Greenhouse Gas (GHG)

What is Greenhouse Gas (GHG)?

Greenhouse gases are the central subject of carbon accounting. They are gases that absorb infrared radiation emitted by the Earth's surface and re-radiate it back, creating the greenhouse effect that warms the planet. Without any greenhouse gases, the Earth's average surface temperature would be approximately −18°C rather than the current ~15°C. The concern is not the greenhouse effect itself but the enhancement of it caused by human activity — primarily the burning of fossil fuels, deforestation, agriculture, and industrial processes.

The GHG Protocol and all major carbon reporting frameworks require organisations to account for seven gases, as specified under the Kyoto Protocol. Carbon dioxide (CO₂) is the most abundant anthropogenic greenhouse gas and the primary output of fossil fuel combustion. Methane (CH₄) has a global warming potential (GWP) approximately 28 times that of CO₂ over 100 years and is released from agriculture, landfill, and natural gas systems. Nitrous oxide (N₂O), with a GWP of 265, is emitted from agricultural soils, combustion processes, and industrial activities. The fluorinated gases — HFCs, PFCs, SF₆, and NF₃ — are synthetic gases with very high GWPs (ranging from hundreds to over 20,000) used in refrigeration, electronics manufacturing, and electrical insulation.

To enable comparison and aggregation, all greenhouse gas emissions are converted to a common unit: carbon dioxide equivalent (CO₂e). This uses the global warming potential of each gas — a measure of how much energy one tonne of the gas absorbs over a given period (typically 100 years) relative to one tonne of CO₂. The GWP values used in carbon accounting are published by the Intergovernmental Panel on Climate Change (IPCC) in its Assessment Reports. The GHG Protocol currently recommends using the GWP values from the IPCC Fifth Assessment Report (AR5), though AR6 values are being adopted by some frameworks.

In practice, most organisations' GHG inventories are dominated by CO₂ from energy use and transport. Methane and nitrous oxide are significant for organisations in agriculture, waste management, and water treatment. Fluorinated gases matter most for organisations operating refrigeration, air conditioning, or semiconductor manufacturing. Understanding which gases are material to your operations determines what data you need to collect and which emission factors to apply.

UK regulations including SECR, the Carbon Reduction Plan (PPN 06/21), and the UK ETS all require reporting of greenhouse gas emissions. The DEFRA/DESNZ emission factors provide conversion ratios that already account for the CO₂, CH₄, and N₂O content of each fuel type, expressing the result as a combined CO₂e figure per unit of activity.

How Climatise Helps

Climatise applies emission factors that account for all relevant greenhouse gases — CO₂, CH₄, N₂O, and fluorinated gases — and converts everything to CO₂e automatically, so your inventory captures the full warming impact of your operations without manual GWP calculations.

Frequently Asked Questions