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The numbers behind the budget: Six ways to explore the Sixth Carbon Budget dataset

In 2019, the UK became the first major economy to set a legally-binding Net Zero emissions target for 2050. In December 2020, we published our advice to Government on the Sixth Carbon Budget (6CB), outlining the year-by-year pathway to achieve this ambition over the next 30 years. Details of the measures, and the policies required to meet them, are set out in our Advice, Methodology and Policy reports.

We have always published the data underpinning our findings, but this year we wanted to go further. Our comprehensive Sixth Carbon Budget dataset compiles all the data behind our scenarios and presents them in an easy-to-digest graphical format, using interactive charts. Alongside the core charts, we provide additional insights through a “key metrics” tab, which includes data on many of the underlying trends associated with decarbonisation (for example, the uptake of electric vehicles, or the number of heat pumps installed in a particular time period).

Together with a tab covering key analytical assumptions (which complements the sector specific assumptions in a new charts workbook), our Sixth Carbon Budget dataset provides an important new way to quickly understand the future of UK decarbonisation and make best use of our analysis.

The dataset includes all the core statistics that people would expect from our analysis, such as emissions and energy pathways alongside investment data. Here we highlight just a few examples of the things you can do with it.

Exploring emissions sources over time

We break down UK emissions into 14 different sectors, ranging from surface transport to land use to greenhouse gas removals. To date, these sectors have decarbonised at different rates and this will continue into the future. That means the emissions mix in the UK will change dramatically over time. This can be seen in the dataset, which provides detailed breakdowns of emissions by sector, over time.

For example, the chart below shows how emissions sources in the UK are likely to change between 2020 to 2050. In 2020, emissions predominantly come from transport, buildings, power and manufacturing. By 2050, agriculture, aviation and land use make up the bulk of UK emissions, requiring equivalent amounts of emissions to be removed from the atmosphere through nature-based (such as trees) and engineered removals (such as carbon capture), in order to reach Net Zero.

Comparable emissions stacks are shown for the four most common greenhouse gases (GHGs); carbon dioxide, methane, nitrous oxide and Fluorinated-gases (F-gases). We have also added the ability to see our pathways under different global warming potentials and with or without international aviation and shipping.


Understanding the energy implications of the transition

Decarbonisation has profound implications for the type, amount and sources of energy that the UK uses. Over the next 30 years we will need to see a rapid and permanent move away fossil fuels towards an economy principally powered by low-carbon electricity, hydrogen and sustainable bioenergy. In the dataset we present an abundance of charts showing the evolution of the UK’s energy supply and demand.

For example, below we extract the electricity demand in our Balanced Net Zero Pathway, showing that electricity supply more than doubles by 2050, driven by electrification of the surface transport and fuel supply sectors.


Scrutinising investments, savings and costs of Net Zero

The CCC’s analysis includes bottom-up estimates of investment requirements and ongoing operational savings of all our decarbonisation measures. The overall picture that emerges is that the investment required to achieve Net Zero is broadly offset through savings in operating costs resulting from those investments. For example, investments in charging infrastructure and electric vehicles are offset by the fact that driving electric vehicles is much cheaper than petrol and diesel vehicles.

The figure below is an extract from the dataset which shows the upfront investment required compared to the associated savings of investments.


Comparing data across different scenarios and UK nations

We recommended a Sixth Carbon Budget which would see UK emissions capped at 965 MtCO2e between 2033-37 – a 78% reduction in emissions from 1990 levels, based on our Balanced Net Zero Pathway. Alongside this pathway, we explored other routes to Net Zero that could be achieved with greater or lesser levels of innovation and behaviour change. All of these scenarios are broken out in the dataset, allowing users to explore a wider range of pathways open to the UK.

The figure below shows the pace of change predicted for each of our five Net Zero scenarios. Our Tailwinds scenario shows that with extremely high levels of behaviour change and rapid innovation, the UK could achieve Net Zero by the early 2040s. Conversely, our Headwinds scenario shows that pessimistic assumptions about engagement and innovation result in a slower path to Net Zero.


We also advise the Scottish, Welsh and Northern Irish Governments on emissions pathways to 2050. In the dataset we have separated out the pathways for each nation, providing the same data across the board, at a devolved administration level.

Conducting sector-level analysis

All of our sectors can be split further, into subsectors, allowing even more granular analysis of the Sixth Budget pathways. These charts can be used to highlight where the big drivers of emissions reduction are within a particular sector. For example, the surface transport sector can be split out into cars and vans, heavy goods vehicles and rail and public transport. The chart below clearly shows that decarbonising cars and vans is the greatest driver of emissions reduction in the surface transport sector.


Studying additional statistics

On top of the core analysis you would expect from the CCC, we have included more advanced charts too. For example, the chart below shows emissions intensity over time, as calculated in the UK Government’s 2017 clean growth strategy.


We hope that publishing our dataset will promote greater understanding of our modelling and highlight our ongoing commitment to transparency. As the UK looks toward COP26, it’s more important than ever for all organisations, including ours, to engage in open conversations informed by evidence and data.

Jake Langmead-Jones is an Analyst within the Climate Change Committee Secretariat.