In 2019, Lea became a climate advisor to Knut Storberget and was a youth ambassador for Norway at the UNICEF summit for World Children's Day. In October 2019, Lea became the first climate ambassador for UNICEF; her age of 15 made her the second-youngest UNICEF ambassador in history. She was the fifth Norwegian ambassador and the first to be appointed since 2007. At the 2019 United Nations Climate Change Conference (COP25), Lea was one of five child activists to speak at an event organized by UNICEF and the OHCHR.