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The UK net-zero target
The UK has committed to reaching a target of net-zero greenhouse gas emissions by 2050. But what does this actually mean in practice?
Which emissions are covered by the target?
Under the United Nations Framework Convention on Climate Change (UNFCCC), signatory countries are required to estimate and monitor emissions of a basket of greenhouse gases which have a warming impact on the earth’s atmosphere.
Prior to 2021, the UK had emissions reduction targets agreed under the Kyoto Protocol to the UNFCCC. The Kyoto Protocol, in very simple terms, is the United Nations (UN) convention which commits countries to limiting and reducing their greenhouse gas emissions. Since 2021, the UK now has new targets agreed under the Paris Agreement to the UNFCCC. Under the Paris Agreement, the UK is required to set targets every five years known as Nationally Determined Contributions (NDCs)
The UK net-zero target uses the same basket of gases, which consists of seven greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride and nitrogen trifluoride. These last four gases are collectively referred to as fluorinated compounds, or F-gases for short. In accordance with international reporting protocols, each of these gases is weighted by its global warming potential (GWP), so that total greenhouse gas emissions can be reported on a consistent basis. This is because some gases are more harmful in the atmosphere than others. The GWP for each gas is defined as its warming influence relative to that of carbon dioxide. So a tonne of methane, for example, is considered to be 28 times more potent in the atmosphere than a tonne of carbon dioxide, giving a GWP of 28. Greenhouse gas emissions are then presented in carbon dioxide equivalent (CO2e) units.
In the UK, emissions are dominated by carbon dioxide, which accounted for about 79% of all greenhouse gas emissions in 2023. Weighted by global warming potential, methane accounted for about 15% of UK emissions and nitrous oxide about 5%. F-gases accounted for the remainder, less than 2%.
Emissions arise from a wide variety of sources and activities. These sources are categorised by the UK Government under what are called Territorial Emissions Statistics sectors. These sectors provide a defined breakdown which can be used to monitor and report emissions over time.
Prior to April 2021, the UK’s total emissions covered by the net-zero target included all emissions occurring within its territorial boundaries, but not international aviation and shipping. In April 2021 though, the independent Climate Change Committee set the sixth Carbon Budget (explained below), covering the five-year period 2033-37. In doing so, they recommended that this Budget should for the first time incorporate the UK’s share of international aviation and shipping emissions. Those emissions are now also covered by the 2050 target.
What is the UK’s net-zero target, and what are the stages we need to reach between now and 2050?
The 2008 Climate Change Act introduced a legally binding target for the UK to reduce its greenhouse gas emissions by at least 80% below base year levels by 2050. The base year varied for different gases – 1990 for carbon dioxide, methane and nitrous oxide, and 1995 for fluorinated compounds. This was consistent with the approach applied by the Kyoto Protocol.
The Climate Change Act also put in place a long-term legally binding framework for emission reductions, by way of five-yearly carbon budgets to set a trajectory towards 2050.
In June 2019, an amendment was made to the Act which committed the UK to a more challenging target of a 100% reduction in emissions by 2050 – the net-zero target.
Re-setting the target to zero doesn’t mean that base year emissions are now irrelevant though. That’s because the carbon budgets are based on 5-yearly emissions reductions which go from base year levels down to zero. We are currently in the fourth carbon budget, covering the period 2023-2027.
What is meant by “net-zero”?
Although the UK is required to report emissions in gross terms - in other words, as tonnes of greenhouse gases from defined sources - the Climate Change Act allows for emissions to be reduced and reported as net emissions. This means that the UK is able to take account of “removals” of greenhouse gases from the atmosphere, and the monitoring of progress towards the 2050 target, done by way of monitoring compliance with the 5-yearly carbon budgets, will take these into account.
Which emissions are covered by the target?
Under the United Nations Framework Convention on Climate Change (UNFCCC), signatory countries are required to estimate and monitor emissions of a basket of greenhouse gases which have a warming impact on the earth’s atmosphere.
Prior to 2021, the UK had emissions reduction targets agreed under the Kyoto Protocol to the UNFCCC. The Kyoto Protocol, in very simple terms, is the United Nations (UN) convention which commits countries to limiting and reducing their greenhouse gas emissions. Since 2021, the UK now has new targets agreed under the Paris Agreement to the UNFCCC. Under the Paris Agreement, the UK is required to set targets every five years known as Nationally Determined Contributions (NDCs)
The UK net-zero target uses the same basket of gases, which consists of seven greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride and nitrogen trifluoride. These last four gases are collectively referred to as fluorinated compounds, or F-gases for short. In accordance with international reporting protocols, each of these gases is weighted by its global warming potential (GWP), so that total greenhouse gas emissions can be reported on a consistent basis. This is because some gases are more harmful in the atmosphere than others. The GWP for each gas is defined as its warming influence relative to that of carbon dioxide. So a tonne of methane, for example, is considered to be 28 times more potent in the atmosphere than a tonne of carbon dioxide, giving a GWP of 28. Greenhouse gas emissions are then presented in carbon dioxide equivalent (CO2e) units.
In the UK, emissions are dominated by carbon dioxide, which accounted for about 79% of all greenhouse gas emissions in 2023. Weighted by global warming potential, methane accounted for about 15% of UK emissions and nitrous oxide about 5%. F-gases accounted for the remainder, less than 2%.
Emissions arise from a wide variety of sources and activities. These sources are categorised by the UK Government under what are called Territorial Emissions Statistics sectors. These sectors provide a defined breakdown which can be used to monitor and report emissions over time.
Prior to April 2021, the UK’s total emissions covered by the net-zero target included all emissions occurring within its territorial boundaries, but not international aviation and shipping. In April 2021 though, the independent Climate Change Committee set the sixth Carbon Budget (explained below), covering the five-year period 2033-37. In doing so, they recommended that this Budget should for the first time incorporate the UK’s share of international aviation and shipping emissions. Those emissions are now also covered by the 2050 target.
What is the UK’s net-zero target, and what are the stages we need to reach between now and 2050?
The 2008 Climate Change Act introduced a legally binding target for the UK to reduce its greenhouse gas emissions by at least 80% below base year levels by 2050. The base year varied for different gases – 1990 for carbon dioxide, methane and nitrous oxide, and 1995 for fluorinated compounds. This was consistent with the approach applied by the Kyoto Protocol.
The Climate Change Act also put in place a long-term legally binding framework for emission reductions, by way of five-yearly carbon budgets to set a trajectory towards 2050.
In June 2019, an amendment was made to the Act which committed the UK to a more challenging target of a 100% reduction in emissions by 2050 – the net-zero target.
Re-setting the target to zero doesn’t mean that base year emissions are now irrelevant though. That’s because the carbon budgets are based on 5-yearly emissions reductions which go from base year levels down to zero. We are currently in the fourth carbon budget, covering the period 2023-2027.
What is meant by “net-zero”?
Although the UK is required to report emissions in gross terms - in other words, as tonnes of greenhouse gases from defined sources - the Climate Change Act allows for emissions to be reduced and reported as net emissions. This means that the UK is able to take account of “removals” of greenhouse gases from the atmosphere, and the monitoring of progress towards the 2050 target, done by way of monitoring compliance with the 5-yearly carbon budgets, will take these into account.
- Carbon sinks
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Carbon dioxide is reported in terms of net emissions, which means total emissions minus total removals of CO2 from the atmosphere by carbon sinks. A carbon sink removes greenhouse gases through natural solutions, such as planting trees or land management changes in order to increase the amount of carbon stored into soil. Carbon sinks are incorporated within the Land Use, Land Use Change and Forestry (LULUCF) sector when reporting emissions.
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- Emissions trading
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Prior to 2021, the UK was able to take into account a number of what are called flexible mechanisms when reporting its emissions. These mechanisms effectively act as international offsets which countries can use to meet their own emissions reduction targets. They are typically used when it is difficult for the country to reduce some of its own territorial emissions; their purpose is to enable efforts to reduce emissions to be re-directed to other countries where the greatest reductions can be achieved at the same cost.
These mechanisms include emissions trading, which applies a “cap and trade” principle in order to limit emissions. The market in which emissions allowances are traded effectively puts a price on a tonne of carbon, thereby incentivising emissions reductions in the most cost effective way. Until 2020, the UK was a participant in the European Union Emissions Trading System (EU ETS), and any emissions reductions achieved by way of trading through the EU ETS were taken into account when reporting progress against carbon budgets. Since 2021 however, the UK is no longer a participant in the EU ETS, and reported UK emissions are no longer adjusted to allow for trading. |
It is possible that new negative emissions technologies such as Direct Air Capture (DAC) and Bioenergy with Carbon Capture and Storage (BECCS) will also play a part in meeting the 2050 target. However, these technologies are still in development, and do not currently affect the UK’s reported emissions.
