Overview of greenhouse gases - Defra, UK (2024)

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.

Introduction

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 <20%, 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 (NO_x)
• 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.

Targets

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 applies from 2013 to 2020 inclusive. For this second commitment period, the EU and the Member States communicated an independent quantified economy-wide emission reduction target of a 20 percent emission reduction by 2020 compared with 1990 levels (base year) (“the EU2020 target”). The EU2020 target is based on the understanding that it will be fulfilled jointly by the European Union and the Member States. The EU2020 target is unconditional and supported by EU legislation in place since 2009 (The EU Climate and Energy Package). This Kyoto target covered the UK, and the relevant Crown Dependencies and Overseas Territories for whom the ratification is extended.

Get data on Kyoto emissions

The Climate Change Act became UK Law on the 26th November 2008. This legislation introduced a new, more ambitious and legally binding target for the UK to reduce GHG emissions to 80% below base year by 2050, with legally binding five year GHG budgets. The independent Committee on Climate Change (CCC) was set up to advise the UK Government on the setting and meeting of UK carbon budgets as well as monitoring progress against them scope and level of UK carbon budgets.

The Climate Change Act was amended in 2019 to revise the greenhouse gas emission reduction target for 2050 from 80% to 100%, i.e. net-zero.

Get data on Carbon Budgets (gov.uk website)

Countries that have signed and ratified the Paris Agreement are asked to declare a Nationally Determined Contribution (NDC), where countries set out what targets they intend to meet to contribute to mitigating climate change, and information on how the country plans to achieve those targets. The UK’s NDC commits the UK to reducing economy-wide greenhouse gas emissions by at least 68% by 2030, compared to 1990 levels.

Page last modified: 14 October 2022