Whilst carbon dioxide (CO₂) is the most well known, there are several other important gases that contribute to global warming. The UK’s carbon budgets are therefore legislated in terms of all greenhouse gas (GHG) emissions, as recommended in CCC’s 2008 report.

The budgets cover the greenhouse gases included in the Kyoto protocol:

• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous Oxide (N₂O)
• F-gases: Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), Sulphur hexafluoride (SF₆)

Since they are included in the budgets, it is important to understand the sources of non-CO₂ gases, their trends and the opportunities to reduce emissions:

Non-CO₂ emissions generally result from more complex processes than CO₂ (which results primarily from the burning of fossil fuels), and have a wide and disparate range of sources – agriculture, waste disposal, industrial and energy-related processes.

Non-CO₂ emissions (currently 95 MtCO₂e) account for 15% of total GHG emissions (628 MtCO₂e in 2008).

Non-CO₂ emissions have fallen far more quickly than CO₂ since 1990 (48% compared to 9%).

The Committee’s analysis suggests that there are significant opportunities to reduce emissions further, by up to 15 MtCO₂ by 2020. These will require use of new policies that are  focused specifically on greenhouse gas emissions.

Non-CO₂  Emissions by sector 1990 - 2006