Harmonized GHG Emission Factors for Air Travel in Germany

ifeu paper 01/2026

Authors: Michel Allekotte, Jan Kräck, Claudia Kämper

Air travel is a significant and growing contributor to global greenhouse gas (GHG) emis-sions. Although it accounts for around 2-3% of global CO₂ emissions, the sector’s overall climate impact is substantially higher when non-CO₂ effects — such as nitrogen oxides (NOₓ), water vapor, and contrail-induced cloud formation — are included. These high-altitude emissions increase radiative forcing and make aviation one of the most climate-intensive modes of transport per passenger kilometre. As climate ac-countability grows in importance, accurate emission factors become essential for informed decision-making, transparency, and effective climate action.

Emission intensity factors are widely used in climate reporting, including within frame-works such as the Greenhouse Gas Protocol and European Corporate Sustainability Re-porting Directive (CSRD), and play a key role in both institutional GHG inventories and personal carbon footprint calculators. But harmonized emission intensity factors are not available for all geographies. Often applied factors lack transparency. The aim of this paper is to illustrate how flight emission intensity factors are derived, what influences their variability, and why accurate estimates matter. The data source and calcu-lation method are derived from the Transport Emission Model for Aviation (TREMOD-AV) developed by ifeu for the Federal Environment Agency (Umweltbundesamt). TREMOD-AV allows a wide range of settings to adapt to specific calculation requirements. This paper will present generally applicable emission factors for air travel which can be used by public or private institutions to calculate their GHG emissions from air travel.