The term “Brussels effect” introduced by Anu Bradford, (The Brussels effect: How the European Union rules the world. Oxford University Press, 2020) suggests the ability of the European Union (EU) to act as a world-shaping power through its unilateral regulation. This chapter investigates the EU’s ambitious climate targets, which often surpass those of other regions and multilateral fora, including the International Civil Aviation Organization (ICAO). The aim is to provide a detailed analysis of how the 2023 amendments to the EU Emissions Trading System (ETS) through Directive 2023/958 have already induced the world to keep pace with raising their aviation environmental effort. The doctrinal legal research methodology combined with comparative approaches was employed, leading to the findings and discussions presented in this chapter. Through the examination of legal provisions, policy documents, and legal development trends, the strengthened EU ETS can arguably be seen as an expanding emissions system extending to states in close proximity to the EU. This shift is adding to a growing demand for moving beyond ICAO’s scheme. Stakeholders outside the EU should start considering their position in the re-expanding effect of the EU ETS, as the ETS may be expanded again to cover all flights to and from Europe from 2027.