In 2009, ACI Europe (Airport Council International) launched an initiative, called Airport Carbon Accreditation, seeking to promote an effective contribution by the airports in the fight against climate change.

This project has received the immediate support of SEA and of the main European airport operators. The project provides for the activation of a number of control activities and for the reduction of direct and indirect emissions of CO2 by the Airport Management, the operators, the aircraft and all the people who work at the airport.

Airport Carbon Accreditation consists of 4 possible accreditation levels:

• Mapping - Emissions assessment under the direct control of the Airport Management (type 1 and 2);
• Reduction - In addition to level 1, creation of an emission reduction plan aiming at the continuous improvement of emission levels (type 1 and 2);
• Optimisation - In addition to Level 1 and 2, calculation of the emissions produced by the airport stakeholders and their involvement in the reduction plan (type 3);
• Neutrality - In addition to level 1, 2 and 3, achievement of the "Carbon Neutrality" emissions objective, under the direct control of the Airport Management (type 1 and 2).

Carbon emissions are calculated by taking into consideration both the direct activities carried out by the Airport Management (thermal systems for heating and air conditioning, airport energy consumption, operating vehicles that are necessary for airport activities) and by third parties who can be directed or affected by the airport company, and that concern more specifically:

• the LTO (Landing Take Off Operation) cycle,
• the emissions from operating vehicles that are necessary for groundhandling activities,
• third party emissions that may be directly or indirectly influenced by SEA.

Specifically excluded are the emissions about which SEA, as a result of its regulatory and control "profile", can only exert influence and increase awareness thereof: emissions from vehicles (owned or managed by the airlines) and emissions from the operating vehicles that are necessary for groundhandling activities (owned and managed by the handlers, with the exception of the SEA handling, where the portion controlled by SEA itself has made possible a full alignment with the commitments set forth by the initiative).

The emissions calculation has been based on the GHG Protocol (published by the World Business Council for Sustainable Development and the World Resources Institute) and the data submitted by SEA has been validated by WSP Environmental, a London company which scientifically supports the ACI Europe project.

In 2018, SEA confirmed its European leadership positioning for both Linate and Malpensa airports within the 3+ neutrality grouping, together with 40 other airports, of which 4 Italian (Rome and Venice), representing 24.2% of European traffic.