Heathrow’s Flight Emissions Have Dropped 7%, Third Runway Closer Than Ever

Key Points

• Heathrow’s flight emissions in 2025 are 7% below 2019 levels, largely due to increased use of sustainable aviation fuel (SAF).
• The airport is on track to meet its 2030 goal of cutting flight emissions by 15%, which is closely linked to its plans for a third runway.
• Future supply constraints of SAF, especially HEFA-based fuel, may challenge Heathrow's long-term decarbonization and expansion efforts.

Summary

Heathrow Airport has reported a 7% drop in flight carbon emissions from 2019 to 2025, largely attributed to the increased use of sustainable aviation fuel (SAF), which made up 3.1% of fuel used last year. This progress supports Heathrow’s ambitious goal to cut flight emissions by 15% by 2030 and strengthens its case for building a third runway, provided it can meet the UK’s net zero targets. However, availability of SAF—especially those derived from used cooking oil and animal fats—could limit future progress, as demand is expected to exceed supply by 2030, highlighting the need for alternative fuel technologies and ongoing government investment.