Megawatt hour
(MWh) is 1000 kWh.
Explanations
Terminology related to climate change can be difficult to understand – especially for those with infrequent contact with the topic. Below are explanations for some commonly used terms:
Carbon Accounting
carbon accounting covers a wide range of varying practices, and means different things to different groups of people. However, it can generally be split into two categories:
- physical carbon accounting, which quantifies physical amounts of greenhouse gas emissions to the atmosphere; and
- financial carbon accounting, which assigns carbon a financial market value.
Physical carbon accounting can be used to help companies and countries work out how much carbon they are emitting into the atmosphere; the result is known as a ‘greenhouse gas inventory’. Once it has been established how much carbon is being emitted, reduction targets can be set. This method is also important for helping to assign responsibility to different parties for their associated carbon emissions.
Carbon accounting provides the tools to not only quantify and measure carbon emissions but also to help make informed decisions about mitigation strategies, through asking question such as:
- How much carbon is being emitted?
- Who is responsible for these emissions?
- Which methods should we employ to achieve the greatest carbon reductions?
- Are there strategies or policies that appear ‘green’ but which actually increase our carbon emissions?
Carbon accounting can help to answer all these questions, but it can be a complex process.
Source – Carbon accounting (opens in a new tab)
Net Zero Carbon
It is clear from the science that the amount of CO2 in the atmosphere resulting from human activity largely determines the extent of global warming. This means that to prevent catastrophic climate change, CO2 emissions need to be reduced to zero. The science led to governments worldwide deciding, in the Paris Agreement (opens in a new tab), to achieve a balance between emissions and the removal of greenhouses gases. ‘Net zero’ refers to achieving an overall balance between emissions produced and emissions taken out of the atmosphere. If we imagine a bathtub with the taps turned on, the approach to achieving such a balance can either involve turning down the taps or draining an equal amount of water down the plughole. The former approach equates to reducing carbon emissions; the latter equates to removing emissions from the atmosphere, including storage for the emissions such as ‘carbon sinks (opens in a new tab)’ – i.e. anything that absorbs more carbon than it releases as carbon dioxide. (European forests are currently a net carbon sink, as they take in more carbon than they emit.)
Source - What is Net Zero? (opens in a new tab)
Carbon Neutral
carbon neutrality means achieving annual zero net anthropogenic (human-caused or -influenced) CO2 emissions by a certain date. By definition, carbon neutrality requires every tonne of anthropogenic CO2 emitted to be compensated for by an equivalent amount of CO2 removed (e.g. via carbon offsetting).
Source – Carbon Neutral (opens in a new tab)
- The Council has committed to becoming a ‘Net Zero Carbon’ local authority while the Welsh Government has an ambition for a ‘Carbon Neutral’ Welsh public sector. Within the confines of this document, both these terms are inter-changeable.
Carbon Offsetting
put simply, offsetting refers to securing carbon credits equivalent to your carbon impact. This means compensating for every tonne of CO2 emitted by ensuring there is one tonne less in the atmosphere. Because one unit of CO2 has the same climate impact wherever it is emitted, the benefit is the same wherever it is reduced or avoided. Achieving verified carbon reductions could include protecting rainforests in Sierra Leone or, potentially, local tree planting here in Pembrokeshire.
Source - Carbon Offsetting (opens in a new tab)