Biden Climate Envoy John Kerry Stepping Down After 3 Years
• John Kerry, Biden's climate envoy, is leaving his role this winter after 3 years
• Kerry, 80, was Obama's Secretary of State and a long-time Senator for Massachusetts
• He took the envoy job to showcase Biden's climate commitment globally
• Kerry led climate negotiations with China and at 3 UN conferences
• He feels progress on climate is "lagging" and the situation seems "more dire"