Notable events
| Start year | End year | Sector | Information | Impact |
| 1990 | 2018 | Energy - Energy Industries | Deregulation in the use of gas for electricity production. Increased use of Combined Cycle Gas Turbine (CCGT) stations and other gas fired plant rather than coal for electricity generation | Decrease in emissions |
| 1990 | 2018 | Energy - Industry and Other Combustion | Decline in the use of solid fuels (use of coal for domestic combustion has been restricted in the UK by the Clean Air Acts) in favour of gas with lower carbon content | Decrease in emissions |
| 2009 | 2012 | Industrial process | The economic downturn has caused significant reductions in energy demands and many industries have made cut backs or closures, resulting in reduced emissions | Decrease in emissions |
Carbon dioxide contributes to climate change due to its positive radiative forcing effect and it is the most significant greenhouse gas emitted in the UK. Total emissions are dominated by those from power stations, refineries and other users of fossil fuels (including transport, domestic and industrial sectors). Fuel combustion contributed more than 89% of carbon dioxide emissions in 2021, excluding net carbon stock changes in Land Use Land Use Change and Forestry (LULUCF). Total annual UK emissions have reduced by 43% between 1990 and 2021, largely as a result of a gradual switch away from more carbon-intensive fuels such as coal and fuel oil, to fuels such as natural gas. Improvements in the efficiency of fuel use, and the use of renewable energy sources have also contributed.
Since 1990, emissions from most major energy-using sectors fell. Particularly significant emission reductions were observed between 2008 and 2009 for energy producers and for industry, reflecting a decrease in demand for fuel and electricity, probably caused by the economic downturn. Emissions increased the following year. As well as reflecting longer term trends in fuel use, variations in the emissions from year to year will reflect shorter-term changes in the fuel mix used for power generation due to changes in the prices of different fuels and changes in the total demand for electricity. There can also be changes to the demand for heat depending on average temperatures.
As a result of the COVID-19 pandemic, carbon dioxide emissions from road transport and aviation were 19% and 60% lower than they had been in 2019 respectively. As a result of easing restrictions, carbon dioxide emissions from road transport and aviation in 2021 were 11% and 24% higher than in 2020 respectively.