The aviation sector is subject to increasing scientific and regulatory examination due to its disproportionate contribution to global climate change. While CO2 emissions have traditionally dominated the public and regulatory discourse, scientific consensus now recognizes the significant role of additional climate-relevant factors, such as nitrogen oxides (NOx) and water vapor emitted at high altitudes, which contributes to aviation-induced cloudiness (AIC) in the form of (persistent) contrail cirrus. Despite the availability of carbon calculators and offsetting tools, there is no standardized and transparent framework for labeling the environmental impact of air travel. The approach presented here incorporates not only non-CO2 climate effects, but also noise and local air pollutant emissions in the vicinity of airports. This paper introduces a comprehensive framework of environmental labels for aviation, covering three domains: Aircraft Labels, Airline Labels, and Flight Labels. These labels offer a unified method for evaluating and comparing environmental performance using certified aircraft data, life cycle assessment (LCA) methods, and emissions modeling. A fourth construct, the Multimodal Trip Score, extends the labeling concept by integrating travel time and cost, enabling holistic comparisons across travel alternatives. Analyses of typical narrowbody and widebody aircraft, major international airlines, and comparisons between multi-leg and direct flights demonstrate the feasibility and utility of this labeling system. The proposed framework aims to enhance transparency, influence consumer behavior, and support climate mitigation policies in the transportation sector.