Business travel emission factor trends

External decarbonisation trends for business travel activities — curated sources, uncertainty ranges, and pathway-ready projections.

• Global

  Decarbonisation of diesel vehicle rental — Global

  The UK DESNZ historic data released in 2024 show a consistent downward path in emission factors from 2015 to 2024, with the figures moving from 0.185363 down toward 0.16983 across the period. This pattern aligns with broader decarbonization efforts in road transport, where fleet renewal toward newer, more efficient diesel models and a gradual shift to low-emission fleets are reducing per-kilometre emissions. As the IEA notes, “the transport sector continues to decarbonize as efficiency improves and electrification expands,” which supports observed reductions in emission factors. The official UK framework also underpins these calculations: BEIS/Department for Energy Security and Net Zero and related conversion factors provide the benchmarks used for estimating emissions from organizational activities, with downward revisions reflecting technological gains and policy-driven fleet changes. In 2025, the downward trend is likely to persist as rental fleets increasingly favor efficiency and alternative propulsion options.

• Global

  Decarbonisation of economy air travel — Global

  International business travel by air in economy class (businesstravel_air_internationaleconomy) sits within a sector where emissions intensity per passenger-kilometre is shaped by aircraft efficiency, load factors, and route mix. The ICCT’s Aviation Vision 2050 (Sept 2025) projects that, under the Current Commitments scenario, the warming impact attributable to aviation per unit of travel is expected to fall from 0.118 mC in 2025 to 0.107 mC in 2050, signaling a decarbonization trajectory that increasingly decouples growth in international travel from emissions—provided technology progress and policy commitments continue (ICCT, 2025). This aligns with broader assessments that aviation remains a relatively small share of global CO2 but that substantial emissions reductions are achievable through sustained efficiency gains, sustainable aviation fuels (SAF), and policy measures (IEA, 2023; ICCT, 2025). Driving factors behind the projected trend include: (1) accelerated SAF deployment supported by regulatory mandates and incentives—such as the EU ReFuelEU Aviation framework and U.S. SAF incentives—which reduce the carbon intensity of jet fuel used in international operations (European Commission, 2023; IATA, 2024); (2) continued fleet renewal with next-generation, more fuel-efficient aircraft that lower fuel burn per passenger-kilometre (ICAO, 2023); and (3) improvements in air traffic management and route optimization (e.g., SESAR/NextGen initiatives) that shorten flight distances and reduce unnecessary holds, further trimming fuel use (Eurocontrol, 2023). Collectively, these dynamics support a downward trajectory in the economy-class international emission factor even as activity recovers, with policy-backed decarbonization pathways forecasting a gradual reduction in the sector’s warming impact through 2050 (ICCT, 2025; ICAO CORSIA).

• Global

  Decarbonisation of first-class air travel — Global

  The UK’s business travel footprint shows that international first‑class air travel remains a small but highly emissions‑intensive portion of travel-related emissions. The 2016–2024 trend for the international first‑class flight emission factor moves from about 0.548 to a high near 0.562 in 2021–2022, before easing to around 0.539 in 2023–2024, indicating that fleet efficiency gains and shifts in premium travel demand have partially offset growth in emissions. BEIS/DEFRA’s GHG Conversion Factors for Company Reporting state that “emissions from air travel are calculated from fuel burn and occupancy and vary by seating class” (BEIS/DEFRA, GHG Conversion Factors for Company Reporting, 2024). ICAO also notes that “improvements in aircraft efficiency have not fully offset rising demand for international aviation” (ICAO, 2023). In the UK context, this trend is relevant across all regions and aligns with policy aims to decarbonise aviation while allowing necessary business mobility.

• Global

  Decarbonisation of international business-class air travel — Global

  International air travel emission factors for businesstravel_air_internationalbusiness have historically fluctuated around the 0.39–0.41 kg CO2e per passenger-km range, with pandemic-related disruptions contributing to short-term volatility (DESNZ, 2024). The ICCT’s Aviation Vision 2050 update, issued in September 2025, shows a notably stronger decarbonization path under the GHG Forward scenario: aviation warming intensity is projected to decline from 0.118 mC in 2025 to 0.089 mC by 2050, a reduction of roughly 25%—signaling meaningful efficiency and fuel-shift progress even as demand for international travel grows (ICCT, 2025). This trajectory reflects a confluence of policy, market, and infrastructure dynamics that collectively dampen emissions intensity while sustaining growth in travel. Key drivers include accelerated SAF deployment and uptake supported by regulatory and fiscal measures: the EU ReFuelEU Aviation blending mandates, the UK Jet Zero strategy, and US SAF incentives under the Inflation Reduction Act collectively improve SAF economics and market uptake (European Commission, 2023; UK Government, 2022; IRS, 2022). In parallel, continued fleet modernization and engine-efficiency improvements, together with optimized routing and higher-capacity aircraft, reduce fuel burn per passenger-km (IATA, 2023). International coordination through ICAO’s CORSIA further reinforces efficiency gains and SAF adoption where feasible (ICAO, 2023). However, SAF supply constraints and higher costs remain potential constraints that could temper the pace of decarbonization, even as policy momentum and technological advances support a durable downward trend in emissions intensity (IATA, 2023).

• Global

  Decarbonisation of long-haul business-class air travel — Global

  Air travel emission factors for businesstravel_air_business have historically fluctuated around the 0.39–0.41 kg CO2e per passenger-km range, with pandemic-related disruptions contributing to short-term volatility (DESNZ, 2024). The ICCT’s Aviation Vision 2050 update, issued in September 2025, shows a notably stronger decarbonization path under the GHG Forward scenario: aviation warming intensity is projected to decline from 0.118 mC in 2025 to 0.089 mC by 2050, a reduction of roughly 25%—signaling meaningful efficiency and fuel-shift progress even as demand for international travel grows (ICCT, 2025). This trajectory reflects a confluence of policy, market, and infrastructure dynamics that collectively dampen emissions intensity while sustaining growth in travel. Key drivers include accelerated SAF deployment and uptake supported by regulatory and fiscal measures: the EU ReFuelEU Aviation blending mandates, the UK Jet Zero strategy, and US SAF incentives under the Inflation Reduction Act collectively improve SAF economics and market uptake (European Commission, 2023; UK Government, 2022; IRS, 2022). In parallel, continued fleet modernization and engine-efficiency improvements, together with optimized routing and higher-capacity aircraft, reduce fuel burn per passenger-km (IATA, 2023). International coordination through ICAO’s CORSIA further reinforces efficiency gains and SAF adoption where feasible (ICAO, 2023). However, SAF supply constraints and higher costs remain potential constraints that could temper the pace of decarbonization, even as policy momentum and technological advances support a durable downward trend in emissions intensity (IATA, 2023).

• Global

  Decarbonisation of premium-economy air travel — Global

  Global flight emission factors continue to decline, driven by newer aircraft, growing SAF use, and policies that price carbon or mandate cleaner fuels. The ICCT’s Aviation Vision 2050 (Sept 2025) projects international premium-class warming impacts falling from 0.118 mC in 2025 to 0.089 mC by 2050—a roughly 25% drop in intensity. This is consistent with trends from 2016–2024, where efficiency gains and early SAF uptake lowered emission factors even as demand increased (IATA; IEA; ICAO). Policy frameworks—including CORSIA and national or regional SAF strategies such as the UK Jet Zero Strategy and EU ReFuel Aviation—reinforce this downward pressure. Three main drivers underpin the trend: (1) SAF scale-up supported by mandates and market-based measures, which cut life-cycle emissions for long-haul international aviation; (2) continued fleet modernization and propulsion improvements that reduce fuel burn per passenger-kilometre; and (3) operational and air-traffic efficiency gains that limit avoidable fuel use. Together, these dynamics point to continued, though increasingly policy- and SAF-dependent, reductions in the carbon intensity of international premium air travel.

• Global

  Decarbonisation of taxi travel — Global

  Across all regions, the emission factor for taxis has reduced over 2016–2024, with an overall roughly 9% reduction. This pattern mirrors broader shifts in business travel and taxi fleets: newer, more efficient engines, tighter urban emission rules, and greater use of cleaner fuels or hybrid configurations are replacing older, higher-emitting vehicles. According to DESNZ, this historic trend reflects steady efficiency gains and fleet renewal rather than short-term volatility. The trend is reinforced by global and national policy momentum toward lower transport emissions, including incentives for fleet modernization and the growing prevalence of low-emission zones; the ICCT notes that electrification and tighter standards are increasingly shaping taxi emissions, which supports the observed downward trajectory.

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