The county has hired its first chief climate officer, who will step into a role of great interest to coastal communities facing the threat of sea-level rise. In her new post, Nadia Seetaram will head up Marin’s Climate and Sustainability Division, established last year as part of County Executive Derek Johnson’s government reorganization. In her last job, Dr. Seetaram directed buyouts for a $250 million New York State program that acquired and demolished homes in…