This document reports the findings of the Earth System Grid Federation Future Architecture Face-to-Face Meeting held in the UK 5-7 November 2019, attended by technical representatives from the ESGF partner organisations. ESGF is an International federated archive that provides access to Earth science data. It is fundamentally a distributed file management system with its main function being data dissemination through the provision of services for efficient replication and search. It has been in operation for over ten years and has undergone continuous improvements and enhancements over this time span. The Future Architecture is a major review of the software system including a fundamental reassessment of its requirements with a view to develop a new overall system architecture. This has been initiated in the light of challenges around the maintenance of the existing software legacy and a changing technology landscape and practices in the communities it serves. The work is being carried out under the oversight of the ESGF Executive Committee and is coordinated activity between ESGF and the European IS-ENES3 project.