Overview of greenhouse gases 

You can select information about greenhouse gases pollutants below. Each description page will allow you to find out more about the pollutant itself, related issues and a timeseries graph.

Greenhouse gases

Sector, Gas and Uncertainty Summary Factsheets

Factsheets for each National Communication sector and greenhouse gas (GHG), reported on within the most recent UK Greenhouse Gas Inventory, are available to view here.

The Sector, Gas and Uncertainty Summary Factsheets provide a snapshot of historic emissions and their sources, data sets and methods used for estimating emissions, uncertainties and improvements associated with them. More detailed information is available in the latest National Inventory Report in the Reports section.


The GHG inventory covers the seven direct greenhouse gases under the Kyoto Protocol:

  • Carbon dioxide (CO2)
  • Methane (CH4)
  • Nitrous oxide (N2O)
  • Hydrofluorocarbons (HFCs)
  • Perfluorocarbons (PFCs)
  • Sulphur hexafluoride (SF6)
  • Nitrogen trifluoride (NF3)

These gases contribute directly to climate change owing to their positive radiative forcing effect. HFCs, PFCs, SF6 and NF3 are collectively known as the 'F-gases'.

In general terms, the largest contributor to global warming is carbon dioxide which makes it the focus of many climate change initiatives.  Methane and nitrous oxide contribute to a smaller proportion, typically <10%, and the contribution of f–gases is even smaller (in spite of their high Global Warming Potentials) at <5% of the total.

Also reported are four indirect greenhouse gases:

  • Nitrogen oxides (NOx)
  • Carbon monoxide (CO)
  • Non-methane volatile organic compounds (NMVOC)
  • Sulphur dioxide (SO2)

Nitrogen oxides, carbon monoxide and NMVOCs are included in the inventory because they can produce increases in tropospheric ozone concentrations and this increases radiative forcing (warming of the atmosphere). Sulphur dioxide is included because it contributes to aerosol formation which can either warm (through absorption of solar radiation on dark particles) or cool (from forming cloud droplets and reflecting radiation) the atmosphere.


Countries that have signed and ratified the Kyoto Protocol are legally bound to reduce their greenhouse gas emissions by an agreed amount. A single European Union Kyoto Protocol reduction target for greenhouse gas emissions of -8% compared to base-year levels was negotiated for the first commitment period, and a Burden Sharing Agreement allocated the target between Member States of the European Union. Under this agreement, the UK reduction target was -12.5% on base-year levels. The first commitment period of the Kyoto Protocol was from 2008 to 2012.

The second commitment period of the Kyoto Protocol will run for eight years, from 2013 to 2020 inclusive. For this second commitment period, alongside the EU and its member States, the UK (including Gibraltar) communicated an independent quantified economy-wide emission reduction target of a 20 percent emission reduction by 2020 compared with 1990 levels (base year). The target for the European Union and its Member States is based on the understanding that it will be fulfilled jointly with the European Union and its Member States. The 20 percent emission reduction target by 2020 is unconditional and supported by legislation in place since 2009 (Climate and Energy Package).  Once ratified this Kyoto target will cover the UK, and the relevant Crown Dependencies and Overseas Territories that wish to join the UK’s ratification. As ratification is not yet complete the exact details of the UK’s target for the second commitment period are still being finalised.

Get data on Kyoto emissions

The UK Climate Change Act, which became part of UK law in November 2008, introduced an ambitious and legally binding target for the UK to reduce GHG emissions to  80% below base year levels by 2050. This will be achieved by way of legally binding five year Carbon Budgets.

Get data on Carbon Budgets (gov.uk website)

Further information on the UK's action to tackle climate change can be found on the BEIS website.

Page last modified: 20 November 2017