UK emissions could rise by 15% if government uses ‘surplus’ to weaken climate goal, CCC warns

The UK would be able to increase its emissions while still meeting its next legally binding climate goal if the government uses a “surplus” to weaken the target, official advisers warn.

The government has asked the Climate Change Committee (CCC) if it should carry over “surplus” emissions, after the UK overachieved the third “carbon budget” for 2018-2022.

This surplus is equivalent to an extra year’s worth of emissions, so carrying it forward would increase the size of the fourth carbon budget for 2023-2027 by a fifth.

Doing so would make it far easier for the next government to meet that budget, allowing emissions to rise by around 15% from current levels – instead of falling towards net-zero.

In a letter, published today, the CCC says its “unequivocal” advice is that doing this would place the UK’s future climate goals at “very serious risk” and would make the 2050 net-zero target “more expensive and harder to achieve”.

The letter says that the surplus is largely the result of a sluggish economy and the impact of Covid-19. The committee emphasises that the UK’s emissions cuts need to accelerate to stay on course for long-term goals, rather than slow down.

‘Surplus’ emissions cuts

Under the Climate Change Act, the UK must hit legally binding interim emissions targets, known as carbon budgets, that get gradually lower on a pathway to net-zero emissions by 2050.

Earlier this month, the government published final greenhouse gas emissions figures showing that the UK overachieved in its third carbon budget. Total net emissions were 2,153m tonnes of carbon dioxide equivalent (MtCO2e) between 2018 and 2022, the figures show, against a target of 2,544MtCO2e. 

This means the UK came in 391MtCO2e – or 15% – below the budget for this five-year period. This “overachievement”, largely due to the impact of the Covid-19 pandemic and other external factors (see below), is equivalent to around one year of UK emissions.

Earlier this month, UK climate minister Graham Stuart asked the CCC for its view on “carrying forward” the emissions “surplus” to the next carbon budget.

Under section 17 of the Climate Change Act, the government is legally entitled to do this if it wishes, but must first seek and take into account the CCC’s advice.

Carrying forward some or all of the surplus effectively weakens the UK’s next carbon budget, by an equivalent amount. Nevertheless, the flexibility was included in the Climate Change Act in order to encourage – and reward – early action to cut emissions.

Five years ago, the CCC issued a similar warning that the UK should not carry forward the surplus from the second carbon budget to the third period, because that overachievement was also largely due to external factors rather than genuine early action.

However, the government ignored the CCC’s advice – the first time it had done so – and carried forward 88MtCO2e into the third carbon budget.

Today, the CCC has once again written to the government warning it not to weaken the fourth carbon budget by making use of surplus emissions.

Indeed, as the chart below shows, making full use of the third budget surplus would allow the UK to legally increase its emissions in the current fourth carbon budget period 2024-2027, rather than cutting them in line with its longer-term goals. 

With the third carbon budget surplus of 391MtCO2e being equivalent to a whole extra year of emissions in the UK, the country could emit around 20% more over the five-year budget than the amount officially legislated.

Adding this amount to the fourth carbon budget would enable the UK to emit 200MtCO2e more between 2023-27 than it did over the course of its third carbon budget, following decades of relatively consistent cuts.

This would amount to a 9% increase in emissions between budgets and an increase of as much as 15% from 2022 levels, across the fourth budget period.

It would also push the UK far off course from the government’s own carbon budget delivery plan for meeting near- and long-term targets, which it set out last year. 

If the government decides to carry over the surplus and emissions are allowed to rise to their maximum level under a looser fourth carbon budget, getting back on track for the fifth carbon budget would require a “huge and impractical” total emissions reduction of 1,036MtCO2e over the following five years, according to the CCC. 

This is twice as fast as anticipated in the government’s plan – and 40% quicker than the most ambitious scenario devised by the CCC.

‘Very serious risk’

In light of these potential outcomes, interim CCC chair Prof Piers Forster writes in his response to Stuart’s request that the surplus should not be used:

“The committee’s unequivocal advice is that surplus emissions from the third carbon budget should not be carried forward.”

The committee warns against “setting conditions that allow for a legally compliant slowdown in progress” when the focus “should be on accelerating and broadening emissions reductions”.

It concludes that both the UK’s domestic goal of the sixth carbon budget for 2033-37 and its 2030 international climate target under the Paris Agreement would be placed at “very serious risk” if the carryover is allowed.

The fourth carbon budget was set when the UK’s 2050 emissions goal was an 80% reduction rather than 100%. This means that the government should be overachieving, rather than underachieving, on the budget’s target emissions reductions in order to stay on a “sensible” track for its future goals, according to the CCC.

The CCC’s response reiterates its previous recommendations to Stuart’s predecessors about carrying forward surplus from the first and second carbon budgets.

Moreover, the committee points out that “most” of the surplus emissions cuts in recent years have not been the result of the government’s climate policies. 

According to the committee, roughly half of them resulted from a “tighter than expected” EU ETS cap. This meant “less was required” of government policy in areas outside of the ETS, such as transport and heating buildings.

Most of the remaining surplus is accounted for by “lower-than-expected GDP” and less travel due to the Covid-19 pandemic, the CCC adds.

The CCC emphasises the need for continued incentives and pressure to make emissions cuts across all sectors, concluding:

“The Climate Change Act and the carbon budgets provide a clear, longrun signal to investors and businesses on the UK’s decarbonisation trajectory. Carrying forward the third carbon budget surplus would weaken this message, causing uncertainty, and could ultimately result in net-zero being more expensive and harder to achieve.”