The report of the 15th Session of the CliC Scientific Group is available. The CliC SSG met on December 14-15, 2019, at the Hyatt Centric Fisherman’s Wharf Hotel in San Francisco, in conjunction with the AGU Fall Meeting, and funded by WCRP. Thirty-three participants (25 in person; 8 remotely) working in thirteen different countries attended the meeting. The meeting was co-chaired by CliC Co-Chairs James Renwick and Fiamma Straneo and WCRP Officer In Charge Mike Sparrow. The meeting participants discussed the ongoing CliC activities, interactions with other organizations and the future of CliC.