{"id":3509902,"date":"2025-03-04T09:27:41","date_gmt":"2025-03-04T09:27:41","guid":{"rendered":"https:\/\/www.resilience.org\/?p=3509902"},"modified":"2025-03-04T09:27:41","modified_gmt":"2025-03-04T09:27:41","slug":"analysis-uk-would-need-forest-twice-size-of-london-to-offset-new-airport-expansion","status":"publish","type":"post","link":"https:\/\/www.resilience.org\/stories\/2025-03-04\/analysis-uk-would-need-forest-twice-size-of-london-to-offset-new-airport-expansion\/","title":{"rendered":"Analysis: UK would need forest \u2018twice size of London\u2019 to offset new airport expansion"},"content":{"rendered":"

A forest twice the size of Greater London would need to be planted in the UK to cancel out the extra emissions from the expansion of Heathrow, Gatwick and Luton airports, Carbon Brief analysis reveals.<\/p>\n

New runways at these airports surrounding London would result in cumulative emissions of around 92m tonnes of extra carbon dioxide equivalent (CO2e) by 2050, if the number of flights increases in line with their operating company targets.<\/p>\n

If the UK is to remain on track for\u00a0net-zero<\/a>, it would need to cut emissions further in other sectors of the economy or remove an equivalent amount from the atmosphere.<\/p>\n

For example, offsetting these emissions would require more than 300,000 hectares of trees to be planted within just a few years. This equates to all the trees planted in the UK since 2000.<\/p>\n

The Labour government is set to back all three airport expansions, according to\u00a0media<\/a>\u00a0reporting<\/a> ahead of a speech by chancellor Rachel Reeves.<\/p>\n

This is in spite of\u00a0opposition<\/a>\u00a0from within the Labour party and the government\u2019s climate advisors\u00a0recommending against<\/a>\u00a0airport expansion.<\/p>\n

Reeves has\u00a0stressed<\/a>\u00a0that \u201csustainable aviation fuels\u201d (SAFs) and electric planes could help to offset these emissions.<\/p>\n

However, such technologies are still in the early stages of deployment and previous Carbon Brief\u00a0analysis<\/a>\u00a0suggests the role of SAFs in achieving net-zero may be limited.<\/p>\n

Two Londons<\/h3>\n

Reeves revealed plans for a third runway at Heathrow on 29th January.<\/p>\n

This, alongside\u00a0suggestions<\/a>\u00a0she will also announce her support for the expansion of Gatwick and Luton airports, has prompted days of political debate over the friction between the government\u2019s climate and economic plans.<\/p>\n

Reeves sees the expansion of airports as a key part of the government\u2019s \u201cgrowth strategy\u201d. However, senior Labour politicians,\u00a0notably<\/a>\u00a0energy secretary Ed Miliband, have previously opposed such expansions on environmental grounds.<\/p>\n

For her part, the chancellor told\u00a0BBC News<\/a>\u00a0that she thought \u201csustainable aviation and economic growth go hand in hand\u201d.<\/p>\n

Carbon Brief has used estimates of passenger numbers from the airports\u2019 planning applications, combined with assumptions used by UK government advisors the\u00a0Climate Change Committee<\/a>\u00a0(CCC), to calculate emissions from the three expansions.<\/p>\n

As the chart below shows, the CCC assumes aviation emissions fall in the coming years due to technological and efficiency improvements.<\/p>\n

However, the expansion of Heathrow, Gatwick and Luton would drive an uptick in emissions around 2040 as the projects are completed, if the expected number of extra flights take off and if there are no additional improvements in aircraft efficiency.<\/p>\n

This would amount to an additional 92MtCO2e being emitted cumulatively by 2050.<\/p>\n

In order to remain on track for the UK\u2019s net-zero target, these emissions would need to be avoided by additional technological innovations in the aviation sector, balanced by faster cuts in other parts of the economy \u2013\u00a0or removed from the atmosphere after being emitted.<\/p>\n

<\/p>\n

Annual UK aviation emissions, MtCO2e. The blue line indicates the trajectory for emissions set out by the CCC. The three red lines indicate the additional emissions that would result from the expansion of Heathrow, Gatwick and Luton airports, plus the resulting flights. The airport expansions are assumed to follow approximate timelines based on their respective planning applications, with some dates assumed based on the views of AEF. The Heathrow expansion is assumed to be in operation in 2035 and at full capacity by 2040. The Gatwick expansion is assumed to be operational in 2028 and at full capacity by 2038. The Luton expansion is assumed to be operational in 2033 and at full capacity by 2043. Sources: DESNZ, CCC, AEF, airport planning documents.<\/em><\/p>\n

Aviation is\u00a0generally viewed<\/a>\u00a0as a difficult sector to decarbonise, due to the lack of cheap and effective technologies to cut emissions from planes.<\/p>\n

This is why\u00a0campaigners<\/a>\u00a0and\u00a0researchers<\/a>\u00a0frequently stress demand reduction as the most effective way to cut aviation emissions.<\/p>\n

The UK\u2019s net-zero plans already allow for aviation to be one of the final sectors producing sizable volumes of emissions in 2050, when most of the economy has decarbonised.<\/p>\n

One strategy to remove the excess emissions from the additional Heathrow, Gatwick and Luton flights would be to\u00a0plant more trees<\/a>. However, this would be a significant undertaking, as Carbon Brief analysis shows.<\/p>\n

It would require planting around 301,000 hectares of new forest by around 2028 so that the trees are large enough by the middle of the century to absorb significant amounts of CO2.<\/p>\n

This is equivalent to around twice the size of Greater London, which covers 157,000 hectares. It is 10 times higher than the UK\u2019s most recent annual\u00a0tree-planting target<\/a>\u00a0and equates to all of the trees planted in the past 24 years across the country.<\/p>\n

More passengers<\/h3>\n

Government advisors at the CCC have\u00a0recommended<\/a>\u00a0that there should be no more than a 25% growth in the number of air passengers from 2018 levels, in order to meet the UK\u2019s net-zero goal by 2050.<\/p>\n

This amounts to an increase from 292 million passengers to 365 million by 2050. The number of UK flights collapsed during Covid-19 lockdowns and has been slow to recover to pre-pandemic levels, but the number of air passengers in 2023 reached\u00a0273 million<\/a>.<\/p>\n

The CCC has\u00a0consistently<\/a>\u00a0stressed<\/a>\u00a0that there should be \u201cno net increase\u201d in airport capacity if the UK is to reach net-zero by the middle of the century, meaning any expansion is \u201cbalanced by reductions in capacity elsewhere\u201d. It has also stated there should be no airport expansion without a UK-wide framework for managing capacity.<\/p>\n

The committee\u00a0criticised<\/a>\u00a0the previous Conservative government for setting \u201cno plans\u201d to limit growth in passenger numbers in its \u201cjet-zero<\/a>\u201d strategy, which envisaged demand for flying increasing by 70% out to 2050.<\/p>\n

Airport expansion at Heathrow, Gatwick and Luton would help bring the total number of passengers at these three sites up to 243 million in 2050, according to the airports\u2019 own planning applications,\u00a0compiled by<\/a>\u00a0the\u00a0Aviation Environment Federation<\/a>\u00a0(AEF).<\/p>\n

This amounts to an additional 100m passengers passing through these airports, compared to 2018 levels. This would bring the total number of UK passengers to 392 million \u2013 equivalent to a 34% increase in UK airport traffic \u2013 meaning that growth at Heathrow, Gatwick and Luton alone would be enough to breach the CCC\u2019s guidance.<\/p>\n

(In reality,\u00a0more than<\/a>\u00a020 UK airports have plans for more capacity and some already have unused capacity, so it is unlikely that expansion would be limited to three airports around London.)<\/p>\n

SAF concerns<\/h3>\n

The CCC leaves some flexibility in its advice to the government, allowing for future capacity growth, if \u201cthe carbon intensity of aviation is outperforming the government\u2019s emissions reduction pathway\u201d.<\/p>\n

Essentially, if clean technologies slash aviation emissions faster than expected, then there will be space for more flights within a pathway to net-zero by 2050.<\/p>\n

This has been alluded to by Reeves in recent days. She has\u00a0stated<\/a>\u00a0that a \u201clot has changed in terms of aviation\u201d and\u00a0reportedly<\/a>\u00a0based an internal proposal to expand Heathrow on the use of \u201csustainable aviation fuels\u201d (SAFs).<\/p>\n

In reality, there has been very limited progress in developing SAFs or any other technologies to decarbonise planes in the UK. In 2023, the CCC\u00a0chastised<\/a>\u00a0the Conservative government for \u201crel[ying] heavily on nascent technologies\u201d.<\/p>\n

Government modelling\u00a0has shown<\/a>\u00a0SAFs will have a limited impact on cutting UK aviation emissions. Experts have\u00a0pointed to<\/a>\u00a0the issues with the supply of materials for making SAFs and\u00a0noted<\/a>\u00a0that none of the five SAF plants\u00a0originally pegged<\/a>\u00a0to start construction in the UK this year are being built yet.<\/p>\n

Methodology<\/h3>\n

This analysis is based on the CCC\u2019s sixth carbon budget \u201cbalanced pathway<\/a>\u201d for the aviation sector, combined with data obtained from AEF on the expected increase in passenger numbers from the expansion of Heathrow, Gatwick and Luton airports.<\/p>\n

The CCC pathway assumes that the emissions per passenger fall from 0.14 tCO2 in 2020 to 0.06tCO2 in 2050, accounting for the rollout of SAF and more efficient aircraft. It also assumes that no net expansion of airport capacity occurs.<\/p>\n

Therefore, in this analysis, the three airport expansions are considered additional to the emissions included within the CCC pathway.<\/p>\n

To calculate the additional emissions from the expansion of the three airports, the additional passenger numbers this would facilitate are multiplied by the emissions intensity per passenger in each year of the CCC pathway.<\/p>\n

The additional passenger numbers from each airport are added to a Department for Transport pathway that assumes no further expansion. Each airport expansion is assumed to ramp up linearly from the year of operation to the year of operation at full additional capacity.<\/p>\n

Based on the airport planning applications and AEF, it is assumed that:<\/p>\n