Results
From a legal perspective, the introduction by the Netherlands of a CO2 ceiling does not immediately appear to have a direct consequence for the EU-US Air Transport Agreement. While not affecting traffic rights, the CO2 ceiling may lead to a reduction in the number of slots available at Dutch airports. As a party to the agreement, the Netherlands must not unilaterally place limitations on the volume of traffic or aircraft type unless environmental reasons exist. One of the scenarios studied considers a binding CO2 ceiling. Such a binding ceiling may result in a reduction of air transport movements or a limitation of growth. The threat of a reduction in slots gives an incentive to airlines with large share of slots to (partially) internalise the environmental cost. In general, given a total amount of ATMs, carriers can take other measures to reduce CO2 emissions. They may, for example, implement route changes (shorter distances), improve fleet usage (cleaner planes) and fuel usage (SAF uptake). The availability and plausibility of these strategies does differ between the different types of users (carriers) of Schiphol. Carriers with larger shares of slots have a larger ability and incentive to adopt than those with smaller shares. 

Study and methodology
To meet the CO2 reduction targets dictated by the Civil Aviation Policy Memorandum (Luchtvaartnota 2020-2050), a CO2 ceiling for departing flights from the Netherlands is proposed in the same memorandum. In this way, CO2 would become a factor for the development of Dutch civilian airports, akin to noise and (external) safety (Luchtvaartnota, 2020). The Ministry of Infrastructure & Water Management (hereafter: “I&W”) commissioned SEO Amsterdam Economics to study the economic and legal impacts for airlines of the proposed CO2 ceiling. The study includes in-depth legal context of the ceiling with respect to other treaties and an economic analysis of the evidence (and expected scenarios) about the impact of the ceiling on the aviation sector given current available details of the ceiling and exogenous developments. These developments include, among others, demand and connectivity recovery from COVID-19, economic growth scenarios, and other policy instruments having an impact on the ATM levels at Schiphol. Finaly, by applying economic theory and desk research, the study explores the most likely impacts (and timing of these impacts) of a CO2 ceiling on the sector in general and airlines, specifically.