Guest post: Why the UK’s carbon footprint is decreasing

Dr Anne Owen is senior research fellow at the University of Leeds’ Sustainability Research Institute.

In a recent Carbon Brief article, my colleague Prof John Barrett and I revealed that the UK’s carbon footprint is at its lowest level for 20 years, including emissions embedded in imported goods.

However, the reasons for this decline are not well understood. The UK’s footprint is also falling more slowly than its territorial emissions, which is used more often but sometimes contested.

Given the UK’s emissions are falling too slowly to meet its own climate goals against either measure – let alone the aspirational 1.5C limit of the Paris Agreement – there is a pressing need to better understand the underlying reasons for emissions reductions.

In this new analysis, I explore why the UK’s carbon footprint is decreasing – and what that means for future emissions targets.

Drivers of change

Understanding trends in the UK’s historical carbon footprint is important because it helps untangle the impact of climate policies and other drivers of change. This information can be used to design more effective policies in future and to try to avoid unintended consequences.

There are a number of factors which can contribute to either increasing or decreasing the carbon footprint from the previous year. Six such drivers of change are listed in the table, below.

	Factor	Description
1	Population	A change in the UK’s population
2	Total spend	A change in the total expenditure on goods and services per person
3	Changed need	Changes in the types of goods bought, for example more services and fewer products
4	Imports	Changes in the UK’s reliance on imported goods, for example increasing imports from China.
5	Production energy efficiency	Changes in the total amount of energy needed to make goods and services
6	Carbon intensity of energy	Changes in the CO2 emissions associated with each unit of energy use

Using a technique known as “structural decomposition analysis”, it is possible to calculate how each of these six factors contributes to the overall change in carbon footprint between one year and the next.

Each factor can either contribute to increases in the footprint or drive reductions overall. The net sum of these increases and decreases gives the change in the year-on-year carbon footprint.

To make sure that the calculations are not simply showing the effects of price increases due to inflation, the economic data used for every year is in 2010 prices.

Behind the fall

This analysis shows that total spend, energy efficiency and decarbonisation of energy supplies had the largest influence on the UK’s carbon footprint 1997-2016.

These factors are shown in coloured lines on the chart, below, alongside the total change in the UK’s carbon footprint over this period (thick red line). The UK’s footprint grew before falling sharply during the global financial crisis and recession. It has declined more slowly since then.

Changes in the UK’s carbon footprint 1997-2016 (thick red line) and contributions from each driver of change (thin coloured lines). Source: University of Leeds. Chart by Carbon Brief using Highcharts.

Breaking down that overall trend, the decomposition analysis results in the chart, above, show how the decarbonisation of energy supplies (orange) and improvements in energy efficiency (light blue) have tended to reduce the UK’s carbon footprint over time.

For example, the shift from coal-fired electricity generation towards gas and renewables – in the UK and abroad – has reduced the carbon content of our energy needs. Similarly, energy efficiency improvements mean factories require less energy to make the same volume of goods.

On the other hand, the UK’s slowly growing population (green) pushes up the country’s carbon footprint as it tends to increase the need for food, transport and energy.

The remaining drivers of change have pushed the UK’s carbon footprint in varying directions over the time period covered by our analysis.

Total spend (dark blue) is the most important driver overall. Before the recession, rising consumption contributed strongly to increasing emissions – and much of the decline during the crisis stemmed from falling expenditure. Interestingly, between 2011 and 2016 total spend is again tending to raise the UK’s footprint, but it has been more than outweighed by other factors.

During the early years, imports (grey) pushed up the UK’s footprint. This is due to the UK importing more products and/or the carbon intensity of those products increasing, for example due to the surge of coal-fired electricity generation in China during the 1990s and 2000s.

The effect of imports reversed during the recession due to the UK relying relatively more on domestic products. Post-recession, the effect of imports flattened out, meaning they are neither adding to nor reducing the UK’s footprint overall.

Imported goods have been meeting an increasing share of UK consumption needs in the post-recession period, but their carbon content is falling as other countries make progress in tackling their emissions.

The changing needs (yellow) of UK consumers is also closely related to the global recession. During this period, the “changing needs” factor increased UK emissions. This is because UK households change their expenditure behaviour when disposable income is scarce.

Pre-recession, as households became richer, they spent their additional money on less carbon-intensive services such as theatre and the cinema. During the recession, households prioritised home heat, power and transportation – a more carbon-intensive basket of goods.

Three-act play

The chart below shows more clearly how these trends have played out in three distinct periods before (1997-2007), during (2007-2011) and after the recession (2011-2016).

Factors driving the changes in the UK’s carbon footprint before (left column), during (centre) and after the great recession (right). Source: University of Leeds. Chart by Carbon Brief using Highcharts.

Displaying the data in this format clearly highlights structural changes that have occurred in the UK, with the recession having a strikingly different character to the periods before and after it took place.

For example, the effect of “total spend” during the recovery has not been as large as it was before the recession. Meanwhile, imports have switched from driving up emissions before the recession to having close to a net-zero impact during the recovery from 2011-2016.

Overall, there has been a small reduction in the UK’s carbon footprint in the post-recession period as increases due to total spend and population have been more than outweighed by cuts due to energy efficiency, carbon intensity and changed need.

If the effect of total-spend increases can continue to be outpaced by improvements in the carbon content of energy supplies, production efficiencies and consumers choosing “greener” baskets of goods, then the UK’s carbon footprint will continue to reduce. However, as our previous article explains, the current pace of reduction is well short of that needed to meet the Paris Agreement.

Future footprint

Much of the reduction in the UK’s carbon footprint to date has been due to the decarbonisation of domestic electricity supplies. To see further reductions, the UK will need to look towards decarbonisation of the heating and transport sectors – arguably, a more difficult challenge.

In addition, the carbon footprint covers emissions due to production beyond national borders – outside the traditional reach of UK climate policy. This issue is discussed in the recent Committee on Climate Change report, on cutting territorial emissions to net-zero by 2050.

As the committee notes, this means that further cuts in the UK’s carbon footprint may need to go beyond traditional measures and also consider tackling demand.